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projects > linking land, air and water management in the southern everglades and coastal zone to water quality and ecosystem restoration > work plan
Project Work PlanDepartment of Interior USGS GE PESFiscal Year 2008 Study Work PlanStudy Title: Linking Land, Air and Water Management in the Southern Everglades and Coastal Zone to Water Quality and Ecosystem Restoration Overview & Objective(s): Water quality remains one of the biggest issues facing restoration of the Everglades. However, a complete understanding of all the factors (external and internal) the regulate past and present water quality in the Everglades, and even more challenging to anticipate future water quality conditions that will occur in response to the restoration effort, is a significant challenge to both scientists and resource managers. Water quality studies in the Everglades over the past 10-20 years have largely focused on the phosphorus contamination and its ecological impacts. Concerns over phosphorus contamination have resulted in one of the most expensive aspects of the Everglades Restoration program, the establishment of over 45,000 acres of storm water treatment area (STAs). Because so much attention has been focused on phosphorus in south Florida, however, in some ways water quality and phosphorus have become synonymous, and thus a complete understanding of all the potential linkages between various pollutant sources, physical and hydrologic changes resulting from the restoration, and water quality is not being realized. While we recognize that excessive phosphorus loading has deleterious effects on the Everglades, other contaminants also warrant attention so that the overall restoration goal of "...to improve the quantity, quality, timing, and distribution of clean fresh water needed to restore the South Florida Ecosystem" can be achieved. The USGS has been assessing two other important contaminants, mercury (Hg) and sulfate, which are present at concentrations sufficient to pose a threat in larger portions of the ecosystem than phosphorus. Mercury, an atmospherically transported contaminant, affects the entire ecosystem. Sulfate, on the other hand, is dominantly derived from the same contamination source as phosphorus (runoff from agricultural uses), but affects a larger fraction of the Everglades presently (about 30 to 60 percent) due to its greater mobility in the environment and because the STAs in their current configuration due little or nothing to abate sulfate transport to the downstream Everglades. Sulfate alone can have profound impacts on natural redox conditions in wetlands, which can stress and/or kill native vegetation. In addition, the co-contamination of the environment with Hg and sulfate has an extremely important synergistic effect on the toxicity of Hg through the conversion of inorganic Hg (form atmospheric deposition) to methylmercury (MeHg), the most toxic and bioaccumulative form of Hg. Methylmercury comprises >95% of all the Hg in predator-level species and thus is responsible for essentially all of the toxicological concern for this widespread contaminant. Wildlife toxicologists are only now determining many of the important ways that MeHg may be affecting fish and wildlife, including the new observations on White Ibis from the Everglades that population level effects may be occurring through toxicity to the unborn, or through substantial hormone disruption (Dr. Peter Frederick, U. of Florida). Mercury methylation in the environment is dominantly the result of respiration of sulfate by reducing bacteria (SRB). These organisms utilize sulfate and organic carbon for their normal function. However, if inorganic Hg is present, MeHg can be produced as an accidental byproduct. Thus any actions that increase sulfate reduction (such as sulfate loading) or increase Hg availability (such as increases in Hg deposition) may serve to exacerbate Hg toxicity on ecosystems by yielding more MeHg. In addition, seemingly unrelated activities like alterations to hydrologic cycles (wetting and drying periods), flushing rates, other water quality constituents (especially dissolved organic carbon [DOC], iron and pH), can have pronounced effects on Hg methylation. For example, oxidation of soils leads to conversion of organic sulfur to sulfate, and thus subsequent stimulation of sulfate reduction and methylation upon re-inundation. In addition, substantial amounts of DOC are also derived from EAA runoff and shows about the same aerial extent as sulfate. We know DOC plays an important role in facilitating Hg availability to methylating microbes, but other important processes that may be affected by DOC increases include light penetration limitation, nutrient uptake, and cycling of other exogenous metals. Lastly, another byproduct of sulfate reduction, sulfide, is deleterious to many freshwater wetland plants and infauna that are indigenous to the Everglades through oxygen deprivation and suffocation, limiting nutrient uptake, and or direct toxicity. To this point, the USGS studies on Hg and sulfate contamination in south Florida have largely focused on the water conservation areas (WCAs). Our studies have served as a template worldwide on how to conduct studies of Hg in the environment and why wetland-rich ecosystems are areas of heightened concern for MeHg exposure. In addition, our study demonstrated for the first time, the important linkages that exist between an air derived contaminant (Hg) and another from land-based sources (sulfate). During our period of study, we have documented a substantial (>90%) decline of MeHg concentrations in water, sediment and mosquito fish at our study site in central WCA3A-15, but that our other sites in WCA2A, WCA2B, and WCA1 showed no apparent change. Our data clearly show that the MeHg declines in WCA3A are directly related to declines in sulfate concentration at this site. Mesocosm dosing tests at this site confirm that MeHg abundance is strongly controlled by sulfate additions, without any additional Hg added. This observation poses the question whether there have been large declines in sulfur uses in the EAA, or changes in water routing internal to the Everglades. Since sulfate levels over time at our northern canal and WCA2 sites show similar or modestly lower levels of sulfate, we hypothesize that changes to water routing within the Everglades are responsible for the dramatically reduced sulfate levels at WCA3A that in turn lead to near-detection level concentrations of MeHg. If this is true, then we might expect that the sulfate-rich waters that previously flowed through our study site are now discharging elsewhere, likely south to Everglades National Park (ENP) or west to Big Cypress National Preserve (BCNP), where increased water delivery is a priority for the Restoration program. Indeed, evidence for steadily increasing fish Hg concentrations in the ENP over the past 5 years is available for at least one monitoring site, North Prong Creek (Ted Lange, Florida Fish and Wildlife Conservation Commission). However, since our research has focused primarily north of the ENP, we do not have contemporaneous water quality data to support or refute the conclusion that the increasing fish Hg levels are due to increasing sulfate loads due to increasing water delivery from canals to the Shark River Sough. We hypothesize that the delivery of larger volumes of water to ENP will result in a greater load of sulfate, and increases in MeHg production and bioaccumulation. The overall objective of this next phase of our research is to extend our understanding of the interactions of Hg, sulfate, DOC contamination to areas of the Everglades that are anticipated to receive increasing water delivery from sulfate rich EAA runoff or ASR waters, including: ENP, BCNP, and Loxahatchee National Wildlife Refuge (LNWR). Specific Relevance to Major Unanswered Questions and Information Needs Identified: This study supports several of the projects and overall goals listed in the DOI science plan. The DOI science plan lists three overarching restoration questions (page 9) that this study has direct relevance and provides information toward answering, including: (1) What actions will improve the quantity, timing, and distribution of clean fresh water needed to restore the South Florida ecosystem? (2) What actions will restore, protect, and manage natural resources on DOI lands in South Florida? (3) What actions will recover South Florida's threatened and endangered species? Aquifer Storage and Recovery (ASR) has substantial potential to affect water quality everywhere recovered water is released to the south Florida ecosystem, and is an area of concern in the DOI Science Plan (page 27). This study has demonstrated links between water quality characteristics of waters to be injected (sulfate, DOC, DO, and pH), the water quality characteristics of water recovered, and the water quality characteristics of water within the receiving surface and ground waters. In addition, the Comprehensive Integrated Water Quality Feasibility Study (CIWQFS; page 84) identifies degraded water bodies, types and sources of waterborne pollution, establishing load reduction targets for pollutants, and the need to improve water quality. Findings from this study will assist the DOI in providing needed information to multiagency CIWQFS Project Delivery Team in identifying the linkages between water quality targets and ecosystem restoration. The need to understand the sources, cycling and fate of critical chemical constituents like mercury, and to quantify the types and sources of pollution is stated on page 85. Linked to cycling and fate, the Science Plan cites the need for water quality performance targets (page 85) that can be used to evaluate the progress of restoration, and to identify areas in need of adaptive management. This project has shown clear linkages between water quality, land management (siting and operation of STAs; page 86), and restoration plans, which will be critical for evaluating the overall success of the Restoration effort. Finally, the Science Plan specifically identifies the need to predict the effects of hydroperiod alterations and soil and water chemistry on the bioavailability of mercury to methylation (Page 89). This project not only discovered these hydro-cycle mercury-methylation linkages, but continues to unravel its complexities. The intent of these studies is to help land managers to make decisions that reduce the effects of hydroperiod alterations on mercury methylation. Task 1: Linking Land, Air and Water Management in the Southern Everglades and Coastal Zone to Water Quality and Ecosystem Restoration: Task 1, Mercury Cycling, Fate and Bioaccumulation Status and Plans: Mercury research in the Everglades was originally initiated under Phase I and Phase II of the Aquatic Cycling of Mercury in the Everglades (ACME) project, which has concluded. This project focused on deriving a complete understanding of the ecosystem scale factors regulating MeHg generation in the Everglades. The second project "Integrated Biogeochemical Studies in the Everglades", which focused on the execution of in-field experimentation (dosing experiments) to confirm the inferred effects of Hg, carbon and sulfate on MeHg production ad bioaccumulation. Finally, we have proposed to extend our findings to relatively less well studied portions of the Everglades, especially those that may receive greater amounts of canal water discharge as a result of the restoration efforts (e.g., ENP, BCNP, and LNWR). This three year project will seek to extend our knowledge of the controlling factors of mercury toxicity in the Everglades, with specific attention to geographical areas and land use and changes related to the restoration that may affect methylmercury production and bioaccumulation. Because work under ACME was largely conducted in the WCA's, we propose to direct our current and future efforts on the federally managed lands. Three specific areas of work will be conducted in FY07: (1) sampling surveys on the federally managed lands, particularly those that are receiving canal water discharge; (2) sampling in the newly operating periphyton/limerock STAs and previously existing cattail/peat STAs; (3) sampling of the McCormick canal water dosing mesocosms in LNWR; (4) participation on the planning and execution of the Water Quality of the Greater Everglades: Fate and Transport of Nutrients and Other Contaminants symposium at the Spring 2008 GEER conference; and, (5) continued efforts toward publication of past and current results. Task 2: Linking Land, Air and Water Management in the Southern Everglades and Coastal Zone to Water Quality and Ecosystem Restoration: Task 2, Sulfur and Nutrient Contamination, Biogeochemical Cycling, and Effects Task 2 focuses on sulfur and nutrient biogeochemistry in the Everglades, and in concert with the other tasks also examines the complex interactions of sulfur with mercury (synergistic and antagonistic). Emphasis is placed on ecosystem responses to variations in contaminant loading (changes in external and internal loading over time and space dimensions), and how imminent ecosystem restoration may affect existing contaminant pools and their impacts on natural resources in the ecosystem. The major objectives are to determine: (1) anthropogenic-induced changes in the water chemistry of the Everglades ecosystem, (2) biogeochemical processes within the ecosystem affecting water chemistry, (3) the predicted impacts of restoration efforts on water chemistry, and (4) the impacts of contaminants on natural resources in the ecosystem. The approach used includes a combination of field surveys, contaminant monitoring at key sites, experimental studies in the ecosystem using experimental chambers (mesocosms), and laboratory experiments using microcosms. The experimental field and laboratory studies are utilized to confirm conceptual models and hypotheses developed from field surveys. Study results will provide critical elements for building ecosystem models and screening-level risk assessment for the principal contaminants impacting water quality in the ecosystem (nutrients/sulfur/mercury/organics), and provide CERP (3005-1;3050-1,2,3,6,7,11;3060-1;3080-3,4,8,9,10), and GEER management with quantitative information for critical decisions, such as estimates of the maximum sulfur, nutrient, and mercury loads producing permissable levels of methylmercury in the ecosystem, the toxic effects of sulfur on biotic assemblages, estimates of the time required for ecosystem recovery from chemical contamination, and the effects of restoration on contaminant loads and impacts of contaminants. Results are incorporated into conceptual, mathematical, and risk assessment models of the Everglades ecosystem. Specific Relevance to Major Unanswered Questions and Information Needs Identified: This study supports several of the projects and overall goals listed in the DOI science plan. The DOI science plan lists three overarching restoration questions (page 9) that this study has direct relevance and provides information toward answering, including: (1) What actions will improve the quantity, timing, and distribution of clean fresh water needed to restore the South Florida ecosystem? (2) What actions will restore, protect, and manage natural resources on DOI lands in South Florida? (3) What actions will recover South Florida's threatened and endangered species? Aquifer Storage and Recovery (ASR) has substantial potential to affect water quality everywhere recovered water is released to the south Florida ecosystem, and is an area of concern in the DOI Science Plan (page 27). This study has demonstrated links between water quality characteristics of waters to be injected (sulfate, DOC, DO, and pH), the water quality characteristics of water recovered, and the water quality characteristics of water within the receiving surface and ground waters. In addition, the Comprehensive Integrated Water Quality Feasibility Study (CIWQFS; page 84) identifies degraded water bodies, types and sources of waterborne pollution, establishing load reduction targets for pollutants, and the need to improve water quality. Findings from this study will assist the DOI in providing needed information to multiagency CIWQFS Project Delivery Team in identifying the linkages between water quality targets and ecosystem restoration. The need to understand the sources, cycling and fate of critical chemical constituents like mercury, and to quantify the types and sources of pollution is stated on page 85. Linked to cycling and fate, the Science Plan cites the need for water quality performance targets (page 85) that can be used to evaluate the progress of restoration, and to identify areas in need of adaptive management. This project has shown clear linkages between water quality, land management (siting and operation of STAs; page 86), and restoration plans, which will be critical for evaluating the overall success of the Restoration effort. Finally, the Science Plan specifically identifies the need to predict the effects of hydroperiod alterations and soil and water chemistry on the bioavailability of mercury to methylation (Page 89). This project not only discovered these hydro-cycle mercury-methylation linkages, but continues to unravel its complexities. The intent of these studies is to help land managers to make decisions that reduce the effects of hydroperiod alterations on mercury methylation. Status and Plans: Mercury research in the Everglades was originally initiated under Phase I and Phase II of the Aquatic Cycling of Mercury in the Everglades (ACME) project, which has concluded. This project focused on deriving a complete understanding of the ecosystem scale factors regulating MeHg generation in the Everglades. The second project "Integrated Biogeochemical Studies in the Everglades", which focused on the execution of in-field experimentation (dosing experiments) to confirm the inferred effects of Hg, carbon and sulfate on MeHg production ad bioaccumulation. Finally, we have proposed to extend our findings to relatively less well studied portions of the Everglades, especially those that may receive greater amounts of canal water discharge as a result of the restoration efforts (e.g., ENP, BCNP, and LNWR). This three year project will seek to extend our knowledge of the controlling factors of mercury toxicity in the Everglades, with specific attention to geographical areas and land use and changes related to the restoration that may affect methylmercury production and bioaccumulation. Because work under ACME was largely conducted in the WCA's, we propose to direct our current and future efforts on the federally managed lands. Three specific areas of work will be conducted in FY08: (1) sampling surveys on the federally managed lands, particularly those that are receiving canal water discharge; (2) sampling in the newly operating periphyton/limerock STAs and previously existing cattail/peat STAs; (3) sampling of the McCormick canal water dosing mesocosms in LNWR; (4) continued monitoring of canals for sulfate and sulfur isotope analysis; (5) participation on the planning and execution of the Water Quality of the Greater Everglades: Fate and Transport of Nutrients and Other Contaminants symposium at the Summer 2008 GEER conference; and, (6) continued efforts toward publication of past and current results. Work to be undertaken during the proposal year and a description of the methods and procedures: Task 2 work will be conducted in coordination with Tasks 1 and 3 of this project and will include the following activities in FY 2008: (1) Field Surveys in ENP, BCNP, and LOX - Field surveys will be conducted in the study areas (ENP, BCNP, LOX). The proposed field surveys will be similar to surveys we have previously conducted in the northern and central Everglades. Samples of surface water, pore water, sediments, and biota are collected using "clean" methods previously validated by our team in the Everglades, and now used by other researchers. Samples for Task 2 are analyzed for sulfur species, nutrients, and ancillary biogeochemical parameters. The work in ENP will include freshwater slough areas potentially impacted by contaminated canal water, and will focus on how restoration is impacting sulfur loads to ENP, and how the sulfur loads impact mercury methylation and bioaccumulation, sulfur toxicity to native flora and fauna, and internal eutrophication of the system from excess sulfate. Sampling will be conducted at sites specifically selected to answer the question. Sites where canal water is discharged into ENP (sites P33 and P34) will be targeted. Field surveys conducted in BCNP will examine potential impacts of the planned diversion of sulfate contaminated water from the L28 feeder canal. This diversion has not yet been implemented, but is likely to result in increased MeHg production in BCNP. Proposed field surveys would establish present conditions within BCNP, and examine areas where water with elevated sulfate levels is currently entering the Preserve. The threat of sulfate contaminated canal water infiltrating LOX from the new STA-1E and associated drainage canals bordering LOX is also of concern, with regard to increased sulfate loads and stimulation of MeHg production. We plan field surveys here to examine this issue, following up on work conducted by Paul McCormack (USGS-BRD; now with SFWMD). McCormack has been working with LOX staff to establish sites where contaminated canal water is infiltrating the Refuge, and sites chosen for our field survey would be established after consultation. The surveys provide information supporting the Comprehensive Integrated Water Quality Feasibility Study in the Landscape Science needs of the DOI Science Plan (p. 85), by examining links between water quality and ecosystem structure and function, identifying degraded parts of the ecosystem and quantifying links to contaminants (nutrients, sulfur, organics, and mercury). It also provides CERP (3005-1;3050-1,2,3,6,7,11;3060-1;3080-3,4,8,9,10), and GEER management with quantitative information on the effects of restoration on the movement of toxic substances (sulfur, mercury) into pristine parts of the ecosystem, especially protected federal lands. This work also addresses the Combined Structural and Operational Plan (CSOP) and the Water Conservation Area 3 Decompartmentalization and Sheetflow Enhancement by addressing the potential for increases in toxic contaminant loads (especially sulfur) and its ecological impact, p. 71. We will continue collaboration with Paul McCormick on water quality in LOX (WCA 1), specifically focused on sulfur geochemistry and the paleoenvironmental chemical conditions in WCA 1. This supports the Arthur R. Marshall Loxahatchee NWR Internal Canal Structure Project by addressing the impacts of water quality (sulfur/nutrients/mercury) and water management practices on refuge resources, p. 40. (2) PASTA and STA Studies - In coordination with USACE we will conduct initial field surveys in the PASTAs (periphyton STAs) to examine mercury and sulfur biogeochemistry. We will also examine the macrophyte-dominated STAs for comparison. Questions to be asked include: (a) how do the different STA approaches differ in terms of mercury chemistry and production and bioaccumulation of methylmercury, (b) how do PASTAs perform in terms of sulfate removal compared to the macrophyte-dominated STAs, (c) how do these two different STA systems differ in terms of sulfur biogeochemistry, and nutrient remobilization from internal eutrophication effects. The proposed field surveys will be similar to surveys we have previously conducted in the northern and central Everglades, and STA 1W (Formerly ENR). Samples of surface water, pore water, sediments, and biota are collected using "clean" methods previously validated by our team in the Everglades, and now used by other researchers. Samples for Task 2 are analyzed for sulfur species, nutrients, and ancillary biogeochemical parameters. (3) Mesocosm Studies in LNWR - The Loxahatchee National Wildlife Refuge (LNWR) represents one of the last vestiges of the historic soft-water Everglades. This is evidenced by the low conductivity of surface water in the marsh interior (~100 µS) compared with that in the canal surrounding the Refuge (1000-1500 µS). Low conductivity waters in LNWR interior are associated with a characteristic soft-water periphyton community, wetland plant species that may also be adapted to the soft-water conditions, and lower rates of key ecosystem processes (e.g., decomposition) than in areas of the Everglades impacted by canal discharges. While it has long been known that the fringes of the LNWR are affected by high conductivity canal water, recent monitoring data indicate a trend towards increased intrusion of this water into the LNWR interior with noticeable impacts on water chemistry and sensitive biota, including the possibility of increased methylmercury production and bioaccumulation. Both scientists and managers have expressed concern over the spread of such impacts and their relationship to water management activities. To address this concern, Paul McCormick (USGS-BRD, now at SFWMD) established a suite of experimental plots (mesocosms) in the LNWR to examine the effects of this encorachment of contaminated canal water on the Refuge. We are cooperating with Paul and LNWR staff on this project to examine mercury, sulfur, and DOC biogeochemistry in the dosed mesocosms. The mesocosms are dosed with an artificial canal water that mimics the chemical composition of the canal water surrounding the refuge. We will collect samples of surface water, pore water, sediments, and using "clean" methods. Samples for Task 2 are analyzed for sulfur species, nutrients, and ancillary biogeochemical parameters. (4) Canal water Monitoring - We propose to continue to monitor canal water for sulfur species and sulfur isotopes. Canals are the major conduit of sulfur-contaminated water to enter the Everglades from the source in the Everglades Agricultural Area. Our monitoring effort began in 1997, and represents an important dataset since SFWMD data only recently incorporated sulfate analysis. The sulfate entering the Everglades has significant impacts on the ecosystem, including acting as a major control on mercury methylation in the ecosystem, enhancing remobilization of nutrients from soils (internal eutrophication), and posing a threat to macrophytes and other biota through toxic sulfide buildup in soils. (5) GEER Meeting - Orem will act as a co-organizer of a symposium entitled "Water Quality of the Greater Everglades: Fate and Transport of Nutrients and Other Contaminants" at the Greater Everglades Ecosystem Restoration meeting in summer 2007. Orem will also make a presentation and prepare a manuscript for this symposium. (6) Publications - FY08 publications will include papers on: (1) sulfur toxicity mesocosms, (2) contaminants in Big Cypress National Preserve. and (3) sulfur species across the Everglades. Task 3: Linking Land, Air and Water Management in the Southern Everglades and Coastal Zone to Water Quality and Ecosystem Restoration: Task 3, Natural Organic Matter-Mercury Interactions Task 3 focuses on the factors that control the occurrence, nature and reactivity of dissolved organic matter (DOM) in the Florida Everglades, especially with regard to the biological transformation and accumulation of mercury (Hg). Our goal is to provide fundamental information on the nature and reactivity of DOM in the Everglades and to elucidate the mechanisms and pathways by which the DOM influences the chemistry of Hg throughout the system. This research is relevant because of the high natural production of organic carbon in the peat soils and wetlands, the relatively high carbon content of shallow ground water systems in the region, the interactions of organic matter with other chemical species, such as trace metals, divalent cations, mercury, and anthropogenic compounds, the accumulation of organic carbon in corals and carbonate precipitates, and the potential changes in the quality and reactivity of DOC resulting from land use and water management practices. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the current transport of organic matter from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. The results of this research are critical for the design of effective management strategies for the ecological restoration of the Everglades and for mitigating mercury contamination of game fish in South Florida. Status and Plans: Work conducted under Phase I and Phase II of the Aquatic Cycling of Mercury in the Everglades (ACME) project has largely come to a conclusion, with the exception of the "synthesis" component of that work that is described in a separate work plan. This three year project will seek to extend our knowledge of the controlling factors of mercury toxicity in the Everglades, with specific attention to geographical areas and land use and changes related to the restoration that may affect methylmercury production and bioaccumulation. Because work under ACME was largely conducted in the WCA's, we propose to direct our current and future efforts on the federally managed lands (Big Cypress National Preserve, Loxahatchee National Wildlife Refuge, and Everglades National Park). The following specific areas of work will be conducted in FY08: (1) sampling surveys on federally managed lands, particularly those that are receiving canal water discharge; (2) sampling in the newly operating periphyton/limerock STAs and previously existing cattail/peat STAs; (3) sampling of the McCormick canal water dosing mesocosms in LNWR; (4) continued monitoring of canals for DOC concentration, composition and reactivity; (5) participation in the Summer 2008 GEER conference; and, (6) continued efforts toward publication of past and current results. Work to be undertaken during the proposal year and a description of the methods and procedures: Task 3 work will be conducted in coordination with tasks 1 and 2 of this project and will include the following activities in FY 2007: (1) Field Surveys in ENP, BCNP, and LOX - Beginning in FY07, field surveys will be conducted in the study areas (ENP, BCNP, LOX). The proposed field surveys will be similar to surveys we have conducted previously in the northern and central Everglades. Samples of surface water, pore water, sediments, and biota are collected using "clean" methods previously validated by our team in the Everglades, and now used by other researchers. Samples are analyzed for DOC concentration and composition, sulfur species, nutrients, and ancillary biogeochemical parameters. The work in ENP will include both the freshwater areas and the coastal zone. Survey work in the freshwater area of ENP will focus on how restoration is impacting DOC loads, composition, and reactivity to ENP, and how DOC impacts mercury methylation and bioaccumulation. Sampling will be conducted at sites specifically selected to answer the question. Sites where canal water is discharged into ENP (sites P33 and P34) will be targeted. Field surveys conducted in BCNP will examine potential impacts of the planned diversion of DOC contaminated water from the L28 feeder canal. This diversion has not yet been implemented, but is likely to result in increased MeHg production in BCNP. Proposed field surveys would establish present conditions within BCNP, and examine areas where water with elevated DOC levels is currently entering the Preserve. The threat of DOC contaminated canal water infiltrating LOX from the new STA-1E and associated drainage canals bordering LOX is also of concern, with regard to increased stimulation of MeHg production and other ecological impacts associated with the transport of reactive DOC (metals, pesticides and herbicides, controls on primary productivity). We plan field surveys here to examine these issues and to follow up on research conducted by Paul McCormack (SFWMD). McCormack has been working with LOX staff to establish sites where contaminated canal water is infiltrating the Refuge, and sites chosen for our field survey would be established after consultation. The surveys provide information supporting the Comprehensive Integrated Water Quality Feasibility Study in the Landscape Science needs of the DOI Science Plan (p. 85), by examining links between water quality and ecosystem structure and function, identifying degraded parts of the ecosystem and quantifying links to contaminants (nutrients, sulfur, organics, and mercury). It also provides CERP (3005-1;3050-1,2,3,6,7,11;3060-1;3080-3,4,8,9,10), and GEER management with quantitative information on the effects of restoration on the movement of toxic substances (sulfur, mercury) into pristine parts of the ecosystem, especially protected federal lands. This work also addresses the Combined Structural and Operational Plan (CSOP) and the Water Conservation Area 3 Decompartmentalization and Sheetflow Enhancement by addressing the potential for increases in toxic contaminant loads, and, specifically, the ecological impacts of increased DOC concentrations, p. 71. We will continue collaboration with Paul McCormick on water quality in LOX (WCA 1), specifically focused on DOC geochemistry in WCA 1. This supports the Arthur R. Marshall Loxahatchee NWR Internal Canal Structure Project by addressing the impacts of water quality (sulfur/nutrients/mercury) and water management practices on refuge resources, p. 40. (2) PASTA and STA Studies - In coordination with USACE we will conduct initial field surveys in the PASTAs (periphyton STAs) to examine mercury and DOC biogeochemistry. We will also examine the macrophyte-dominated STAs for comparison. Questions to be asked include: (a) how do the different STA approaches differ in terms of mercury chemistry and production and bioaccumulation of methylmercury, (b) how do PASTAs perform in terms of DOM removal or generation compared to the macrophyte-dominated STAs, (c) how do these two different STA systems differ in terms of DOM biogeochemistry, and nutrient remobilization from internal eutrophication effects. The proposed field surveys will be similar to surveys we have previously conducted in the northern and central Everglades, and STA 1W (Formerly ENR). Samples of surface water, pore water, sediments, and biota are collected using "clean" methods previously validated by our team in the Everglades, and now used by other researchers. Samples for Task 3 are analyzed for DOM, common anions and cations. (3) Mesocosm Studies in LNWR - The Loxahatchee National Wildlife Refuge (LNWR) represents one of the last vestiges of the historic soft-water Everglades. This is evidenced by the low conductivity of surface water in the marsh interior (~100 µS) compared with that in the canal surrounding the Refuge (1000-1500 µS). Low conductivity waters in LNWR interior are associated with a characteristic soft-water periphyton community, wetland plant species that may also be adapted to the soft-water conditions, and lower rates of key ecosystem processes (e.g., decomposition) than in areas of the Everglades impacted by canal discharges. While it has long been known that the fringes of the LNWR are affected by high conductivity canal water, recent monitoring data indicate a trend towards increased intrusion of this water into the LNWR interior with noticeable impacts on water chemistry and sensitive biota, including the possibility of increased methylmercury production and bioaccumulation. Both scientists and managers have expressed concern over the spread of such impacts and their relationship to water management activities. To address this concern, Paul McCormick (now at SFWMD) established a suite of experimental plots (mesocosms) in the LNWR to examine the effects of this encroachment of contaminated canal water on the Refuge. We are cooperating with Paul and LNWR staff on this project to examine mercury, sulfur, and DOC biogeochemistry in the dosed mesocosms. The mesocosms are dosed with artificial canal water that mimics the chemical composition of the canal water surrounding the refuge. We will collect samples of surface water, pore water, sediments, and using "clean" methods. Samples for Task 3 are analyzed for DOM, common anions and cations. (4) Canal water Monitoring - We propose to continue to monitor canal water for DOM transport and reactivity. Canals are the major conduit of water to enter the Everglades from the source in the Everglades Agricultural Area. The DOM entering the Everglades has significant impacts on the ecosystem, including acting as a major control on mercury methylation in the ecosystem, enhancing remobilization of nutrients and metals from soils (internal eutrophication), and posing a threat to macrophytes and other biota through facilitated transport of undesirable compounds (metals, pesticides) and limiting the depth of the photic zone by the absorption of light. (5) Other: Laboratory studies designed to provide fundamental information about chemical interactions between DOC and Hg that are needed to improve Everglades Hg Cycling models will continue. This aspect of our work is providing improved binding constant data required for chemical speciation models, data on the nature and strength of interactions of DOC with HgS that control Hg solubility, data on the influence of DOC on the bioavailability of both Hg and MeHg, and data on the role of DOC in the photolytic reduction and subsequent evasion of Hg from the Everglades. In addition, analytical support and technical advise are provided to Laurel Larson (Univ of Colorado) working with Jud Harvey and Greg Noe (both USGS) to study the factors controlling formation of ridge and slough structures in the Everglades and the transport of phosphorous in the system. (6) GEER Meeting - Presentation planned for the Greater Everglades Ecosystem Restoration meeting in summer 2008. In addition, Aiken is an organizer of symposium (American Geophysical Union Fall meeting, Dec 2007) entitled "Mercury Biogeochemistry in Wetlands" that will focus, in part, on the current understanding of mercury biogeochemistry in the Everglades. Recent Products: (1) Larsen, LG, Aiken, GR, Harvey, JW, Noe, G, Crimaldi, JP, (in USGS review, to be submitted to Limnology and Oceanography) Resolution of small-scale changes in organic matter source and redox state with fluorescence spectroscopy in a subtropical peatland, Florida Everglades (2) Gasper, J. D., Aiken, G. R. and Ryan, J. N. (2007) A critical review of three methods for the measurement of mercury (Hg+2)-dissolved organic matter stability constants, Appl Geochem, doi:10.1016/j.apgeochem.2007.03.018. (3) Aiken, GR, Krabbenhoft, DK, Orem, WH, and Gilmour, CC, (2007) "Dissolved organic matter and mercury in the Everglades: Implications for Ecosystem restoration" 2nd National Conference on Ecosystem Restoration, Apr 22-27, 2007, Kansas City, MO. Abstract (4) Aiken, G., Ryan, J. and Nagy, K "Challenges in the study of mercury-dissolved organic matter interactions" Spring 2007 Meeting of the American Society of Limnology and Oceanography, February 2007 Santa Fe, New Mexico Abstract. (5) G Aiken, 2006, Challenges in the study of DOM-Hg interactions, Mercury 2006 Conference, Aug 2006, Madison WI Abstract (6) G. Aiken, D. Krabbenhoft, W. Orem, C. Gilmour, Dissolved Organic Matter and Mercury in the Everglades: Implications for Ecosystem Restoration, 2006 Greater Everglades Ecosystem Restoration Conference, Orlando, FL, June 2006. Abstract. (7) Aiken, G.R. and Ryan, J.N., 2005, Interactions of mercury with dissolved organic matter in the Florida, Everglades: Evidence for stabilization of colloidal mercuric sulfide, Humic Science and Technology VIII Conference, March 16-18, 2005, Boston, MA., Abstract (8) Nagy, K.L., Waples, J.S., Aiken, G.R., and Ryan, J.N., 2005, Dissolution of cinnabar in the presence of dissolved organic matter, 15th Annual V.M. Goldschmidt Conference, May 20-25, 2005, Moscow, Idaho, Abstract (9) Aiken, G.R., Ryan, J.N., and Nagy, K.L., 2005, Interactions between dissolved organic matter and mercury in aquatic environments, 15th Annual V.M. Goldschmidt Conference, May 20-25, 2005, Moscow, Idaho (10) Waples, J.S., Nagy, K.L., Aiken, G.R. and Ryan, J.N., 2004, Dissolution of Cinnabar (HgS) in the Presence of Natural Organic Matter, Geochim. Cosmochin. Acta, vol. 69, pp. 1575-1588. (11) Aiken, G., 2004, Mercury and Dissolved Organic Matter in the Florida Everglades, National Conference on Ecosystem Restoration, Orlando, FL, Dec 2004, Abstract (12) Aiken, G., 2004, Carbon, Sulfur and Mercury - A Biogeochemical Axis of Evil, Keynote Address, 2004 CALFED Science Conference, Sacramento, CA October 4-6, 2004 Abstract (13) Aiken, G., Haitzer, M., Ryan, J.N., and Nagy, K. 2003 Interactions between dissolved organic matter and mercury in the Florida Everglades, J. du Physique, vol. 107, 29-32. (14) Haitzer, M., Aiken, G.R., Ryan, J.N. 2003 Binding of Mercury to Aquatic Humic Substances, Environmental Science and Technology, vol. 37, 2436-2441. (15) Aiken, G., Haitzer, M., Ryan, J.N., and Nagy, K., 2003, Interactions between dissolved organic matter and mercury in the Florida Everglades, Journal du Physique IV France, v. 107, p. 29-32. (16) Aiken, G., 2003, Interactions of dissolved organic matter with mercury in the Florida Everglades, Joint Conference on the Science and Restoration of the Greater Everglades and Florida Bay Ecosystem, Palm Harbor, Florida, Apr 13-18, 2003 Abstract (17) Drexel, E.T., Haitzer, M., Ryan, J.N., Aiken, G.R., Nagy, K. 2002 Mercury Sorption to two Florida Everglades Peats: Evidence for Strong and Weak Binding and Competition by Dissolved Organic Matter Released from Peat. Environmental Science and Technology, vol. 36, 4058-4064. (18) Haitzer, M., Aiken, G.R., Ryan, J.N. 2002 Binding of Mercury to Dissolved Organic Matter, Environmental Science and Technology, vol. 36, 3564-3570. (19) Aiken, G., Haitzer, M., Ryan, J., Nagy, K., 2002, Interactions Between Dissolved Organic Matter and Mercury in the Florida Everglades, 2002 AGU Meeting, Dec. 2002, San Francisco, CA Abstract. Planned Products (1) Biogeochemistry of Dissolved Organic Matter in the Florida Everglades Paper, (2) paper on influences of hydroperiod on the geochemistry of porewaters in the Everglades, (3) Joint papers (with Krabbenhoft, Orem and Gilmour) on (a) Mercury Mesocosm Studies, and (b) Dry/Rewet Studies of Sulfur Remobilization and Methylmercury Production. |
U.S. Department of the Interior, U.S. Geological Survey
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