Two data sets are available for this project. The Northern Everglades Research Site and Sample Information data set contains a summary of the site locations, data types, and measurement periods in ENR, WCA2A, and WCA2B. The Seepage Meters Site and Sample Information data set contains vertical fluxes across wetland peat surface measured by seepage meters at research sites in ENR, WCA2A, WCA2B, and WCA3A.
Orem, W. H. Harvey, J.. W. Spiker, E. C.
Orem, William H. Harvey. Judson W. Spiker, Elliot C.
Krupa, Steven L. Gefvert, Cynthia J. Choi, Jungyill Mooney, Robert H. Giddings, Jefferson B.
Krupa, Steven L. Gefvert, Cynthia Mooney, Robert H. Choi, Jungyill King, Susan A. Giddings, Jefferson B.
Harvey, J. W.
Harvey, Judson W.
Jackson, Jonah M. Mooney, robert H. Choi, Jungyill
In total, flux measurements have been made at more than 30 study sites where mercury and nutrient fluxes are under study, including ENRI WCA-2a. and Taylor Slough wetlands. Groundwater hydraulic head and chemical measurements have been made at 60 sites; in collaboration with Mike Reddy (USGS, WRD, Boulder) peat porewater chemistry has been measured at six depths at 7 sites for almost 3 years. The major benchmarks of progress for the study are:
1) Establish research sites on transects across the wetland interior in ENR, WCA-2A, and Taylor Slough (and single sites in WCA-2B and WCA-3A). Measure porewater solute concentrations and vertical seepage and quantify vertical fluxes of groundwater and surface water across the sediment interface using these two independent sources of information. Measure groundwater hydraulic heads and compute vertical hydraulic gradients (that indicate the direction of vertical fluxes and changes in that direction over time). Also measure hydraulic conductivity of the peat and layers within the aquifer and measure groundwater chemical and isotopic concentrations for use as tracers to quantify area-averaged fluxes to surface water,
2) Combine the site-specific vertical flux estimates described above with other water budget data (surface-water flow, precipitation, evapotranspiration) and other chemical data from surface-water locations. Use expanded data sets to constrain area-averaged water and chemical mass balance models in ENR, WCA-2a, and Taylor Slough,
3) Relate vertical exchange fluxes of water, mercury and nutrients between ground and surface water to past and current water-level management strategies. Consider factors such as hydrogeologic characteristics, regional water balance, and effect of management of water levels in canals and in WCA-l.
Determined recharging water in ENR is transporting dissolved mercury downward through peat and into storage in the Surficial Aquifer. The conclusion is that dissolved mercury is being retained in the Surficial Aquifer as a result of biogeochemical reactions with aquifer surfaces.
Efforts using major ions and radium isotopes have identified a significant flux of groundwater into Taylor Slough from the west side of the slough, but quantification of that flux has been slowed due to the lack of a documented analysis fo athe surface-water velocity data in Taylor Slough. There is also uncertainty about the effect of particle-reactivity of the radium isotopes that will be addressed in upcoming work. Finally there was the difficulty of identifying actual flow paths of Taylor Slough water south of Taylor Slough Bridge. Significant progress was made on that front in FY2000 by teaming up with Clint Hittle and Mark Zucker to coordinate wetland and coastal sample collections. Sampling from July, 1999 through November, 1999 identified the pathway of movement of large pulses of freshwater that resulted from Tropical Storm Harvey and Hurricane Irene from source areas that began in upper Taylor Slough, in lower L31-W canal, and in the C-111 canal.
Completion of QA and QC of all of our measurements to date in Taylor Slough, including surface water staff measurements and ground water-level measurements, water depths, peat depths, estimates of peat hydraulic conductivity, and major-ion chemistry in surface and ground water is progressing. Our data set is the only type of its kind representing broad spatial patterns during time periods when intensive velocity gaging was being conducted in the Slough (September and November 1997, July 1998, and September 1999). A data report is presently being prepared after which all data will be made available on the SOFIA web site.
Like the work in Everglades National Park, our work in the north Everglades work involves developing and testing new methods to quantify groundwater-surface water interactions. Unlike the ENP work, our north Everglades work began earlier (in FY1996) and is now reaching maturity. Having completed the task of quantifying surface and ground water exchange fluxes, work is now emphasizing chemical reactions that occur at the interface between surface water and ground water. Interest is in those biogeochemical reactions that affect the fate of contaminants such as mercury, sulfate, and nutrients in the Everglades. At this stage fieldwork is largely complete (except for continuation fieldwork that has been funded by SFWMD). In large part activities at this point involve additional data analysis and modeling that are needed to reliably determine water fluxes and chemical reaction rates in flow paths connecting surface and ground water. The project is also developing model analyses that are compatable with the data sets to quantify the role of groundwater and peat in storing contaminants and releasing them slowly over time to surface water.
The advantage of using environmental geochemical tracers is flux estimates are obtained at larger spatial scales that are more similar to the scales of interest for practical problems of restoring flows and protecting water quality. The problem with using many of the existing methods in the Everglades is that the source waters to Everglades National Park have already interacted with groundwater, and therefore already have a 'groundwater' chemical signature. The ground water signature in Everglades source waters therefore interferes with the use of commonly used tracers to delineate groundwater interactions that occur within the Park. Our approach is to use Uranium series isotopes to quantify surface water and ground water interactions that occur within the confines of Everglades National Park.
The detailed experimental study of solute transport in Shark Slough involves releasing by steady injection (for a period ranging between 4 and 24 hours) a small amount of salt solution (sodium bromide) in "flumes" in Everglades National Park. We will track both the downstream movement and longitudinal spreading of the tracer in surface water, as well as the exchange between surface water and peat porewater. Our collaborator, Jim Saiers from Yale University, will be conducting a co-injection of fine (neutrally-buoyant) latex particles to learn about processes affecting transport of fine particulate organic matter. As outlined above, we have particular interest in quantifying the rate and extent to which surface water and subsurface porewater are exchanged. This information is embedded within the surface-water tracer measurements but will be verified independently through measurements of concentrations of the bromide tracer in porewater of the peat. Our modeling will account for advection and longitudinal dispersion of solute in surface water, as well as the effects of exchange with peat porewater. Jim Saiers will have primary responsibility for measurement and modeling of fine particulate transport.
We are still active in publishing results from on-going (but nearly completed) investigations in Water Conservation Area 2A, and will add to the production line new products from FY03 activities in Shark Slough. In FY04/05 we plan to continue reporting our results, The first product in mid FY04 will document results from the bromide tracer test at an FIU flume facility in Shark Slough. The second product in mid to late FY04 will feature a watershed-scale modeling application in Taylor Slough that uses environmental radium measurements as well as detailed results from the bromide tracer test.
Hydrologic Transport Processes Affecting Movement and Retention of Dissolved Constituents and Contaminants in the Everglades:
The principal work to be conducted in FY04 include both 1) detailed experimental studies and modeling of solute transport at relatively small scales (10-m), combined with 2) synoptic investigations of natural distributions of radium isotopes and modeling of solute transport at larger scales (10- km) in Taylor and Shark Sloughs. The general plan for detailed experimentation involves releasing a bromide salt solution (NaBr) by steady injection (for a period ranging between 4 and 24 hours) into surface water in Everglades National Park. We track both the downstream movement and vertical and longitudinal spreading of the tracer in surface water, as well as the exchange between surface water and peat porewater. Of particular interest is quantifying the rate and extent to which surface water and subsurface porewater are exchanged. This information is embedded within the surfacewater tracer measurements but will be verified independently through measurements of concentrations of the bromide tracer in porewater of the peat. The modeling will account for advection and vertical and longitudinal dispersion of solute in surface water, as well as the effects of exchange with peat porewater.
To obtain measurements and modeling necessary to scale up our information about solute transport to the watershed scale, the strategy is to modify the site-specific radium isotopic tracer technique that previously developed to quantify ground water and surface water interactions at a watershed scale. To accomplish the goal of scaling up, we will need to extend our site specific method using the radium tracer in a way that will allow us to quantify interactions between surface and subsurface water along a surface-water 'flowpath' in the main flow-ways in Shark Slough and Taylor Slough. Some kilometer-scale sampling of the radium tracer and other physical and biogeochemical parameters have already been completed in Taylor Slough. Similar work will be conducted in Shark Slough beginning either in the 1st or 2nd quarter of FY04. Modeling solute transport and dispersion at the 10-km scale will require not only the radium measurements, but also information from the detailed tracer studies and meterologic and hydrologic information from existing hydrology data sets and sources in the Park.
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