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Geochemistry of Wetland Sediments from South Florida

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Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: William H. Orem
Publication_Date: 2005
Title: Geochemistry of Wetland Sediments from South Florida
Geospatial_Data_Presentation_Form: spreadsheet
Online_Linkage: <https://sofia.usgs.gov/projects/wetland_seds/>
Description:
Abstract:
This project is examining (1) sources of nutrients (nitrogen and phosphorus), sulfur, and carbon to wetlands of south Florida, (2) the important role of chemical and biological processes in the wetland sediments (biogeochemical processes) in the cycling of these elements, and (3) the ultimate fate (i.e. sinks) of these elements in the ecosystem. The focus on nutrients and carbon reflects the problem of eutrophication in the northern Everglades, where excess phosphorus from agricultural runoff has dramatically altered the biology of the ecosystem.

Major project objectives are as follows - (1) use isotope and other tracer methods to examine the major sources of nutrients, carbon, and sulfur to the south Florida ecosystem, (2) use geochemical methods to examine the major forms of nutrients, carbon, and sulfur in the sediments, the stabilities of the observed chemical species, and sinks of these elements in the sediments, (3) examine the biogeochemical processes controlling the cycling of nutrients, carbon, and sulfur in the ecosystem, and use geochemical modeling of porewater and sediment chemical data to determine the rates of these recycling processes, (4) develop geochemical sediment budgets for nutrients, carbon, and sulfur on a regional scale, including accumulation rates of these elements in the sediments, fluxes out of the sediments, and sequestration rates, (5) collaborate with mercury projects (USGS ACME team and others) to examine the role of sulfur and sulfate reduction in the production of methyl mercury in wetlands of south Florida, and the bioaccumulation of mercury in fish and other wildlife, (6) develop a geochemical history of the south Florida ecosystem from an examination of changes downcore in the concentration, speciation, and isotopic composition of nutrients, carbon and sulfur; use organic marker compounds and stable isotopes to develop a model of seagrass history in Florida Bay, (7) incorporate information from nutrient studies in overall ecosystem nutrient model, and results from sulfur studies in ecosystem mercury model.

Purpose:
This project addresses three major areas of interest to land and water managers in south Florida: (1) nutrients and eutrophication of the Everglades, (2) the role of sulfur in the methylation of mercury and its bioaccumulation, and (3) the geochemical history of the south Florida ecosystem. Our nutrient studies are focused on using isotope methods to examine the sources of nutrients to the ecosystem, and on using sediment and porewater geochemical studies to determine the rates of nutrient recycling and nutrient sinks within the sediments. A nutrient sediment budget will be developed for incorporation in the nutrient model for the ecosystem. Results will assist managers in determining the fate of excess nutrients (especially phosphorus) stored in contaminated sediments (e.g. will the excess nutrients be buried, or recycled for movement further south into protected areas). The sediment studies will also provide managers with information relevant to the effectiveness of planned remediation methods.

Studies of sulfur within the ecosystem relate directly to the issue of methyl mercury production and bioaccumulation, a serious threat to both wildlife and to the human population. Microbial sulfate reduction in wetlands (an anaerobic process) is the primary driver of mercury methylation. Understanding the source of sulfate to the wetlands of south Florida may be a key to understanding why mercury methylation rates are so high, and on how remediation efforts in the Everglades may impact mercury methylation rates. We are also examining the sulfur geochemistry of sediments on a regional scale, with emphasis on areas that are methyl mercury "hotspots". We are emphasizing co-sampling with USGS mercury researchers (ACME team).

The geochemical history component of this project will provide information on historical changes in the chemical conditions existing in south Florida wetlands. This will provide wetland managers with baseline information on the water quality goals needed to achieve "restoration" of the ecosystem. It will also provide land managers with an estimate of the range of water quality and environmental conditions that have affected the south Florida ecosystem in the past. Geochemical history data in combination with information from paleontologic studies of the USGS paleoecology group and others will also provide insights on how organisms in the south Florida ecosystem have responded to environmental change in the past, and predict how these organisms will likely respond to changes in the ecosystem resulting from restoration efforts.

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1994
Ending_Date: 1999
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -81.3
East_Bounding_Coordinate: -80.1
North_Bounding_Coordinate: 27
South_Bounding_Coordinate: 24.4
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: biogeochemistry
Theme_Keyword: isotope geochemistry
Theme_Keyword: nutrients
Theme_Keyword: peat
Theme_Keyword: sulfur
Theme_Keyword: seagrass
Theme_Keyword: sediments
Theme_Keyword: chemistry
Theme_Keyword: hydrology
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: biota
Theme_Keyword: environment
Theme_Keyword: geoscientificInformation
Theme_Keyword: inlandWaters
Theme_Keyword: 002
Theme_Keyword: 007
Theme_Keyword: 008
Theme_Keyword: 012
Place:
Place_Keyword_Thesaurus:
Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, National Institute of Standards and Technology
Place_Keyword: United States
Place_Keyword: US
Place:
Place_Keyword_Thesaurus:
U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, DC, NIST
Place_Keyword: Florida
Place_Keyword: FL
Place:
Place_Keyword_Thesaurus:
Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology
Place_Keyword: Broward County
Place_Keyword: Hendry county
Place_Keyword: Glades County
Place_Keyword: Palm Beach County
Place_Keyword: Collier County
Place_Keyword: Miami-Dade County
Place_Keyword: Monroe County
Place:
Place_Keyword_Thesaurus: USGS Geographic Names Information System
Place_Keyword: Big Cypress National Preserve
Place_Keyword: Shark River Slough
Place_Keyword: Taylor Slough
Place_Keyword: Pass Key
Place_Keyword: Bob Allen Key
Place_Keyword: Whipray Basin
Place_Keyword: Russell Key
Place_Keyword: Florida Bay
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: Central Everglades
Place_Keyword: Greater Lake Okeechobee
Place_Keyword: SW Big Cypress
Place_Keyword: Florida Keys
Place_Keyword: Everglades Agricultural Area
Place_Keyword: Everglades Nutrient Removal area
Place_Keyword: Water Conservation Area 1
Place_Keyword: Water Conservation Area 2
Place_Keyword: Water Conservation Area 3
Place_Keyword: WCA1
Place_Keyword: WCA2
Place_Keyword: WCA3
Stratum:
Stratum_Keyword_Thesaurus: none
Stratum_Keyword: surficial peat/soil/sediment
Stratum_Keyword: sediment/peat porewater
Stratum_Keyword: surface water
Stratum_Keyword: vegetation and periphyton
Temporal:
Temporal_Keyword_Thesaurus: none
Temporal_Keyword: seasonal
Access_Constraints: none
Use_Constraints: none
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: William H. Orem
Contact_Organization: U.S. Geological Survey
Contact_Position: Project Chief
Contact_Address:
Address_Type: mailing address
Address: 956 National Center
City: Reston
State_or_Province: VA
Postal_Code: 20192
Contact_Voice_Telephone: 703 648 6273
Contact_Facsimile_Telephone: 703 648 6419
Contact_Electronic_Mail_Address: borem@usgs.gov
Hours_of_Service: 9:00-6:00 M-F
Browse_Graphic:
Browse_Graphic_File_Name: <https://sofia.usgs.gov/publications/fs/wetland_seds/fig1.gif>
Browse_Graphic_File_Description:
map showing major regions of the South Florida wetlands ecosystem
Browse_Graphic_File_Type: GIF
Data_Set_Credit:
Robert Zielinski, Carol Kendall, Harry Lerch, Anne Bates, Margo Corum, Ann Boylan, and Cheryl Hedgman provided technical support for this project.
Native_Data_Set_Environment: MS Excel spreadsheets
Cross_Reference:
Citation_Information:
Originator:
Gough, L. P.

Kotra, R. K.; Holmes, C. W.; Orem, W. H.; Hageman, P. L.; Briggs, P. H.; Meier, A. L.; Brown, Z. A.

Publication_Date: 2000
Title:
Regional Geochemistry of Metals in Organic-Rich Sediments, Sawgrass, and Surface Water from Taylor Slough, Florida
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: USGS Open-File Report
Issue_Identification: OFR 00-327
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://sofia.usgs.gov/publications/ofr/00-327/>
Cross_Reference:
Citation_Information:
Originator:
Bates, Annie L.

Spiker, Elliott C.; Holmes, Charles W.

Publication_Date: 1998
Title:
Speciation and isotopic composition of sedimentary sulfur in the Everglades, Florida, USA
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: Chemical Geology
Issue_Identification: 146 (3-4)
Publication_Information:
Publication_Place: Amsterdam, Netherlands
Publisher: Elsevier
Cross_Reference:
Citation_Information:
Originator:
Orem, W. H.

Holmes, C. W.; Kendall. C.; Lerch, H. E.; Bates, A. L.; Silva, S. R.; Boylan, A.; Corum, M.; Marot, M.; Hedgman, C.

Publication_Date: 1999
Title:
Geochemistry of Florida Bay sediments: I. nutrient history at five sites in eastern and central Florida Bay
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: Journal of Coastal Research
Issue_Identification: v. 15
Publication_Information:
Publication_Place: Royal Palm Beach, FL
Publisher: Coastal Research and Education Foundation (CERF)
Other_Citation_Details:
The entire paper is available from the Journal of Coastal Research website at <http://www.cerf-jcr-org>. Journal membership is required for download.
Online_Linkage: <https://sofia.usgs.gov/publications/papers/geochem_flbaysed>
Cross_Reference:
Citation_Information:
Originator:
Orem, W. H.

Lerch, H. E.; Rawlik, P.

Publication_Date: 1997
Title:
Geochemistry of surface and pore water at USGS coring sites in wetlands of South Florida, 1994 and 1995
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: USGS Open-File Report
Issue_Identification: 97-454
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://sofia.usgs.gov/publications/ofr/97-454>
Cross_Reference:
Citation_Information:
Originator: Jahnke, R. A.
Publication_Date: 1988
Title: A simple, reliable, and inexpensive pore-water sampler
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: Limnology and Oceanography
Issue_Identification: v. 33, n. 3
Publication_Information:
Publication_Place: Washington, DC
Publisher: American Society of Limnology and Oceanography
Other_Citation_Details:
Articles in this volume are FREE Access Publications and are available without a subscription
Online_Linkage: <http://aslo.org/lo/toc/vol_33/issue_3/index.html>

Data_Quality_Information:
Logical_Consistency_Report: not applicable
Completeness_Report: not available
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
The positional accuracy is determined by the average of two GPS readings for each sample site. The sites are mainly accessed by helicopter. One GPS receiver is taken to the site and the other remains in the helicopter.
Lineage:
Process_Step:
Process_Description:
Piston cores of sediments from various sites in Florida Bay (Pass Key, Russell Key, Bob Allen Keys, and Whipray Basin) and from nearby areas of lower Taylor Slough were returned to shore facilities (NOAA-NURC, KeyLargo) for extrusion and sectioning. Cores were extruded vertically because of the generally "soupy" nature of the sediments. Cores were sectioned into 2 cm, 5 cm, or 10 cm intervals in the field, placed in ziplock plastic bags (double bagged), and refrigerated until return to our lab facilities in Reston, VA. In the lab, each section was homogenized and about half of each core was wet sieved. The other half was frozen as an archive for future analyses. Brass sieves (10 mesh and 60 mesh) were used in the wet sieving. The sieves were coupled together over a large glass beaker and the sample was poured onto the 10 mesh sieve. The sample was then sequentially washed through the sieves with deionized/distilled water. Sieving produced three fractions: >10 mesh (>850 micron), 10-60 mesh (850-63 micron), and <60 mesh (<63 micron). Typically, the coarse and medium fractions contained mostly shells and fragments of seagrass, and the finest fraction contained only fine grained sediment. The finest fraction generally accounted for >90% of the total sediment weight. After sieving, each fraction was lyophilized, weighed, and stored in glass or plastic vials until chemical analysis. Analyses were carried out on the <63 micron fraction and on seagrass fragments collected from the >850 and 850-63 micron fractions.

Total carbon, total nitrogen, and total sulfur contents of the lyophilized sediments and seagrass fragments were determined using a Leco 932 CHNS Analyzer. Organic carbon contents were determined on the Leco 932 CHNS Analyzer after treatment of the samples in acid to remove carbonates. We used an acid fuming method adapted from Hedges and Stern (1984) and Yamainuro and Kayanne (1995) to remove carbonates. Our procedure involved: (1) weighing of the sample into silver Leco sampling cups on a microbalance, (2) placing the weighed silver cups in a sealed chamber (dessicator) with concentrated HCl in the bottom, (3) allowing a minimum of 72 hours for the acid fuming to remove all carbonates from these carbonate-rich sediments and seagrass fragments, and (4) redrying and reweighing the cups prior to analysis.

Total phosphorus was determined by a method adapted from that of Aspila et al. (1976). Lyophilized sediment was weighed into crucibles and baked for 2 hrs. at 55°C. The baked sediment was cooled and quantitatively dumped into 250 ml plastic centrifuge cones containing 50 ml of 1M HCl. The baked sediment was extracted on a shaker in the 1M HCl for 16 hrs. An aliquot of each extract was centrifuge filtered through 0.45 micron centrifuge filters, and the filtrate adjusted to pH 7 with NaOH and transferred to plastic test tubes. The filtrate was then analyzed for phosphate using the standard phospho-molybdate calorimetric method (Strickland and Parsons 1972).

The stable isotopic composition (delta C and delta N) of selected sediments and seagrass fragments was determined using a Micromass Optima continuous flow mass spectrometer coupled to a Carlo Erba elemental analyzer. Delta 15N was determined on whole sediment or seagrass samples, while delta 13C was determined on sediment and seagrass fragments after acid fuming of the samples, as described above.

Analytical precision (percentage relative standard deviation) for the elemental analysis of sediments and seagrass fragments varied from sample to sample, but generally was as follows: 2% for total carbon, 1% for total nitrogen, 10% for total sulfur, 3% for total phosphorus, and 4% for organic carbon. Stable isotope analysis of the fine sediment had an analytical precicion (1 sigma) of about 0.1 to 0.2 per mil for both delta 13C and delta 15N, but the precision for seagrass fragments was as high as 0.5 per mil due to sample heterogeneity.

Porewater Analysis Sediment porewater was obtained from cores using an in situ squeezing technique described in detail elsewhere (Orem et al. 1997). In brief a piston core is taken using an acrylic core tubewith a series of threaded ports at intervals along its length. The ports are closed during coring with screws and small O-rings. After the core is collected, it is returned to a dry land site (parking lot at hotel, etc.) and bolted onto a squeezer board. The squeezer board consists of a vertical metal frame with threaded metal plates attached to the frame, threaded rod through the plates, and pusher pistons at the ends of the rods. The core barrel containing the sample already has a piston at the top used for coring, and a second piston is inserted at the bottom. The threaded rods with pusher pistons are advanced through the threaded plates with a ratchet until they make contact with the pistons in the core barrel at both the top and bottom. Depth intervals in the core are selected, and the screws and O-rings in the threaded ports are removed and replaced with a threaded fitting. The fitting is threaded into the port and has a piece of tubing on the inside which extends to the middle of the core. Thus, during squeezing only porewater from the center of the core is collected. The fitting has a luer lock on the outside on which a syringe filter (0.45 micron) is attached. The syringe filter is attached to a collection bottle or a syringe by a shorth piece of tubing. Typically, 10-14 ports are selected downcore for porewater sampling, with close interval sampling near the surface and greater spacing of intervals at depth. Squeezing is initiated by turning the threaded rods with a ratchet so that the core is compressed by the pistons. After squeezing is initiated, most squeezing is done from the bottom to preserve the integrity of the core near the surface. Porewater is forced into the tube at the center of the core and exits the core through the syringe filter and is collected. Porewater yields obtained range from none in some dry holes to more than 100 ml. Florida Bay sediments are more difficult to squeeze than peat from the Everglades due to the fine-grained nature of the carbonate muds and their incompressibility compared to peat. Typical yields from Florida Bay sediments was 10-20 ml of porewater.

Porewater was analyzed for the following parameters where sufficient volume was available: phosphate, ammonium, chloride, fluoride, sulfate, sulfide, redox, pH, titration alkalinity, conductivity, salinity, and metals. Phosphate and ammonium were analyzed calorimetrically after removal of sulfides (Strickland and Parsons 1972). Chloride, fluoride, and sulfate were analyzed by ion chromatography. Sulfide, redox, conductivity, salinity, pH, and titration alkalinity were determined by electrochemical methods in the field. Metals were determined by ICP/MS after acidification of the samples.

Lignin Phenols Lignin phenols are being used in this study to examine seagrass history in selected sites in Florida Bay. In brief, fine sediment or seagrass fragments are first soxhiet extracted (methylene chloride), dried, and a weighed amount (usually @ 0.5 g) placed into monel mini bombs under an O2-free atmosphere with CuO, Fe(NH4)2(SO4)2-6H2O, and deaerated 8% NaOH. Four mini bombs at a time are placed inside a larger bomb and reacted for 3hr. 20 min. at a temperature of 170 deg C. After the reaction is complete, the bombs are quenched under running tap water and the contents of the bombs are rinsed into separate 250 ml plastic centrifuge cones with 1M NaOH. The free lignin phenols are present in the dissolved phase. The cones are centrifuged and the solutions decanted into glass round bottom flasks. The residue in the cones are washed and centrifuged twice with the 1M NaOH, which is then added to the round bottom flasks. The solutions in the round bottom flasks are then acidified to pH <2 with 6M HCl to protonate the lignin phenols. The solutions are then liquid/liquid extracted with diethyl ether (4 times) and the ether phase containing the lignin phenols isolated using a separatory funnel. The diethyl ether is dried with anhydrous Na2SO4, and blown to dryness in a small glass vial under a stream of N2. The vials are stored frozen until analysis. For analysis, the samples are redissolved in 50 ml of pyridine and derivatized with BSTFA. Samples are quantified by gas chromatography using Turbochrom software, with final confirmation of peak identities by gas chromatography/mass spectrometry using authentic standards.

Process_Date: 1999
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: William H. Orem
Contact_Organization: U.S. Geological Survey
Contact_Position: Project Chief
Contact_Address:
Address_Type: mailing address
Address: 956 National Center
City: Reston
State_or_Province: VA
Postal_Code: 20192
Contact_Voice_Telephone: 703 648 6273
Contact_Facsimile_Telephone: 703 648 6419
Contact_Electronic_Mail_Address: borem@usgs.gov
Hours_of_Service: 9:00-6:00 M-F

Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Heather S.Henkel
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address: 600 Fourth St. South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727 803-8747 ext 3028
Contact_Facsimile_Telephone: 727 803-2030
Contact_Electronic_Mail_Address: hhenkel@usgs.gov
Resource_Description: Florida Bay sediment geochemical data
Distribution_Liability: The data have no implied or explicit guarantees.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: Excel
Format_Version_Number: unknown
Transfer_Size: 0.44
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: <https://sofia.usgs.gov/exchange/orem/oremsed.html>
Access_Instructions: The data may be downloaded from the SOFIA website
Fees: none

Metadata_Reference_Information:
Metadata_Date: 20070410
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Heather Henkel
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: 600 Fourth Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727 803-8747 ext 3028
Contact_Facsimile_Telephone: 727 803-2030
Contact_Electronic_Mail_Address: sofia-metadata@usgs.gov
Metadata_Standard_Name: Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

This page is <https://sofia.usgs.gov/metadata/sflwww/metorem.html>

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