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Geochronology in the South Florida Ecosystem and associated Ecosystem Programs

Project Proposal for 1998

Project Title: Geochronology in the South Florida Ecosystem and associated Ecosystem Programs
Location of Study Area: South Florida and Chesapeake Bay
Project Start Date: October 1996
Project End Date: September 1999
Project Number: 7-7242-37652
Project Chief: Charles W. Holmes
Region/Division/Team/Section: Eastem/WRD-GD/Marine and Coastal/St.Pete
Phone: 813-893-3100 (3056)
Fax: 813-893-3366
Mailing Address: 600 4th Street South, St. Petersburg, Fl, 33701
Program Element(s)/Task(s)Ecosystem History/5.1 ( 75%)/ Florida Bay/6.3 (25%)
Collaborators, Clients: The clients for the data and information provided by this study are the modelers and the engineers who must design the strategy to restore the ecosystem to the desired levels. These are the hydrologic and chemical models of the USGS, the Scientist and engineers for South Florida Water Management District and the U.S. Army Corp. of Engineers, the cites and country environmental planners and engineers of South Florida and the managers for Everglades National Park and Big Cypress Preserve . Describe plans to address client requirements,


Project Summary: Many ecological questions require temporal information before a management decision can be reached. This projects supplies the important time series information for process-based studies (both in the terrestrial and coastal environment), time information for the ecological and fire history research, the timing of sealevel rises and storm events, the rate of sediment transport and deposition in Florida Bay and the "age" of ground water seeping under the fringing topographic ridge.

Project Justification: Resource managers, in order to provide adequate leadership in balancing the environment between natural and anthropogenic needs, must understand how the natural system works. The document South Florida Ecosystem Restoration: Scientific Needs list many such questions requiring temporal data in the answer. The timing of chemical loading in the terrestrial or coastal zones, or the formation of certain features which affect water flow is of paramount importance to management of the natural resources within the South Florida Area. This project will provides information on the timing of events.

Project Objectives: Over the past three decades there has been a dramatic increase in the volume and range of research on recent sediments. Much of this research effort has been aimed at understand short-lived sedimentologic processes and the result of anthropogenic manipulation of natural processes. In south Florida, ecological changes have alarmed all who are concerned with maintaining the south Florida way of life. In order to understand what has influenced the natural processes that have caused these changes, it is necessary to understand the processes at work within the system and to determine the rates at which these changes are occurring. The lack of historical records documenting changes dictates that other methods be used to measure "rates of change." A common method is to use the decay of naturally occurring radioactive nuclides. The usefulness of any radioactive nuclides requires certain conditions be met. These conditions are 1. the chemistry of the nuclide (element) is known; 2. The nuclide onces incorporated into the substrate changes only by decay, and 3. in order to be useful, it is relatively easy to measure. The objectives of the project is to measure the distribution of short- lived radionuclides to provide a temporal component to the processes at work within the Ecosystem.

Overall Strategy, Study Design, and Planned Major Products:


Overall: Sufficient data has been collected in the South Florida Region and in Chesapeake Bay to confirm that the radiometric methods proposed do yield a valid chronology. The ecological variability within the South Florida Area, however, is considerable requiring that a separate chronology be ascertained for each site of interest. Because of different analytical methods require a lot of sediment, many "dated" cores will be adjacent to those used for geochemistry. For the ecological and fire history studies, the same core will be used. The emphasis this year is to understand the processes that have worked and are working within the Taylor Slough area, define a chronology of ecological change in Chesapeake Bay, and define the changes in the chemical systems in Florida Bay.

A poll of the investigators presently working in the south Florida Ecosystem and the Chesapeake Bay program has indicated the following needs for the coming year:
1. The terrestrial geochemical process study-- l7cores
2. The geochemical study of bay sediments -- 4 cores
3 Chesapeake Bay cores - Tom Cronin 13 cores
4. Florida and Biscayne bays cores - 6 Cores

These projects have indicated a need to have a chronological record established for 36 sites. It is proposed that a chronology at various sites will be established by used of natural and man-made short-lived radioisotopes (7Be, 137CS, 21OPb, in some case's uranium/thorium, or 14C).


                                         FY 1998
                            Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept
Analysis of:
Taylor. Cores               -------------------------------------------------
Fla.Bay and
Adjacent Bays
Cores		            --------------------------------------------------
Chesapeake Bay	             -----------------
Florida Bay meeting               ----
Measurements of
sediment/fluid transport     -------------------------------------------------
Year Report						               -------

Planned Deliverables/Products: As this is primarily a support project that is providing data to other projects, most to the data is incoportated in the products of others. This data is supplied in a timely fashion to those projects chiefs and has been and is being used in their reports. In additon speicific chronology reports are being prepared which deal with the analysis of the chronological data and the probelms of using some elements without confirmation.

Planned Outreach Activities: The information derived from this project will be presented at the anual meeting of the Ecosystem program, the Ecological history workshop, and at the international Environmental Geochemical meeting. In addtion, the Paelocological investigators will be present data from this project at the AGU on other conferences dealing with the presentaion of this data.

Prior Accomplishments in Proposed Area of Work:

New Directions, Expansion of Continuing Project (if applicable): The addition of low-level counting equipment has added a new dimension to the cabablitiy of the geochronology project. In addition to measuring timing of events on decadal time scales, we are now capable of measuring events on a daily time scale. This allows us to determine such processes such as how much sediment is eroded during a single event such as storm, or flood. Such information will allow us to determine the transportation of sediment within system, information that is important in the developernent of water qualitiy models, such as t he one presently being developed for Florida Bay. This part of the project addresses the issues that are part of Element 6 / Task 6.3. These systems also permit the measurement the flow of ground water by the determination of the relative amount of "tracer" isotopes in fluid "leaking" from the strata. There are numerous pieces of evidence that "tracer" loaded fluid are interacting with the bay water and sediment. This new direction would be an attempt to quanitify this interaction.


Accomplishments and Outcomes, Including Outreach: During 1997, there has been 35 cores anlayzed and the data reported to the investigators. In addtion, experiments were preformed to examine the mobility of Cs in the sediment the Florida Ecosystem. This experiment awaits the aquiring of additional 14C data. This information is essential to confirm the distribution of cesium. Preliminary information suggests ythat in systems that are have high rates of sedimentation, Cs is mobile. These zone are the most critical in understanding the ecological development of South Florida. In the case of the terrestrial part of the study area, it is critical to define as accuaracy as possible, the accumulation rates, as this data is used in defining the number of acres need to storm treament areas.

Deliverables, Products Completed:
1. Gough, L.P., Kotra, R.K., Holmes, CW. Briggs, P.H., Crock, J.G., Fey, D.L.,Hagman, P.L.,Meirer, A.L., and Papp, C.S.E., 1996, Geochemistry of Mercury and Trace elements in Vegetation, Water, and Organic-Rich sediments, South Florida -- Chemical Results, U.S.Geological Survey Open File Report 96-91.
2. Holmes, C.W., 1996, Geochronology in South Florida, Fact Sheet
3. Holmes, C.W., Robbins, J., Bothner, M, Halley, R., Shinn, E., Rudnick, D., Ten-Brink, M., Marot, M., Morehead, N., Gill,P., Casso,M., Graney, J., Keeler, G., and Rendings, R., 1996, Ecological change in Florida Bay -- Can we tell when it happen?, S.E.P.M. Congress, St. Petersburg, Fl., p 69
4. Willard, D.A., Brewster-Wingard, G.L., and Holmes, C.W., 1996, The paleontological record from southern Florida: application to restoration of the Everglades ecosystem,Sixth North American Paelontological Convention, Abstracts of papers, The Paleontological Socitey, Special Publication, no 8,p. 422.
5. Willard, D.A., Weimer, L.M., and Holmes, C.W., Vegetational changes over the Last Millenia in South Florida: Evidence from the pollen record, G.S.A. Annual Meeting, in press.
6. Holmes, C.W. and Marot, M.E., 1997, Geochronological data for the terrestrial portion south Florida Ecosystem, U.S.Geological Survey Open File Report, in review.
7. Holmes, C.W. and Marot, M.E. 1997, Ecological changes in Florida Bay, Can we tell when it happened? 4th International Symposium on Environmental Geochemistry, in press
8. Willard, D.A., and Holmes, C.W., 1997. Pollen and geochronological data from South Florida: Taylor Creek Site 2. U.S. Geological Survey Open-File Report 97-35, 28 pp.
9. Brewster-Wingard, G.L., Ishman, S.E., Willard, D.A., Holmes, C.W., and Halley, R.B., 1996. The biotic record of change in Florida Bay and the south Florida ecosystem. Program and Abstracts, 1996 Florida Bay Science Conference, Key Largo, FL, p. 25-26.
1O. Halley, R.B., Roulier, L. Holmes, C.W., Rudnick. D. , and Shinn, E.A., 1997, Circulation history and the carbon isotope record of east/central Florida Bay: Preliminary observations, Southeasterm estuarine Meeting, Key Largo.
11. T M Cronin, D C.Grinbaum, D A Willard, C W Holmes, R Kerhin, 1997 Climate change and its impact on the Chesapeake Bay., AGU Spring meeting
12. A W Karlsen, T M Cronin, C W Holmes, 1997, Trends in Benthic Faunal Response to Environmental Change in the ChesapeakeBay. AGU Spring Meeting


Required Expertise: For all Fiscal years, A project Chief (Charles W. Holmes, Geochemist) and a Lab technician ( Marci Marot, Marine Chemist), and part time Technician (Julie Donald)

Names of Key Project Staff:
Charles W. Holmes, geochemist Fy96 - Fy99
Marci Marot, Marine Chemist FY96 Fy99
Julie Donald, Technician (Fy98)

Major Equipment/Facility Needs: Laboratory and counting equipmental

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