Using limestone-based treatments to reduce phosphorus flux in Everglades Water Conservation Areas, Florida

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Title:
Using limestone-based treatments to reduce phosphorus flux in Everglades Water Conservation Areas, Florida
Physical Description:
1 online resource (101 p.)
Language:
english
Creator:
Barrette,Kiah Kathleen
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
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Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Interdisciplinary Ecology
Committee Chair:
Li, Yuncong
Committee Co-Chair:
Migliaccio, Kati W
Committee Members:
Wang, Qingren
Gu, Binhe

Subjects

Subjects / Keywords:
agricultural -- conservation -- cycling -- eaa -- everglades -- florida -- flux -- nutrient -- phosphorus -- sediment -- soil -- treatment -- water -- wca
Interdisciplinary Ecology -- Dissertations, Academic -- UF
Genre:
Interdisciplinary Ecology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Hydrologic input from the Everglades Agricultural Area (EAA) and other anthropogenic and natural sources has led to increased nutrient levels in the sediment and water of the greater Everglades ecosystem including the Everglades Water Conservation Areas (WCAs). Increased concentrations of phosphorus (P), a major component of fertilizers and urban runoff and a limiting nutrient in many wetland ecosystems, has led to excessive eutrophication of Everglades; changes in P availability have also led to a shift from pre-development sawgrass marshes to present-day cattail-dominated ecosystems. Problematic in the WCAs, WCA-2A especially, is the biogeochemical process referred to as P-flux which describes the portion of the sorption-desorption cycle wherein P transitions from the sediment to the water column as the sediment becomes equilibrated with a P-free or low-P hydrologic input. Because of this behavior, non-nutrient impacted Everglades soils function as P sinks while nutrient-enriched soils, such as those in the WCAs, act as P sources when exposed to surface water with P concentrations lower than the equilibrium P concentration. Phosphorus-retention is regulated by calcium-based minerals in alkaline soils such as those found in South Florida. The goal of this study is to evaluate and compare the ability of three limestone-based treatments to limit the P-flux from nutrient-impacted sediment collected from WCA-2A to the overlying low-nutrient water column. Standard hydrologic and geochemical conditions in WCA-2A were mimicked using ex-situ sediment columns in a laboratory incubation lasting three months. Twelve columns were treated with one of three limestone-based treatments (horticultural hydrated lime, limestone gravel, or Ordinary Portland Cement) and compared to control columns receiving no treatment. Samples were extracted from porewater, the overlying water column, and flowthrough water in each column on a weekly basis and analyzed for total- and ortho-P. Correlation coefficients indicated negative correlation between porewater and water column samples and between porewater and flowthrough samples in gravel-treated and cement-treated columns; this indicates that limestone treatments may be an effective approach to reducing P-flux in WCAs of the Florida Everglades.
General Note:
In the series University of Florida Digital Collections.
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Includes vita.
Bibliography:
Includes bibliographical references.
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Description based on online resource; title from PDF title page.
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This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Kiah Kathleen Barrette.
Thesis:
Thesis (M.S.)--University of Florida, 2011.
Local:
Adviser: Li, Yuncong.
Local:
Co-adviser: Migliaccio, Kati W.

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UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2011
System ID:
UFE0043409:00001


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1 USING LIMESTONE BASED TREATMENTS TO REDUCE PHOSPHORUS FLUX IN EVERGLADES WATER CONSERVATION AREAS, FLORIDA By KIAH KATHLEEN BARRETTE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFIL LMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011

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2 2011 Kiah Kathleen Barrette

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3 To my parents and Chris

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4 ACKNOWLEDGMENTS I express my sincere gratitude to my committee chair Dr. Yuncong Li and commit tee members Drs. Kati Migliaccio, Qingren Wang, and Binhe Gu for their support during each phase of this study. I would also like to thank Tina Dispenza and Guiqin Yu, whose combined lab expertise were invaluable as I conducted hundreds of water analyses; their patience and knowledge played an important role during laboratory incubation and analyses. Additionally, there have been several graduate students and TREC team members who offered their assistance in the field and laboratory and to whom I am sincerely grateful. Additionally, many thanks are due to all of the members of the UF TREC team for their friendship and tireless assistance in important phases of this study, and to the faculty, staff, and students of the School of Natural Resources and Envir onment for their friendship and guidance from day one. Most importantly, I would like to thank my parents, extended family, Chris Cook, Colleen Kennedy, and Carlo Rossi for their unwavering and heartfelt guidance, love, and support throughout my life and d uring my time at the University of Florida.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 8 LIST OF FIGURES ........................................................................................................ 10 ABSTRACT ................................................................................................................... 12 CHAPTER 1 PHOSPHORUS FLUX IN WATER CONSERVATION AREAS OF THE FLORIDA EVERGLADES ....................................................................................... 14 Introductory Remarks .............................................................................................. 14 The Everglades ....................................................................................................... 15 Geology and Soils ............................................................................................ 16 Hydrology ......................................................................................................... 16 Vegetation ........................................................................................................ 18 History of Management .................................................................................... 19 Early management ..................................................................................... 19 United States v. South Florida Water Management District ....................... 21 The Everglades Forever Act ...................................................................... 22 Comprehensive Everglades Restoration Plan ............................................ 23 The Everglades Agricultural Area ..................................................................... 23 Be st Management Practices ............................................................................. 24 Phosphorus ............................................................................................................. 25 Sources ............................................................................................................ 25 Forms ............................................................................................................... 27 Behavior ........................................................................................................... 28 Flux .................................................................................................................. 29 Negative Impacts .............................................................................................. 30 Phosphorus Reduction and Removal Technology .................................................. 31 Constructed Treatment Wetlands ..................................................................... 32 Substrate .................................................................................................... 32 Vegetation .................................................................................................. 35 Chemical Amendments .................................................................................... 36 Iron ............................................................................................................. 36 Aluminum ................................................................................................... 37 Calcium carbonate ..................................................................................... 37 Concluding Remarks ............................................................................................... 38

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6 2 COMPARI SON OF THREE LIMESTONE BASED TREATMENTS AS MECHANISMS FOR LIMITING PHOSPHORUS FLUX IN EVERGLADES WATER CONSERVATION AREAS, FLORIDA ....................................................... 40 Introductory Remarks .............................................................................................. 40 Objective ................................................................................................................. 42 Hypotheses ............................................................................................................. 42 Hypothesis (a) Ordinary Portland Cement ........................................................ 42 Hypothesis (b) Limestone Gravel ..................................................................... 43 Hypothesis (c) Horticultural Hydrated Lime ...................................................... 43 Materials and Methods ............................................................................................ 44 Site Description ................................................................................................ 44 Collection of Sediment Cores ........................................................................... 45 Collection of Water ........................................................................................... 45 Laboratory Incubation and Chemical Analysis .................................................. 46 Treatments ................................................................................................. 48 Water sample coll ection ............................................................................. 49 Analysis of water samples .......................................................................... 50 Statistical Analysis of Data ............................................................................... 51 Re sults .................................................................................................................... 52 ANOVA ............................................................................................................. 52 Total P .............................................................................................................. 52 Flowthrough samples ................................................................................. 52 Water column samples .............................................................................. 53 Porewater samples .................................................................................... 53 Ortho P ............................................................................................................. 54 Flowthrough samples ................................................................................. 54 Water column samples .............................................................................. 54 Porewater samples .................................................................................... 55 Electrical Conductivity ...................................................................................... 55 Flowthrough samples ................................................................................. 55 Water column samples .............................................................................. 55 Porewater samples .................................................................................... 56 pH ..................................................................................................................... 56 Flowthrough samples ................................................................................. 56 Wate r column samples .............................................................................. 56 Porewater samples .................................................................................... 57 Discussion .............................................................................................................. 57 Control Treatment ............................................................................................ 57 Total phosphorus ....................................................................................... 57 Ortho phosphate ........................................................................................ 58 Hydrated Horticultural Lime .............................................................................. 58 Total phosphorus ....................................................................................... 58 Ortho phosphate ........................................................................................ 59 Efficacy ...................................................................................................... 59 Limestone Gravel ............................................................................................. 60

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7 Total phosphorus ....................................................................................... 60 Ortho phosphate ........................................................................................ 60 Efficacy ...................................................................................................... 61 Ordinary Portland Cement ................................................................................ 61 Total phosphorus ....................................................................................... 61 Ortho phosphate ........................................................................................ 62 Efficacy ...................................................................................................... 62 3 CONCLUSIONS ..................................................................................................... 70 Hydrated Hort icultural Lime .................................................................................... 70 Limestone Gravel .................................................................................................... 70 Ordinary Portland Cement ...................................................................................... 71 Concluding Remarks ............................................................................................... 72 APPENDIX A LIME APPLICATION CALCULATIONS .................................................................. 73 B AR 60 METHODS ................................................................................................... 75 C DATA TABLES ....................................................................................................... 76 D DATA FIGURES ..................................................................................................... 85 LIST OF REFERENCES ............................................................................................... 93 BIOGRAPHIC AL SKETCH .......................................................................................... 101

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8 LIST OF TABLES Table page 2 1 Characterization of lime, gravel and cement (OPC) used for the study. ............. 63 2 2 Correlation coefficient ( r ) association definitions ................................................ 63 2 3 ANOVA values .................................................................................................... 63 2 4 Mean, standard deviation, standard error, minimum, and maximum of pH and EC in all sample types ........................................................................................ 64 2 5 Mean, standard deviation, standard error, minimum, and maximum o f total P in all sample types .............................................................................................. 64 2 6 Mean, standard deviation, standard error, minimum, and maximum of orthoP in all three sample types ..................................................................................... 65 2 7 Correlation coefficients of pH, EC, total P, and orthoP in all sample types from lime treated columns. ................................................................................. 65 2 8 Correlation coefficients of pH, EC, total P, and orthoP in all sample types from gravel treated columns ............................................................................... 66 2 9 Correlation coefficients of pH, EC, total P, and orthoP in all sample types collected from OPC treated columns .................................................................. 66 B 1 Detection limits and methods for laborator y analysis of total P, ortho P, pH, and EC ............................................................................................................... 74 C 1 Total P and orthoP concentrations in water samples collected from the Chekika Visitors Center canal ........................................................................... 76 C 2 Laboratory column treatments. ........................................................................... 76 C 3 Amount of Chekika water supplied to each core after initial application of treatments. .......................................................................................................... 77 C 4 Means of total P concentrations in f lowthrough water samples ......................... 77 C 5 Means of orthoP concentrations in flowthrough water sam ples ......................... 78 C 6 Mean EC in flowthrough samples ....................................................................... 78 C 7 Mean pH in flowthrough samples ...................................................................... 79 C 8 Means of total P con centrations in water column water samples ....................... 79

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9 C 9 Means of orthoP concentrations in water column samples ............................... 79 C 10 Mean EC in water colu mn samples .................................................................... 80 C 11 Mean pH in water column samples ..................................................................... 80 C 12 Means of total P concentrati ons in porewater samples ..................................... 80 C 13 Means of orthoP concentrati ons in porewater samples ..................................... 81 C 14 Mean EC in porewater samples .......................................................................... 81 C 15 Mean pH in porewater samples .......................................................................... 81 C 16 Mean total P in control columns over t he duration of the study .......................... 82 C 17 Mean orthoP i n control columns over t he duration of the study ......................... 82 C 18 Mean total P in lime treated columns over t he duration of the study .................. 82 C 19 M ean orthoP in lime treated columns over t he duration of the study ................. 83 C 20 Mean total P in gravel treated columns over t he duration of the study ............... 83 C 21 Mean orthoP in gravel treated columns over t he duration of the study ............. 83 C 22 Mean total P in OPC treated columns over t he duration of the study ................ 84 C 23 Mean orthoP in OPC treated columns over the duration of the study .............. 84

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10 LIST OF FIGURES Figure page 2 1 Map of loc ation within WCA 2A where all sediment cores were collected .......... 67 2 2 Cattail stand surrounding sample collection area in WCA 2A ............................ 68 2 3 C anal near Chekika Visitors Cent er in Everglades National Park ...................... 68 2 4 Laboratory i ncubation setup ............................................................................... 69 2 5 Schematic of water containers and sampling ports ............................................ 69 D 1 Total P concentrations in flowthrough water samples ........................................ 85 D 2 M ean total P concentrations in water column samples ....................................... 85 D 3 Mean total P concentrations in porewater samples ............................................ 85 D 4 M ean orthoP concentrations in flowthrough water samples .............................. 86 D 5 M ean orthoP concentrations in water column samples ..................................... 86 D 6 Mean orthoP concentrations in porewater samples ........................................... 86 D 7 Mean EC in flowthrough samples ....................................................................... 87 D 8 Mean E C in water column samples .................................................................... 87 D 9 Mea n EC in porewat er samples .......................................................................... 87 D 10 Mean pH in flowthrough samples ....................................................................... 88 D 11 Mean pH in water column samples ..................................................................... 88 D 12 Mea n pH in porewater samples .......................................................................... 88 D 13 Mean total P in contro l columns ........................................................................ 89 D 14 Mean or tho P in control columns ........................................................................ 89 D 15 Mean total P in lime treated columns ................................................................ 90 D 16 Mean orthoP in lime treated columns ................................................................ 90 D 17 Mean total P in gravel treated columns ............................................................. 91 D 18 Mean orthoP in gravel treated columns ............................................................ 91

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11 D 19 Mean total P in OPC treated columns ................................................................ 92 D 20 Mean orthoP in OPC treated columns .............................................................. 92

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12 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science USING LIMESTONE BASED TREATMENTS TO REDUCE PHOSPHORUS FLUX IN EVERGLADES WATER CONSERVATION AREAS, FLORIDA By Kiah Kathleen Barrette August 2011 Chair: Yuncong Li C ochair: Kati Migliaccio Major: Interdisciplinary Ecology Hydrologic input from the Everglades Agricultural Area (EAA) and other anthropogenic and natural sources has led to increased nutrient levels in the sediment and water of the greater Everglades ecos ystem including the Everglades Water Conservation Areas (WCAs). Increased concentrations of phosphorus (P), a major component of fertilizers and urban runoff and a limiting nutrient in many wetland ecosystems, has led to excessive eutrophication of Evergl ades; changes in P availability have also led to a shift from predevelopment sawgrass marshes to present day cattail dominated ecosystems. Problematic in the WCAs, WCA 2A especially, is the biogeochemical process referred to as P flux which describes the portion of the sorptiondesorption cycle wherein P transitions from the sediment to the water column as the sediment becomes equilibrated with a P free or low P hydrologic input. Because of this behavior, nonnutrient impacted Everglades soils function as P sinks while nutrient enriched soils, such as those in the WCAs, act as P sources when exposed to surface water with P concentrations lower than the equilibrium P concentration. Phosphorus retention is regulated by calcium based minerals in alkaline soi ls such as

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13 those found in South Florida. The goal of this study is to evaluate and compare the ability of three limestonebased treatments to limit the P flux from nutrient impacted sediment collected from WCA 2A to the overlying low nutrient water column. Standard hydrologic and geochemical conditions in WCA 2A were mimicked using ex situ sediment columns in a laboratory incubation lasting three months. Twelve columns were treated with one of three limestonebased treatments (horticultural hydrated lime, limestone gravel, or Ordinary Portland Cement) and compared to control columns receiving no treatment. Samples were extracted from porewater, the overlying water column, and flowthrough water in each column on a weekly basis and analyzed for total and orthoP. Correlation coefficients indicated negative correlation between porewater and water column samples and between porewater and flowthrough samples in gravel treated and cement treated columns; this indicates that limestone treatments may be an effe ctive approach to reducing P flux in WCAs of the Florida Everglades.

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14 CHAPTER 1 PHOSPHORUS FLUX IN WATER CONSERVATION AREAS OF THE FLORIDA EVERGLADES Introductory Remarks The Everglades is a unique place made distinct by its vegetation, wildlife, and va ried ecosystems. Historically, the region was dominated by southerly sheetflow from Lake Okeechobee; vegetative profiles were characterized by sawgrass marshes, tree islands, and slough (Loveless, 1959). Since the mid1800s, inflows of nutrient impacted water and modifications to the natural hydrology have disrupted the physical and biogeochemical processes unique to the Everglades ecosystem (Grunwald, 2006; Lodge, 2005). Hydrologic input from the Everglades Agricultural Area (EAA) has caused an increase in nutrient levels in the sediment and water of the Everglades and Everglades Water Conservation Areas (WCAs) leading to changes in habitat stability, vegetation profiles, and water quality (Lodge, 2005; McCormick et al., 2002; Miao and DeBusk, 1999; Reddy et al., 1998; Reddy et al., 1999). Phosphorus (P) biogeochemical behavior and tendency to accumulate in wetland sediment makes it a limiting nutrient in most ecosystems and it is necessary to know basic P chemistry when rehabilitating these nutrient im pacted ecosystems (Davis, 1994; Khan and Ansari, 2005; Mitsch and Gosselink, 2007). A series of legal battles and environmental legislation including the Central and Southern Florida Project (C&SF Project), the Florida Everglades Forever Act (FEFA), and t he Comprehensive Everglades Restoration Plan (CERP) have sought to restore the Everglades to historic conditions but continued agricultural and urban development have hampered these efforts. Due to the ongoing efforts to restore the Everglades, there is a large body of literature examining methods of nutrient removal that may effectively restore this distinctive ecosystem. This chapter

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15 offers an introduction to the Everglades ecosystem and history as well as to the characteristics and behavior of P while examining current methods of nutrient removal in wetlands. The Everglades Prior to drainage, the Florida Everglades covered 11,700 km2 of South Florida and hydrology was dominated by pulsed sheet flow from Lake Okeechobee to Florida Bay (Reddy and DeLaune, 2008). Natural levels of P were between 4 and 10 mg L1 (Lodge, 2005). This native landscape was predominantly characterized by saw grass, wet prairies, sloughs, tree islands, and marl forming mars hes (Reddy and DeLaune, 2008). Now, f ollowing a series of drainage and water control projects, the Everglades is a shallow 161 km long by 97 km wide river flowing south from Lake Okeechobee to Florida Bay When the northern Everglades were designated as agricultural land by the C&SF Project in 1948, the regi on became a major source of P and concentrations in stormwater runoff from the agricultural area were measured in excess of 500 mg P L1 (Lodge, 2005). The post EAA Everglades are characterized by sloughs, sawgrass prairies, hardwood hammocks, and cypres s domes, among other unique and varied ecosystems but the impact of high nutrient levels can be seen in the abundance of cattail stands in the WCAs (George, 1972 ; Lodge, 2005; Miao and DeBusk, 1999). In addition to ecological problems associated with drainage, environmental degradation has occurred as a result of extensive development in South Florida, including residential development, tourism development, and agriculture (Davis and Ogden, 1994; Lodge, 2005; Miao and DeBusk, 1999) Because the wildlife is not as plentiful as it once was, nor is the water as pure, rehabilitation is needed to protect it for future generations (George, 1972; Lodge, 2005)

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16 Geology and Soils The limestone geology of South Florida is characterized by several layers of varying permeability that regulate movement of surface water and groundwater through the Floridan aquifer The upper portion of the aquifer is surrounded by calcium carbonate that can be dissolved to form cracks and openings, called karsts, which allow for the movement of groundwater. Above this portion is a less permeable confining layer that allows for the accumulation of water in the perched water table (Mylavarapu, 2008). Soils in the EAA and WCAs tend to be rich organic Histosols, an order classified by its h igh percentage (greater than 50%) of organics in the upper 81 cm of soil (Vasilas et al., 2010) or that contains at least 12 to 18% organic C by weight (Reddy et al., 1998) In the EAA, soil is classified as a Histosol because of the high organic matter content and the absence of frigid conditions (Rice et al., 2005) ; in the Everglades, Histosols range in thickness from 0.3 to 4 m overlying Floridas limestone bedrock (Gleason and Stone, 1994; Richardson and Vaithiyanathan, 1995). In the Everglades and EA A, Histosols are classified into three suborders: Fibrists, Hemists, and Saprists, depending on the organic matter content; these suborders are not appropriate for naming WCA soils (McCollum et al., 1976; Reddy et al., 1998). Unlike most organic soils, wh ich are acidic, Histosols found in the Everglades are alkaline because of the calcareous composition of the regions geology (Richardson and Vaithiyanathan, 1995). Hydrology Wetland hydrology defines the physiochemical conditions in wetland systems (Chin 2006; Mitsch and Gosselink, 2007). A wetlands hydroperiod is the seasonal pattern of water level and is determined by the balance of inflows and outflows, topography, local geology, subsurface soil, and groundwater (Chin, 2006; Mitch and

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17 Gosselink, 200 7). Hydrology in the Everglades differs spatially and can be characterized by two main ecosystem types: sawgrass plains in the north and slough wetlands in the central and southern Everglades (Fling et al., 2004). The Everglades are segmented into three main WCAs: WCA 1, WCA 2, and WCA 3, each characterized by unique sizes, hydrology, and water control structures (Water Conservation Areas, 2011). WCA 1 includes over 590 km2 of sawgrass marsh and cypress forest as well as the Arthur R. Marshall Loxahat chee National Wildlife Refuge. The land is surrounded by over 90 km of canals and levees and the water budget is maintained by pump stations (S 5A and S 6), control structures (S 10A, S 10C, S 10D, and S 10E) and rain (Water Conservation Areas, 2011). WC A 2 is divided into two portions: WCA 2A and WCA 2B. As with WCA 1, WCA 2 is surrounded by levees that control hydrology. Additionally, a combination of gravity, pumps, culverts (S 144, S 145, and S 146), and a control structure (S 11) manage hydrology by guiding water to WCA 1, WCA 3, and Broward County (Water Conservation Areas, 2011). Water levels in this region fluctuate more than 1 m seasonally in response to precipitation and the aforementioned water control structures (Richardson and Vaithiyanatha n, 1995). Finally, WCA 3 (also divided into two portions, WCA 3A and WCA 3B) is the largest WCA. Leveed on the northern, southern, and eastern boundaries, the WCA has approximately 11 km of natural landscape on the western side to allow water to flow fr om the WCA to Big Cypress Swamp (Water Conservation Areas, 2011). Additional hydrologic management includes Control Structure S 11 and Pump Stations S 8, S 9, and S 140 (Water Conservation Areas, 2011).

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18 Vegetation Vegetation found in the Everglades is unique because the region lies between temperate and tropical zones and, thus, is hospitable to a wide variety of flora (McCormick et al., 2002). Historically, the Everg lades were characterized by four major landscape profiles: sawgrass communities, wet prairies, tree islands, and slough (Loveless, 1959). Sawgrass communities, the most common vegetation, covered between 65 and 75% of the Everglades vegetative cover and were comprised of three types of communities: Mariscus SagittariaPanicum hemitomon, Mariscus Myrica Ilex and Mariscus Panicum hemitomon (Loveless, 1959). Wet prairie communities, the second most historical common profile, were also composed of three pri ncipal associations: Rhynchospora flats, Eleocharis flats, and maidencane flats (Loveless, 1959). Third most common were the slough communities, wet for most of the year and eventually replaced by wet prairies following an increase in drainage projects (Loveless, 1959). Finally, tree islands constituted the fourth type of everglades vegetation and were composed primarily of myrtle, holly, willow, and redbay (Loveless, 1959). Because it is located in a transitional zone, the present day Everglades is cha racterized by organisms from temperate and tropical climates (Gunderson, 1997). A study conducted by Avery and Loope (1983) estimated that there were over 830 species just within ENP in the southern portion of the Everglades; about 17% of these organisms were labeled as exotics (Gunderson, 1997). The Everglades is characterized by two major vegetative regions made unique by their hydrologic profiles. The upland complex is comprised of pine forest, tropical hardwood hammocks, and areas of anthropogenicall y altered land (Gunderson, 1997). The wetland complex, wherein the soil is saturated for some part of the year, contains willow heads, cypress

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19 forests, pond apple forests, sawgrass marshes, sloughs, and peat or marl dominated wet prairies (Gunderson, 1997). History of Management The original flow regime of Florida provided Central and South Florida with a substantial amount of water, flowing from the Kissimmee River, through Lake Okeechobee and the Everglades, and finally to the Atlantic Ocean and Gulf of Mexico. Proposals to drain the Everglades began in 1847; s ince then, the southern part of the state has undergone a series of modifications and augmentations to reduce and reroute the flow of water in the Everglades (Lodge, 2005; Rutchey et al., 2008) Early management The first major management of the Everglades involved three major phases: drainage from 1904 to 1928, general flood control from 1928 to 1948, and finally comprehensive water management, which began in 1948 and continues to be a major effort in the state. The peak of drainage efforts began i n 1926 after a hurricane hit South Florida, flooding Miami and the Lake Okeechobee region, killing more than 200 people and creating financial devastation. Again, in 1928, a hurricane hit the Palm Beach area and moved toward Lake Okeechobee, overflowing the lakeshore and drowning approximately 2,400 people (Grunwald, 2006; Lodge, 2005). Following these massive storms, the federal government worked to alleviate the subsequent flooding around O keechobee by creating the Okeechobee Flood Control District, which was authorized to cooperate with the United States Army Corps of Engineers (USACE) in flood control. In 1947, following a period of local subsidence and muck fires in the Everglades, the s tate was hit by two more hurricanes within 25 days, causing flooding that extended to the drier rocklands to the south (Grunwald, 2006; Lodge, 2005). In

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20 response to this episode of flooding, water managers had to expel billion of gallons [of water] down the St. Lucie, disrupting the delicate balance of fresh and salt water in the estuary at its mouth, thus beginning USACEs management of the Everglades (Grunwald, 2006). Following a series of public hearings, USACE developed the C&SF Project (Development of the C&SF Project, 2011). The C&SF Project was authorized by Congress in 1948 and outlined the most elaborate water control system ever built (Grunwald, 2006; Lodge, 2005). The project is responsible for 1,600 km of levees, 1,160 km of canals, and almost 200 water control structures including spillways, floodgates, and pumps (Development of the C&SF Project, 2011). The plan, published in House Document No. 643, 80th Congress, Second Session, was part of the Flood Control Act of June 30, 1948, and was aimed at transforming Central and South Florida into an area with less flood potential by, establishing protective works, controls, and procedures for conservation and use of water and land (House Document No. 643, 80th Congress, Second Session). A year after approving the plan, the legislature created the Central and Southern Florida Flood Control District which would later become the South Florida Water Management District (SFWMD), to work with the federal government on issues pertaining to the new leg islation. Since its creation in 1948, the C&SF Program has facilitated the implementation of numerous restoration projects as facilitated by updates to the original Flood Control Act. These projects included increasing water flow to ENP through the Everg lades National Park Protection and Expansion Act of 1989 and restoring the Kissimmee River through the Water Resources Development Act of 1992 (Development of the C&SF Project, 2011).

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21 United States v. South Florida Water Management District Litigation has played a significant role in the evolution of the Everglades landscape. In 1988, a lawsuit known as United States v. South Florida Water Management District 922 F.2d 704 (11th Cir. 1991) asserted that water quality standards were being violated in federal lands within the Everglades (Lodge, 2005; Rizzardi, 2001). In a complaint (Case No. 881886Civ Hoeveler) issued as part of the lawsuit, the plaintiff, United States of America, stated: Large quantities of polluted water are discharged by SFWMD into Loxahatchee from the Everglades Agricultural Area and Lake Okeechobee. These discharges of polluted water have resulted in the destruction of lower forms of aquatic life essential to the preservation of the sensitive ecosystems in Loxahatchee, including but not limited to: (a) Loss of natural periphyton mat; (b) Change from a diverse vegetative community to a monoculture of cattails; and (c) Loss of dissolved oxygen. The complaint also stated that, Florida law recognizes that excessive nutrients (total nitrogen and total phosphorus) constitute one of the most severe water quality problems facing the State. In addition, the Florida Administrative Code requires that particular consideration be given to protection from nutrient pollution those waters containing v ery low nutrient concentrations. Natural waters of Everglades and Loxahatchee fall within this category. Following two years of litigation, Florida Governor Lawton Chiles announced a settlement in May 1991. According to the settlement agreement (847 F. Supp 1567 [S.D. Fla 1992]) reached in response to United States v. South Florida Water Management District (Case No. 881886Civ Hoeveler), The Agreement establishes interim and long term phosphorus concentration limits for the Park and Refuge and delineates specific remedial programs designed to achieve these limits. The remedial programs consist of stormwater treatment areas (STAs) and a regulatory permitting program aimed at agricultural discharges from the Everglades Agricultural Area (EAA). The s ettlement describes the stormwater treatment areas (STAs) as,

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22 Large water filtration marshes designed to process and remove nutrients from agricultural runoff destined for the Park and RefugeThe STAs will thus act as a buffer zone between the agricultural area and the Park and Refuge, receiving stormwater directly from agricultural drainage canals and purifying the water before it enters the Park and Refuge. The Everglades Forever Act The landmark United States v. South Florida Water Management District case ultimately led to the creation of a Statement of Principles that put an end to all Everglades litigation and administrative proceedings and established the Technical Plan to balance the needs of the agricultural sector with ecosystem restoration and assuring long term protection for Everglades National Park, as well as the [Loxahatchee National Wildlife] Refuge, [Miccosukee Tribe of Indians] Reservation lands, and downstream waters. In 1994, FEFA incorporated the goals of the Technical Plan into an expansive restoration effort that included both federal and state lands as well as agricultural areas upstream of the Everglades (Rizzardi, 2001). In addition to mandating the creation of six STAs, FEFA established the Everglades Protection Area (EPA) and defined it to include, the remnant areas of the Everglades, including the northern section of the Everglades that is the Loxahatchee National Wildlife Refuge, the middle sections that are known as Water Conservation Area 2 and 3, and the terminal, south ern part of the Everglades that is Everglades National Park ( Id. 373.4592(2)). Finally, and perhaps most importantly, the 1994 FEFA tackled the issue of P pollution by asserting that, waters flowing into the Everglades Protection Area contain[ed] exces sive levels of phosphorus, and that, a reduction in the levels of phosphorus [would] benefit the ecology of the Everglades Protection Area ( Id. 373.4592(1)(d)).

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23 Comprehensive Everglades Restoration Plan Most recently, CERP was developed to meet the ever changing needs of the Everglades ecosystem and of South Floridas residents and investors. CERP was approved in 2000 as part of the Water Resources Development Act, which also provided federal funds to jumpstart the project. The plan was established to restore a more natural and ecologically sound flow regime to the Everglades through a series of guiding principles and by combining more than sixty management elements. At the time of its inception, it was expected to take about thirty years to complete and cost around $7.8 billion at 1999 price levels. A 2006 report estimated the cost at closer to $10.5 billion. With help from USACE CERP aims to restore natural water flows, quality, and hydroperiods to South Florida, thereby improving the health of Lake Okeechobee and of the South Florida ecosystem as a whole. Additionally, USACE intends to maintain the flood control put in place by the C&SF Project Overall, it is anticipated that approximately 9,700 km2 of the South Florida ecosystem will be imp roved over time (CERP, 2009). The Everglades Agricultural Area The EAA is located south of Lake Okeechobee and north of the Everglades WCAs and covers an area of about 2,800 km2 ( Lodge, 2005). Just over 1,780 km2 of the EAA are developed by sugarcane g rowers and 80% of this area is on muck soils ( Sugar Farmers Best Management Practices 2009). According to the Everglades Soil Testing Laboratory, proper sugarcane growth requires application of 03,700 kg P km2 between plant and fir st harvest (ratoon), 0 3,500 kg P km2 to the second ratoon, and 2,000 kg P km2 for every subsequent ratoon (Rice et al ., 2006). In addition to fertilizer requirements, water in sugarcane growing areas must be maintained at a depth of

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24 about 50 cm (Lodge, 2005). This constant flooding promotes the oxidation of partially decayed organic matter by aerobic bacteria. Although oxidation destroys the organic components of the muck soil, inorganic components remain and contain high concentrations of N and P (McCally, 1999). There fore, fertilizer use, in combination with necessary water control mechanisms, is a large contributor to nutrient loading in the Everglades Protection Area. The w ater supply to the Everglades comes from both the EAA, in the form of agricultural runoff, and from Lake Okeechobee as natural and engineered flow. Because of the limestone bedrock underlying South Florida and the relatively thin Histosols of the EAA, water storage potential is low and agricultural runoff must be directed elsewhere. Agricultural runoff and water from Lake Okeechobee are controlled by a series of canals and pump stations managed by SFWMD. Best Management Practices In addition to the $200$300 million in agricultural taxes required by the 1994 FEFA sugar farmers spend millions of dollars annually to implement Best Management Practices (BMPs) on their farms (Sugar Farmers Best Management Practices 2009) Since being fully implemented by all EAA sugar farmers, these management techniques have reduced nutrients such as P in agricul tural water outflow by an average of 50% ( Sugar Farmers Best Management Practices, 2009). These BMPs and recommendations are aimed at reducing and monitoring nutrient inputs to the Everglades by ensuring proper P management of point and nonpoint sources (Daroub et al., 2005; Diaz et al., 2005a; Diaz et al., 2005b; Lang et al., 2006 ; Rice and Izuno, 2001). Several studies have suggested that the best way to reduce P enrichment in the Everglades is to limit and monitor fertil izer application in the EAA (L ang et al., 2006 ;

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25 Morgan et al., 2 009). Other studies indicate that improvements to internal drainage in agricultural areas would allow for more uniform drainage and reduce P concentrations and loads for all crops (Daroub et al., 2003). EAA growers are also subject to the BMPs set forth by EPA Florida Regulations, Section 373.4592(4)(f), and chapters 40E 61 and 40E 63, Florida Administrative Code. Phosphorus Because P is the most common nutrient limiting production in freshwater ecosystems, e levated l evels of any form of P can lead to accelerated and excessive growth of algae and other aquatic plants (Bridgham et al., 2001; Schindler, 1977). In order to reduce and maintain lower P levels in the Everglades, it is necessary to identify the natural processes within the Everglades ecosystem as well as the behavior and role of P in wetlands. Sources Phosphorus is introduced into the natural environment in a variety of natural and anthropogenic processes and can enter from both point and nonpoint sources ; increased eutrophication of aquatic systems is generally a result of nonpoint source pollution (Mylavarapu, 2008; Reddy et al., 1999). Because P is an immobile element it must be transported by streams or other dynamic systems including atmospheric proc esses; all P inputs to the Everglades arrive in this manner (Khan and Ansari, 2005; Lodge, 2005; McCormick et al., 2002). While the natural concentration of P in surface water bodies is minimal, there are a few substantial natural contributors including a tmospheric deposition from rainfall and dry fallout, the biological oxidation of organic matter, and natural disturbances including fire (Mylavarapu, 2008; McCormick et al., 2002; Reddy et al., 1998) Average annual atmospheric P deposition has been

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26 measured between 20 and 80 mg P m2 yr 1 and this type of deposition is thought to account for 10% of measured inputs in Florida (Reddy et al., 1999). Additionally, polyphosphates are naturally occurring in bacteria, yeasts, filamentous fungi, and photosynthet ic algae At healthy levels, P is stored in intracellular volutin granules in prokaryotes and eukaryotes and is a necessary component of adenosine triphosphate, adenosine diphosphate, nicotinamine adenosine dinucleotide phosphate, nucleic acids, and phospholipids (Khan and Ansari, 2005). Anthropogenic sources include agricultural runoff, domestic sewage, lawn fertilizers, pet excrement, and animal feed (Reddy et al., 1998; Reddy et al., 1999). Prior to agricultural development, P entered the Everglades in low amounts via atmospheric processes and in higher amounts as inflows from Lake Okeechobee, which are P enriched compared to naturally occurring levels in other regions (Gleason and Stone, 1994; McCormick and Scinto, 1999; McCormick et al., 2002; Miao and DeBusk, 1999). Following the development of agriculture in the northern Everglades and urban communities to the east and west, P is predominantly from water drainage from the EAA, densely populated urban areas, and bulk precipitation (Miao and DeBusk, 1999; Reddy et al., 1998; Surface Water Improvement and Management, 1992) Without treatment, stormwater runoff from the EAA contains P concentrations often in excess of 500 mg L 1 (Lodge, 2005). Additional degraded water enters the Everglades Protecti on Area from the S 9 pump station, which pumps stormwater from developed areas of southwestern Broward County (Lodge, 2005). While interior portions of the Everglades remain relatively oligotrophic, like historic conditions, the outer fringes including the STAs and associated WCAs exhibit much

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27 higher levels (McCormick et al., 2002). Additionally, in outer areas impacted by canal inflows, such as WCA 2A, P levels are higher than in interior areas (McCormick et al., 2002). A study by Reddy et al. (1993) evaluated nutrient storage in wetland soil from WCA 2A that is affected by nutrient loading from a water inflow structure. Over a study period of five years, the authors found that total and soluble P concentrations in water column samples decreased exponent ially as a function of distance from the inflow of anthropogenically nutrient impacted water. Whats more, P accumulation rates decreased as a function of distance from the inflow; the highest rates of accumulation (between 0.54 and 1.14 g P m2 yr 1) oc curred 0.31.9 km from the inflow structure while the lowest rates (between 0.11 and 0.25 g P m2 yr 1) were measured 815 km from the same inflow structure (Reddy et al., 1993). A similar study conducted by Richardson and Vaithiyanathan (1995) measured P adsorbed on soil surfaces (Q) down a spatial gradient and produced analogous results; soil samples collected the shortest distance from the inflow structure exhibited the highest Q values while those collected the farthest from the inflow structure had t he lowest Q values (Reddy et al., 1991). A later study by Reddy et al. (1998) showed similar patterns of total P accumulation in soil moving away from water inflow structures; soil closer to the water inflow exhibited higher concentrations of total P than did soil taken from farther away from the inflow. Additionally, a study conducted by DeBusk et al. (2001) illustrated a decrease in total P concentrations moving away from water inflow structures. Forms Inorganic phosphorus. Phosphorus occurs in two maj or forms: inorganic and organic, each with varied storage and sorption characteristics. Inorganic P compounds contain either calcium (Ca) or iron (Fe) and aluminum (Al); P availability is generally

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28 determined by the solubility of these chemicals. For thi s reason, inorganic forms of phosphorus are classified based on their differential solubilities in various chemical extractants (Reddy et al., 2005). Organic phosphorus. Organic P generally dominates the total P in aquatic and wetland systems, accounti ng for >50% of sediment total P and up to 90% of total P in the water column (Newman and Robinson, 1999). Behavior Precipitation and dissolution. Chemical precipitation can be defined as, the interaction of dissolved P with dissolved cations present in water that, has the net result of converting dissolved phosphorus into solid mineral phosphorus that accumulates in the system (Strang and Wareham, 2006). Studies have shown that under acid conditions, P is fixed as Al and Fe phosphates whereas alkaline conditions, like those found in Everglades soils, promote P fixation by Ca and Mg (Reddy and DAngelo, 1994; Strange and Wareham, 2006). Sorption and desorption. P sorption is defined as the removal of P from solution (water) by association with the solid phase (sediment) (Leader et al., 2008). Alternately, desorption of P is the release of that P from the solid state back into the solution when it becomes equilibrated with a P free or low P solution (Leader et al., 2008). The sorptiondesorption cycl e is referred to as flux, the process by which P is transferred back and forth across the sediment water interface in a wetland or other body of water. As with precipitation and dissolution, sorption and desorption reactions are controlled by the formation of Fe and Al phosphates and oxyhydroxides at low pH and Ca phosphates at alkaline pHs (Bridgham et al., 2001; Reddy and DeLaune, 1998; Stevenson, 1986).

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29 Flux Phosphorus can be transferred across the soil water interface or travel through soil by a variety of mechanisms including the sedimentation and accretion of particulate matter, porewater flow of dissolved P, molecular diffusive flux, or a physical mixing of water and sediment at the soil water interface due to bioturbation or water turbulence (Reddy et al., 2005). Following the uptake of soluble inorganic P by aquatic plants and the subsequent death of the plant, the organic form of P is decomposed by bacteria and then converted into the inorganic form. This organic form is then free to diffuse back up into the photic zone of the water column where it is again recycled via absorption, photophosphorylation, growth, death, and decay by bacteria (Khan and Ansari, 2005). Based on these processes, it has been suggested that nonnutrient impacted E verglades soils function as P sinks while already enriched soils can act as P sources when exposed to surface water with P concentrations lower than the equilibrium P concentration (Richardson and Vaithiyanathan, 1995). The diffusive flux of soluble P var ies across numerous Florida wetlands but has been shown to be 0.02 to 0.7 mg P m2 d1 in WCA 2A (Koch and Reddy, 1992; Fisher and Reddy, 2001; Reddy et al., 2005). The inflow of low nutrient water from STA 1 into WCA 2A creates a steep gradient between P concentrations in the sediment and the water column; this gradient can cause the aforementioned rapid flux of P from the sediment to the overlying low nutrient water column. Additionally, it has been suggested that a large portion of this P is bioavai lable and will cause continued and accelerated growth of cattail in nutrient impacted regions of the WCAs; this will further reduce native plant populations while promoting anthropogenic eutrophication and hampering ecosystem rehabilitation efforts.

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30 Nega tive Impacts Because it is a limiting nutrient in most wetland environments, P loading can have negative impacts on many components of an ecosystem, including flora and fauna, and soil and water quality (McCormick and Scinto, 1999; Miao and DeBusk, 1999). In the Everglades, when concentrations are 10 mg L1 or less, P has been identified as a limiting nutrient (Lodge, 2005). However, it has been posited that surface waters in the Everglades with organic and total P concentrations between 0.01 and 0.02 mg L1 are susceptible to accelerated rates of eutrophication and pose a serious threat to ecosystem health (Daniel et al., 1998; Sawyer, 1947). The excess algal growth promoted by P loading creates eutrophic conditions in bodies of water where P is a limiting nutrient. As nutrient levels in surface waters increase so does algal growth, making it difficult for higher level vegetation to receive adequate sunlight and oxygen. In addition to reducing light penetration, P loading can cause aesthetic degradation to surface waters and promote the growth of algal blooms dangerous to human health (Mylavarapu, 2008). One damaging effect of P loading in the Everglades, and especially in the WCAs, is the change in vegetation. It is well documented that nutrient impa cted areas of the region, especially those near canals and water inflow sites, have undergone a transition from native sawgrass ( Cladium jamaciense Crantz) to cattail ( Typha spp.) as a result of high levels of P in surface water and sediment (Chiang et al. 2000; Craft and Richardson, 1997; Davis, 1991; Davis 1994; Doren et al., 1997; Kushlan, 1990; Lodge, 2005; Miao and DeBusk, 1999; Reddy and DeLaune, 2008; Reddy et al., 1998; Urban et al., 1993). Cattails and other exotic plants can outcompete native vegetation for

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31 nutrients and sunlight thus altering the plant diversity in, and community structure of, the Everglades (Rutchey et al., 2008). Phosphorus Reduction and Removal Technology Extensive research has been conducted regarding potential P management practices. Numerous processes aid in the removal of P from wetland soils; these include sorption, complexation, and precipitation reactions with minerals in the sediment (Zurayk et al., 1997). The removal of P can occur via sedimentation, substratum adsorption, chemical precipitation and dissolution, bacterial immobilization, plant and algal uptake, incorporation into organic matter, and sediment uptake (Ballantine and Tanner, 2010; DeBusk and Dierberg, 1999; Kadlec and Knight, 1996; Moustafa et al., 1999). These processes are affected by numerous other variables such as pH, redox potential, clay, lime, iron and aluminum content (Richardson, 1985; Zurayk et al., 1997); in constructed wetlands, oxygen availability, microorganisms, and the sorption charac teristics (chemical composition and hydraulic conductivity) of the substrate influence P removal capacity (Ballantine and Tanner, 2010; Haberl et al., 2003). Although generally more efficient and cost effective for removing N or C, c onstructed we tlands can be a useful method of P removal and utilize a variety of methods of eliminating P from wetland soils and water (Ballantine and Tanner, 2010; DeBusk and Dierberg, 1999). Land application of chemical amendments has also been used to reduce P levels in wet land soils and substrates are generally chosen based on physical and chemical characteristics that aid in P adsorption and retention (Ballantine and Tanner, 2010; DeBusk and Dierberg, 1999).

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32 Constructed Treatment W etlands Constructed wetlands are engineered systems that mimic and utilize natural processes to treat effluent from municipal, industrial, agricultural, and stormwater sources (Chin, 2006; Haberl et al., 2003; Vesilind and Morgan, 2004). There are two categories of constructed wetlands: surface flow wetlands and subsurfaceflow wetlands. Surfaceflow wetlands are the most similar to naturally occurring wetlands and are characterized by overland flow. Structurally, these constructed wetlands generally utilize a series of basins or channels underlain with an impervious layer of clay or artificial lining; this layer prevents seepage of wastewater into underlying groundwater (Chin, 2006; Vesilind and Morgan, 2004). Basins are filled in with soils and, in some cases, seeded with emergent vegetation. Surfaceflow wetlands may also incorporate areas of openwater area where submerged vegetation can aid in the treatment process (Chin, 2006). Subsurfaceflow wetlands utilize subsurface drains to filter water through a porous medium; as with surfaceflow wetlands, these systems are underlain with an impervious layer to prevent seepage (Chin, 2006). Emergent aquatic vegetation can be rooted in the porous media but is not necessary to the systems efficacy (Chin, 2006). Because subsurfaceflow treatment wetlands offer greater exposure of nutrient impacted water to substrate sorption sites, they may be more effective in treating water with high P concentrations (DeBusk and Dierberg, 1999). Substrate The primary substrate in a constructed wetland can i mpact the rate and effectiveness of phosphorus reduction and removal. Substrates used in constructed

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33 treatment wetlands should be fine textured with a high surface area to allow for the greatest number of active binding sites (Ballantine and Tanner, 2010) Additionally, maximum P removal has been shown to occur in porous substrates with a particle size between 10 and 20 mm (Ballantine and Tanner, 2010; Drizo et al., 1999). While particle size and adsorption capacity are important characteristics, it is also important that treatment wetland substrates be resistant to varying flow conditions (Ballantine and Tanner, 2010); substrate particles small enough to be carried by hydraulic or aeolian forces will be ineffective regardless of their adsorption capacity Irrespective of the materials used, treatment wetland substrates have a finite capacity for adsorbing P and, with time, may become a source of internal P loading (Ballantine and Tanner, 2010). For this reason, substrate should be occasionally removed and replaced or, in some cases, reactivated to ensure that stored P is not rereleased into the water column (Ballantine and Tanner, 2010). A study by Burgoon et al. (1991) showed that P removal in a nonvegetated gravel microcosm batch loaded for 58 days w ith 9.4 cm d1 of municipal wastewater effluent averaged 220 mg P m2 d1; alternately, microcosms with plastic substrate experienced a phosphorus removal of only 1 mg P m2 d1 (DeBusk and Dierberg, 1999). This indicates that the type of substrate utiliz ed in subsurfaceflow wetlands plays an important role in the rate of phosphorus sorption in these systems. Limestone is a common substrate and soil amendment used in constructed wetlands to increase soil pH and, subsequently, improve P retention capacity of soils (Ballantine and Tanner, 2010). A study by Zurayk et al. (1997) found that P removal in soils is positively correlated with the quantity of lime added to soils. Another study by

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34 Yin et al. (2006) compared the efficacy of limestone as a filter compared to several other substrates and soil amendments; of the five materials tested, limestone was shown to have the greatest P sorption characteristics in subsurface flow constructed wetlands. Some studies have shown sand as a removal mechanism for P in constructed wetlands but there are still questions regarding the most effective type of sand. Additionally, sand has a low cation exchange capacity because it has no electrical charge (Cation Exchange Capacity, 2002) In their study of P removal by sand in subsurface construct ed reed beds, Arias et al. (2001) compared the removal capacities of 13 Danish sands and then evaluated the physicochemical characteristics of each (Arias et al., 2001). This is valuable information because sand characteristi cs vary widely based on provenance, weathering, and other factors. For example, data indicated that, though initially effective, the P removal capacity of quartz sands was diminished after only a few months. This may indicate that the Pleistocene quartz sands overlying the Tamiami and Miami formations found in South Florida would not be an effective mechanism for removing P (Davis, 1994). Another study looked at the use of lightweight expanded shale and masonry sand in subsurfaceflow treatment wetlands (Forbes et al., 2005). In agreement with other studies, Forbes et al (2005) found that, while sand does exhibit variable P removal capabilities, it is not a viable option for long term P storage. Results also indicated that expanded shale could be help ful in long term P retention in constructed wetlands due to its high hydraulic conductivity and P sorption capacity. While sands and gravels have been shown to reduce organics, solids, and excess nutrients in constructed wetlands,

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35 removal rates are highly variable and often temporary (Forbes et al., 2005) making it necessary to identify other mechanisms for P management. Because the P removal capacity of constructed wetlands has been documented to decrease over time, soil amendments have also been tested for their ability to restore the capacity of older wetlands. Vegetation Plant assimilation and decomposition of organic matter play an integral role in the cycling of P in wetlands (DeBusk and Dierberg, 1999). Although assimilation by algae and macrophy tes can be considerable, assimilation capacity varies among organisms; varied decomposition rates of these plants also affect the P cycle in wetlands (DeBusk and Dierberg, 1999; Kadlec and Knight, 1996; Richardson and Craft, 1993). In treatment wetlands, vegetation serves the purpose of nutrient uptake rather than providing restorative aid and increased biodiversity. Macrophytes are utilized in constructed wetlands for numerous reasons. Underwater plants aid in wetland restoration because of their abili ty to filter large debris, increase aerobic breakdown of organics, and aid in the uptake of nutrients (Brix, 1997; DeBusk and Dierberg, 1999). Aerial macrophytes create a layer of vegetation that blocks out some light to reduce algal growth that can becom e accelerated in the presence of high nutrient levels; these plants can also reduce wind velocity which can decrease the chance of resuspension (Brix, 1997). Additionally, floating macrophytes can be more easily harvested than emergent and submerged plant s (DeBusk and Dierberg, 1999). Finally, roots in the sediment have physical effects on nutrient and sediment stability by slowing water velocity and reducing erosion also aid in the uptake of nutrients while increasing nitrification (Brix, 1997; Haberl et al., 2003). However, the decay of these organisms

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36 rereleases nutrients into sediment and water; plants should be harvested regularly to minimize or avoid this problem (Haberl et al., 2003). Chemical Amendments A reduction in P flux from sediment to the water column can be achieved by immobilizing soluble P with a chemical soil amendment; Ca, Fe, or Al containing amendments will bind soluble P into insoluble forms, thus preventing flux (Ann et al., 2000; DeBusk and Dierberg, 1999). Each of these amendments follows a different chemical pathway and has different levels of efficacy under different conditions; chemical amendments can be introduced to a wetland system via water inflow, direct application to drained sediment, or as a substrate incorporated int o a contructed wetland (DeBusk and Dierberg, 1999). Amendments are presented in the order of efficacy as determined by a study by Ann et al. (2000). Iron Anaerobic conditions created in submerged soils lead to the reduction of iron from the ferric (Fe3+) to the ferrous (Fe2+) state; this change releases P that had been stored as insoluble ferric phosphate compounds (Chin, 2006). Alternately, when an aerobic zone is exposed to air, ferrous sulfides are oxidized and become ferric oxyhydroxide which has both a large surface area and a high affinity for SRP (Bhada et al., 2010; De Groot and Van Wijck, 1993). FeP compounds can be a major source of phosphorous to the water column and to porewater in the soil under anaerobic conditions (Mitsch and Gosselink, 2000). Therefore, soils with higher Al and Fe content are more effective in removing P from effluent because of their high affinity for P (Chin, 2006). A study by Ryan et al. (1985) and reported by Zhou and Li (2001) indicated that P sorption in soils i s related more to the Fe oxide content of the soil opposed to the

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37 CaCO3 content. Also reported by Zhou and Lis 2001 study, Solis and Torrent (1989) found that P sorption capacity of soil is highly correlated with Fe oxide and clay content with CaCO3 cont ent being less important to the process. Aluminum Phosphorus sorption by Al is also contributes to P sorption in treatment wetlands. Unlike Fe, sorption by Al is not affected by the availability of O2 but is controlled by pH and organic matter (Bhada et al., 2010). When organic matter content is high, the level of organic anions formed by decaying matter increases and makes P more available; organic anions compete with P for adsorption sites found in clays and FeAl minerals (Bhada et al., 2010; El Dewiny et al., 2006). In a study investigating the effect of Al containing amendments to wetland soil, alum and three Al containing alternatives (alum residual [from wastewater treatment], polyaluminum chloride [PAC], and partially neutralized aluminum sulfate [PNAS]), were applied to reduce P concentrations (Malecki Brown and White, 2009). The study found that all Al amendments were effective at sequestering P, but alum and PNAS were most effective and alum residual was the least efficient (time for removal v s. total amount sequestered). The practice of applying alum to wetlands can have toxicological effects on plant and benthic communities in environments where the water pH remains displaced from neutral. Calcium carbonate Limestone is a commonly used amendment in constructed wetlands because of its high percentage of calcium carbonate, which has the ability to reduce soil acidity and enhance P retention and precipitation (Ballantine and Tanner, 2010). In organic soils, like those in the Everglades, lime has been identified as a useful amendment for

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38 reducing P solubility in repeatedly flooded environments (Ann et al., 2000). Additionally, Yin et al. (2006) found that lime amendments have the best characteristics for P sorption in subsurfaceflow constructed wetlands. Since limestone is readily available in many wetland regions, especially South Florida, it is an effective, low cost, and accessible material for nutrient reduction in constructed wetlands. Concluding Remarks Historically dominated by southerly sheetflow from Lake Okeechobee, sawgrass marshes, tree islands, and slough, the Everglades have undergone a series of hydrologic, biologic, and structural changes since the mid1800s. Hydrologic input from the EAA has caused an increase in nutrient l evels in the sediment and water of the greater Everglades and WCAs leading to major changes in habitat stability, vegetation profiles, and water quality (Lodge, 2005; McCormick et al., 2002; Reddy et al., 1998; Reddy et al., 1999). Perhaps most problemati c in the WCAs is P which can, in elevated concentrations, lead to eutrophication and the proliferation of nonnative plant species such as Typha domingensis (cattail) (Bridgeham et al., 2001; Chiang et al., 2000; Daniel et al., 1998; Davis, 1991; Mylavarapu, 2008; Sawyer, 1947; Schindler, 1997). Outer fringes of the Everglades including STAs and WCAs are shown to be more nutrient impacted than interior regions that are not affected by canal inflows (McCormick et al., 2002; Reddy et al., 1991; Reddy et al., 1993; Vaithiyanathan, 1995). Because P undergoes diffusive flux between the sediment and overlying water column, sediment in nutrient enriched areas can act as a sink, releasing P into the water column when exposed to P concentrations lower than the equi librium P concentration (Khan and Ansari, 2005; Reddy et al., 2005; Richardson and Vaithiyanathan, 1995). The process of P flux makes ecosystem rehabilitation difficult because even low concentrations of P

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39 in water inflow can cause additional release of P from the sediment to the water column. Several studies have evaluated the roles of vegetation and varying chemical amendments and substrate material in wetland rehabilitation but continued research developing and evaluating methods of P removal and storage in nutrient impacted areas of the Florida Everglades is needed (Arias et al., 2001; Ballantine and Tanner, 2010; Brix, 1997; Chin, 2006; Davis, 1994; DeBusk and Dierberg, 1999; Forbes et al., 2005; Haberl et al., 2003; Malecki Brown and White, 2009; Ric hardson, 1985; Solis and Torrent, 1989; Vesilind and Morgan, 2004; Yin et al., 2006; Zurayk et al., 1997; Zhou and Li, 2001).

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40 CHAPTER 2 COMPARISON OF THREE LIMESTONE BASED TREATMENTS AS MECHANISMS FOR LIMITING PHOSPHO RUS FLUX IN EVERGLADES WATER CONSERVATION AREAS, FLORIDA Introductory Remarks Hydrologic input from the Everglades Agricultural Area (EAA) and other anthropogenic and natural sources has led to increased nutrient levels in the sediment and water of the greater Everglades ecosystem including the Everglades Water Conservation Areas (WCAs). Increased concentrations of phosphorus (P), a major component of fertilizers and urban runoff and a limiting nutrient in many wetland ecosystems, has led to excessive eutrophication of Everglades; changes in P availability have also led to a shift from preagricultural sawgrass marshes to present day cattail dominated ecosystems (Miao and DeBusk, 1999; Qian et al., 2009). Problematic in the WCAs, and WCA 2A especially, is the biogeochemical process referred to as P flux (Community Watershed Fund and D.B. Environmental, Inc. 2009; Khan and Ansari, 2005; Reddy et al., 2005; Richardson and Vaithiyanathan, 1995). In wetlands, the P cycle consists of the uptake of soluble inorganic P by plants followed by death of the plant and subsequent decomposition of organic P by microorganisms (Khan and Ansari, 2005; Reddy et al., 2005; Richardson and Vaithiyanathan, 1995). Once converted to inorganic P by the bacteria, it is free to diffuse to the photic zone where it is once again recycled via absorption, photophosphorylation, growth, death, and decay (Khan and Ansari, 2005; Reddy and DeLaune, 1998). Phosphorus sorption occurs when P is removed from solution by association with the sediment (Leader et al., 2008). Desor ption of P occurs when P is released back into solution when the sediment becomes equilibrated with a P free or low P solution (Leader et al., 2008). In alkaline

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41 environments such as WCA 2A, P sorption and desorption are controlled by calcium containing m inerals (Bridgham et al., 2001; Reddy and DeLaune, 1998; Stevenson, 1986). P flux is the sorptiondesorption cycle facilitated by fluctuations in P concentrations in soil porewater and the water column (Community Watershed Fund and D.B. Environmental, Inc 2009 ; Khan and Ansari, 2005; Richardson and Vaithiyanathan, 1995). Because of this behavior, nonnutrient impacted Everglades soils function as P sinks while nutrient enriched soils, such as those in the WCAs, act as P sources when exposed to surface w ater with P concentrations lower than the equilibrium P concentration (Community Watershed Fund and D.B. Environmental, Inc. 2009; Richardson and Vaithiyanathan, 1995). Phosphorus flux poses a threat to WCAs because of the high concentrations of P in th e existing sediment and the lower concentrations in hydrologic inputs ( Community Watershed Fund and D.B. Environmental, Inc. 2009) Despite the success of nutrient reducing Best Management Practices (BMPs) in the Everglades Agricultural Area (EAA), low n utrient water entering the WCAs has the potential to trigger the release of additional P from nutrient impacted soils into the overlying water column. Numerous studies have evaluated potential mechanisms for reducing P flux in the Everglades and other wetland ecosystems ( Community Watershed Fund and D.B. Environmental, Inc. 2009). Because P is a limiting nutrient in these systems, elevated levels of any form of P can lead to accelerated and excessive growth of algae and other aquatic plants, thus disrupting vegetation, wildlife, and water quality (Daniel et al., 1998; Miao and DeBusk, 1999; Mylavarapu, 2008; Sawyer, 1947).

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42 It is well established that P retention is regulated, to some extent, by calcium based minerals in alkaline soils such as those fou nd in South Florida (Reddy and DeLaune, 1998). The goal of this study was to compare the ability of three limestonebased treatments to limit the P flux from nutrient impacted sediment to the overlying low nutrient water column by looking at orthoP and t otal P concentrations in porewater, water column, and flowthrough samples. Standard hydrologic and geochemical conditions in WCA 2A were replicated in a laboratory setting using ex situ sediment columns in an incubation lasting from 11 Oct. 2010 through 1 3 Dec. 2010. Objective The objective of this study was to compare the movement of P between sediment and water column when sediment is treated with three limestonebased materials: ( a) Ordinary Portland C ement (OPC), (b) limestone gravel, and (c) ho rticultural hydrated lime powder. Hypotheses Hypothesis (a) Ordinary Portland Cement Treating the natural sediment with a layer of cement will create a physical barrier between the sediment and water, preventing the sediment from behaving as an internal si nk and releasing phosphorus into the water column through natur al flux. The cement will also provide some chemical removal via co precipitation with CaCO3 (Sharpley and Smith, 1985), Fe oxides and clay (Solis and Torrent, 1989) which are shown to have positive correlation with P sorption. Chemical removal will be limited due to the small surface area of the ce ment layer and will be reduced as chemical binding sites become saturated over time (Amer et al., 1985; Debusk and Dierberg, 1999; Mann, 1990).

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43 Hyp othesis (b) Limestone G ravel Covering natural sediment with a layer of coarse limestone gravel will provide a semi permeable physical barrier between the sediment and water. Additionally, the presence of CaCO3 will promote the coprecipitation of P during the crystal growth phase of calcite in CaCO3rich waters ; in alkaline soils, P sorption can occur on CaCO3 surfaces and Ca2+ ions are available for the coprecipitation of P as calcium phosphate (DanenLouwerse et al., 1995; DeBusk and Dierberg, 1999; Reddy and DeLaune, 2008). In gravel treated columns, the gravel will facilitate P sorption by CaCO3 but this effect may decrease as P binding sites become saturated (Amer et al., 1985; DeBusk and Dierberg, 1999; Mann, 1990). Despite this, a study by Johanss on (1999) found that, while limestone may absorb less P (30% after equilibration) under conditions of lower initial P concentration (10 g m3), limestone exposed to higher initial P concentrations (25 g m3) absorbed a higher concentration of P (80%). These findings indicate that the efficacy of limestone gravel in treating nutrient impacted water may be dependent upon the P concentration of water entering the system (Johansson, 1999; Strang and Wareham, 2006). Hypothesis (c) Horticultural Hydrated Lime Adding lime to wetland soil has been shown to facilitate and improve the removal of P from nutrient impacted soils (Zurayk et al., 1997). In a study by Zurayk et al. (1997) comparing multiple levels of lime application, it was found that the highest tested concentration of lime amendment yielded the greatest P removal and the lowest tested lime concentration yielded greater P removal rates than soil beds without treatment. Additionally, b ecause the P sorption capacity of carbonate is related to surface ar ea and the availability of binding sites (Amer et al., 1985; Burgoon et al., 1991; Davies and

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44 Cottingham, 1993 ), this treatment will promote higher rates of P sorption in the lime layer than in control columns and will reduce the f lux of P from sediment to water (Zhou and Li, 2001). The lime will increase the pH of the sediment (pH>9) resulting in the formation of CaCO3 which can coprecipitate P under CaCO3saturated conditions; in alkaline soils, P sorption can occur on CaCO3 surfaces and Ca2+ ions are a vailable for the coprecipitation of P as calcium phosphate ( DanenLouwerse et al., 1995; DeBusk and Dierberg, 1999; Reddy and DeLaune, 2008). Finally, the ability of lime to promote P sorption and removal, while high at the time of initial application, h as been shown to decrease over time as illustrated by Zurayk et al. (1997). Based on studies showing the reduced capacity of lime to aid in P removal over time, it is expected that P removal rates will slow and become fixed as the study progresses (Davies and Cottingham, 1993; Zurayk et al. 1997). Materials and Methods Site Description Sediment columns were taken from a P impacted area of northern WCA 2A WCA 2A covers an area of 543 km2 and receives drainage water from WCA 1 and runoff from the EAA (Light and Dineen, 1994; Rutchey et al., 2008; Sklar et al., 2002). Generally characterized as sawgrass marsh, nutrient nonimpacted portions of the WCAs are dominated by Cladium and open water sloughs (Lodge, 2005; Reddy and DeLaune, 2008; Rutchey et al., 2008) The more heavily nutrient impacted areas of WCA 2A are characterized by Typha domingensis (cattail) (Lodge, 2005; Miao and DeBusk, 1999; Reddy and DeLaune, 2008 ; Reddy et al., 1993). Cores were collected within one square kilometer of coordinates 26o2109.34N 80o2115.08 W (Figure 2 1 ). This location was chosen because of its proximit y to a cattail stand (Figure 22 ), the

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45 presence of which indicates an increase in P concentrations in soil and water (Chiang et al., 2000; Davis, 1991; Davis, 1994; Doren et al., 1997; Kushlan, 1990; Lodge, 2005; Reddy and DeLaune, 2008; Reddy et al., 1993; Rutchey et al., 2008); c attail colonization generally occurs in soils with a total P content between 650 and 1,200 mg L 1 (Urban et al., 1993; Doran et al., 1997; Miao and DeBusk, 1999; Vaithiyanathan and Richardson, 1997). Collection of Sediment Cores All sediment core collection took place on 28 June 2010. Seventeen cores were collected from undisturbed land in WCA 2A using 30 cm long PVC pipe segments with a sharpened bottom edge. The PVC pipe segments were 30 cm in diameter and were used to collect sediment cores from the sediment surface to a depth of 20 cm. After each core was collected, the PVC pipe with intact sediment was inserted into a 30 cm diameter by 10 cm tall PVC cap and sealed with fast setting WELD*ON 725 WET R DRY PVC cement. Overlying water was removed from each core. In addition to the seventeen intact sediment cores, grab samples were collected at four major collection sites within the overall sampling region; samples were taken from the soil surface and from approxim ately 20 cm below the surface. G rab samples were refrigerated at 4C prior to analysis pursuant to standard laboratory protocol. Collection of Water Over the duration of the stu dy, approximately 1,500 L of water were collected from the Chekika Visitors Center canal in Everglades National Park (Figure 23) The source of water was chosen because of 0.01 mg P L1 criterion established by FEFA and officially adopted by the state o f Florida in June 2005 (Florida Administrative Code FAC 62302.540; Payne et al., 2006). Additionally, average total P concentrations in ENP

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46 floc and surface soils have been measured between 140 and 310 mg P kg1, indicating that the region is the most pr istine hydrologic region of the Everglades ecosystem in terms of P enrichment (Reddy et al., 2011). All water samples were obtained under National Park Service Scientific Research and Collecting Permit number EVER 2010SCI 0061. Approximately 250 L were collected from the same location each month and analyzed for total P and orthophosphate to ensure low P concentrations (Table C 1) A 30day hydraulic retention time (HRT) was selected based on the mean HRT in Stormwater Treatment Area2 (STA 2) during the dry season (Huebner, 2008). The monthly water use value was determined by multiplying the total daily flow of water into each container (~471 mL) by 16 units to obtain the daily water need of 7.5 L. Daily need was the n multiplied by 31 to obtain the monthly need of 233.6 L. In order to predict the volume of water necessary to provide flowthrough to all 16 columns over the threemonth study, the monthly water need was multiplied by three to yield approximately 700 L. Additional water was collected to hydrate the sediment prior to beginning the study period and to rinse out storage containers prior to their use. Laboratory Incubation and Chemical Analysis After core collection, the capped PVC pipe segments were moved to a lab space and covered with ClingWrap clear plastic wrap (GLAD ) to reduce evaporative loss of water from the sediment ; ambient room temperature was maintained at 20C for the duration of the study Capped segments were then fitted with 37 cm tall PVC couplers to increase the height of the column structures to 51 cm Internal pipecoupler seams were sealed with 100% silicone waterproof caulk (Premium Waterproof Silicone, General Electric) to avoid loss of water during the study. External seams between the cap and pipe and between the pipe and coupler were also sealed with 100% silicone

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47 waterproof caulk (Premium Waterproof Silicone, General Electric). Each core was treated with 1 L of nonnutrient impacted water from ENP to maintain water within the sediment A 2.55 mm diameter hole was drilled through the sid e of each unit 5cm below the water/sediment interface. The location of the porewater sampling port was chosen because of documented vertical distributions of soil P in WCA 2A Total P is shown to be higher in the floc layer and decrease in concentration down the profile (Reddy and DeLau ne, 2008; Reddy et al., 1993). Soil profiles analyzed in Reddy et al. (1993) show differences between nutrient impacted (eutrophic) and nutrient nonimpacted (oligotrophic) sites to a depth of approximately 15 cm; there were no differences below this depth, suggesting that the upper 10 cm of a profile is accreted as a result of nutrient loading (Reddy and DeLaune, 2008; Reddy et al., 1993). Holes were plugged with Rhizon samplers (Rhizosphere Res earch Products The Netherlands ) and silicone tubing ; syringes were attached to the Rhizon samplers and used to collect water from sediment Each container was fitted with an input and output siphon; the input siphon flowed from a plastic source container into the water column and the output siphon flowed from the water column into the flowthrough sample collection container (Figure 2 4 ). The ends of each siphon were maintained at the same level to ensure a proper rate of hydraulic loading. DuPont Teflon PFA 340 Fluoropolymer Resin tubing with a 0.762 mm internal diameter was used to maintain the proper rate of hydraulic loading. At a velocity of 1.524 cm sec1, this tubing has a dynamic coefficient of friction of 0.210; this coefficient decreases as velocity decreases. Because the velocity of the water needed to mimic the slow natural flow in the WCAs (~471 mL day1), the friction factor, siphon

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48 internal diameter, and siphon input and output levels played a significant role in the behavior of the siphon system. The water column of each column structure was manually mixed for 30 seconds with a slotted spoon once a week following sample collection. Treatments Prior to the input of standing water, each hydrated sediment column was overlain with one of three treatments: OPC limestone gravel, or horticultural hydrated lime powder; each treatment was replicated four times (Tables C 2, 2 1). An additional f our columns were maintained as controls with no treatment (Table C 2). Treatments were assigned to cores without bias using a random number generator. After receiving assigned treatments, containers were flooded with nonnutrient impacted water from ENP to a depth of 20 cm and began receiving water inflow from the source container at a rate of approxi mately 471 mL day1 to achieve an HRT of 30 days. Ordinary Portland C ement. The OPC used in this study was mixed according to ratios established by Quickrete. A single batch of cement was mixed using one part Type I/II Portland Cement Commercial Grade Quickrete two parts Quickrete AllPurpose Sand, and three parts small limestone pea gravel as aggregate for increased structural stability. The three solid constituents were mixed with DDI water until viscous and immediately poured on top of sediment columns 2, 3, 5, and 7; each sediment column was overlain with 2 L of cement (3 cm thick layer). Limestone gravel. Limestone gravel was chosen because P is known to react with calcium ions and solidphase calcium carbonate (Burgoon et al., 1991). Small pea gravel was used because of its high surface area to volume ratio; P adsorption is related to the amount of contact between water column P and sediment so removal of P

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49 is generally highest in substrates with high surface area ( Amer et al., 1985; Burg oon et al., 1991; Davies and Cottingham, 1993; DeBusk and Dierberg, 1999). Gravel was first rinsed five times with water, washed with Liquinox phosphatefree detergent, and rinsed five times with deionizeddistilled (DDI) water. After the treatment material was rinsed according to laboratory protocol, a 5 cm thick layer of gravel was placed on top of the sediment in columns 1, 3, 6, and 9. Horticultural hydrated lime. Twelve grams of hydrated horticultural lime powder was incorporated into the upper 2 c m of sediment in columns 8, 13, 14, and 16 (Appendix A). Lime application was determined based on use requirements established by Hi Yield horticultural hydrated lime for shrubs and flowers; product packaging suggests the application of 453.5 g lime m2 i n order to increase soil pH. Water sample collection Samples were collected from sediment columns once every seven days, beginning 11 Oct. 2010 and concluding 13 Dec. 2010. On every collection day, a sample was extracted from three portions of each of the 16 sediment columns: the overlying water column, siphon flowthrough in collection containers, and porewater from the sediment columns (Figure 25). Water column. One 100 mL sample was taken from the water column overlying each sediment column once every seven days. Samples were scooped from the middle of the column at a depth of 10 cm with sampling containers and water was transferred to 100 mL containers. In order to prevent the collection of mineral and organic detritus, samples were collected prior t o the weekly mixing process. Flowthrough. A second 100 mL sample was taken from the siphon outflow collection container of each column every seven days. Prior to collection, the entire 8 L

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50 siphon outflow collection container was thoroughly mixed and then reduced and transferred to a 100 mL sample bottle. Because the siphon diameter was narrow (0.762 mm), particulate matter greater than the size of the tubing was not present in these samples. Porewater. Porewater was sampled from each core using Rhiz on samplers inserted below the sediment water interface (Rhizosphere Research Products, Wageningen, The Netherlands). A 10 mL total capacity syringe was attached to each sampler and held open with a segment of bamboo during sampling. Once the syringe filled with water, the sample was transferred to a 100 mL sample bottle and the process was repeated until approximately 20 mL of porewater was collected. Because the pore size of the Rhizon samplers water extraction stem is 0.150.20 m, particulate matter was not present in these samples. Analysis of water samples Total P Total P in water column samples was measured according to EPA M ethod 365.1 using an autoanalyzer with digital colorimeter and compact s ampler (AA3, BRAN+LUEBBE, Mequon, Wisconsin). Tot al P in porewater samples was measured according to EPA method 365.1 using a discrete analyzer (AQ2, SEAL Analytical, Mequon, Wisconsin). Refer to Appendix B for the detection limits of these instruments. All s amples regardless of their provenance and a nalytic method, were prepared by adding 1 mL of 11 N sulfuric aci d solution and 0.4 g of ammonia persulfate to 50 mL of each sample; prepared samples were then heated for 30 minutes in an autoclave at 121C (15 20 psi). In cases where particulates were pr esent, samples were filtered through Grade 42 Whatman ashless paper filters following standard digestion for total P analysis Smaller samples that did not yield 50 mL were reduced to 30 mL or 10 mL

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51 samples and sulfuric acid solution and ammonium persulfate quantities were reduced accordingly; each sample was then diluted to 50 mL with DDI water and analyzed according to methods established for the operation of the AA3 or AQ2, depending on the samples provenance. Ortho phosphate. Ortho P was measur ed according to EPA M ethod 365.1 using an AA3 or AQ2, depending on the samples provenance. Flowthrough and water column samples were analyzed using the AA3, while porewater samples were analyzed with the AQ2 to better measure higher P concentrations characteristic of the porewater samp les Refer to Appendix B for the detection limits of these instruments. All samples were filtered through Grade 42 Whatman ashless paper filters and then analyzed according to methods established for th e operation of the AA3 or AQ2. pH and electrical conductivity (EC) The pH and EC of all samples was measured using a pH/Ion/Conductivity/Dissolved Oxygen Meter (AR60, Fisher Scientific, Pittsburg, Pennsylvania). Refer to Appendix B for the detection limits of these instrument s and Appendix C for methods of operation. Statistical Analysis of Data The efficacy of each treatment method was analyzed using correlation coefficients ( r ) calculated between porewater samples and flowthrough samples and between porewater samples and water column samples. A coefficient equal to one indicates that the measurements were perfectly correlated, a coefficient equal to zero indicates that the two measurements being compared are not related, and a coefficient equal to negative one indicates t hat the compared values are perfectly inversely correlated. A correlation implies that when one value increases, the value to which it is being compared will also increase; an inverse correlation implies that when one value

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52 increases, the value to which i t is being compared will decrease. Refer to Table 22 for definitions of correlation coefficient associations. Additionally, statistically significant differences among treatment types, replicates, sample types, and sample collection dates were determined using Analysis of Variance (ANOVA). Although the data set does not satisfy ANOVAs assumption of normal distribution, ANOVA is considered robust to violations of its assumptions and can still be utilized with little chance of incorrectly rejecting the null hypothesis (incurring a Type I error). Results ANOVA ANOVA values indicated statistically significant differences between experimental treatments in all four parameters of analysis: pH, EC, total P, and orthoP. Statistically significant differences are not desired between replicates, however, they were found in EC, total P, and orthoP; this indicates that a greater number of replicates could be used to obtain more significant results. Statistically significant differences were also found between sa mple types in all four parameters of analysis. Finally, statistically significant differences were found among sampling dates for pH, EC, and total P measurements. However, significant differences were not found among sampling dates for ortho P analysis; a longer sampling period could have yielded significant differences for this parameter of analysis. Refer to Table 23 for ANOVA values. Total P Flowthrough samples Total P concentrations of samples taken from collection tanks varied depending on the sediment treatments being deployed in each core. On average, flowthrough water

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53 from control cores, wherein no treatment was applied, experienced the highest concentrations of total P with a mean concentration of 0.4331 mg L1 over the course of the study. C ores treated with lime exhibited the second highest levels of total P in flowthrough water with a mean concentration of 0.3356 mg L1 over the course of the study. The third highest total P concentrations in flowthrough samples were found in cores treated with a layer of gravel; the mean total P concentration in these samples was 0.1456 mg L1. Finally, the lowest total P concentrations in flowthrough samples occurred in cores treated with a layer of OPC; the mean total P concentration of these samples was 0.0282 mg L1. Refer to Table D 4 and Figure E 1. Water column samples In samples taken from the water column of each core, total P concentrations were, on average, the highest in cores treated with lime; the mean total P concentration of these cores was 1.0056 mg L1 over the course of the study. The second highest mean concentration occurred in control cores that were not treated; samples taken from the water column of these cores had a mean total P concentration of 0.9063 mg L1. The third highest total P concentrations in water column samples were found in cores treated with a layer of gravel and exhibited a mean concentration of 0.2219 mg L1. Finally, cores treated with a layer of OPC were characterized by the lowest total P concentrations among water column samples; the mean total P concentration of these samples was 0.0315 mg L1. Refer to Table D 8 and Figure E 2. Porewater samples Samples extracted from the porewater of cores treated with OPC exhibited the highest levels of total P with a mean concentration of 15.6422 mg L1.The second highest total P concentrations measured in porewater occurred in samples from gravel -

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54 treated cores and had a mean concentration of 11.9749 mg L1.The third highest total P concentrations measured in porewater were in cores treated with lime; the mean total P concentration of these samples was 6.3213 mg L1. Finally, the lowest concentrations of total P in sediment porewater were measured in control cores that did not undergo any treatment method; the m ean total P concentration of these samples was 1.80148 mg L1. Refer to Table D 12 and Figure E 3. Ortho P Flowthrough samples Ortho P concentrations in flowthrough samples followed the same pattern among treatment methods. Control cores with no treatment exhibited the highest orthoP concentrations and had a mean of 0.07492 mg L1 over the course of the study. Flowthrough samples in cores treated with lime had a mean orthoP concentration of 0.0636 mg L1. As with total P concentrations, the orthoP concentration of flowthrough samples in gravel treated cores was the third highest with a mean of 0.0267 mg L1. Finally, the lowest orthoP concentration in flowthrough samples occurred in cores treated with a layer of OPC; the mean orthoP concentrati on of these samples was 0.0121 mg L1. Refer to Table D 5 and Figure E 4. Water column samples As with total P concentrations in water column samples, cores treated with lime exhibited the highest levels of orthoP with a mean concentration of 0.2641 mg L1. Just below this concentration were the control cores with no treatment method; the mean orthoP concentration of water column samples in these cores was 0.2348 mg L1. Ortho P levels in water column samples taken from gravel treated cores were lower and had a mean concentration of 0.0359 mg L1. Similarly, cores treated with OPC yielded

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55 water column samples with lower orthoP concentrations; the mean orthoP concentration of these samples was 0.0101 mg L1. Refer to Table D 9 and Figure E 5. Porewater samples As with total P concentrations, the cores treated with OPC exhibited the highest levels of orthoP in porewater samples; the mean orthoP concentration of these samples was 9.9566 mg L1. Cores treated with gravel produced porewater with the second highest levels of orthoP with a mean concentration of 7.2028 mg L1. Ortho P concentrations in porewater samples were the third highest in cores that had been treated with lime and exhibited a mean concentration of 3.8357 mg L1. Finally, the lowest concentrations of orthoP in porewater occurred in control columns that did not undergo any kind of treatment; the mean concentration of these samples was 0.8153 mg L1. Refer to Table D 13 and Figure E 6. Electrical Conductivity Flowt hrough samples Flowthrough EC remained stable for the duration of the study. On average, control columns exhibited the highest EC (916.4130 S cm1); the second highest EC occurred in columns treated with lime (803.9194 S cm1) and the third highest EC w as measured in columns treated with gravel (677.4222 S cm1). The lowest flowthrough EC occurred in columns treated with OPC (580.3333 S cm1). Refer to Table D 6 and Figure E 7. Water column samples Water column sample EC remained mostly stable for the duration of the study with fluctuations similar to those in flowthrough samples. On average, control columns exhibited the highest EC (873.9375 S cm1); the second highest EC occurred in

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56 columns treated with lime (842.1719 S cm1) and the third highest EC was measured in columns treated with gravel (667.7469 S cm1). The lowest water column sample EC occurred in columns treated with OPC (587.7656 S cm1). Refer to Table D 10 and Figure E 8. Porewater samples Porewater EC remained mostly stable for the duration of the study. On average, columns treated with gravel exhibited the highest EC (1153.7514 S cm1); the second highest EC occurred in columns treated with OPC (1071.1097 S cm1) and the third highest EC was measured in columns treate d with lime (927.0458 S cm1). The lowest water column sample EC occurred in control columns with no treatment (886.5806 S cm1). Refer to Table D 14 and Figure E 9. pH Flowthrough samples The pH of flowthrough samples fluctuated over the cours e of the study; despite some changes, the pH in all columns remained between 7.89 and 8.5 over the course of the study. Control columns with no treatment exhibited the highest average pH over the duration of the study (8.29). Limetreated columns had the second most alkaline average pH in flowthrough samples (8.27). Finally, gravel and OPC treated columns exhibited the most basic flowthrough pH of the column (8.15 and 8.16, respectively). Refer to Table D 7 and Figure E 10. Water column samples Th e pH in water column samples fluctuated over the course of the study but the pH in all treatment columns remained between 7.85 and 8.58. Columns treated with lime exhibited the highest average pH over the course of the study (8.35). More acidic

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57 than thes e columns were the control columns, which exhibited an average pH of 8.33 over the course of the study. As with flowthrough samples, the lowest average pH values were measured in gravel and OPC treated columns (8.16 and 8.18, respectively). Refer to Tabl e D 11 and Figure E 11. Porewater samples In porewater samples, the pH in all treatment columns displayed an overall decrease over time. OPC treated columns exhibited the highest average pH over time (8.63). The second highest average pH was recorded i n gravel treated columns (8.61). Finally, lime treated and control columns exhibited the most acidic pHs (8.45 and 8.43, respectively). Refer to Table D 15 and Figure E 12. Discussion Control Treatment Total phosphorus On average, porewater sam ples exhibited the highest total P concentrations in the control columns (Table D 16; Figure E 13). Over the duration of the study, porewater samples had an average concentration of 1.7978 mg L1; water column samples had the second highest average concentration (0.9996 mg L1) and flowthrough samples had the lowest average concentration (0.5024 mg L1). Although total P concentrations are the highest in porewater samples in all treatment columns, control columns exhibit the smallest difference between porewater concentrations and concentration in water column and flowthrough samples. The average difference between porewater and water column samples over the course of the study was 1.0277 mg P L1; the average difference between porewater and flowthrough samples was 1.3683 mg P L1. This implies that there was a more open transfer between the sediment water column

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58 interface than in other treatment columns where a more distinct gradient was present. Forty two days after the treatments were applied, the water column total P concentration exceeded the porewater concentration; this could be explained by increased exchange between the sediment and water column due to the physical mixing process. Refer to Table 25 for mean, standard deviation (SD), standard error (SE), minimum, and maximum of total P in flowthrough, water column, and porewater samples. Ortho phosphate Ortho P concentrations were also highest in porewater samples and averaged 0.7144 mg L1 (Table D 17; Figure E 14). As with total P, ort hoP concentrations were second highest in water column samples, averaging 0.2510 mg L1, and flowthrough samples had the lowest average orthoP concentration (0.0448 mg L1). The average difference between porewater and water column concentrations and between porewater and flowthrough concentrations were 0.4624 mg L1 and 0.6685 mg L1, respectively. Refer to Table 26 for mean, SD, SE, minimum, and maximum of orthoP in flowthrough, water column, and porewater samples. Hydrated Horticultural Lime Total phosphorus Total P concentrations were, on average, the highest in porewater samples (6.2288 mg L1), second highest in water column samples (1.1504 mg L1), and lowest in flowthrough samples (0.3856 mg L1) (Table D 18; Figure E 15). The averag e difference between total P concentrations in porewater and water column samples was 5.2894 mg L1, while the difference between porewater concentrations and flowthrough

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59 concentrations was 5.9857 mg L1. Refer to Table 25 for mean, SD, SE, minimum, and maximum of total P in flowthrough, water column, and porewater samples. Ortho phosphate Ortho P concentrations were, on average, highest in porewater samples (3.2255 mg L1), second highest in water column samples (0.2938 mg L1), and lowest in flowthrough samples (0.0415 mg L1) (Table D 19; Figure E 16). The average difference between orthoP concentrations in porewater and water column samples was 3.1840 mg L1, while the difference between porewater concentrations and flowthrough concentr ations was 2.9317 mg L1. Refer to Table 26 for mean, SD, SE, minimum, and maximum of ortho P in flowthrough, water column, and porewater samples. Efficacy Columns treated with lime did not exhibit any moderate or strong correlation between p orewater samples and flowthrough samples or between porewater samples and water column samples for any of the four testing parameters: pH, EC, total P, and orthoP. The strongest negative correlation occurred between mean pH in porewater samples and water column samples ( r = 0.47). This weak moderate negative correlation implies that, while the lime did not promote a reduction in flowthrough or water column P concentrations in comparison to porewater P concentrations, the application of lime did impact t he pH of the sediment. Refer to Table 27 for correlation coefficients of pH, EC, total P and orthoP in flowthrough, water column, and porewater samples.

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60 Limestone Gravel Total phosphorus As with the control and limetreated columns, total P concentratio ns were, on average, highest in porewater samples (13.4647 mg L1), second highest in water column samples (0.1988 mg L1), and lowest in flowthrough samples (0.1956 mg L1) (Table D 20; Figure E 17). The small difference in concentration between water column samples and flowthrough samples implies that, because of the physical barrier between the sediment and water column, particulates were not as prevalent in the limestonetreated water columns as they were in control or limetreated columns. Additional ly, the average porewater concentration in the gravel treated columns is more than twice that of lime treated columns and more than six times that found in control columns; this indicates that less total P was released from the sediment in the limeand gr avel treated columns than from the sediment in the control columns. The average difference between total P concentrations in porewater and water column samples was 13.0584 mg L1, while the difference between porewater concentrations and flowthrough conce ntrations was 11.8291 mg L1. Refer to Table 25 for mean, SD, SE, minimum, and maximum of total P in flowthrough, water column, and porewater samples. Ortho phosphate Over the duration of the study, orthoP concentrations were, on average, the highest in porewater samples (7.0265 mg L1); average orthoP concentrations were second highest in water column samples (0.0179 mg L1) and were the lowest in flowthrough samples (0.0205 mg L1) (Table D 21; Figure E 18). The average difference between orthoP concentrations in porewater and water column samples was 7.0086 mg L1, while the difference between porewater concentrations and flowthrough

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61 concentrations was 7.0060 mg L1. Refer to Table 26 for mean, SD, SE, minimum, and maximum of ortho P in flowthrough, water column, and porewater samples. Efficacy Gravel treated columns also exhibited weak to moderate negative correlations between porewater samples and flowthrough samples and between porewater samples and water column samples in all four analysis parameters. Correlations coefficients for pH ranged from 0.16 to 0.08, from 0.15 to 0.09 for EC measurements, and from 0.33 to 0.20 for total P; these relationships all exhibited weak negative correlations. Despite these weak correlations, orthoP measurements exhibited moderate negative correlations between porewater sample sand flowthrough samples ( r = 0.64) and between porewater samples and water column samples ( r = 0.58). Refer to Table 28 for correlation coefficients o f pH, EC, total P and orthoP in flowthrough, water column, and porewater samples. Ordinary Portland Cement Total phosphorus The average total P concentration in OPC treated columns was highest in porewater samples (16.9111 mg L1), second highest in wat er column samples (0.0331 mg L1), and lowest in flowthrough samples (0.0312 mg L1) (Table D 22; Figure E 19). The average difference between total P concentrations in porewater and water column samples was 17.0287 mg L1, while the difference between porewater concentrations and flowthrough concentrations was 16.9235 mg L1. Similar to graveltreated columns, the total P concentration in water column samples was only slightly higher than the total P concentration in flowthrough samples; this suggests t hat the physical barrier provided by the OPC prevented the release of particulates into the water column. Refer

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62 to Table 25 for mean, SD, SE, minimum, and maximum of total P in flowthrough, water column, and porewater samples. Ortho phosphate Over the duration of the study, orthoP concentrations were, on average, the highest in porewater samples (9.7871 mg L1); average orthoP concentrations were second highest in water column samples (0.010275 mg L1) and were the lowest in flowthrough samples (0.010255 mg L1) (Table D 23; Figure E 20). The average difference between orthoP concentrations in porewater and water column samples was 9.7768 mg L1, while the difference between porewater concentrations and flowthrough concentrations was 9.7768 mg L1. Refer to Table 26 for mean, SD, SE, minimum, and maximum of ortho P in flowthrough, water column, and porewater samples. Efficacy OPC treated columns exhibited weak moderate negative correlation between pH in porewater and flowthrough samples ( r = 0.28) and in porewater and water column samples ( r = 0.25). There was moderate negative correlation between the EC measurements in porewater ad flowthrough samples ( r = 0.64) and in porewater and water column samples ( r = 0.58). Similar to gravel treated columns, there was weak moderate negative correlation between total P concentrations in porewater and flowthrough samples ( r = 0.39) and in porewater and water column samples ( r = 0.49). Also similar to gravel treated columns, there was a moderatestrong negative correlation between orthoP concentrations in porewater and flowthrough samples ( r = 0.73) and in porewater and water column samples ( r = 0.74). Refer to Table 29 for correlation coefficients of pH, EC, total P and orthoP in flowthrough, water column, and porewater samples.

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63 Table 21 Characterization of lime, gravel and cement (OPC) used for the study. Material Description Lime Hydrated horticultural lime (Hi Yield) applied as a powder and incorporated into the upper 2 cm of sediment. Columns 8, 13, 14, and 16 each received the material at a concentration of 453.5 g lime m 2 Gravel Pea gravel was composed of limestone and had an average grain diameter of 0.64 cm. Columns 1, 3, 6, and 9 each received a 5 cm thick layer of the gravel. OPC OPC was composed of one part Type I/II Portland Cement Commercial Grade Quickrete, two parts Quickrete AllPurpose Sand, and three parts aforementioned gravel. Columns 2, 3, 5, and 7 received 2 L of OPC each (3 cm thick layer ). Table 22. Correlation coefficient ( r ) association definitions r 1 0.8 0.5 0 0.5 0.8 1 Association Strong Moderate Weak None Weak Moderate Strong Table 23. ANOVA values Material pH EC Total P Ortho P Pr > F Sig level Pr > F Sig level Pr > F Sig level Pr > F Sig level Treatment 0.0300 <.0001 *** <.0001 *** <.0001 *** Replicate 0.4716 NS <.0001 *** 0.0427 0.2996 NS Sample type <.0001 *** <.0001 *** <.0001 *** <.0001 *** Sampling date <.0001 *** <.0001 *** 0.0026 ** 0.2002 NS ** and *** are significant at 0.05, 0.01, and 0.001 levels, respectively.

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64 Table 24. Mean, standard deviation (SD), standard error (SE), minimum (Min), and maximum (Max) of pH and electrical conductivity (EC) in flowthrough, water column, and porewater samples that were collected during two months of treatments. Table 25. Mean, standard deviation (SD), standard error (SE), minimum (Min), and maximum (Max) of total phosphorus (TP) in flowthrough, water column, and porewater samples that were collected during two months of treatments Parameter TP (mg L 1 ) Control Lime Gravel OPC Flowth rough Samples Mean 0.43 0.34 0.15 0.03 SD 0.43 0.34 0.15 0.03 SE 0.05 0.03 0.02 0.00 Min 0.06 0.11 0.01 0.01 Max 1.38 0.94 0.49 0.07 Water Column Samples Mean 0.91 1.01 0.22 0.03 SD 0.51 0.72 0.14 0.01 SE 0.09 0.13 0.03 0.00 Min 0.16 0.29 0.01 0 .02 Max 2.08 3.62 0.73 0.06 Porewater Samples Mean 1.85 6.40 11.90 15.64 SD 1.20 6.91 6.37 4.90 SE 0.19 1.10 1.02 0.78 Min 0.15 0.15 0.19 0.97 Max 5.06 22.05 23.06 21.87 Parameter pH EC (S/cm) Control Lime Gravel OPC Control Lime Gravel OPC Flowthrough Samples Mean 8.29 8.27 8.15 8.16 916.45 812.30 677.42 580.33 SD 0.20 8.27 8.15 8.16 916.45 812.30 67 7.42 580.33 SE 0.03 0.03 0.04 0.04 33.51 24.31 33.54 12.87 Min 7.95 7.76 7.36 7.66 535.00 530.09 456.60 421.10 Max 8.61 8.66 8.53 8.47 1464.00 1154.00 1167.00 832.40 Water Column Samples Mean 8.33 8.35 8.16 8.18 873.94 842.17 667.75 587.77 SD 0.23 0 .26 0.23 0.22 153.73 121.23 191.89 86.57 SE 0.04 0.05 0.04 0.04 27.18 21.43 33.92 15.30 Min 7.89 7.95 7.63 7.78 597.60 650.50 436.60 408.20 Max 8.66 8.85 8.51 8.53 1180.00 1036.00 1435.00 795.00 Porewater Samples Mean 8.42 8.45 8.61 8.62 912.64 927.0 5 1148.40 1062.19 SD 0.17 0.21 0.21 0.19 120.02 106.25 95.91 113.71 SE 0.04 0.04 0.04 0.04 27.54 21.69 20.45 24.81 Min 8.13 8.08 8.16 8.12 711.40 704.80 992.40 846.30 Max 8.72 8.74 9.06 8.88 1104.00 1091.00 1313.00 1266.00

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65 Table 26. Mean, standard deviation (SD), standard error (SE), minimum (Min), and maximum (Max) of orthophosphorus (OP) in flowthrough, water column, and porewater samples that were collected during two months of treatments Parameter OP (mg L 1 ) Control Lime Gravel OPC Flowthrough Samples Mean 0.074 0.064 0.027 0.012 SD 0 .099 0.079 0.027 0.012 SE 0.016 0.013 0.005 0.001 Min 0.015 0.014 0.003 0.004 Max 0.486 0.393 0.156 0.046 Water Column Samples Mean 0.24 0.26 0.03 0.01 SD 0.188 0.275 0.067 0.003 SE 0.033 0.048 0.012 0.001 Min 0.012 0.015 0.004 0.003 Max 0.642 1. 402 0.389 0.019 Porewater Samples Mean 0.815 3.836 7.203 9.884 SD 0.532 4.554 4.133 2.572 SE 0.109 0.930 0.844 0.536 Min 0.070 0.136 0.066 6.287 Max 1.980 14.886 15.645 14.602 Table 27. Correlation coefficients of pH, electrical conductivity (EC ), total phosphorus (Total P), and orthophosphorus (OrthoP) in flowthrough, water column, and pore water samples that were collected from limetreated columns during two months of treatments. Parameters Flowthrough Water Column Porewater pH Flowthroug h 1.00 Water Column 0.19 1.00 Porewater 0.09 0.47 1.00 EC Flowthrough 1.00 Water Column 0.73 1.00 Porewater 0.08 0.08 1.00 Total P Flowthrough 1.00 Water Column 0.09 1.00 Porewater 0.09 0.21 1.00 Ortho P Flowthrough 1.00 Wa ter Column 0.08 1.00 Porewater 0.10 0.01 1.00

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66 Table 28. Correlation coefficients of pH, electrical conductivity (EC), total phosphorus (Total P), and orthophosphorus (OrthoP) in flowthrough, water column, and pore water samples that were collecte d from gravel treated columns during two months of treatments. Parameters Flowthrough Water Column Porewater pH Flowthrough 1.00 Water Column 0.62 1.00 Porewater 0.16 0.08 1.00 EC Flowthrough 1.00 Water Column 0.88 1.00 Porewater 0.09 0 .15 1.00 Total P Flowthrough 1.00 Water Column 0.66 1.00 Porewater 0.33 0.20 1.00 Ortho P Flowthrough 1.00 Water Column 0.66 1.00 Porewater 0.64 0.58 1.00 Table 29. Correlation coefficients of pH, electrical conductivity (EC), total phosphorus (Total P), and orthophosphorus (OrthoP) in flowthrough, water column, and pore water samples that were collected from OPC treated columns during two months of treatments. Parameters Flowthrough Water Column Porewater pH Flowthrough 1.00 Water Column 0.50 1.00 Porewater 0.28 0.25 1.00 EC Flowthrough 1.00 Water Column 0.66 1.00 Porewater 0.64 0.58 1.00 Total P Flowthrough 1.00 Water Column 0.94 1.00 Porewater 0.39 0.49 1.00 Ortho P Flowthrough 1.00 Water Colum n 0.81 1.00 Porewater 0.73 0.74 1.00

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67 Figure 21. Map indicating the location within WCA 2A where all sediment cores were collected [Image courtesy of Isayya Kisekka.]

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68 Figure 22. Cattail stand surrounding sample collection area in WCA 2A. [Photo courtesy of the author.] Figure 23. Canal near Chekika Visitors Center in Everglades National Park. [Photo courtesy of the author.]

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69 Figure 24. Laboratory incubation setup with source water container, treatment column, and siphon outflow collection container. [Photo courtesy of the author.] Figure 25. Schematic showing the set up of source water containers, water column and porewater, and flowthrough sample containers. [Image courtesy of the author.]

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70 CHAPTER 3 CONCLUSIONS Hydrated Horticultural Lime There was no statistically significant difference between orthoP or total P concentrations in limetreated columns compared to control columns. Over the course of the laboratory incubation, mean orthoP and total P values in water column and flowthrough samples were most similar to concentrations measured in control columns; water column and flowthrough samples in gravel treated and Ordinary Portland Cement (OPC) treated columns exhibited lower orthoP a nd total P concentrations. Porewater from lime treated columns indicated higher concentrations of orthoP and total P than porewater from control columns and lower concentrations than those measured in gravel and OPC treated columns. This difference indicates the lime was least effective at limiting the flux of orthoP and total P from the sediment to the water column. Limestone Gravel Seven out of 10 and five out of eight sampling dates exhibited a statistically significant difference in total P and ortho P, respectively, between gravel treated columns and control columns. In addition to there being differences between gravel treated columns and control columns, there were differences in total P and orthoP concentrations between the three sample types. As with lime treated columns, total P and orthoP concentrations were highest in porewater samples and water column and flowthrough samples were characterized by lower concentrations. Gravels superiority to lime as a treatment mechanism for reducing P flux is further illustrated by the difference between porewater concentrations and water column and flowthrough. On average, the difference between total P in porewater and water column samples was

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71 5.2894 mg L1 for lime and 13.0584 mg L1 for gravel tr eated columns; this difference of 7.0727 mg L1 implies that the gravel is preventing total P from moving from the nutrient impacted sediment to the low nutrient water column. When comparing porewater samples to flowthrough samples, a weak negative correl ation was found in pH ( r = 0.16), EC ( r = 0.09), and total P ( r = 0.33). Ordinary Portland Cement Compared to other treatments, orthoP and total P concentrations were the lowest in flowthrough and water column samples collected from OPC treated colum ns. Conversely, orthoP and total P concentrations were highest in porewater samples collected from OPC treated columns. These differences imply that OPC was the most effective treatment for limiting P flux from the nutrient impacted sediment to the low nutrient water column. OPCs superiority to gravel and lime treatments was illustrated by the differences between porewater P concentrations and concentrations in flowthrough and water column samples. Porewater in OPC treated columns had a total P concentration 17.0287 mg L1 higher than water column samples and 16.9235 mg L1 higher than flowthrough samples. Porewater in gravel treated columns had a total P concentration 13.0584 mg L1 higher than water column samples and 11.8291 mg L1 higher than flow through samples. OrthoP concentrations followed the same pattern and also indicated the superior efficacy of OPC over gravel. A negative correlation of weak moderate strength was found between total P concentrations in porewater and flowthrough samples ( r = 0.39) and between porewater and water column samples ( r = 0.49). The differences in porewater concentrations between treatments indicate that the layer of OPC was more effective at limiting the flux of P from the nutrient impacted sediment to the l ow nutrient water column. A moderatestrong negative correlation was

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72 found between the orthoP concentrations in porewater and flowthrough samples ( r = 0.73) and in porewater and water column software ( r = 0.74). Concluding Remarks The hypothesis was su pported by orthoP and total P data collected and analyzed in this study. As predicted, the hydrated horticultural lime treatment had limited effect on P flux from the nutrient impacted sediment to the low nutrient water column; water samples collected fr om these columns exhibited the lowest porewater orthoP and total P concentrations, next to control columns, and the highest P concentrations in water column and flowthrough samples. However, although negative correlation between the porewater and flowthr ough samples and other sample types were very weak, there appeared to be a small difference between limetreated columns and control columns. The layer of limestone gravel prevented a greater amount of orthoP and total P from transitioning from sediment to water column, as illustrated by the higher porewater P concentrations and the lower concentrations in water column and flowthrough samples. Because the gravel layer was not impermeable, it can be said that some reduction in P flux resulted from adsorpt ion by CaCO3 binding sites. Finally, as hypothesized, the OPC offered the greatest reduction in P flux of the three treatments evaluated in the study. Data indicates moderatestrong negative correlation between P concentrations in the porewater and other sample types in OPC treated Columns. Additionally, orthoP and total P concentrations in porewater were higher than in any other treatment columns and concentrations in water column and flowthrough samples were the lowest. This indicates that the P was physically blocked from fluxing between the sediment and the water column.

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73 APPENDIX A LIME APPLICATION CAL CULATIONS Lime needs: 2787 2 5 453 m g Core area = 2 r = 215 14 3 cm = 25 706 cm L ime application for each core = core g cm m m g core cm 498 11 000 10 1 787 2 59 453 5 7062 2 2 2

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74 APPENDIX B LABORATORY METHODS A ND DETECTION LIMITS Table B 1. Detection limits and methods for laboratory analysis of total phosphorus (Total P), ortho phosphorus (OrthoP), pH, and electrical conductivity (EC). Parameter Sample Preparation Instrument Detection Limit Total P EPA 365.1 AQ2 0.004 mg L 1 EPA 365.1 AA3 0.0012 mg L 1 Ortho P Filtered AQ2 0.001 mg L 1 Filtered AA3 0.0012 mg L 1 pH ---------AR 60 0.1 pH EC ---------AR 60 10 S/c m

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75 APPENDIX C AR 60 METHODS Prior to measurement of pH, the AR 60 was calibrated at three pH levels (4, 7, and 10) using Fisher Scientifics proprietary buffer solutions certified within 0.01 pH at 25 degrees Celsius. The pH probe was rinsed with DI water and dried with Kimwipes after initial calibration and prior to the measurement of each sample. Readings were recorded as pH when the meter stabilized. Prior to measurement of EC, the AR 60 was calibrated using a LabChem Inc. proprietary conductivity standard (1,409 mho cm1 at 25C). The conductivity probe was rinsed with DDI water and dried with Kimwipes after initial calibration and prior to the measurement of each sample. Once the meter reading stabilized, readings were recorded in S cm1.

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76 APPENDIX D DATA TABLES Table C 1 Total P and orthoP concentrations in water samples collected from the Chekika Visitors Center canal in mg L1. Sample Collection Date Total P Ortho P 11 Aug. 2010 0.0106 Below Detection Limit (0.0012 mg P L 1 ) 1 Sept. 2 010 0.0098 Below Detection Limit (0.0012 mg P L 1 ) 9 Oct. 2010 0.0100 Below Detection Limit (0.0012 mg P L 1 ) 18 Nov. 2010 0.0221 Below Detection Limit (0.0012 mg P L 1 ) 18 Dec. 2010 0.0102 Below Detection Limit (0.0012 mg P L 1 ) Table C 2 Laborator y column treatments. Column Treatment 1 Gravel 2 Ordinary Portland Cement 3 Ordinary Portland Cement 4 Gravel 5 Ordinary Portland Cement 6 Gravel 7 Ordinary Portland Cement 8 Hydrated Horticultural Lime 9 Gravel 10 No Treatment 11 No Tre atment 12 No Treatment 13 Hydrated Horticultural Lime 14 Hydrated Horticultural Lime 15 No Treatment 16 Hydrated Horticultural Lime

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77 Table C 3 Amount of Chekika water supplied to each core after initial application of treatments Column Amount of Water (L) 1 19 2 19.5 3 18 4 20 5 19 6 20.5 7 17 8 19 9 22.5 10 23.5 11 19 12 17 13 17 14 18.5 15 21.5 16 18.5 Table C 4 Means of total P concentrations in flowthrough water samples in mg L1. Number of Days After Application o f Treatments No Treatment Lime Gravel OPC 0 0.2560 0.1771 0.0788 --------7 0.3961 0.3401 0.1275 0.0271 14 0.3422 0.2536 0.1297 0.0212 21 0.2588 0.2849 0.0839 0.0215 28 0.4826 0.4064 0.1996 0.0310 35 0.4412 0.3032 0.1223 0.0279 42 0.5367 0.2904 0.1 164 0.0254 49 0.3584 0.2937 0.1873 0.0395 56 0.4674 0.3224 0.0684 0.0210 63 0.7920 0.6841 0.3449 0.0388

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78 Table C 5 Means of orthoP concentrations in flowthrough water samples in mg L1. Number of Days After Application of Treatments No Treatment L ime Gravel OPC 0 0.2888 0.2077 0.1008 0.0305 7 0.0404 0.1174 0.0147 0.0094 14 0.0239 0.0392 0.0194 0.0111 21 0.0550 0.0466 0.0187 0.0096 28 0.0318 0.0753 0.0186 0.0057 35 0.0465 0.0271 0.0182 0.0117 42 0.0408 0.0271 0.0215 0.014 3 49 0.0351 0.0210 0 .0109 0.0047 56 0.0941 0.0301 0.0124 0.0088 63 0.0928 0.0448 0.0321 0.0156 Table C 6. Mean EC in flowthrough samples (S/cm). Number of Days After Application of Treatments No Treatment Lime Gravel OPC 7 1087.325 0 816.975 0 621.275 0 577.725 0 14 888 .975 0 797.475 0 604.425 0 569.75 00 21 942.15 00 831.725 0 676.825 0 605.15 00 Table C 6. Continued Number of Days After Application of Treatments No Treatment Lime Gravel OPC 28 943.2 000 950.1 000 783.875 0 688.375 0 35 819.5 000 661.4 000 552.475 0 562.075 0 42 874.775 0 759.275 0 619.3 000 497.075 0 49 1059.775 0 1016.55 00 818.525 0 625.225 0 56 915.166 7 750.475 0 765.5 000 581.4 000 63 716.85 00 651.3 000 654.6 000 516.225 0

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79 Table C 7. Mean pH in flowthrough samples (S/cm). Number of Days After Application of Tre atments No Treatment Lime Gravel OPC 7 8.24 8.32 8.18 8.06 14 8.11 8.07 8.05 8.00 21 8.07 8.05 8.11 8.21 28 8.34 8.42 8.19 8.26 35 8.50 8.39 8.38 8.39 42 8.31 8.32 8.33 8.33 49 8.27 8.06 7.89 8.00 56 8.38 8.32 7.98 7.96 63 8.36 8.48 8.27 8.29 Table C 8 Means of total P concentrations in water column water samples in mg L1. Number of Days After Application of Treatments No Treatment Lime Gravel OPC 14 0.4368 0.446 2 0.1100 0.0246 21 0.5465 0.631 2 0.2128 0.0234 28 0.926 2 1.281 9 0.1869 0.0319 35 0.931 7 0.9912 0.2137 0.0270 42 1.735 7 2.194 9 0.1819 0.0302 49 0.720 4 1.0914 0.2591 0.0370 56 0.7741 0.6704 0.3546 0.0366 63 1.1788 0.7375 0.2563 0.0416 Table C 9 Means of orthoP concentrations in water column samples in mg L1. Number of Days After Application of Treatments No Treatment Lime Gravel OPC 14 0.1343 0.1466 0.0178 0.0114 21 0.1484 0.2751 0.1484 0.0088 28 0.4558 0.6604 0.0143 0.0059 35 0.2927 0.2897 0.0229 0.0125 Table C 9. Continued Number of Days After Application of Treatme nts No Treatment Lime Gravel OPC 42 0.2838 0.2936 0.01945 0.0141 49 0.1 262 0.2586 0.0200 0.0069 56 0.182 0 0.0792 0.0165 0.0084 63 0.2549 0.1099 0.0282 0.0131

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80 Table C 10. Mean EC in water column samples (S/cm). Number of Days After Application of Treatments No Treatment Lime Gravel OPC 14 806.875 0 823.675 0 591.375 0 566.45 00 21 846.05 00 844.525 0 608.775 0 602.85 00 28 938.325 0 968.475 0 690.55 00 707.6 000 35 822.75 00 754.1 000 596.9 000 540.925 0 42 855.15 00 789.7 000 613.475 0 492.75 00 49 1087.9 000 1011.25 00 856.5 000 662.85 00 56 827.5 000 776.825 0 700.875 0 550.175 0 63 806.95 00 768.825 0 683.525 0 578.525 0 Table C 11. Mean pH in water column samples (S/cm). Number of Days After Application of Treatments No Treatment Lime Gravel OPC 14 8.28 8.14 8.04 8.09 21 8.14 8.33 8.21 8.18 28 8.47 8.32 8.22 8.05 35 8.56 8.58 8.30 8.46 42 8.40 8.32 8.33 8.33 49 8.16 8.33 7.85 7.99 56 8.29 8.35 8.03 8.01 63 8.35 8.44 8.29 8.32 Table C 12. Means of total P concentrations in porewater samples in mg L1. Number of Days After Application of Treatments No Treatment Lime Gravel OPC 0 0.3476 2.6171 1.7675 3.8576 7 2.1953 10.2365 11.7390 16.0828 14 2.2245 9.7060 12.5923 16.2453 21 2.2125 8.0121 13.6045 17.1788 28 2.1978 6.8675 15.9288 17.0260 35 1.3790 5 .9945 13.0013 15.6813 42 0.9808 5.3535 11.0738 15.5173 49 0.9028 6.0508 12.9363 17.4385 56 2.8915 5.2088 12.3135 19.0660 63 2.6830 3.1663 14.7923 18.328 5

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81 Table C 13. Means of orthoP concentrations in porewater samples in mg L1. Number of Days After Application of Treatments No Treatment Lime Gravel OPC 7 1.3248 6.8872 8.0846 10.804 14 0.8529 4.1382 7.3 309 9.8161 28 1.0892 4.2194 9.85 00 11.6355 42 0.6731 2.3393 5.0643 7.3151 49 0.49 00 3.8448 8.8398 12.3996 63 0.4615 1.5856 4.0475 7.7693 Table C 14. Mean EC in porewater samples (S/cm) Number of Days After Application of Treatments No Treatment Lime Gravel OPC 7 750 920.9 1203.3333 1073.633 3 14 810 934.85 1174.5 1086.625 28 886.3333 918.675 1222 1163.5 42 854.675 870.6 1177.75 1072.25 49 992.2 947.725 1012.675 920.9 63 1026.275 969.525 1132.25 1109.75 Table C 15. Mean pH in porewater samples (S/cm) Number of Days After Application of Treatments No Treatment Lime Gravel OPC 0 8.30 8.08 8.20 8.06 7 8.48 8.55 8.83 8.76 14 8.43 8.50 8.74 8.74 21 7.93 7.89 8.11 8.20 28 8.52 8.56 8.62 8.74 35 7.86 7.79 7.87 7.87 42 8.47 8.32 8.59 8.62 49 8.37 8.42 8.48 8.51 56 7.89 7.85 8.02 8. 07 63 8.29 8.36 8.39 8.43

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82 Table C 16. Mean total P in control columns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 0.3476 -------------0.256 7 2.1953 -------------0 .3961 14 2.2245 0.4368 0.3422 21 2.2125 0.5465 0.2588 28 2.1978 0.9262 0.4826 35 1.379 0.9317 0.4412 42 0.9808 1.7357 0.5367 49 0.9028 0.7204 0.3584 56 2.8915 0.7741 0.4674 63 2.683 1.1788 0.792 Table C 17. Mean orthoP in control columns over t he duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 14 0.8529 0.1343 0.0239 28 1.0892 0.4558 0.0318 42 0.6731 0.2838 0.0408 49 0.49 0.1262 0.0351 63 0.4615 0.25488 0.0928 Table C 18. Mean total P in lime treated columns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 2.6171 ---------------0.1771 7 10.2365 ---------------0.3401 14 9.706 0.4462 0.2536 21 8.0121 0.6312 0.2849 28 6.8675 1.2819 0.4064 35 5.9945 0.9912 0.3032 42 5.3535 2.1949 0.2904 49 6.0508 1.0914 0.2937 56 5.2088 0.6704 0.3224 63 3.1663 0.7375 0.6841

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83 Table C 19. Mean orthoP in lime treated columns over the duration of the st udy in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 14 4.1382 0.1466 0.0392 28 4.2194 0.6604 0.0753 42 2.3393 0.2936 0.0271 49 3.8448 0.2586 0.0210 63 1.5856 0.1099 0.0448 Table C 20. Mean total P in gr avel treated columns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 1.7675 -------------0.0788 7 11.739 -------------0.1275 14 12.5923 0.11 0.1297 21 13.6045 0.212825 0 .0839 28 15.9288 0.1869 0.1996 35 13.0013 0.2137 0.1223 42 11.0738 0.1819 0.1164 49 12.9363 0.2591 0.1873 56 12.3135 0.3546 0.0684 63 14.7923 0.2563 0.3449 Table C 21. Mean orthoP in gravel treated columns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 14 7.3309 0.0178 0.0194 28 9.85 0.0143 0.0186 42 5.0643 0.0195 0.0215 49 8.8398 0.0100 0.0109 63 4.0475 0.0282 0.0321

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84 Table C 22. Mean total P in OPC treated colum ns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 3.8576 ------------------------7 16.0828 ------------0.0271 14 16.2453 0.0246 0.0212 21 17.1788 0.0234 0.0215 28 17.026 0.0319 0.031 35 15.6813 0.027 0.0279 42 15.5173 0.0302 0.0254 49 17.4385 0.0370 0.0395 56 19.066 0.0366 0.021 63 18.3285 0.0416 0.0388 Ta ble C 23. Mean orthoP in OPC treated columns over the duration of the study in mg L1. Number of Days After Application of Treatments Porewater Water Column Flowthrough 14 9.8161 0.0114 0.0111 28 11.636 0.0059 0.0057 42 7.3151 0.0141 0.0143 49 12.40 00 0.0069 0.0047 63 7.7693 0.0131 0.0156

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85 APPENDIX E DATA FIGURES Fig ure D 1 Total P concentrations (mg L1) in flowthrough water samples over the course of the study Figure D 2 Mean total P concentrations (mg L1) in water column samples ov er the course of the study Figure D 3 Mean total P concentrations (mg L1) in porewater samples over the course of the study 0 0.2 0.4 0.6 0.8 1 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC 0 0.5 1 1.5 2 2.5 3 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC 0 2 4 6 8 10 12 14 16 18 20 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC

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86 Figure D 4 Mean orthoP concentrations (mg L1) in flowthrough water samples over the course of the study Figur e D 5. Mean ortho P concentrations (mg L1) in water column samples over the course of the study Figure D 6. Mean orthoP concentrations (mg L1) in porewater samples over the course of the study 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 7 14 21 28 35 42 49 56 63Ortho P Concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC 0 0.2 0.4 0.6 0.8 7 14 21 28 35 42 49 56 63Ortho P Concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC 0 2 4 6 8 10 12 14 7 14 28 42 49 63 Ortho P concentration (mg L1)Number of Days After Application of Treatments Control Lime Gravel OPC

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87 Figure D 7. Mean EC in flowthrough samples (S cm1) Figure D 8. Mean EC in water column samples ( S cm1) Figure D 9. Mean EC in porewater samples (S cm1) 0 200 400 600 800 1000 1200 7 14 21 28 35 42 49 56 63EC (S/cm)Number of Days After Application of Treatments Control Lime Gravel OPC 0 200 400 600 800 1000 1200 14 21 28 35 42 49 56 63EC (S/cm)Number of Days After Application of Treatments Control Lime Gravel OPC 0 200 400 600 800 1000 1200 1400 7 14 28 42 49 63 EC (S/cm)Number of Days After Application of Treatments Control Lime Gravel OPC

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88 Figure D 10. Mean pH in flowthrough samples over duration of laboratory incubation Figure D 11. Mean pH in water column sampl es over duration of laboratory incubation Figure D 12. Mean pH in porewater samples over duration of laboratory incubation 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 7 14 21 28 35 42 49 56 63pHNumber of Days After Application of Treatments Control Lime Gravel OPC 5.00 6.00 7.00 8.00 9.00 14 21 28 35 42 49 56 63pHNumber of Days After Application of Treatments Control Lime Gravel OPC 5.00 6.00 7.00 8.00 9.00 10.00 7 14 28 42 49 63pHNumber of Days After Application of Treatments Control Lime Gravel OPC

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89 Figure D 13. Mean total P in control columns over duration of laboratory incubation. Figure D 14. Mean orthoP in control columns over duration of laboratory incubation. 0 1 2 3 4 0 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Sample Collection Date Porewater Water Column Flowthrough 0 0.5 1 1.5 14 28 42 49 63Ortho P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough

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90 Figure D 15. Mean total P in lime treated columns over duration of laboratory incubation. Figure D 16. Mean orthoP in lime treated columns over duration of laboratory incubation. 0 2 4 6 8 10 12 0 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 1 2 3 4 5 14 28 42 49 63Ortho P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough

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91 Figur e D 17. Mean total P in gravel treated columns over duration of laboratory incubation. Figure D 18. Mean orthoP in gravel treated columns over duration of laboratory incubation. 0 2 4 6 8 10 12 14 16 0 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 2 4 6 8 10 12 14 28 42 49 63Ortho P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough

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92 Figure D 19. Mean total P in OPC treated columns over duration of laboratory incubation. Figure D 20. Mean orthoP in OPC treated columns over duration of laboratory incubation. 0 2 4 6 8 10 12 14 16 18 20 0 7 14 21 28 35 42 49 56 63Total P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough 0 2 4 6 8 10 12 14 16 14 28 42 49 63 Ortho P Concentration (mg L1)Number of Days After Application of Treatments Porewater Water Column Flowthrough

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93 LIST OF REFERENCES Amer, F., A.A. Mahmoud, and V. Sabet. 1985. Zeta potential and surface area of calcium carbonate as related to ph osphate sorption. Soil Sci. Soc. Am. J. 49:11371142. Ann, Y., K.R. Reddy, and J.J. Delfino. 2000. Influence of chemical amendments on phosphorus immobilization on soils from a constructed wetland. Ecol. Eng. 14:157167. Arias, C.A., M. Del Bubba, and H. Brix. 2001. Phosphorus removal by sands for use as media in subsurface flow constructed reed beds. Water Res. 35: 11591168. Avery, G.N. and L.L. Loope. 1983. Plants of Everglades National Park: A preliminary checklist of vascular plants. South Flor ida Research Center Report T 574. Everglades National Park, Homestead, FL. Ballentine, D.J. and C.C. Tanner. 2010. Substrate and filter materials to enhance phosphorus removal in constructed wetlands treating diffuse farm runoff: A review. New Zealand J. Ag. Res. 53:71 95. Barlow, P.M. 2003. Ground water in freshwater saltwater environments of the Atlantic coast. Circular 1262. United States Geological Survey, Reston, VA. Bhada, J.H., W.G. Harris, J.W. Jawitz. 2010. Soil phosphorus release and storage capacity from an impacted subtropical wetland. Soil Sci. Soc. Am. J 74:18161825. Bridgham, S.D., C.A. Johnston, J.P. Schubauer Berigan, and P. Welshampel. 2001. Phosphorus sorption dynamics in soils and coupling with surface and pore water in riv erine wetlands. Soil Sci. Soc. Am. J. 65:577588. Brix, H. 1997. Do macrophytes play a role in constructed treatment wetlands? Water Sci. Technol. 35:1117. Burgoon, P.S., K.R. Reddy, T.A. DeBusk, and B. Koopman. 1991. Vegetated submerged beds with ar tificial substrates. II: N and P removal. J. Environ. Eng. 24:408424. Cation Exchange Capacity. 2002. Agriculture: soil health and fertility. http://www.dpi.nsw.gov.au/ag riculture/resources/soils/structure/cec NSW Department of Primary Industry. Orange, NSW. Cheng, X.Y., M.Q. Liang, W.Y. Chen, X.C. Liu, an d Z.H. Chen. 2009. Growth and contaminant removal effect of several plants in constructed wetlands. J. Int. Plan t Biol. 51: 325 335.

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101 BIOGRAPHICAL SKETCH Kiah Kathleen Barrette was born and raised in Orlando, Florida and has always had a passion for the environment. Following gr aduation from Cypress Creek High Schools International Baccalaureate Program, she attended the University of Miami where she further developed her interest in environmental policy and the environmental sciences. During her time at UM, Kiah was an active member of the Universitys Undergraduate Honor Council, Student Government, Greenpeace, and Zeta Tau Alpha. Ms. Barrette graduated cum laude from the University of Miami in 2009 with a bachelor degree in geological science and ecosystem science and policy Following the completion of her masters degree, Kiah will relocate to Colorado where she will pursue a career in environmental science and/or natural resource law. Ultimately, she hopes to use her interdisciplinary background to bridge the gap between scientists and policy makers as a climate change policy advisor.