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projects >
geochemistry of wetland sediments >
1999 proposal
USGS Geologic Division
Continuing Project Work Plan - FY 1999
IDENTIFYING INFORMATION
Project Chief: William H. Orem
Program: INATURES (Formerly Ecosystems Program)
Program Element(s)/Task(s): 4.1, 4.2, 4.5, 6.1, 7.3
BACKGROUND NARRATIVES
Project objectives and strategy: 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.
This project uses both field studies and laboratory experiments to examine
the biogeochemical cycling of nutrients, carbon, and sulfur in sediments.
Field studies involve the collection of surface water, vegetation, sediment
cores, and sediment porewater for chemical analysis. Appropriate protocols
are used for the collection of samples and for chemical analysis. Sampling
areas were selected to cover as wide an area as possible in the initial
reconnaissance stages of the project. More recently, sampling areas were
selected to reflect specific processes to be studied. Thus, samples for
examining sources of nutrients and sulfur to the Everglades have focused
on canals running the EAA. Biogeochemical cycling studies have focused
on eutrophied and pristine sites for nutrients, and on areas of high and
low methyl mercury production for the sulfur studies. Sampling sites were
also chosen based on recommendations and requests from land and water management
agencies. Emphasis on Taylor Slough and ENR reflects the needs of managers
to understand the effects of proposed remediation efforts on the ecosystem.
Isotope studies provide information on the sources of nutrients, carbon,
and sulfur to the ecosystem, and information on biogeochemical cycling.
Studies of nutrient, carbon, and sulfur speciation in sediments provides
information on the processes occurring in sediments and on the major sinks
for these elements in the sediments. Porewater studies are particularly
useful for determining the major biogeochemical processes in sediments
and for geochemical modeling aimed at quantitative estimates of reaction
and recycling rates, and fluxes of chemical species between sediments and
surface waters. Organic geochemical studies of sediments are useful for
examine differences in chemical reactions among various sediments types
(e.g. cattail peat and sawgrass peat), and how this may affect the ecosystem.
Laboratory studies are primarily aimed at validating and extending observations
from field studies. Experiments to be conducted will include: (1) laboratory
decomposition of cattail and sawgrass under different simulated environmental
conditions, (2) estimation of diffusion coefficients for nutrients and
sulfate using a diffusion cell approach, and (3) adsorption studies of
nutrients on various organic substrates (i.e. cattail peat, sawgrass peat,
marl peat). Geochemical history studies emphasize analysis of dated cores,
thus co-sampling with the USGS dating team is essential. Core samples are
typical shared with the USGS paleontology group. Sampling sites are chosen
in areas of suspected recent environmental change (e.g. lower Taylor Slough
saltwater intrusion), areas of continuous sediment accumulation (Florida
Bay sites), and to reflect different regions of the ecosystem.
Potential impacts and major products: 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 (uranium/uranium isotopes, 18O of phosphate,
15N, and 13C) 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. For example, will the type of sediments
deposited in the artificial buffer wetlands or Stormwater Removal Areas
(e.g. mostly cattail peat) be effective for the long-term storage of nutrients
removed from agricultural runoff water? Also, what will be the effect of
increased hydrologic flow from the ìreplumbingî of the canal network in
the Everglades on nutrient mobility and recycling in the wetlands? How
will this ìreplumbingî affect nutrient flow to the mangrove areas and Florida
Bay?
Studies of sulfur within the ecosystem relate directly to the issue
of methyl mercury production and bioaccumulation within the ecosystem,
a serious threat to both wildlife and to the human population. Microbial
sulfate reduction in wetlands (an anaerobic process) is the principal process
for the methylation of mercury. Recent findings show that for south Florida
wetlands methyl mercury production and bioaccumulation is highly correlated
with sulfide. Thus, sulfur geochemistry plays a central role in this methylation
process. Our studies are focused on examining the sources of sulfur to
the Everglades using stable isotope methods (34S and 18O
of sulfate). 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 ìhotspotsî.
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 ìrestorationî 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 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.
Geochemical history studies in the southern part of the south Florida ecosystem
are focused on (1) historical salinity change in the Taylor Slough area,
and (2) the use of organic markers and stable isotopes to examine seagrass
history in eastern Florida Bay. Both of these topics are of interest to
land and water managers in south Florida.
From the beginning, one goal of this project has been to remain flexible
and responsive to the needs of land and water managers in south Florida.
As a result, project goals, while remaining largely intact, have been altered
to reflect management and regulatory needs. This will continue to be a
priority through the anticipated end date of this project.
Prior products include USGS Open-File Reports, articles in international
science journals, USGS Fact Sheets, abstracts and presentations at national
and international scientific meetings and at client agencies, contributions
to USGS and interagency synopsis reports, databases, and the posting of
reports and databases on the WWW. A complete listing of products to date
is appended to the proposal.
Collaborators, Clients:
WORK PLAN
FY 1999 activities: We propose to complete activities on Phase
I of this project in FY 1999. This includes: (1) completing analytical
work on samples collected through 8/98, (2) completing the project database
in spreadsheet (Excel) and GIS (format), and putting the database on the
south Florida WWW site, and (3) completing manuscripts, including outside
publications and contributions to synopsis reports. With regard to analytical
work, we will complete sulfate and sulfur isotope analyses on surface water,
groundwater, fertilizer, and sediment samples collected through 8/98. This
work is politically sensitive since our data implicates agricultural practices
with ëfate input to the Everglades which appears to be largely controlling
mercury methylation in the Everglades. Completion of these analyses will
be essential to support our argument for additional BMPís to apply to sulfate
usage in the Everglades Agricultural area. We will also complete lignin
phenol analyses of Florida Bay sediments for seagrass history studies.
This approach to examining seagrass history has proved quite successful
on the two cores examined to date, and we will extend the analyses to dated
Florida Bay cores from central Florida Bay in FY 1999. We have been requested
to complete analyses for lignin phenols from central Florida Bay cores
by the SFWMD and other client agencies in south Florida. We will also complete
analysis on surficial cores carefully collected in cattail and sawgrass
areas of the northern Everglades to examine relative rates of decomposition
and N and P recycling in cattail and sawgrass peat. This work is crucial
for understanding how effective the constructed STAís will be in long-term
storage of P. It is feared that the STAís will grow only cattail vegetation,
and that this may not sequester P for the long-term due to the fast rates
of decomposition of cattail peat. Again, client agencies have encouraged
us to complete this work. Finally, analyses of surface water, porewater
and sediment samples collected through 8/98 for various parameters will
be completed during FY 1999 to complete our database. Analytical work in
FY 1999 will be carried out by Lerch, Bates, Corum, Boylan, and Neuzil.
Lerch and Bates are analytical chemists, who will do the bulk of the detailed
analytical work. Neuzil is a geologist, and Boylan and Corum are student
aides (part time) who will do most of the sample prep work and the routine
chemical analyses.
In addition to the above analytical work to be carried out in Reston,
The Menlo Park Isotope Team (C. Kendall, C. Chang, and J. Langston) will
be completing isotope studies on samples collected through 8/98 during
FY 1999. This will include 18O analysis of phosphate in surface
water, groundwater, and peats previously collected to trace the sources
of phosphate to the Everglades. This work nicely complements the uranium/uranium
isotope work of Zielinski in tracing the sources of phosphate into the
ecosystem. The uranium/uranium isotope and 18O on phosphate
work provides the first and only direct link between phosphate from fertilizer
and eutrophication in the northern Everglades. The analytical procedure
for looking at 18O in phosphate required a significant
development period, but the first data from the Everglades has recently
been obtained showing a definitive isotopic difference between fertilizer
phosphate and background phosphate in the Everglades. The analytical work
on water and sediment samples will be completed during the first half of
FY 1999, and a paper completed prior to the end of FY 1999 on this topic.
In addition to the 18O on phosphate work, the Menlo Park Isotope
Team will complete isotope studies of sediments samples (13C,
15N, and 34S) and groundwater samples (18O
on sulfate) in collaboration with Orem et al. for determining sources and
biogeochemical cycling of these elements in the Everglades and Florida
Bay.
Methods and procedures to be employed will be the same ones developed
over the past four years for our work in the Everglades.
The Principal Investigators on this project (Orem/Zielinski/Kendall)
will spend the majority of their effort in FY 1999 in completing manuscripts.
Zielinski will complete work on a manuscript on uranium/uranium isotopes
as a tracer for phosphorus from fertilizer in the northern Everglades for
publication in Applied Geochemistry. Kendall will complete a paper on the
isotope geochemistry of south Florida wetlands for publication in a journal.
Orem will complete the following papers during FY 1999: (1) Biogeochemical
Cycling of
Finally, completion of a database for the project will be a major effort
for FY 1998. This work will be primarily completed by Orem and two student
aids (Corum and Boylan). Data will be available in both spreadsheet (Excel)
and GIS (ARCview format). The database will be placed on the south Florida
WWW site for public access.
FY 1999 deliverables/products: Papers from this project for submission
to international journals during FY 1999 will include: (1) Biogeochemical
Cycling of Phosphorus in the Everglades, Orem et al. (Limnology and Oceanography),
(2) Biogeochemical Cycling of Sulfur in the Everglades, Orem et al. (Limnology
and Oceanography), (3) Lignin Phenols in Sediments as Indicators of Seagrass
History in Florida Bay, Orem et al. (Geochimica et Cosmochimica Acta),
(4) Uranium and Uranium Isotopes as Tracers of Phosphorus from Fertilizer
in the Northern Everglades, Zielinski et al. (Applied Geochemistry), and
(5) Stable Isotopes as Tracers of Biogeochemical Cycling in the Everglades
Kendall et al. (to be determined). Contributions to Synopsis Reports will
include: (1) Sources of Sulfur and Sulfur Cycling in the Everglades, W.H.
Orem (Mercury Synopsis), (2) Geochemistry of Florida Bay Sediments, W.H.
Orem (Florida Bay Synopsis), and (3) Geochemical History of the Everglades
and Florida Bay (Paleoecology Synopsis). In addition, the principal Investigators
(Orem/Zielinski/Kendall) will give presentations and prepare abstracts
for meetings during FY 1999. Orem will also prepare a Fact Sheet on the
Geochemistry of Florida Bay Sediments in FY 1999. Finally, a database will
be completed during FY 1999 for posting on the WWW.
FY 1999 outreach: Client needs are being addressed in a number
of different ways: (1) frequent calls and visits to collaborators, (2)
presentations at science conferences and program reviews in south Florida,
(3) presentations USGS meetings in south Florida(4) distribution of reports
to interested clients. A database will be completed in FY 1999 for placement
of the south Florida WWW site for public access. Orem will contribute to
a Fact Sheet on Mercury to be completed by Krabbenhoft (USGS-Madison, WI)
during FY 1999. Orem also plans a Fact Sheet on Florida Bay for FY 1999.
New directions or major changes for FY 1999: The project will
shift from field-intensive investigations, to completion of analytical
work and writing reports. One relatively new area is tree island research
studies. This work is being conducted in collaboration with Deb Willard
(USGS), Chuck Holmes (USGS), F. Sklar and S. Newman (SFWMD), and scientists
from the Florida Fish and Game commission. A number of tree islands were
sampled in 4/98, and a modest amount of travel money has been allocated
for possible brief follow-up work in FY 1999. Tree islands are an area
of current intense interest in south Florida, and may be a major emphasis
in Phase II studies. USGS will have the first paleoecology and geochemical
data from tree islands in the Everglades.
ACCOMPLISHMENTS, OUTCOMES, PRODUCTS, OUTREACH
FY 1998 deliverables, products completed:
Bates A.L., Spiker E.C., and Holmes C.W. (1998) Speciation and isotopic
composition of sedimentary sulfur in the Everglades Water Conservation
Area 2A, Florida, USA. Chemical Geology, in press.
Orem W.H., Lerch H.E., Holmes C.W., Corum M., Boylan A., Bates A., and
Hedgman C. (1998) Geochemistry of sediments from USGS cores in Taylor Slough,
1996. USGS Open-File Report, in review.
Bates A.L., Orem W.H., Harvey J.W. and Spiker E.C. (1998) Sources of
sulfate to the northern Everglades. Nature, in review.
Bates A.L., Orem W.H. and Harvey J.W. (1998) Sulfate in the northern
Everglades: Concentrations and sulfur isotopic composition [abs.]. AGU
Spring Meeting, Boston, MA, May 1998, in review.
Orem W.H., Bates A.L., Lerch H.E. and Harvey J.W. (1998) Sulfur geochemistry
of the Everglades: Sources, sinks and biogeochemical cycling. South Florida
Mercury Science Program Annual Workshop, West Palm Beach, FL, May 1998,
Abstracts with Program.
Orem W.H., Lerch H.E., Corum M., Boylan A., Hedgman C., and Zielinski
R. (1998) Phosphorus geochemistry of the south Florida wetlands ecosystem:
Sources and biogeochemical cycling [abs.]. AGU Spring Meeting, Boston,
MA, May 1998, in review.
Orem W.H., Holmes C.W., Kendall C., Lerch H.E., Bates A.L., Boylan A.
and Corum M. (1998) Geochemistry of Florida Bay sediments: Investigation
of nutrient and seagrass history. Annual Florida Bay Science Conference,
Miami, FL, May 1998, Extended abstract with Program, 3 pp.
Zielinski R.A., Simmons K.R., and Orem W.H. (1997) Uranium and uranium
isotopes as tracers of nutrient addition: A case study in south Florida
[abs.]. 4îí International Symposium on Environmental Geochemistry, Vail,
CO. October .1997.
Orem W.H. (1998) Geochemistry of Florida Bay sediments. Management Presentation
at South Florida Water Mamagement District, West Palm Beach, FL, May 1998.
Orem W.H., Lerch H.E., Bates A.L., Boylan A., Corum M. and Hedgman C.
(1998) Organic geochemical studies of Florida Bay sediments: Application
to problems of eutrophication and seagrass history. International Coastal
Symposium, Palm Beach, FL, May 1998, Abstracts with Program.
Kendall C., Silva S. and Chang C. (1998) Isotope studies in the Everglades:
Food webs, mapping of redox conditions, and phosphates. South Florida Mercury
Science Program Annual Workshop, West Palm Beach, FL, May 1998, Abstracts
with Program.
Kendall C., Silva S.R., Stober Q.J. and Meyer P. (1998) Mapping spatial
variability in marsh redox conditions in the Florida Everglades using biomass
stable isotopic compositions. AGU Spring Meeting, Boston, MA, Abstracts
with Program.
PROJECT SUPPORT REQUIREMENTS
All expertise needs are staffed in project or are acquired by collaboration
with other USGS projects, or collaboration with researchers in outside
agencies (e.g. SFWMD, FDEP, FGS, USEPA, NPS, USFWS, USDA). Principal expertise
needs include: organic chemistry, porewater geochemistry, sulfur geochemistry,
isotope geochemistry, uranium geochemistry, geochemical modeling, GIS computer
data handling (support from Mark Levine, EERT, Reston, VA), trace metal
geochemistry, mercury geochemistry and
Other required expertise for which no individual has been identified:
None.
Major equipment/facility needs: Geochemical laboratories are
located in Reston, VA. Stable Isotope laboratories are located in Reston,
VA and in Menlo Park, CA. Uranium laboratory is located in Denver, CO.
No new major equipment needs anticipated for FY1999.
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U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology This page is: http://sofia.usgs.gov/proposals/1999/wetlandp99.html Comments and suggestions? Contact: Heather Henkel - Webmaster Last updated: 11 October, 2002 @ 09:31 PM (KP) |