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Temporal and Spatial Benthic Variation Along the Bransfield and Gerlache Straits, Antarctica

Permanent Link: http://ufdc.ufl.edu/UFE0042997/00001

Material Information

Title: Temporal and Spatial Benthic Variation Along the Bransfield and Gerlache Straits, Antarctica
Physical Description: 1 online resource (81 p.)
Language: english
Creator: MINER,MITCHELL R
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ANALOG -- ANTARCTICA -- BRANSFIELD -- FORAMINIFERA -- GEOCHEMISTRY -- GERLACHE -- GOULD -- HETEROGENEITY -- INTERSTITIAL -- ISOTOPE -- MICROBIAL -- PATCHINESS -- POREWATER -- PROXY -- REDOX -- REMINERALIZATION -- SEASONALITY -- SEASONS -- SEDIMENT -- SEDIMENTATION -- SPATIAL -- VARIATION -- WAP
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Paleoenvironmental reconstructions are commonly based on benthic foraminiferal assemblages and the elemental and isotopic compositions of individual tests. These proxies may vary depending on seasonal changes to the environmental conditions. To assess the effects of seasonal environmental variation on live foraminifera, collections were made of sediment, pore-water and bottom water samples during two cruises, one in April 2008 (after the summer bloom), and in June 2008 (prior to complete sea ice coverage) to the southern Bransfield and northern Gerlache straits located along the Western Antarctic Peninsula. The region experiences large seasonal variations in organic carbon input to the sediment but the sampled summer bloom was smaller and earlier than typical because of the strong 2007-2008 La Ni?a. Seven stations were sampled along a known productivity gradient and samples were collected from three sites at each station via multicorer drops. The stations can be separated into 3 groups based on extent of organic carbon remineralization. The least remineralization of organic carbon occurs in the southern Bransfield Strait stations (1-3), while deep basins in the northern Gerlache Strait stations (5 and 6), displayed the greatest remineralization of organic carbon. Stations 4 and 7 were intermediate between the other two groups. All stations display strong redox zonation in their pore water concentrations and none reflect elevated organic matter input during the summer bloom. Pore-water compositions occasionally varied more between individual drop sites at stations than between stations, indicating that environments may be more heterogeneous at small spatial scales than across major productivity gradients. The largest observed variations correlated more strongly with differences in water depth than in differences in distance between sites or season and consequently, seasonal variations in pore-water compositions are obscured by the variations associated with water depth. Stations with high productivity have high foraminiferal abundances and low species diversity dominated by the opportunistic species B. pseudopunctata and H. parkerae. Stations defined by low productivity have lower abundances and higher species diversity than other sites. Regardless of the lack of evidence for seasonality in the pore water compositions, foraminiferal assemblages display variations from one season to another. Those sites with variable pore water compositions correlate well with differences in the foraminifera at the sites, reflecting control of microhabitats. This work indicates that variations in organic input to various sections is important to compositions of foraminiferal assemblages, but finer spatial and temporal resolution will be required to determine the effects of seasonal organic carbon deposition on the foraminifera.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: 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 MITCHELL R MINER.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Martin, Jonathan B.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042997:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042997/00001

Material Information

Title: Temporal and Spatial Benthic Variation Along the Bransfield and Gerlache Straits, Antarctica
Physical Description: 1 online resource (81 p.)
Language: english
Creator: MINER,MITCHELL R
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ANALOG -- ANTARCTICA -- BRANSFIELD -- FORAMINIFERA -- GEOCHEMISTRY -- GERLACHE -- GOULD -- HETEROGENEITY -- INTERSTITIAL -- ISOTOPE -- MICROBIAL -- PATCHINESS -- POREWATER -- PROXY -- REDOX -- REMINERALIZATION -- SEASONALITY -- SEASONS -- SEDIMENT -- SEDIMENTATION -- SPATIAL -- VARIATION -- WAP
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Paleoenvironmental reconstructions are commonly based on benthic foraminiferal assemblages and the elemental and isotopic compositions of individual tests. These proxies may vary depending on seasonal changes to the environmental conditions. To assess the effects of seasonal environmental variation on live foraminifera, collections were made of sediment, pore-water and bottom water samples during two cruises, one in April 2008 (after the summer bloom), and in June 2008 (prior to complete sea ice coverage) to the southern Bransfield and northern Gerlache straits located along the Western Antarctic Peninsula. The region experiences large seasonal variations in organic carbon input to the sediment but the sampled summer bloom was smaller and earlier than typical because of the strong 2007-2008 La Ni?a. Seven stations were sampled along a known productivity gradient and samples were collected from three sites at each station via multicorer drops. The stations can be separated into 3 groups based on extent of organic carbon remineralization. The least remineralization of organic carbon occurs in the southern Bransfield Strait stations (1-3), while deep basins in the northern Gerlache Strait stations (5 and 6), displayed the greatest remineralization of organic carbon. Stations 4 and 7 were intermediate between the other two groups. All stations display strong redox zonation in their pore water concentrations and none reflect elevated organic matter input during the summer bloom. Pore-water compositions occasionally varied more between individual drop sites at stations than between stations, indicating that environments may be more heterogeneous at small spatial scales than across major productivity gradients. The largest observed variations correlated more strongly with differences in water depth than in differences in distance between sites or season and consequently, seasonal variations in pore-water compositions are obscured by the variations associated with water depth. Stations with high productivity have high foraminiferal abundances and low species diversity dominated by the opportunistic species B. pseudopunctata and H. parkerae. Stations defined by low productivity have lower abundances and higher species diversity than other sites. Regardless of the lack of evidence for seasonality in the pore water compositions, foraminiferal assemblages display variations from one season to another. Those sites with variable pore water compositions correlate well with differences in the foraminifera at the sites, reflecting control of microhabitats. This work indicates that variations in organic input to various sections is important to compositions of foraminiferal assemblages, but finer spatial and temporal resolution will be required to determine the effects of seasonal organic carbon deposition on the foraminifera.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: 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 MITCHELL R MINER.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Martin, Jonathan B.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042997:00001


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1 TEMPORAL AND SPATIAL BENTHIC VARIATION ALONG THE BRANSFIELD AN D GERLACHE STRAITS, ANTARCTICA B y MITCHELL DYLAN ROBERT MINER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011

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2 2011 Mitchell Dylan Robert Miner

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3 To Bentley the wrinkliest and best friend a guy could ask for I miss you homie.

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4 ACKNOWLEDGMENTS First and foremost I would like to thank my advisor, Jon Martin, for all his help, wisdom and patience over the last 5 years I would also like to thank George Kaminov for his seemingly endless series of ideas, all the time he spent with me in the lab and introducing me to the sport of futbol. Thanks to my other committee members, Tony Rathburn, Ellen Martin and Patrick Inglett for their insightful comments along the way Additional thanks are due to Paul Mueller, Derrick Newkirk, Mary Beth Day, Jason Curti s, Paul Bremner, Mark Brenner, Nita Fahm, Pamela Haines, Ray Thomas and Dow Van Arnam for providing assistance when it was needed. To the National Science Foundation and its grants ANT 0635870 and OCE 0550396 for the financial support over the duration of the projects. I thank my father and mother for their support over the years as well as my friends scattered around the globe. Special thanks to Dr. Kristin Kirkby for making the worst day of my life as bearable as possible and to Michelle Boyco, the editor and chief, for helping me bring this train into the station.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 7 LIST OF FIGURES .......................................................................................................... 8 LIST OF ABBREVIATIONS ............................................................................................. 9 ABSTRACT ................................................................................................................... 10 CHAPTER 1 INTRODUCTION .................................................................................................... 12 Background ............................................................................................................. 12 Study Area .............................................................................................................. 16 2 MATERIALS AND METHODS ................................................................................ 24 Sampling Locations ................................................................................................ 24 Sample Collect ion ................................................................................................... 25 3 RESULTS ............................................................................................................... 31 Pore Waters ............................................................................................................ 31 Dissolved Inorganic Carbon Isotopes ............................................................... 31 Pore Water Concentrations of Redox Sensitive Metals and the SulfateSulfide Couple ............................................................................................... 32 Sediment Characteristics ........................................................................................ 33 4 DISCUSSION ......................................................................................................... 45 Penetration Depths ................................................................................................. 45 Regional Variations in Pore Water Chemistry ......................................................... 46 Group 1 Stations .............................................................................................. 46 Group 2 Stations .............................................................................................. 47 Group 3 Stations .............................................................................................. 48 Sediment Accumul ation Rates ................................................................................ 50 Carbonate ......................................................................................................... 51 Solid Phase Organic Carbon and Nitrogen ....................................................... 52 Seasonal vs. Local Scale Spatial Variability ........................................................... 53 Preliminary Foraminifera Data ................................................................................ 55 5 CONCLUSION ........................................................................................................ 60

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6 APPENDIX A DISTANT BETWEEN CORING SITE LOCATIONS (IN METERS) ......................... 64 B AVERAGED SITE DATA ........................................................................................ 67 LIST OF REFERENCES ............................................................................................... 75 BIOGRAPHICAL SKETCH ............................................................................................ 81

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7 LIST OF TABLES Table page 2-1 Chemical Analysis of bottom water collected via Rosette Drop at all 7 stations on both cruises. ..................................................................................... 29 2-2 Location information for all cores dedicated for geochemical analyses. ............. 30

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8 LIST OF FIGURES Figure page 1 1 Regional Bathymetry with surface currents and station locations displayed. ...... 19 1 2 Regional map displaying surface primary production, current patterns and station locations. ................................................................................................. 20 1 3 Mean annual seaice coverage cycle, from 19781994. ..................................... 21 1 4 Seasonal change of seaice extent and phytoplankton blooms in the AP and wSC regions in 2005/2006 and 2007/2008. ........................................................ 22 1 5 Decadal scale seasonal to inter annual variations of chlorophyll a along the wAP from October 1997 to March 2008. ........................................................... 23 3 1 Site averaged depth profiles for stations 17.. .................................................... 35 3 2 Alkalinity depth profiles for each of the 7 stations. .............................................. 36 3 3 DIC depth profiles for each of the 7 stations ....................................................... 37 3 4 Depth profiles of ammonium for each of the 7 stations ....................................... 38 3 5 Depth profile of 13C of DIC for stations 4 6. ...................................................... 39 3 6 Depth profiles for dissolved porewater silica at each of the 7 stations. ............. 40 3 7 Depth profiles for redox sensitive metals at each of the seven stations. ............ 41 3 8 Depth profiles for wt. % TOC in sediment for each station except 2. .................. 42 3 9 Averaged tOCS:Nitrogen vs. Depth Profile for all 7 stations. ............................. 43 3 10 Excess 210Pb vs. depth profile for stations 46. Error bars for each point are horizontally displayed. ........................................................................................ 44 4 1 Alkalinity vs. DIC values plotted for all samples collected. ................................. 58 4 2 Pie chart break down of the dominant species within the foraminiferal standing stock by season for all stations as reported by Bordeleon (2009). ....... 59 5 1 Species Mentioned, Plate 1 ................................................................................ 62 5 2 Species Mentioned, Plate 2 ................................................................................ 63

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9 LIST OF ABBREVIATION S Cmbsf Centimeters Below SeaFloor CRS Constant Rate of Supply Model for determination of sediment age and accumulation rate from 210Pb dating. CTD Bottom Water Concentration, Temperature and Depth 13C of DIC ( )( ) ( )( ) 1 1000 DIC Dissolved Inorganic Carbon dpm/g Disintegrations per minute / gram ENSO El Nio Southern Oscillation HCA Hierarchical Cluster Analysis LMG Research Vessel Lawrence M. Gould MBS Meters Below Ocean Surface MC Multi corer mM millimoles NOAA National Oceanographic and Atmospheric Administration RBG Rose Bengal Vital Stain SDI ShannonWeiner Diversity Index SLP Sea level Presure TC Total Carbon in Sediment TN Total Nitrogen in Sediment TOC Calculated difference between TC and CaCO3 concentratio ns of sediment wAP western Antarctic Peninsula

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10 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 TEMPORAL AND SPATIAL BENTHIC VARIATION ALONG THE BRANSFIELD AN D GERLACHE STRAITS, ANTARCTICA By Mitchell Dylan Robert Miner May 2011 Chair: Jonathan B. Martin Major: Geology Paleoenvironmental reconstructions are commonly based on benthic foraminiferal assemblages and the elemental and isotopic compositions of individual tests These proxies may vary depending on seasonal changes to the environmental conditions To assess the effects of seasonal environmental variation on live foraminifera, collections were made of sediment, porewat er and bottom water samples during two cruises one in April 2008 (after the summer bloom) and one i n June 2008 (prior to complete sea ice coverage) to the southern Bransfield and northern Gerlache straits located along the Western Antarctic Peninsula. Th e region experiences large seasonal variations in organic carbon input to the sediment but the sampled summer bloom was smaller and earlier than typical because of the strong 20072008 La Nia. Seven stations were sampled along a known productivity gradient and samples were collected from three sites at each station via multicorer drops The stations can be separated into 3 groups based on extent of organic carbon remineralization. The least remineralization of organic carbon occurs in the southern Bra nsfi eld Strait stations (1 through 3), while deep basins in the northern Gerlache Strait stations (5 and 6),

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11 displayed the greatest remineralization of organic carbon. Stations 4 and 7 were intermediate between the other two groups All stations display strong redox zonation in their pore water concentrations and none reflect elevated organic matter input during the summer bloom Pore water compositions occasionally varied more between individual drop sites at stations than between stations, indicating that env ironments may be more heterogeneous at small spatial scales than across major productivity gradients The largest observed variations correlated more strongly with differences in water depth than in differences in distance between sites or season and consequently, seasonal variations in porewater compositions are obscured by the variations associated with water depth Stations with high productivity have high foraminiferal abundances and low species diversity dominated by the opportunistic species B. pseudopunctata and H. parkerae Stations defined by low productivity have lower abundances and higher species diversity than other sites Regardless of the lack of evidence for seasonality in the pore water compositions, foraminiferal assemblages display variations from one season to another Those sites with variable pore water compositions correlate well with differences in the foraminifera at the sites, reflecting control of microhabitats This work indicates that variations in organic input to various sections is important to compositions of foraminiferal assemblages, but finer spatial and temporal resolution will be required to determine the effects of seasonal organic carbon deposition on the foraminifera.

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12 CHAPTER 1 INTRODUCTION Background The distribution and assemblage of benthic foraminifera, along with isotopic and element compositions of individual tests, are widely used as proxies for the reconstruction of paleoenvironmental parameters such as bottom water oxygen concentrations, water temperature, organic carbon flux and organic carbon source. The value of these proxies derives from the ubiquity and diversity of foraminiferal species found in both fossil and modern assemblages (Altenbach and Sarnthein, 1989) In order to determine the fidelity with which these proxies record paleoenvironments, it is necessary to establish the relationships between modern analogue species and their existing environmental conditions These conditions include organic matter concentrations, redox conditions as well as porewater concentrations of various elements and isotopes (Murray, 2001). Seasonal variations in surface primary productivity may lead to corresponding variations in particulate organic matter flux to the seafloor and food abundances for both microbial and meiofaunal communities. Variations in fluxes of organic carbon also alter redox conditions of the pore water and thus concentrations of terminal electron acceptors available to microbial communities. These conditions influence foraminiferal abundances, assemblages, depth distribution, test geochemistry and taphonomy on an intra annual time scale (Schmiedl et al., 1997; Gooday & Rathburn, 1999; Kit azato et al., 2000; Wollenburg & Kuhnt, 2000; Alve & Murray, 2001; Hayward et al., 2002; Ishman et al., 2007; Heinz & Hemleben, 2003). Because foraminifera and bacteria are responsive to environmental perturbations on the scale of days to weeks these intra-

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13 annual variations can lead to intraannual variability in foraminifera assemblages and test composition of the standing stock (Fontanier et al., 2003; Langezaal et al., 2006), thereby impacting interpretations of long term climactic variations in the prox y records. Epifaunal and infaunal obligate aerobic meiofauna, such as most foraminifera, are dependent on the availability of dissolved O2 in their environment in order to remineralize organic matter Concentrations and sediment penetration depth of O2 display an inverse relationship with the concentration of available organic matter in water saturated environments. This inverse relationship is a result of the microbial communitys ability to remineralize organic carbon via a sequence of terminal electr on acceptors arranged by their decreasing energy yields, and first includes oxygen, then nitrate, manganese oxide, ferric oxide, sulfate and CO2 (Froelich et al., 1979; Postma and Jakobsen, 1996; Langezall et al., 2006). This sequence of terminal electron acceptors results in vertical stratification of redox zones in the porewaters which control microhabitat viability for foraminifera. In many regions, seasonal changes in organic matter flux to the benthos results in microbially mediated changes in the thi ckness of these zones and can initiate vertical shifting and compression of successively deeper redox zones (Jorissen et al., 1998; Van der Zwaan et al., 1999; Fontanier et al., 2002, Langezall et al., 2006) Benthic foraminifera are the first of the meiof auna to respond to an increase in flux of organic matter to the seafloor (Pfannkuche and Soltwedel, 1998) and have been observed to migrate vertically towards the sediment surface, where they increase reproduction, within days of a pulse of organic matter (Fontanier et al., 2003) Because of this rapid response to organic matter pulses, variability in both standing stock assemblage and depth distribution, and to a lesser degree variability in elemental

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14 (Ca2+, Mg2+, Fe 2+, Rb1+, Sr1+1318O) within foraminiferal tests, may occur on subannual time scales Seasonal organic matter pulses, of distinctly different magnitudes, have been observed in different environments, but even in environments receiving large seasonal pulses, the or ganic matter available from the pulse may be small when compared to the quantity of labile organic matter available year round in shallow marine sediments (Isla 2004) A large cache of organic carbon could act to minimize seasonal effects on redox zonation associated with episodic or seasonal fluxes of organic carbon. For example, seasonal analysis of porewater chemistry, bracketing pulsed fluxes of organic carbon in the Bay of Biscay, displays stable redox zonation, with oxygen penetration ranging from 0. 3 0.8 cmbsf, while the foraminiferal standing stock experienced disproportionate fluctuations (Fontanier et al., 2003, 2005) This observation indicates that factors other than, or in addition to, redox chemistry and simple organic matter availability may act to control abundances and distributions of foraminiferal assemblages, either individually or in concert (Langezaal et al., 2006) Laboratory experiments indicate that foraminiferal ecology is controlled by a diverse series of factors including oxygen availability, food quantity and food quality. Studies focusing on effects of shifting redox zonation agree that depletion of oxygen is the primary factor regulating depth distribution and vertical migration of foraminifera (Alve and Bernhard, 1995; Ernst, 2002; Geslin et al., 2004) Foraminiferal abundance increased with food addition in all studies, but the reported numbers of species reacting to the food addition varied between studies (Heinz et al., 2002; Ernst, 2002; Langezaal et al., 2006) The varianc e may be due to species specific feeding strategies and

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15 consequent different reactions to types of food (Heinz et al. 2002, Suhr et al., 2003) Additionally, Ernst (2004) found that under extended periods of anoxia, high concentrations of food availability increased the survival rate of some species Further complicating the use of foraminifera as a paleoenvironmental proxy is spatial heterogeneity of organic matter distribution on the seafloor termed patchiness (Grassle 1989, Fontanier 2002, Isla 2002) This patchiness, suggested to be a result of current activity and microbathymetry (Thiel et al., 1990), may cause variations in foraminiferal standing stock as well as porewater geochemistry on a local scale (< 1000m) Previous workers investigating the relationship between seasonality and benthic foraminifera have noted the potential effects of patchiness while stating the necessity of the study of replicate cores for seasonal verification (Barmawidjaja et al., 1992) Variations in foraminiferal standi ng stock and benthic geochemistry, correlated with seasonal variations in organic matter flux have recently been reported in a variety of environments (Schmiedl et al., 1997; Gooday & Rathburn, 1999; Kitazato et al., 2000; Wollenburg & Kuhnt, 2000; Alve & Murray, 2001; Hayward et al., 2002; Heinz & Hemleben, 2003) One such location is the continental slope of Western Antarctica Peninsula (wAP), where seasonal variation in surficial biomass, organic matter flux to the seafloor and shifts in the benthic micr obial and faunal ecology have been documented (Karl et al., 1991; Isla et al., 2002, 2005; Smith et al., 2008) These seasonal variations have not previously been linked to foraminiferal standing stock and porewater geochemistry and thus to forge this link, we analyze in this paper porewater geochemical composition, sediment geochemistry, and foraminiferal standing stock

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16 from replicate push cores, recovered from 7 stations over 2 seasons, along a productivity gradient connecting the Southern Bransfield and Northern Gerlache Straits Pore water and sediment geochemistry are used to characterize the regional productivity gradient and are compared with previously reported surface productivity, organic matter flux to the seafloor and variations in redox condi tions Cores from replicate sites, within individual stations, are used to examine the prevalence of local scale spatial heterogeneity in benthic geochemistry This information is then compared to distributions of foraminifera to determine the relationship between the standing stock and the regional, local and intraannual variation observed in the benthic geochemistry. Study A rea The study area consists of sections of two back arc extensional basins, known as the Northern Gerlache and Southern Bransfield Straits, on the continental slope of the wAP ( Figure 1 1) (Jeffers, Anderson, 1991) Glacial scouring formed steep bathymetric relief and jagged shorelines, which divert the northeast trending current into a series of clockwise gyres in both straits ( Figu re 1 2) (Hoffman et al., 1996) These gyres increase the residence time for surface water within the straits The high latitude location of the region, between ~63 and ~65 S, leads to a large seasonal difference in light availability, ranging from 20 hours of daylight during austral summer to less than 4 hours in the austral winter and a correspondingly large variation in seaice coverage ( Figure 1 3 ) Sea ice, a dominant control of Southern Ocean marine ecology, has been reported to reach maximum coverage in the region (> 1.0 x 105 km2) around the austral winter solstice and an average minimum coverage (< 0.1 x 105 km2) around the vernal equinox (Stammerjohn and Smith, 1996) During winter, seaice insulates the water

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17 column from light, limiting surfic ial biomass to ~4 mg C m3 and resulting in minimal organic matter flux to the seafloor (Karl et al., 1996) In austral spring, when seaice retreat begins, a combination of factors triggers a rapid increase in surface primary productivity rate. The melt ing of sea ice enhances the bloom by simultaneously increasing light availability, stabilizing the water column (Hoffman et al., 1996; Smith et al., 2008) and releasing a pulse of micronutrients, specifically iron (Fe), deposited on the seaice over the austral winter via aeolian transport (Sedwick and DiTullio, 1997) This seasonal bloom commonly reaches 3, a 3 order of magnitude increase in comparison to austral winter These biomass concentrations are greater than any nonpol luted coastal 2d1 (Karl et al., 1996, Smith et al., 2008) Conversely, organic matter flux to the seafloor during the austral winters is some of the lowest ever recorded (Karl et al. 1996) The relationship between the melting of seaice and surface primary production is many faceted. In fact the timing of the retreat of the seaice greatly affects magnitude of the ensuing bloom The stabilization of the water column as a result of melting is the key The El Nio Southern Oscillation (ENSO) greatly affects weather patterns along the wAP Negative ENSO, termed La Nia, index values are related to anomalously low sea level pressure (SLP) west of the Antarctic Peninsula, leading to cyclonic mer idonal winds pushing warm, stormy air along the wAP and leading to low values of seaice coverage as well as an earlier retreat (Park et al., 2010, Stammerjohn et al., 2008; Vernet et al., 2008) The high SLP associate with El Nio has the opposite effect, leading to cold southern air circulating in an anti cyclonic pattern leading to prime ice

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18 forming conditions and late retreat During La Nia years the early retreat o f the seaice (October December) and subsequent thickening of coastal seaice as a resul t of the mechanical effects of winds leads to a deeper mixing layer limiting nutrient availability to the photic zone and producing a smaller bloom El Nio years typically see a slower, later retreat (January March) of sea ice, allowing for in situ melting and formation of a stable shallow mixing layer and high productivity Thus, generally, El Nio and La Nia years correspond to higher and lower surface productivity respectively (Vernet et al., 2008). The 20072008 austral summer was the strongest La Ni a event of the decade (NOAA) and resulted in an early and rapid seaice retreat in October (Park et al., 2010) ( Figure 1 4) This event resulted in peak surface productivity occurring very early (December) and being of a lower than average magnitude for the entire wAP shelf ( Figure 1 5) Our initial cruise was planned to directly follow peak organic carbon flux to the benthos resulting for peak PPR along the wAP which typically occurs in late January This earlier and smaller bloom resulted in an earlier and smaller organic carbon flux and thus minimal geochemical variations within the benthos which may have stabilized prior to our initial cruise

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19 Figure 1 1. Regional Bathymetry with surface currents and station locations displayed. Stations are broken into groups based on the concentrations of remineralization byproducts observed in pore waters at the stations (modified from Isla et al. 2004)

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20 Figure 1 2. Regional map displaying surface primary production, current patterns and station locat ions The highest surface productivity is found in the slow moving gyres formed by the glacial fjords in the Gerlache Strait. Stations have been categorized by color into groups based on the concentrations of the carbon remineralization byproducts (mod ified from Isla et al. 2004)

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21 Figure 1 3 Mean annual seaice coverage cycle, from 19781994, in km2 for the LTER in the northern Gerlachesouthern Bransfield Straits with error bars one standard deviation (Modified from Stammerjohn and Smith, 1996).

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22 Figure 14. Seasonal change of sea ice extent and phytoplankton blooms in the AP and wSC regions in 2005/2006 and 2007/2008. The green rectangles indicate the region of the study as illustrated in Figure s 1 and 2. The blue (dark grey) and red (grey) colors represent grid cells in which chlorophyll a concentrations were higher than 0.5 and 1.0mg/ m3, respectively. Black lines indicate the mean sea ice extent in October, November, and January. It is appar ent that sea ice retreat in the study area was complete by the beginning of December in 2007 as a result of the La Nina. The comparison with the 2005/2006 El Nino year shows the significant difference in both rate of seaice retreat and magnitude of the s pring bloom. Modified from Park et al. (2010)

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23 Figure 1 5. Decadal scale seasonal to inter annual variations of chlorophyll a along the wAP from October 1997 to March 2008. Eight day composite chlorophyll a data were used. Note that only austral summertime data are shown (October to the following March due to light limitations ). Grid l i nes indicate the first week of each year. The peak PPR for the 07/08 Austral spring can be seen occurring earlier than usual in November December. Modified from Park et al. (2010).

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24 CHAPTER 2 MATERIALS AND METHODS Sampling Locations Seven sampling locations ( Figure 1 2) were chosen along a productivity gradient (Karl et al., 1991, 1996; Isla et al., 2002, 2005) traversing the southern Bransfield and Northern Gerlache straits (Figure 1 1) These locations encompass the spatial and temporal variability of organic matter flux to the seafloor that results from the differential surface productivity between the end of austral summer bloom and beginning of austral winter oligotrophy Stations 1 through 4 are located in the Southern Bransfield strait and are overlain by relati vely low productivity surface waters (12 g C m2d2) (Figure 1 2) Surface productivity overlying stations 1 and 2 is influenced by nutrient poor circumpolar deep water flowing in from the Drake Passage through the Boyd Strait Though the western continental shelf is flooded by Circumpolar Deep Water, defined by temperatures > 1.0C, salinities 34.634.73 ppt, and oxygen values < 4.5ml l1, below a depth of 200 m, only stations 1 and 2 showed evidence for this water ( Table 2 1) All other stations were mor e similar to Bransfield Strait Water (<0C, 34.4534.6) Sampling sites at station 1 range in water depth from 579 to 600 m and is located on the southeastern shelf of the volcanic Snow Islands Station 2 sites, at water depths from 989 to 1228 m, are loc ated in a depression at the intersection of the Boyd and Bransfield Straits while station 3, with site depths of 616 638 m, is on the edge of the primary northeast trending channel of the Bransfield Strait Station 4 (> 600 mbs) lies just north of the Crok er Passage, which marks the intersection of the Gerlache and Bransfield Straits.

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25 Stations 5 and 7 are located in the Northern Gerlache Str a it where surface productivity rates reach 23 g C m2d2 ( Figure 1 2) Station 7 (> 630 mbs) lies outside of the primary channel of the Gerlache in a leg that empties into the Orleans Canyon. Station 5 is in the Croker passage, a basin with water depths greater than 1200 m at the intersection of the Gerlache and Bransfield Straits Station 6 is in a depression greater than 1100 m underlying the highest productivity surface waters in the study area (35 g C m2d2) (Figure 1 2). Sample C ollection Foraminifera, sediment, and porewater samples were collected during two separate cruises in 2008 on the R/V Lawrence M. Gould (LMG) to the wAP The first cruise (LMG 0408) took place in austral autumn, shortly after the vernal equinox, while the second cruise (LMG 0 808) occurred immediately after the austral winter solstice. Seven sampling stations ( Figure 1 2) were chos en along a productivity gradient (Karl et al., 1991, 1996; Isla et al., 2002, 2005) traversing the southern Bransfield and Northern Gerlache straits ( Figure 1 1) These locations encompass the spatial and temporal variability of organic matter flux to the seafloor that results from the differential surface productivity between the end of austral summer bloom and beginning of austral winter oligotrophy. Samples were collected during five dedicated sciences days on both cruises A multicorer (MC) apparatus w as loaded with up to twelve, 10cm diameter, plastic core tubes that were each capable of gathering undisturbed sediment to a depth of ~36 cmbsf At each of the 7 stations, the MC was dropped 3 or more times to retrieve undisturbed sediment cores from water depths ranging from ~580m to ~1230m (Table 2 2) Within this paper, we refer to each drop as a site, and present data from individual

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26 sites as well as averages of all sites at each station A single core from each of two sites per station was allocated f or extraction of porewater The longest and least disturbed of the cores were chosen Bottom water was collected, ~2 m above the seafloor, with a rosette drop during which bottom water salinity, oxygen concentration, temperature and depth (CTD) were recor ded through the water column at each station (Table 2 1 ). Cores designated for foraminifera sampling were rapidly transported to the onboard aquarium room where they were extruded and sliced into 0.5 cm intervals for the top 3cm and into 1.0cm intervals down to 10 cmbsf (Bordelon, 2009) The slices were washed with distilled water (18 Mohm; DI) into labeled Nalgene bottles and preserved using a mixture of 37% formaldehyde, filtered seawater and borax to attain a concentration of 4% formaldehyde. The preser ved slices were treated with a 65ml of rose Bengal (RBG) solution, prepared by mixing 1g RBG/900mL DI 100mL formaldehyde, and allowed to soak for at least 3 weeks to allow the stain to set The RBG stained samples were rinsed into a graduated cylinder wi th 150mL of DI water and the sediment volume was recorded. Nested 63 and 150 m mesh sieves were then used to split the sediment into different size fractions All of the 63 m samples were split using a Folsom splitter due to the high volume of sand retai ned Whole splits or samples were wet picked, sorted, counted and analyzed for each interval. Cores dedicated to the pore water analyses were enclosed in a nitrogenfilled glovebag within 10 minutes of retrieval on deck The cores were sectioned into 1cm thick subsamples over the top 2 cm and in 2cm thick subsamples from 2 cmbsf to the bottom of the core. All subsamples down to 10 cmbsf were placed into nitrogen filled 50mL gradu ated plastic centrifuge vials. Below a depth of 10 cmbsf subsamples were

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27 alt ernatively placed into centrifuge vials and in whirlpack bags, which were sealed and refri gerated for sediment analysis. Loaded vials were centrifuged (5000 rpm, 15 min) after which the volume of supernatant was estimated using gradations on the side of the centrifuge vials Supernatant was extracted from the vials and aliquots were filtered into various vials for subsequent analyses Sediment remaining in the centrifuge tube was retained for shorebased sediment analysis Alkalinity was measured immediatel y after extraction via the Gran Titration method using an Orion 850 pH meter Concentrations of ammonium, via a modification of the Solorzano (1969) method, phosphate via the Strickland and Parsons (1968) method as modified by Presley (1971) for DSDP pore fluids, and sulfide using the p phenelynediamine FeCl3 technique (Cline, 1969) were all determined colorimetrically onship All shipboard colorimetric analyses were performed within 2 hours of extraction on a Milton Roy Spectronic 401 Spectrophotometer Standards were prepared before each sampling run and measured in sequence with the samples so that samples and standards reacted over the same time period. Additional aliquots were preserved for shorebased analysis as follows: two 3 ml aliquots were inje cted into borosilicate glass vials and preserved with 10 l HgCl2 13C analysis, 8 ml were injected into acid washed HDPE vials and preserved with 10 l of optima grade Nitric Acid (Fischer Scientific) for trace met al analysis, and the remaining filtered volume was retained in HDPE vials for major cation/anion analysis All preserved porewater samples were continually refrigerated at a temperature below 4C until they were analyzed. Bottom water and pore water samp13C, trace metals and major ions (Mg2+, Ca2+, SO4 2 -) at the University of Florida (reported errors

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28 reflect analytical precision) using the AutoMate Prep DeviceUIC 5011 CO2 Coulometer system (1.0%), Thermo Finnigan DeltaP lus XL isotope ratio mass spectrometer with a GasBench II universal online gas preparation device ( 0.06), element II (Mn 2.1%, Fe 1.3%) and a Dionex 500 Ion Chromatograph (Mg2+ 2.13%, Ca2+ 1.30%, SO4 2 0.47%) respectively Bottom water and pore water silica concentrations were determined on a Milton Roy Spectronic 401 spectrophotometer by the technique described by Gieskes et al. (1991) Sediment was analyzed for concentration of solid carbonate (all 334 samples) using the AutoMate Prep DeviceUIC CO2 Coulometer system (0.35%) Total carbon (TC) and total nitrogen (TN) (all 334 samples) were measured using Carlo Erba NA1500 CNS Elemental Analyzer (N 0.06%, C 0.28%). Total organic carbon (TOC) was calculated by subtraction of carbonate C from the TC values Sediment cores from stations 4 through 6 were dated using 210Pb (half life 22.3 yr). Radiometric measurements (210Pb and 226Ra) were made using low background gamma counting systems with well type intrinsic germanium detectors (Appleby and Oldfield 1983, Schelske et al. 1994). Sediment ages were calculated using a constant rate of supply (CRS) model (Oldfield and Appleby 1984). Errors in ages were propagated using first order approximations and calculated according to Binford (1990)

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29 Table 21. Bottom Water Tables for LMG 0408 and LMG 0808. Chemical Analysis of bottom water collected via Rosette Drop at all 7 stations on both cruises. Temperatures greater than 0C at station 1 are representative of the influx of Circumpolar Deep Water. Cruise LMG Station Date Time Depth Latitude Longitude Temp C Salinity (ppt) Nitrate (M) O2 (ml/l) DIC (mM) Alkalinity (mM) Fe2+ (M) Mn2+ (M) SO4 2 (mM) 0408 1 4/12/2008 2:10 585 63 03.306 61 35.533 0.6 34.7 5.92 5.48 2.136 2.707 0.035 0.003 28.499 0408 2 4/12/2008 17:40 1227 63 08.875 61 47.389 0.3 34.6 0.5 6.08 2.113 2.693 0.132 0.005 28.385 0408 3 4/13/2008 2:05 618 63 11.272 60 33.816 0.9 34.6 5.07 6.39 2.249 2.318 0.154 0.005 28.390 0408 4 4/13/2008 14:26 628 63 48.017 61 10.077 0.6 34.6 9.05 6.35 2.156 2.422 0.036 0.003 28.418 0408 5 4/14/2008 15:11 1206 63 59.675 61 42.824 0.7 34.6 3.53 6.35 2.177 2.376 0.087 0.004 28.447 0408 6 4/15/2008 9:57 1191 63 15.860 61 48.697 0.5 34.6 0 6.30 2.177 2.455 0.068 0.003 28.467 0408 7 4/15/2008 21:35 630 64 08.340 61 18.582 0.5 34.5 0.68 6.49 2.239 2.454 0.062 0.004 28.268 0808 1 6/30/2008 13:00 585 63 03.306 61 35.533 34.6 5.44 2.180 2.320 0.340 0.049 28.410 0808 2 6/28/2008 6:23 1226 63 08.025 61 47.387 0.4 34.7 7.24 5.61 2.171 2.512 0.257 0.027 28.370 0808 3 7/1/2008 2:05 618 63 11.272 60 33.816 0.9 34.6 27.99 6.19 2.633 2.843 0.094 0.005 28.474 0808 4 6/28/2008 20:43 630 0.7 34.6 21.71 6.21 2.191 2.390 0.285 0.014 28.356 0808 5 6/30/2008 0:29 1176 63 59.747 61 42.536 0.9 34.6 4.72 6.05 2.291 2.481 0.242 0.008 28.438 0808 6 6/29/2008 15:12 1189 64 16.106 61 49.594 0.9 34.6 11.71 6.02 2.199 2.365 0.075 0.004 28.456 0808 7 6/29/2008 5:37 622 64 08.100 61 18.114 0.6 34.6 0 5.83 2.204 2.240 0.176 0.007 28.299

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30 Table 2 2. Location information for all cores dedicated for geochemical analyses. Station Cruise Date Time Depth Latitude Longitude Drop Position Site ID 1 0408 4/11/08 8:59 600m 63 03.212 61 35.590 A 5 1.1 1 0408 4/12/08 5:05 597m 63 03.221 61 35.424 C 12 1.2 1 0808 6/30/08 579M 63 03.245 61 35.446 A 7 1.3 1 0808 7/1/08 20:00 579M 63 03.256 61 35.458 C 7 1.4 2 0408 4/12/08 10:40 1226m 63 08.861 61 47.388 A 8 2.1 2 0408 4/12/08 13:07 989m 63 08.862 61 47.455 B 1 2.2 2 0808 6/28/08 5:14 1227M 63 08.986 61 47.412 B 1 2.3 2 0808 6/28/08 8:38 1227M 63 08.963 61 47.387 C 11 2.4 3 0408 4/13/08 8:35 638m 63 11.284 60 33.722 A 9 3.1 3 0408 4/13/08 14:10 550m 63 11.208 60 33.667 D 3 3.2 3 0808 7/1/08 1:40 616M 63 11.260 60 33.747 A 7 3.3 3 0808 7/1/08 6:03 616M 63 11.339 60 33.865 C 4 3.4 4 0408 4/13/08 23:41 630m 63 48.020 61 09.92 A 8 4.1 4 0408 4/13/08 3:19 628m 63 48.015 61 10.102 C 6 4.2 4 0808 6/28/08 20:04 637M 63 48.01 61 09.89 A 6 4.3 4 0808 6/28/08 23:40 625M 63 48.127 61 09.862 C 11 4.4 5 0408 4/14/08 11:40 1227m 63 59.735 61 42.466 A 12 5.1 5 0408 4/14/08 17:00 1227m 63 59.756 61 42.737 C 12 5.2 5 0808 6/29/08 23:43 1173M 63 59.868 61 42.616 A 12 5.3 5 0808 6/30/08 8:11 1173M 63 59.762 61 42.507 C 3 5.4 6 0408 4/15/08 3:39 1187m 64 15.964 61 49.213 A 1 6.1 6 0408 4/15/08 13:00 1184m 64 16.077 61 49.211 C 7 6.2 6 0808 6/29/08 14:33 1199M 64 16.044 61 49.723 A 8 6.3 6 0808 6/29/08 18:53 1149M 64 16.102 61 49.609 C 5 6.4 7 0408 4/15/08 19:06 615m 64 08.368 61 18.746 A 11 7.1 7 0408 4/15/08 23:00 628m 64 08.351 61.18.535 C 3 7.2 7 0808 6/29/08 4:28 626M 64 08.221 61 18.632 A 5 7.3 7 0808 6/29/08 6:56 624M 64 08.221 61 18.632 B 4 7.4

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31 CHAPTER 3 RESULTS Pore Waters Analysis of bottom water for DIC, alkalinity, ammonium, phosphate, dissolved silica and major and trace element concentrations showed little variation both along the entir e transect and between seasons (Table 21). In contrast, concentrations of these solutes in the porewater varied greatly between stations. Pore water depth profiles for each station reflected standard marine burial diagenesis but the magnit udes, as well as depth of maximum concentration, varied both within and between stations ( Figure s 3 1 through 3 7). Pore waters from stations 1 through 4 are characterized by increasing concentrations of DIC, alkalinity, phosphate and ammonium from sediment water interface values of 2.2 mM, 2.5 mM, 1.6 M and 0 M, respectively, to average maximum values of 3.13.3 mM, 3.3 3.5 mM, 1537 M and 120140 M ( Figure s 3 1 through 3 4). Stations 5 and 6 displayed similar bottom water values but greater siteaveraged concentration maxima for DIC, alkalinity, phosphate and ammonium (6.87.2mM, 7.8 9.0mM, 100 130M, and ~580740M) ( Figure s 3 1 through 3 4). Dissolved silica concentrations for all 7 stations (Figure 36) increased with sediment depth with the highest concentrations (> 1mM) observed at stations 5 and 6. Dissolved Inorganic Carbon Isotopes The lowest site13C values, between -13.1 -13.9 were observed at stations 5 and 6 while at station 4 the siteaveraged minimum was -6.40 ( Figure 3 1 ). 13C throughout the depth profile than their April counterparts ( Figure 3 5). 13C values at station 4 decreased at less than half the rate observed at stations 5 and 6 and display little differ ence in value

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32 13C values as well as the greatest difference in value between sites. Pore Water Concentrations of Redox Sensitive Metals and t he Sulfate Sulfide Couple The redox sensitive trace metals, Fe and Mn, were present in concentrations of < 0.2 M and < 0.02 M respectively in all bottom water samples ( Table 2 1). Bottom water sulfate concentrations were ~ 28 mM at all 7 stations. Maximum concentrations of Mn2+ in porewater occurred at a shallo wer depth than Fe2+ maxima at all 7 stations. Below the Fe2+ maxima, sulfate becomes increasingly depleted with depth. The magnitude and the sediment depth of Fe2+ and Mn2+ peaks, as well as the magnitude of sulfate depletion, varied both between and withi n stations ( Figure s 3 1 and 37). Pore water Fe2+ and Mn2+ concentrations increased from bottom water values by an order of magnitude within the 01 cmbsf interval at all sites at all stations. The highest maximum Mn2+ concentrations, > 9 M, were found at stations 1, 5 and 6 and several sites at station 5 registered values greater than 15 M ( Figure s 3 1 and 37). At stations 4, 5 and 6, the Mn2+ maxima were found in the 12 cmbsf intervals while at all other stations the maxima were found between 2 and 10 cmbsf. Fe2+ concentrations were greater than those of Mn2+ in all analyzed samples, typically by an order of magnitude. Samples from stations 5 and 6 had the highest maximum Fe2+ concentrations with values that ranged from 160230 M occurring at 28 cmbs f. An austral winter core from a station 1 site (Site ID 1.3) displayed maximum Fe2+ concentrations > 156M (46 cmbsf interval) which is three times higher than the maxima identified in any other of the three sites at this station ( Figure 3 7). The Fe2+ m axima at all remaining stations are < 100 M with extensive variation in the depth of

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33 the maxima (218cmbsf). In the majority of cores, rapid depletion of Fe2+ in porewater begins at the interval directly below that of the maxima. Sulfate concentrations decrease with sediment depth at each station ( Figure s 3 1 and 37) Stations 5 and 6 show the greatest decrease in sulfate concentrations (0.090.14 mM/cmbsf) reaching minimum values of ~25 mM at the 2830 cmbsf intervals All other stations had minimum s ul fate concentrations > 27 mM. Sulfide concentrations were below detection limits at all 7 stations. Sediment Characteristics Sediment samples consist primarily of mud with small percentages of sand. The only measurable sedimentary carbonate concentration w as found at a station 4 austral autumn site (Site ID 4.2) which had a maximum concentration of 0.5 0.35 wt. % ( Appendix 2). Maxima for the solid phase total organic carbon were found shallower than 10 cmbsf and displayed a trend of decreasing concentrations with depth at all stations ( Figure s 3 1 and 3 8 ). Station 1 displayed the lowest siteaveraged concentrations of solid phase organic carbon with a maximum < 1.5 0.28 wt. % in the 2 4 cmbsf interval and a minimum of 0.5 0.28 wt. % in the 24 26 cmbsf interval ( Figure s 3 1 and 3 8 ). Stations 3, 4, and 7 displayed the highest site averaged concentrations with maxima > 2.1 0.28 wt. %, observed between 4 and 10 cmbsf. Minimum site averaged concentrations for these 3 stations are < 1.0 0.28 %. The shallowest site averaged maxima were found at Stations 5 and 6 with ~2.0 0.28 % at 2 cmbsf. For these stations organic carbon concentrations displayed the smoothest decrease with depth reaching minimum values of 1.0 1.5 0.28%. The site average sedimentary organic carbon to nitrogen ratio ranged from 5.5 to 9.2 and increased with depth at all stations ( Figure 3 9 ). The lowest values were found at stations 4 and 6.

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34 Sedimentation rates were calculated to be ~1.65 0.01 mm/yr at station 4 and 3.80 0.01 and 2.57 0.01 mm/yr respectively at stations 5 and 6 (Fig ure 3 7 ). The depth of surficial mixing layer, determined by the slope change in the excess 210Pb concentration depth profile ( Figure 3 10), was 2 4 cmbsf interval at stations 4 and 5 and the 12 cmbsf interval at station 6.

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35 Figure 31. Site averaged depth profiles for stations 17. Panels a,b illustrate that TOCs and ONs concentrations decreases with sediment depth. Station 1 concentrations are much lower than other stations. Panel s C H illustrate the significant differences in concentrations of the byproducts or organic material decomposition between stations 5,6 and the rest of the transect. Panels I K illustrate the stratified nature of the redox constituents as well as the sign ificant difference between stations 5,6 and all other stations.

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36 Figure 3 2 Alkalinity depth profiles for each of the 7 stations. Panels A D are distinguished by their limited increase in alkalinity with depth relative to the increase at panels F and G. Panel E is intermediate. Profile variation with water depth where core was collected is visible on panels A C, F and G. Panel A, April cores 20 mbs > than July cores. Panel B, 2nd April core 250 mbs < all others. Panel C, 2nd April core 65 mbs < al l others. Panel F, July cores 55 mbs < April cores. Panel G, 2nd July core 40 mbs < April cores. Panels D and E, all cores collected at similar depths

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37 Figure 3 3 DIC depth profiles for each of the 7 stations. Trends are very similar to those in alkalinity depth profiles. Standard error is 1%. Profile variation with water depth where core was collected is visible on panels A C, F and G. Panel A, April cores 2 0 mbs > than July cores. Panel B, 2nd April core 250 mbs < all others. Panel C, 2nd April core 65 mbs < all others. Panel F, July cores 55 mbs < April cores. Panel G, 2nd July core 40 mbs < April cores. Panels D and E, all cores collected at similar depths.

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38 Figure 3 4 Depth profiles of ammonium for each of the 7 stations. Panels A and B display the lowest increase in ammonium concentrations through the profile while stations 5 6 display the highest. Samples cluster by season at stations 3 5. Pr ofile variation with site water depth is visible on panels A C, F and G. Panel A, April cores 20 mbs > than July cores. Panel B, 2nd April core 250 mbs < all others. Panel C, 2nd April core 65 mbs < all others. Panel F, Jul y cores 55 mbs < April cores. Panel G, 2nd July core 40 mbs < April cores. Panels D and E, all cores collected at similar depths.

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39 Figure 313C of DIC for stations 4 6. Panels B and C have 13C ~2x lighter than illustrated on panel A. Panels B and C display intrastation variation related to depth MC drop.

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40 Figure 36. Depth profiles for dissolved porewater silica at each of the 7 stations. All stations display an increase in dissolved silica with depth. Panels F and G reach the highes t concentrations with values > 1mM. Panels A C and stations D and E group into low and intermediate concentration groups respectively.

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41 Figure 3 7 Depth profiles for redox sensitive metals at each of the seven stations. At stations 1, 5 and 6 all 4 cores were analyzed while at stations 24 and 7 one core from each season was analyzed. Panels A D display redox constituents for stations 24 and 7. It has its own legend to the right of the graph. Panels E K display redox for all cores for stati ons 1, 5 and 6. Stratification of maximum values for the trace metals is apparent at each station. Variation associated with differing water depth is visible. Redox stratification is condensed at stations 5 and 6 where we see our Mn maxima at 12 cmbsf, Fe maxima at 46 cmbsf, and increased sulfate depletion below 8 cmbsf.

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42 Figure 38. Depth profiles for wt. % TOC in sediment for each station except 2. Panel A displays lowest concentrations of sediment TOCS. Panels B, C and F have both the highest concentrations of TOC in their shallow sediments and the lowest remnant TOC concentrations in their core bottoms. Panels D and E display their peak values within the top 2 cmbsf and maintain > 50% of that as the corebottom. Apparent seasonal coupling on Panel A is more likely a result of similar depths cored for both cast in a season.

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43 All Stations Averaged Sediment OC:N Depth ProfileOC:N 6.5 7.0 7.5 8.0 8.5 9.0 9.5 Depth (cmbsf) 0 10 20 30 Station 1 Station 3 Station 4 Station 5 Station 6 Station 7 Figure 39. Averaged tO CS:Nitrogen vs. Depth Profile for all 7 stations. The C:N ratio designated by Redfield is 6.5:1 for marine phytoplankton. Nearly all samples are greater than that as a result of decoupled C:N organic matter degradation processes. Due to the more labile nature of N rich proteins compared to Carbon compounds the C:N ratio will continue to increase with depth.

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44 Figure 310. Excess 210Pb vs. depth profile for stations 46. Error bars for each point are horizontally displayed. The lower bound of the surficial mixing layer, as distinguished by a change in slope of this plot, is represented by the horizontal dotted line. Panel A shows disruption in the SML layer and a non linear decrease of excess 210Pb with depth. Panel B shows the highest concentr ations of excess 210Pb which may have been advectively scavenged by particles being laterally transported and then deposited into the Croker Passage.

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45 CHAPTER 4 DISCUSSION Penetration Depths Previous studies conducted southeast of Anvers Island, just south of our study area, reported maximum oxygen penetration depths ranging from 0.900 0.082 to 3.30 0.410 cmbsf and nitrate penetration from 0.12 0.726 to 5.75 0.75 mmbsf (Hartnett et al 2008), with increasing depth of penetration along an east west transect extending from the Gerlache Strait across the wAP slope. These penetration depths are thought to be a result of the decreasing flux of organic matter with increasing distance fr om shore and the corresponding e ffects on porewater oxygen concentrations ( Reaction 41 ). O2 + CH2O = CO2 + 2 H2O (4 1) In lieu of direct measurements of porewater oxygen concentrations, depth profiles of dissimilatorily reduced Mn and Fe in porewater ar e used as a proxy to estimate the interval at which hypoxic/anoxic conditions are present ( Figure 3 7). Though meiofauna burrows were observed in core tops, the consistent stratification of redox sensitive solutes indicates that bioturbation has minimal ef fects on the redox chemistry at the scale sampled. Pore water depth profiles for biogenic and redox sensitive compounds, including DIC, alkalinity, ammonium, phosphate, dissolved silica, sulfate, manganese and iron, as 13C ), refle ct the amount of remineralization of organic matter between stations, between sites and between seasons. These data are used to assess the redox conditions of the pore water, as well as the decomposition of organic matter in the interval, thus quantifying variations in environmental controls which can affect foraminiferal viability. These environmental controls of foraminiferal ecology are

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46 investigated by comparison of pore water compositions with foraminiferal standing stock observations, such as overall abundance, species diversity and depth distribution. Regional Variations in Pore Water Chemistry Increases of porewater concentrations of DIC, alkalinity, phosphate and 13C value, directly result from the oxidation of ma rine organic matter. Station averaged depth profiles for these solutes reflect standard marine burial diagenesis; the magnitude of changes in concentrations varies between stations ( Figure 3 1). These changes correspond to the late summer surfacewater pro ductivity gradient ( Figure 1 2) (e.g., Karl et al., 1991, 1996; Isla et al., 2002, 2005) and allow the 7 stations to be categorized into 3 geochemical, as well as geographic, groups. Gro up 1 (stations 1 through 3) is located in the region with the lowest s urface productivity in our study area and has the lowest oxidation of organic matter. Group 3 (stations 5 and 6) is located in the region with the highest surface productivity and has the highest oxidation of organic matter. Group 2 (stations 4 and 7), though more similar to group 1 than to group 3, displays an intermediate level of organic matter oxidation. Group 1 Stations The least productive stations, Group 1, lie the furthest from the peninsula in a region previously reported as having low concentratio ns of organic carbon, nitrogen and silica in the sediment along with low sediment accumulation rates and low productivity in overlying surfacewater ( Figure 1 2) (Isla 2002, Varela 2002, Isla 2004). The 2 westernmost stations (1 and 2) in this group are ov erlain by low productivity surface water which is a mixture of open ocean Bellingshausen Sea water (~0.2 g C m2d2) (Varela 2002) and Circumpolar Deep Water, which flows in from the Drake Passage through the Boyd Strait. Mixing of these water masses is shown by higher measured

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47 bottom water temperatures at these stations than the remaining 5 stations ( Table 2 1). Based on the temperature and seafloor currents, bottom water at station 3 is almost exclusively Bransfield Strai t Bottom Water. The geostrophic gyre in the Bransfield Strait increases surface water residence time allowing for austral summer surface productivity to reach 12 g C m2d2. Pore water depth profiles from this group have the smallest maxima for each of th e biogenic compounds ( Figure 3 1 ). Consequently, minor increases of DIC, alkalinity, ammonium and phosphate with depth reflects both the low amounts of organic matter decomposition at these stations, resulting from the overlying low productivity surface waters and limited organic matter input from lateral transport, as well as solute loss via diffusion due to the low reported sedimentation rate. Station 2 displays the lowest maxima of phosphate, ammonium and dissolved silica in the study area, reaching conc entrations of 8, 60 and 804 M respectively. For DIC and alkalinity, the lowest maxima appeared at station 3 (550 640 mbs), located on the edge of the Trinity Island shelf along the primary Bransfield channel. Though station 3 is the nearest to the peninsula of the group 1 stations, it is located immediately down current of the Southern Bransfields largest and deepest basin (> 1000 mbs) which traps sediments and limits deposition of laterally transported organic material at this station. Group 2 Stations The 2 stations in group 2, located near the intersection of the Gerlache and Bransfield Straits, are located down current from the highest productivity region in the area. The porewater depth profiles for biogenic compounds in group 2 validate that ch aracterization. Group 2 stations continue to display standard marine burial diagenesis but with increases in both maximum concentrations and rate of downcore increase compared with group 1.

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48 Group 3 Stations The 2 stations within group 3 are located in s eparate basins (> 1000 m water depth) within the Gerlache strait, which previously had been reported as having high values for sedimentary organic carbon, nitrogen and silica as well as high sediment accumulation rates and high surface primary productivity (Isla, 2004). Pore water depth profiles from this study clearly illustrate that the greatest concentration of organic matter decom position byproducts are found at group 3 stations ( Figure 3 1 ). The high sedimentation rates in these basins may act to prevent diffusion of organic remineralization byproducts to seawater, which when combined with the higher rain rate of organic carbon leads to these elevated remineralization byproduct concentrations. Depth profiles for the analyzed redox sensitive compounds M n2+, Fe2+ and sulfate reinforce the differences in volume of organic carbon remineralized between the geographic groups ( Figure 3 1 ). Group 3 stations have significantly higher concentration maxima for both Mn2+ and Fe2+, as well as lower sulfate minima, ( > 8 M, > 170 M, < 26 mM) than stations of the other 2 groups (< 6 M, < 90 M, >27.5mM), both of which display similar redox profiles. The pore water depth profiles show an increase in the rate of sulfate depletion with depth at about the same depth interval at which rapid Fe2+ depletion begins. These changes in solute concentrations reflect the energy yields for microbially mediated organic matter remineralization (Froelich, 1979). At all 7 stations, the concentration of Mn2+ and Fe2+ increase from botto m water values by more than an order of magnitude in the 01 cmbsf interval as a result of their use as a terminal electron acceptor during organic matter decomposition (e.g., R eactions 4 2 and 4 3). 2 MnO2 + CH2O + 3 CO2 + H22+ + 4 HCO3 (4 2)

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49 4 Fe(OH)3 + CH2O + 7 CO2 2+ + 8 HCO3 + 3 H2O (4 3) Due to the tendency of reduced Fe to undergo rapid oxidation to insoluble Feoxide phases in the presence of free O2, the increase in Fe2+ concentrations indicates depleted O2 conditions below 1 c mbsf. Stations 4, 5 and 6 reach maximum Mn2+ concentrations at 12 cmbsf. Stations 1 through 3 (groups 1) reach maxima at 24 cmbsf, while station 7 is deepest of all states at 6 8 cmbsf. Fe2+ depth profiles follow a similar trend with stations 5 and 6 di splaying the shallowest maxima at 46 cmbsf while the maxima for stations 1 through 3 are found at a depths > 8 cmbsf. The shallowest Fe2+ maxima occurs at Station 4 at 24 cmbsf, while at station 7, the other group 2 station, the Fe2+ maxima is at 68 cmb sf. The stratification of Fe2+ and Mn2+ at all stations indicates anoxic conditions exist at depths greater than a few centimeters. Although pore waters become anoxic at shallow depths, other solute concentrations indicate that organic carbon remineralizat ion continues at all sampled depths and is greatest at the group 3 stations. A linear regression of the DIC and alkalinity depth profiles ( Figure 4 1 ), with R2 value greater than 0.98 ( Appendix 2), reflects consistent degradation of organic matter found at high productivity sites (e.g., Sivan et al. 2005). 13C of porewater DIC values for this group (~ -4.5) also reflects decomposition of large quantities of organic matter and is 2 times lower than the values recorded at station 4 in group 2 ( Figure 3 1 ). At group 3 stations, ammonium concentration maxima increase at a rate of ~22 M/cmbsf making them the highest found in the region with maximum values of 400M 740M ( Figure s 3 1 and 3 4 ). The rapid increase in porewater phosphate over the initial 6 cmbsf ( Figure 3 1 ) can likely be attributed to the early degradation of the highly labile nucleic acids present in

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50 detritus combined with the release of Febound phosphate due to the reduction ferric oxide/hydroxide compounds (e.g., Chambers 1990). As seen in Figure 3 1 this release of phosphate leads to similar profiles of phosphate and iron concentrations. Thus group 3 stations which displayed the greatest reduction of iron also have the highest concentrations of PO4 3 reaching concentration maxima > 100 M by the 46 cmbsf interval, which is 5 and 2 times, respectively the maxima of PO4 3 found in groups 1 and 2. Phosphate depth profiles are further complicated by the pH dependent pr opensity of PO4 3 ions to adsorb to clay minerals. Consequently, porewater PO4 concentrations are more useful in qualitative comparisons than as a quantitative indicator of the amount of organic material being decomposed. Sediment Accumulation R ates The sediment at all stations consists primarily of an olive colored clayey mud with interspersed sand grains. The apparent mean sediment accumulation rate for stations 4, 5 and 6, as calculated from 210Pb analysis, demonstrated significantly higher rates of accumulation in t he deeper group 3 stations, 5 and 6 than in the shallower group 2 station, 4 ( Figure 3 10 ). Our apparent mean sediment accumulation rates for stations 5 and 6 (3.80 0.01 and 2.57 0.01 mm/yr respectively) are higher than the previously reported values (1.80 0.20 and 1.57 0.13 mm/yr respectively) for this section of the Gerlache Strait (Isla et al. 2002). The higher inventories of 210Pb in surface sediments found at the deep water stations 5 and 6 (~60 dpm/g) agree with the previousl y reported trend of increased isotopic inventory with water depth in this region (Isla et al. 2002). The high 210Pb inventories can be explained by considering the 210Pb enrichment of particles as a result of elemental scavenging during advection processes and the

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51 focusing of material into these deepwater basins (Rutgers van der Loeff and Berger, 1991; Isla et al. 2002) Carbonate Carbonate concentrations in the sediment were immeasurable in all but 1 core and foraminifera collected from this project are reportedly smaller than expected (Rathburn personal comm.). When carbonate minerals undergo dissolution, CO3 2 is released which increases alkalinity and DIC at a 2:1 molar ratio. Anaerobic oxidation of organic matter, via the reduction of sulfate, nitrate, Mn or Fe releases HCO3 -, thereby increasing alkalinity and DIC at a 1:1 molar ratio, while aerobic oxidation produces CO2, increasing DIC but not alkalinity. Linear regressions, forced through the origin, applied to an alkalinity vs. DIC scatter plot for each station had slopes ranging from 1.05 to 1.12 0.011 ( Figure 4 1 Appendix 2). The strongest linearity was found at group 3 stations with R2 values > 0.96 while R2 values for other stations ranged from 0.708 0.811, likely as a result of a smaller r ange of concentrations. Though the alkalinity:DIC ratio is not solely controlled by these processes, a majority of porewater DIC may be sourced from anaerobic oxidation of organic matter with small amount of carbonate mineral dissolution. The low concentr ation of carbonate in the sediment, along with smaller than anticipated test size of carbonatesecreting foraminifera in the study area, supports the idea of carbonate dissolution being a minor factor at this location. Maximum concentrations of total organic carbon were observed in the upper 10 cmbsf at all stations, however the maxima were not found in the shallowest intervals (01 cmbsf) (Figure s 3 1 and 3 8 ). Siphoning off the bottom water in the core top may have removed lighter, flocculent particulate organic carbon lying on the sediment surface. The large inter annual variability in primary productivity found in this region, with this

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52 years smaller bloom, maybe an alternative explanation (Fig. 5). At all 7 stations, station averaged total organic carbon minima are < 50% of the maxima, with a decrease of ~1 wt.% at stations 3, 5, 6 and 7 and 1.8 wt % at station 4 ( Appendix 2). Station 1 has notably lower values for total organic carbon than the other stations and thus displays a correspondingly lower depletion of 0.6 wt. %. Total organic carbon concentrations continue to decrease with depth below the zone of oxygen penetration, thereby illustrating the importance of anaerobic processes, particularly sulfate reduction, in shallow sediment diagenesis i n this region. Sulfate concentrations experience deplenishment at each station ( Figure 3 7 ), ranging from a decrease 0.095 mM from bottom water concentrations at the low productivity station 1 to 3.46 mM at the highly productive station 5 ( Appendix 2). The oxidation of organic carbon via sulfate reduction ( Reaction 4 4 ) indicates that for every mM of sulfate reduced we should see 2 mM increase of alkalinity and DIC as well as a 1 mM increase in H2S. SO4 2 + 2 (CH2O) = H2S + 2 HCO3(4 4) Sulfate:alkalini ty:DIC ratios ranged from -1.00:0.85:1.12 at station 2 to -1.00:2.03:2.04 at station 1 ( Appendix 2). The lack of measurable H2S is likely to be a result of the reaction of H2S with Fe2+ to form iron sulfides (Reaction 45) 2 H2S + Fe2+ 2 + 2H2 (4 5) Solid Phase Organic Carbon and Nitrogen Total organic carbon concentrations vary widely between sediment samples at identical depth intervals that are extracted from cores of different sites within the same station. This variation in organic carbon c oncentrations matches trends observed in the porewater profiles, and reflects the highly heterogeneous nature of the seafloor in this region. The C/N ratio defined by Redfield for surface primary productivity is 6.5:1. The

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53 C/N ratios observed at all stati ons were above Redfield values indicating a marine surface source for the organic matter which has undergone some amount of degradation ( Figure 3 9 ). Due to the higher lability of nitrogenrich proteins over carbonrich macromolecules, C/N ratios increase as organic matter is decomposed. Because of this decoupling of the carbon and nitrogen cycles we see the C:N ratio increase down core. Values greater than expected based on the Redfield ratio can be used to estimate the relative level of decomposition of t he remnant organic matter buried at depth. Seasonal vs. Local Scale Spatial Variability Comparison of the porewater depth profiles from the different stations illustrate regional scale (10 160 km) environmental variability caused by differing surface pr oductivity, current patterns and effects of basinal focusing. Local scale comparisons of depth profiles for sites within individual stations are less clear. Though porewaters from each site followed standard marine burial diagenetic patterns, the magnitude of the gradients of the porewater constituents varied greatly between sites at individual stations, including those collected during the same season ( Figure s 3 1 through 3 7 ). This variation in intrastation porewater concentrations seems to indicate t hat local scale (< 1000m) spatial variability in seafloor ecology, or patchiness, previously reported in this region (Smith 2008), is widespread and must be taken into account when characterizing environmental conditions in the region. Station 6 provides a good example of the lack of geochemical consistency between sites at a station. An austral winter core (Site ID 6.4), collected at a water depth ~35 m shallower than the other 3 sites from this station ( Table 2 2), displayed two times lower maximum concentrations 13C and higher sulfate minimum concentrations than all other sites from this station.

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54 Pore water depth profiles from the high productivity station 5 appear to display seasonal signals below a depth of 18 cmbsf for alkalinity, ammonium, DIC, sulfate, Fe2+ and Mn2+ ( Figure s 3 1 through 3 7 ). The depth profiles for the sites sampled during austral winter indicate greater carbon remineralization than during the austral autumn, when high flux of organic carbon and greater remineralization would be expected. Both sites sampled during the austral a utumn cruise were sampled at a depth of 1227 mbs while both sites from the austral winter cruise were sampled at 1173 mbs ( Table 2 1 ). Distances between sites at this station were greater intraseasonally than inter seasonally ( Appendix 1). The correlation between notable differences in porewater compounds associated with carbon remineralization and difference in depths and distances between sites reflects the large control that local scale spatial heterogeneity has on the environmental conditions. The FOO DBANCS project identified the presence of a permanent benthic food source along the wAP which may explain the seeming lack of seasonality visible at the sampling scale for our geochemical analysis (Smith et al. 2008). Through the use of sediment traps, Smi th et al. (2008) reported particulate organic carbon fluxes varying by ~2 to 3 times between austral summer and winter in the year 2000. They reported inter annual differences in particulate organic carbon of 4 to 10 times between the austral summers of 20 00 and 2001. These differences indicate that inter annual variation in surface productivity can be extremely large in this region, exceeding that associated with seasonality. Direct time series measurement of O2 and NO3 concentrations (Hartnett et al. 2008) over the same time period showed microbial oxidation of organic matter in this

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55 region occurred throughout the year, although at a 2.5 to 7 times greater rate during the summer than winter. It was also reported that though the pattern of increased parti culate organic carbon flux and decreased porewater O2 and NO3 concentrations did correlate, the magnitude of change of decrease for the reduced species was lower than would be expected if all the organic carbon was remineralized. Hartnett et al. (2008) s uggested that the extremely low bottom water temperatures (0.6 -0.9 C) reduce the kinetic rate of microbial oxidation of organic matter, dampening the effects of particulate organic matter flux on the benthic community and leading to a permanent carbon source in the food bank. Preliminary F oraminifera D ata Limited information on foraminifera distributions have been reported (Bordelon, 2009), which can be compared with our geochemical data. Using the ShannonWiener Diversity index (SDI), Bordelon (2009) d etermined which of our stations displayed relative species evenness and which stations were dominated by a certain species. A hierarchical cluster analysis (HCA) was then used to group the stations by their similarities in SDI. She found that in austral wi nter the stations fell into the same grouping that has been defined by the geochemistry: group 1 (stations 1 through 3), group 2 (stations 4, 7) and group 3 (stations 5 and 6). Austral autumn groupings differed from austral wi nter groupings, with stations 4 through 7 showing variability in their index, while stations 1 through 3 continued to group. Two species were dominant within the study region ( Figure 4 2 ), Haplophragmoides parkerae ( Figure 5 1 .C) and Bolivina pseudopunctata ( Figure 5.2 .C). These two species were found at every station. Haplophragmoides parkerae previously described as characteristic of environments which experience seasonal organic carbon

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56 fluxes (Rasmussen et al., 2002; Hanagata, 2003; Heinz, and Hemleben, 2003; Rathburn et al., 2001), was dominant at the less productive northern stations (1 through 3) in both seasons. At the more productive southern stations (4 through 7) B. pseudopunctata, described as an opportunistic species defining the high organic matter, low oxygen tolerant ni che (Bergen and ONeil, 1979; Mackensen et al., 1995) is more prevalent. Stations 4 through 7 were characterized by low species diversity and orders of magnitude higher total foraminiferal abundance relative to stations 1, 2 and 3 ( Figure 4 2 ). The highest productivity stations, 5 and 6, are dominated by B. pseudopunctata in both seasons, though H. parkerae remains present in high abundance. Station 4 is notable for its shift from nearly a complete lack of H. parkerae in austral autumn to being the dominant species during austral winter. Station 7 only has the 2 dominant species present with H. parkerae displaying slight dominance which decreases in austral winter. Station 1 displayed the highest species diversity of all stations, with an SDI score of 4.14 in austral winter, as well as the greatest shift in assemblage between seasons. This is interesting as station 1 is geochemically characterized by having the lowest concentrations of compounds associated with organic carbon decomposition as well as the low est solid TOC of any station. It has been previously recognized that ecosystems with high food availability tend toward low species diversity while lower food availability correlates with higher species diversity. In the austral autumn, H. parkerae is the dominant species at station 1 with nearly the entirety of its species abundance living between 0 and 1.5 cmbsf. B. pseudopunctata, though lower in overall abundance than H. parkerae, is the dominant

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57 species between 23 cmbsf. The hypoxic conditions can be predicted at the 12 cmbsf interval based on Mn2+ concentrations increasing from 0.09M to 2.22M between the 0 1 and 12 cmbsf intervals ( Figure s 3 1 and 3 7 ) (Glasby, 2006). Average Fe2+ concentrations increase from 6.14 M to 37.5 M between 12 and 24 cmbsf and reach values only possible under anoxic conditions by the 46 cmbsf interval ( Figure s 3 1 and 3 8 ) (Haese, 2006). These depths for hypoxia and anoxia seem to agree with the descriptions of the ecologic niche for these two species.

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58 Figure 4 1 Alkalinity vs. DIC values plotted for all samples collected. A linear regression, forced though the origin, produces a best fit line with a slope of 1.086. This slope indicat es that the primary carbon source of DIC is the anoxic degradation of organi c carbon, which increases alkalinity and DIC by a 1:1 ratio. Dissolution of CaCO3 increases alkalinity and DIC at a 2:1. Aerobic oxidation increases DIC but not alkalinity.

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59 Figure 42. Pie chart break down of the dominant species within the foraminiferal standing stock by season for all stations as reported by Bordeleon (2009). Haplophragmoides parkerae and Bolivina pseudopunctata are the dominant foraminifera species of the region and are present in each group of stations. Haplophragmoides parkerae has been described as an opportunist while B. pseudopunctata has been reported as very adaptable to low O2 concentrations. The highest productivity stations (group 3) are dominated by B. pseudopunctata wh ile the less productive, possible more seasonally influenced, stations are dominated by H. parkerae The total foraminifera abundance for each core is listed in parentheses beneath the label.

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60 CHAPTER 5 CONCLUSION Based on porewater concentr ation profiles, the 7 stations could be categorized into 3 groups: a low productivity group (Stations 1 through 3), an intermediate productivity group (Stations 4 and 7) and a high productivity group (Stations 5 and 6). The locations of these groups generally agree with previous studies conducted in this area. Local heterogeneity in pore water compositions at the scale of a few meters is a common feature in this region based on comparison of sites sampled at individual stations. A powerful correlation between intrastation water depth variance and variance of pore water depthprofiles appears to be greater than anything solely related to seasonality. This observation supports the suggestion made by Thiel et al. (1990) that local scale microbathymetry has a large impact on distribution of organic matter at the seafloor on a local scale. In several cases, geochemical variations caused by variations in depth at individual stations were greater than the geochemical differences observed between stations. Du ring the study period, seasonal rain rates of organic carbon appear to have little impact on the pore water concentrations of individual stations. This is apparent considering that at stations where all 4 sites sampled were of similar depths overlapping pore water depth profiles are the norm. The lack of a discernable seasonal signal may be due to the early onset, and reduced magnitude, of the 07/08 Austral Summer bloom along the wAP as a result of a strong La Nia event. Additionally, the seasonal signal m ay be muted by the large quantity of remnant organic carbon, buried in the sediment, providing a larger control on pore water compositions than the seasonal flux of organic carbon.

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61 Preliminary foraminiferal data from the project suggest that standing stoc k, species diversity (Figure 51) and distribution depth were largely a factor of the presence, or lack thereof, of the 2 dominant foraminiferal species, H. parkerae and B. pseudopunctata, in the region. The more productive stations, groups 2 and 3, were d ominated by these two species over both seasons with only a mild shift in the ratio associated with seasonality. The lower abundance of these 2 species in the low productivity group results in greater species diversity and greater change in the standing st ock assemblage between seasons. The depth distribution of the opportunistic H. parkerae and low O2 tolerant B. pseudopunctata correlated well with apparent low O2 concentrations reflected in Mn2+ and Fe2+ zonation. Alternatively, a seasonal signal may have been present but at a magnitude which cannot be observed, giving the observed effects of seafloor patchiness. Determination of the patchiness would require dense special sampling across a small region. Variations in the pore water composition may vary at seasonal time scales but only at smaller vertical distances than sampled during this project. Additionally, El Nino years such as 2005/2006, featuring a much larger bloom, may increase the vertical scale at which seasonality in the porewaters can be obser ved. Additional studies similar to this performed during a higher productivity season would be important in determining both the effects of seasonality as well as the effects of large inter annual variations on the geochemistry and benthic community of thi s region.

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62 Figure 5 1 S pecies Mentioned, Plate 1: A. Globocassidulina subglobosa. B. Ammodiscus sp C. Haplophragmoides parkerae. D. Astrononion echolsi E. Labrospira wiesneri F. Adercotryma glomeratum .G. Rosalina globularis H. Pullenia subsphaerica. I. Labrosipra jeffreysii J. Lagenammina difflugiformis K. Portatrochammina stenhouseiTrochammina intermedia. M. Saccammina sp .. N. Nonionella iridea .(Bordelon 2009)

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63 Figure 5 2 S pecies Mentioned, Plate 2: A. Rhummblerella sp. B. Milia mmina lata. C. Bolivina pseudopunctata. D. Dodulina dentaliniformis E. Nodulina kerguelenesis F. Miliammina oblnga. G. Textularia wiesneri H. Fursenkoing fusiformis I. Bulimina aculeata.

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64 APPENDIX A DISTANT BETWEEN CORI NG SITE LOCATIONS (IN METERS) Site I.D. 1.1 1.2 1.3 1.4 2.1 2.2 2.3 2.4 3.1 3.2 3.3 3.4 1.1 0 161 156 158 16564 16610 16774 16722 62045 62053 62008 61945 1.2 161 0 55 82 16660 16707 16869 16817 61886 61894 61849 61786 1.3 156 55 0 26 16609 16655 16817 16765 61892 61900 61855 61791 1.4 158 82 26 0 16584 16630 16792 16740 61896 61904 61860 61796 2.1 16564 16660 16609 16584 0 65 267 217 71053 71096 71026 70924 2.2 16610 16707 16655 16630 65 0 267 225 71117 71160 71090 70988 2.3 16774 16869 16817 16792 267 267 0 55 71055 71098 71028 70925 2.4 16722 16817 16765 16740 217 225 55 0 71035 71078 71008 70905 3.1 62045 61886 61892 61896 71053 71117 71055 71035 0 170 57 181 3.2 62053 61894 61900 61904 71096 71160 71098 71078 170 0 135 338 3.3 62008 61849 61855 61860 71026 71090 71028 71008 57 135 0 203 3.4 61945 61786 61791 61796 70924 70988 70925 70905 181 338 203 0 4.1 98582 98525 98480 98460 90757 90780 90520 90556 85528 85698 85566 85366 4.2 98529 98472 98427 98407 90679 90702 90442 90478 85588 85758 85626 85426 4.3 98734 98676 98632 98612 90917 90940 90680 90716 85606 85775 85643 85443 4.4 98817 98759 98715 98695 90988 91011 90751 90787 85715 85884 85752 85552 5.1 120641 120631 120579 120554 108525 108526 108260 108308 122098 122263 122129 121926 5.2 120700 120690 120638 120614 108559 108560 108294 108342 122273 122438 122304 122101 5.3 120932 120922 120869 120845 108803 108803 108537 108585 122412 122578 122443 122240 5.4 120701 120690 120638 120614 108581 108582 108316 108364 122167 122333 122198 121995 6.1 155586 155580 155527 155503 143023 143020 142757 142806 155152 155320 155187 154985 6.2 155826 155820 155767 155743 143264 143261 142997 143047 155364 155532 155399 155197 6.3 155797 155791 155738 155714 143200 143197 142934 142983 155524 155692 155558 155357 6.4 155911 155905 155852 155828 143322 143319 143056 143105 155583 155752 155618 155417 7.1 139778 139741 139692 139670 129686 129697 129430 129473 128891 129061 128931 128735 7.2 139778 139741 139692 139670 129686 129697 129430 129473 128891 129061 128931 128735 7.3 139479 139442 139393 139371 129403 129414 129147 129190 128560 128730 128600 128404 7.4 139479 139442 139393 139371 129403 129414 129147 129190 128560 128730 128600 128404

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65 Site I.D. 4.1 4.2 4.3 4.4 5.1 5.2 5.3 5.4 6.1 6.2 6.3 6.4 1.1 98582 98529 98734 98817 120641 120700 120932 120701 155586 155826 155797 155911 1.2 98525 98472 98676 98759 120631 120690 120922 120690 155580 155820 155791 155905 1.3 98480 98427 98632 98715 120579 120638 120869 120638 155527 155767 155738 155852 1.4 98460 98407 98612 98695 120554 120614 120845 120614 155503 155743 155714 155828 2.1 90757 90679 90917 90988 108525 108559 108803 108581 143023 143264 143200 143322 2.2 90780 90702 90940 91011 108526 108560 108803 108582 143020 143261 143197 143319 2.3 90520 90442 90680 90751 108260 108294 108537 108316 142757 142997 142934 143056 2.4 90556 90478 90716 90787 108308 108342 108585 108364 142806 143047 142983 143105 3.1 85528 85588 85606 85715 122098 122273 122412 122167 155152 155364 155524 155583 3.2 85698 85758 85775 85884 122263 122438 122578 122333 155320 155532 155692 155752 3.3 85566 85626 85643 85752 122129 122304 122443 122198 155187 155399 155558 155618 3.4 85366 85426 85443 85552 121926 122101 122240 121995 154985 155197 155357 155417 4.1 0 172 166 234 39430 39655 39717 39496 69937 70141 70332 70381 4.2 172 0 308 329 39305 39529 39593 39371 69857 70061 70252 70301 4.3 166 308 0 109 39426 39652 39713 39492 69880 70083 70275 70323 4.4 234 329 109 0 39327 39553 39614 39393 69771 69974 70167 70215 5.1 39430 39305 39426 39327 0 257 316 69 35152 35389 35407 35509 5.2 39655 39529 39652 39553 257 0 264 215 35064 35301 35316 35418 5.3 39717 39593 39713 39614 316 264 0 248 34849 35085 35103 35204 5.4 39496 39371 39492 39393 69 215 248 0 35089 35326 35344 35445 6.1 69937 69857 69880 69771 35152 35064 34849 35089 0 241 502 470 6.2 70141 70061 70083 69974 35389 35301 35085 35326 241 0 479 372 6.3 70332 70252 70275 70167 35407 35316 35103 35344 502 479 0 163 6.4 70381 70301 70323 70215 35509 35418 35204 35445 470 372 163 0 7.1 44145 44124 44037 43931 28762 28928 28689 28755 32567 32684 33061 33030 7.2 44145 44124 44037 43931 28762 28928 28689 28755 32567 32684 33061 33030 7.3 43818 43797 43709 43604 28646 28814 28576 28639 32816 32935 33310 33280 7.4 43818 43797 43709 43604 28646 28814 28576 28639 32816 32935 33310 33280

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66 Site I.D. 7.1 7.2 7.3 7.4 1.1 139778 139778 139479 139479 1.2 139741 139741 139442 139442 1.3 139692 139692 139393 139393 1.4 139670 139670 139371 139371 2.1 129686 129686 129403 129403 2.2 129697 129697 129414 129414 2.3 129430 129430 129147 129147 2.4 129473 129473 129190 129190 3.1 128891 128891 128560 128560 3.2 129061 129061 128730 128730 3.3 128931 128931 128600 128600 3.4 128735 128735 128404 128404 4.1 44145 44145 43818 43818 4.2 44124 44124 43797 43797 4.3 44037 44037 43709 43709 4.4 43931 43931 43604 43604 5.1 28762 28762 28646 28646 5.2 28928 28928 28814 28814 5.3 28689 28689 28576 28576 5.4 28755 28755 28639 28639 6.1 32567 32567 32816 32816 6.2 32684 32684 32935 32935 6.3 33061 33061 33310 33310 6.4 33030 33030 33280 33280 7.1 0 0 331 331 7.2 0 0 331 331 7.3 331 331 0 0 7.4 331 331 0 0

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67 APPENDIX B AVERAGED SITE DATA Core # cmbsf TOC wt% wt% N DIC (ug/g) DIC (mM) 13C Alkalinity (mM) Ammonium Phosphate Silica 1 B.W. 0.00 26.61 2.16 2.71 0.00 1.60 94.61 0-1 0.51 0.07 28.06 2.27 2.40 5.68 6.50 444.29 1-2 0.69 0.09 31.28 2.54 2.55 10.06 8.49 547.65 2-4 1.14 0.14 30.79 2.50 2.64 9.54 9.76 674.81 4-6 1.13 0.14 30.63 2.48 2.64 31.07 8.49 698.49 6-8 0.72 0.09 31.16 2.53 2.65 35.22 8.31 725.18 8-10 0.63 0.08 30.54 2.48 2.63 41.38 8.13 737.93 12-14 0.75 0.09 31.93 2.59 2.67 60.87 9.22 767.62 16-18 0.55 0.07 33.44 2.71 2.82 54.22 10.85 801.33 20-22 0.53 0.07 35.38 2.87 3.00 88.82 13.39 852.33 24-26 0.50 0.06 37.19 3.01 3.31 101.95 13.94 867.46 28-30 0.51 0.06 38.26 3.10 3.45 131.75 13.39 878.03 32-34 0.56 0.07 40.28 3.27 3.50 119.76 15.03 829.61 2 B.W. 0.44 26.42 2.14 2.69 0.00 1.60 90.31 0-1 31.29 2.54 2.64 3.62 4.14 477.33 1-2 0.46 30.27 2.45 2.54 4.58 4.02 615.34 2-4 0.18 31.91 2.59 2.71 4.58 7.36 685.92 4-6 0.50 31.45 2.55 2.72 5.39 6.41 699.44 6-8 0.36 32.21 2.61 2.71 3.26 6.09 680.71 8-10 0.53 33.46 2.71 2.88 25.85 6.45 712.38 12-14 35.27 2.86 3.06 34.48 6.78 789.64 16-18 36.79 2.98 3.19 54.97 7.57 795.49 20-22 38.52 3.12 3.29 59.63 7.89 804.92 Core Information Oxidation of Organic Matter Sediment

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68 Core # cmbsf TOC wt% wt% N DIC (ug/g) DIC (mM) 13C Alkalinity (mM) Ammonium Phosphate Silica 3 B.W. 0.00 0.00 30.11 2.44 2.32 0.00 1.96 84.94 0-1 1.07 0.14 28.17 2.28 2.61 16.53 9.76 510.84 1-2 1.93 0.25 30.29 2.46 2.50 15.24 9.58 629.58 2-4 2.03 0.25 33.65 2.73 2.74 38.51 15.03 712.53 4-6 1.98 0.24 29.98 2.43 2.69 47.83 19.93 782.36 6-8 1.80 0.22 32.51 2.64 2.69 30.80 20.65 799.63 8-10 1.49 0.18 32.99 2.67 2.73 30.70 27.73 834.76 12-14 1.15 0.14 33.09 2.68 2.83 40.27 29.18 866.27 16-18 1.21 0.15 32.78 2.66 2.96 59.25 27.55 875.73 20-22 1.30 0.16 34.45 2.79 2.99 72.12 30.09 889.45 24-26 1.17 0.14 35.87 2.91 3.16 94.55 29.18 889.12 28-30 1.13 0.14 37.23 3.02 3.25 119.33 27.00 901.79 32-34 0.93 0.11 39.32 3.19 3.20 109.41 26.28 932.55 4 B.W. 0.00 0.00 26.81 2.17 2.42 0.00 1.23 86.01 0-1 1.45 0.20 28.59 2.32 -1.52 2.46 15.38 10.88 505.35 1-2 1.37 0.19 30.24 2.45 -2.37 2.60 15.29 13.45 629.37 2-4 2.21 0.29 32.74 2.65 -2.63 2.65 21.11 14.74 726.18 4-6 1.69 0.24 31.19 2.53 -2.93 2.74 43.56 16.58 789.83 6-8 1.90 0.27 32.40 2.63 -3.48 2.76 50.40 20.62 813.27 8-10 1.89 0.26 33.20 2.69 -5.00 2.94 60.15 23.93 849.50 12-14 1.17 0.17 35.49 2.88 -4.78 3.25 93.36 33.13 909.55 16-18 1.11 0.16 38.57 3.13 -5.81 3.46 118.34 37.36 928.64 20-22 0.94 0.14 38.00 3.08 -5.98 3.44 127.42 31.29 948.36 24-26 0.94 0.13 38.25 3.10 -6.00 3.50 122.14 31.84 850.88 28-30 0.68 0.12 38.37 3.11 -6.02 3.45 118.60 27.43 938.53 32-34 0.41 0.11 38.89 -6.40 3.44 101.00 28.17 935.37 Core Information Sediment Oxidation of Organic Matter

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69 Core # cmbsf TOC wt% wt% N DIC (ug/g) DIC (mM) 13C Alkalinity (mM) Ammonium Phosphate Silica 5 B.W. 0.00 0.00 27.56 2.23 2.38 0.00 1.60 87.09 0-1 1.50 0.19 30.19 2.45 -3.31 2.61 4.13 9.14 440.05 1-2 1.90 0.24 33.92 2.75 -4.09 2.73 45.46 14.89 622.27 2-4 1.62 0.20 36.17 2.93 -5.64 3.14 69.47 87.97 826.40 4-6 1.71 0.21 41.48 3.36 -7.10 3.48 124.27 92.08 863.81 6-8 1.72 0.22 46.32 3.76 -7.30 3.88 172.80 87.15 898.54 8-10 1.47 0.18 50.48 4.09 -8.61 4.31 224.22 87.15 934.88 12-14 1.72 0.21 58.85 4.77 -10.14 5.06 313.92 90.44 999.00 16-18 1.62 0.20 65.67 5.32 -11.12 5.89 405.29 109.33 1086.10 20-22 1.34 0.16 73.19 5.93 -12.02 6.54 451.71 115.90 1031.06 24-26 1.21 0.14 81.47 6.60 -12.43 7.16 542.60 127.39 1042.82 28-30 0.96 0.15 88.77 7.20 -13.11 7.88 578.48 130.68 1045.18 6 B.W. 0.00 26.99 2.19 2.45 0.00 1.60 87.09 0-1 1.19 0.18 29.27 2.37 -1.82 2.60 5.85 6.68 411.78 1-2 1.51 0.21 33.70 2.73 -4.08 2.79 35.45 12.42 621.61 2-4 1.43 0.20 38.32 3.11 -5.35 3.28 85.40 51.02 788.72 4-6 1.52 0.22 42.21 3.42 -6.87 3.69 147.88 78.94 806.18 6-8 1.55 0.21 46.43 3.76 -8.38 4.22 204.14 79.76 851.49 8-10 1.44 0.20 50.15 4.07 -8.52 4.62 236.82 75.66 894.77 12-14 1.47 0.19 58.85 4.77 -10.89 5.75 321.20 74.01 947.49 16-18 1.24 0.17 67.02 5.43 -10.62 5.98 405.01 76.48 980.15 20-22 1.27 0.17 72.25 5.86 -10.90 6.53 469.57 87.97 959.09 24-26 1.50 0.20 77.77 6.30 -12.89 7.12 522.00 83.87 968.50 28-30 0.56 0.15 84.23 6.83 -12.87 8.02 559.85 102.76 993.46 32-34 0.61 0.17 103.57 -13.89 9.00 739.58 908.70 Core Information Sediment Oxidation of Organic Matter

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70 Core # cmbsf TOC wt% wt% N DIC (ug/g) DIC (mM) 13C Alkalinity (mM) Ammonium Phosphate Silica 7 B.W. 0.00 27.40 2.22 2.45 0.00 1.60 86.01 0-1 1.82 0.25 29.92 2.43 2.63 0.34 10.51 512.77 1-2 1.87 0.24 31.40 2.55 2.70 2.34 13.27 681.69 2-4 2.05 0.24 30.90 2.50 2.64 28.52 35.89 768.14 4-6 1.82 0.23 30.46 2.47 2.77 39.08 32.58 808.89 6-8 1.84 0.22 33.97 2.75 2.84 57.32 30.74 840.96 8-10 1.72 0.22 34.10 2.76 2.89 58.34 23.75 855.95 12-14 1.60 0.19 32.33 2.62 2.67 88.74 16.39 787.72 16-18 1.44 0.19 32.85 2.66 2.93 85.29 18.23 812.99 20-22 1.39 0.18 37.22 3.02 3.24 132.00 18.97 896.59 24-26 1.46 0.17 41.54 3.37 3.80 172.06 24.67 932.55 28-30 1.32 0.15 46.62 3.78 4.01 205.70 25.04 938.44 32-34 1.09 0.26 47.50 3.85 4.12 216.89 28.90 971.19 Core Information Sediment Oxidation of Organic Matter

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71 Core # cmbsf Sulfate (mM) Iron (M) Manganese (M) Magnesium (mM) Calcium (mM) Chloride (mM) Bromide (mM) Sodium (mM) Potassium (mM) 1 B.W. 28.45 0.29 0.04 27.49 5.37 572.65 0.86 474.91 5.22 0-1 28.49 0.88 0.09 52.89 10.36 554.04 0.84 477.44 11.59 1-2 28.59 6.14 2.22 52.76 10.35 555.26 0.86 478.05 11.72 2-4 28.51 37.47 4.60 52.26 10.49 553.93 0.86 477.71 12.03 4-6 28.64 38.80 4.88 51.90 10.28 556.74 0.88 477.60 12.00 6-8 28.50 43.52 4.32 51.66 10.17 554.32 0.87 477.72 12.14 8-10 28.44 61.10 4.39 51.80 10.16 554.37 0.88 478.58 12.28 12-14 28.40 42.20 2.74 51.88 10.07 554.87 0.89 478.43 12.43 16-18 28.35 38.91 2.31 51.77 10.00 555.15 0.94 479.84 12.56 20-22 28.28 33.56 2.16 51.74 10.07 555.51 0.89 480.26 12.71 24-26 28.16 30.98 2.05 50.96 10.03 555.36 0.88 479.53 12.77 28-30 28.10 18.47 2.13 50.97 9.98 556.22 0.90 480.86 12.89 32-34 28.28 14.95 1.91 50.90 9.92 554.01 0.85 482.28 13.04 2 B.W. 28.38 0.69 0.02 53.39 10.43 560.93 0.86 474.61 10.11 0-1 28.52 6.82 0.23 52.13 10.18 553.31 0.85 476.46 11.80 1-2 28.73 15.17 3.93 52.51 10.28 554.97 0.81 474.36 11.78 2-4 28.42 14.32 4.10 51.57 10.12 552.38 0.82 478.02 11.96 4-6 28.46 21.68 3.16 51.67 10.08 553.74 0.83 481.01 12.29 6-8 26.72 36.49 2.58 48.05 9.36 522.52 0.78 437.73 11.69 8-10 28.24 37.49 2.08 51.98 10.04 552.37 0.81 479.34 12.59 12-14 28.23 37.08 2.34 52.54 10.32 554.36 0.85 480.60 12.37 16-18 28.13 23.69 2.42 35.56 6.77 554.44 0.84 483.32 8.45 20-22 27.85 37.84 2.70 52.81 10.17 551.24 0.82 482.37 12.57 Core Information Redox Observations Ratioed Major Elements Other Majors

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72 Core # cmbsf Sulfate (mM) Iron (M) Manganese (M) Magnesium (mM) Calcium (mM) Chloride (mM) Bromide (mM) Sodium (mM) Potassium (mM) 3 B.W. 28.53 0.12 0.01 53.32 10.49 561.85 0.85 474.91 10.12 0-1 28.59 1.80 0.97 51.91 10.63 552.51 0.83 470.82 11.32 1-2 28.53 2.48 3.11 52.29 10.76 551.46 0.79 475.89 11.51 2-4 28.50 23.85 9.61 52.33 10.72 552.12 0.79 476.74 11.86 4-6 28.53 75.92 4.85 51.76 10.62 551.17 0.77 475.48 11.99 6-8 28.23 82.31 3.19 51.81 10.63 548.83 0.80 476.24 12.09 8-10 28.32 74.04 1.75 51.55 10.54 552.25 0.76 475.84 12.31 12-14 28.22 130.61 2.10 51.32 10.52 550.94 0.78 476.68 12.55 16-18 28.19 54.50 1.25 50.82 10.47 551.05 0.75 476.21 12.56 20-22 27.97 58.76 1.51 50.55 10.41 548.43 0.77 474.79 12.55 24-26 27.82 42.69 1.58 37.87 7.82 547.12 0.77 357.89 9.57 28-30 27.76 31.42 1.70 51.75 10.53 548.47 0.77 478.84 12.62 32-34 27.83 34.12 1.32 51.28 10.43 549.46 0.81 474.52 12.67 4 B.W. 28.39 0.12 0.01 28.09 5.36 561.04 0.83 474.91 5.23 0-1 28.32 2.42 0.47 52.77 10.50 550.73 0.82 478.00 11.22 1-2 28.42 6.02 3.25 52.55 10.51 551.72 0.85 478.17 11.39 2-4 28.30 48.73 1.45 52.32 10.47 550.78 0.94 478.30 11.55 4-6 28.33 44.01 0.70 52.09 10.43 550.82 0.84 478.18 11.68 6-8 28.09 44.58 0.60 52.09 10.50 548.39 0.86 477.66 11.60 8-10 28.09 36.25 0.72 52.14 10.58 550.63 0.88 478.85 11.68 12-14 27.93 22.78 0.80 51.84 10.39 551.18 0.88 478.92 11.92 16-18 27.87 12.59 0.84 52.00 10.46 551.96 0.87 479.71 12.10 20-22 27.89 10.48 0.78 51.76 10.33 551.78 0.84 479.32 12.30 24-26 27.84 14.90 0.77 39.30 7.85 550.73 0.89 361.88 9.20 28-30 27.89 14.11 0.88 52.02 10.34 552.13 0.84 480.17 12.28 32-34 28.10 51.54 10.34 554.45 0.83 481.23 12.37 Ratioed Major Elements Other Majors Core Information Redox Observations

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73 Core # cmbsf Sulfate (mM) Iron (M) Manganese (M) Magnesium (mM) Calcium (mM) Chloride (mM) Bromide (mM) Sodium (mM) Potassium (mM) 5 B.W. 28.44 0.16 0.01 29.13 5.55 561.90 0.84 474.91 5.42 0-1 28.60 4.60 1.43 52.45 10.37 556.97 0.85 474.77 11.09 1-2 28.53 65.99 16.07 52.31 10.45 557.10 0.85 476.20 11.34 2-4 28.37 157.84 7.90 52.43 10.36 556.42 0.85 476.29 11.56 4-6 28.24 200.76 4.92 52.38 10.36 556.65 0.86 475.25 11.58 6-8 28.15 152.01 4.68 52.15 10.33 560.09 0.82 474.58 11.55 8-10 27.79 134.83 3.76 52.55 10.36 557.37 0.83 474.13 11.45 12-14 27.31 89.50 3.29 52.55 10.38 557.60 0.83 475.47 11.61 16-18 26.83 87.17 2.99 52.79 10.43 557.46 0.84 475.49 11.71 20-22 26.51 80.77 2.69 52.66 10.35 558.53 0.85 477.16 11.93 24-26 26.10 78.70 2.50 52.08 10.31 558.46 0.85 476.30 12.00 28-30 25.71 52.42 2.44 51.98 10.38 559.05 0.83 476.01 12.10 6 B.W. 28.43 0.07 0.00 27.65 0.21 561.84 0.86 474.91 5.17 0-1 28.41 1.48 0.63 51.68 10.35 560.24 0.81 475.58 11.27 1-2 28.23 37.09 7.93 51.82 10.37 558.37 0.79 475.46 11.36 2-4 28.12 169.63 5.08 51.73 10.30 559.60 0.77 474.72 11.55 4-6 28.00 172.29 3.40 51.57 10.37 560.82 0.78 474.94 11.59 6-8 27.77 147.78 3.20 51.71 10.27 562.68 0.81 474.60 11.66 8-10 27.45 123.90 2.99 51.86 10.27 562.04 0.78 475.02 11.67 12-14 26.80 83.54 2.62 52.06 10.29 561.35 0.74 475.37 11.75 16-18 26.33 60.99 2.34 52.22 10.29 561.87 0.79 477.21 11.94 20-22 25.92 40.97 2.14 51.68 10.33 563.16 0.82 476.87 12.06 24-26 25.61 40.89 2.12 51.61 10.29 563.38 0.81 476.61 12.16 28-30 25.34 25.55 2.06 51.37 10.15 564.55 0.85 476.31 12.13 32-34 16.54 2.16 Other Majors Core Information Redox Observations Ratioed Major Elements

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74 Core # cmbsf Sulfate (mM) Iron (M) Manganese (M) Magnesium (mM) Calcium (mM) Chloride (mM) Bromide (mM) Sodium (mM) Potassium (mM) 7 B.W. 28.28 0.14 0.01 55.06 10.48 559.19 0.85 481.19 10.28 0-1 28.30 2.88 0.06 54.24 10.39 550.95 0.89 477.53 11.33 1-2 28.25 8.68 0.41 53.75 10.46 549.02 0.88 479.33 11.57 2-4 28.26 21.64 2.67 53.86 10.45 550.85 0.85 477.63 11.51 4-6 28.24 60.98 4.27 53.61 10.45 551.02 0.88 478.38 11.63 6-8 28.25 69.10 5.76 53.79 10.45 551.72 0.87 478.87 11.69 8-10 28.16 52.83 3.44 53.13 10.35 550.43 0.89 477.60 11.77 12-14 28.22 56.77 1.49 53.06 10.36 551.71 0.85 478.52 12.00 16-18 28.13 42.39 1.44 52.82 10.29 551.78 0.87 477.62 12.15 20-22 28.00 111.61 2.51 53.10 10.37 552.72 0.85 479.47 12.21 24-26 27.68 44.85 1.53 53.55 10.30 551.98 0.85 479.83 12.24 28-30 27.39 29.57 1.45 53.27 10.28 551.84 0.82 479.22 12.29 32-34 27.47 14.09 3.07 53.99 10.38 554.09 0.81 482.78 12.48 Core Information Redox Observations Ratioed Major Elements Other Majors

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81 BIOGRAPHICAL SKETCH Mitchell Dylan Robert Miner was born in the NW corner of Iowa in 1975. He graduated from Corona Del Sol High School in Tempe, AZ in 1993. In December of 2005 he graduated with an Associate of Arts degree, with a prebiology specialization, from Saint Peter sburg College and matriculated to the Univers ity of Florida in Gainesville. He was awarded Bachelor of Science degrees from the D epartments of Zoology and Geolog ic Science s in December 2007. This thesis represents the culmination of his graduate work and h e will be receiving a degree of Master of Science from the Department of G eolog ic S ciences with a m inor issued from the Department of Soils and Wetland Science.