Several canals in southern Florida run from Lake Okeechobee through the Everglades Agricultural Area (EAA) and feed water to the northern Everglades. Agricultural and water-management practices affect the water quality of these canals. Fertilizers added in the EAA flow into the canals and are transported to treatment areas which remove much of the phosphorous in the water, but are not as effective in removing dissolved sulfate. Elevated sulfate concentrations, found downstream in the Water Conservation Areas in the northern Everglades, can stimulate sulfur-reducing bacteria which can also convert inorganic mercury to methyl mercury, a bioaccumulative neurotoxin. Chemistry data at 25 canal sites in southern Florida were sampled for water properties (temperature, pH, specific conductance), sulfur isotopes, major anions and cations, nutrients (including ammonium and orthophosphate), and trace metals. Data collection began in 1996 with a small subset of sites, and has continued through 2019. Funding for this data collection was provided by the USGS Priority Ecosystems Studies Program for South Florida (Nick Aumen, Program Executive).

This dataset includes field and laboratory measurements of surface waters, pore waters, sediment, and fish from Water Conservation Areas and adjacent canals of the Florida Everglades (USA). Water, sediment, and fish samples were collected from Water Conservation Areas 1 (Arthur R. Marshall Loxahatchee National Wildlife Refuge), 2, and 3 and neighboring canals between 2012 and 2019. The sites sampled in Water Conservation Areas 2 and 3 follow hydrologic flow paths. Field measurements reported for surface and pore waters include specific conductance, pH, dissolved oxygen (DO) concentration, and oxidation-reduction potential (ORP). Pore waters were filtered (quartz fiber filter) and measured for major cations, inorganic anions, inorganic sulfide, dissolved organic carbon (DOC) concentration, dissolved organic matter (DOM) ultraviolet and visible light (UV-Vis) absorption and fluorescence, total mercury (HgT), and methylmercury (MeHg)concentrations. Surface water samples were collected and filtered (quartz fiber filter); particulate concentrations of MeHg and HgT were measured, and filtered aliquots were measured for major cations, inorganic anions, inorganic sulfide, DOC concentration, DOM UV-Vis and fluorescence, HgT and MeHg. Sediments were collected by push-core and measured for HgT, MeHg, organic matter content by loss on ignition (LOI), and percent dry weight. Resident mosquitofish (Gambusia holbrooki) were collected and measured for HgT and MeHg.

This dataset includes field and laboratory measurements of surface waters, pore waters, sediment, and fish from Water Conservation Areas and adjacent canals of the Florida Everglades (USA). Water, sediment, and fish samples were collected from Water Conservation Areas 1 (Arthur R. Marshall Loxahatchee National Wildlife Refuge), 2, and 3 and neighboring canals between 2012 and 2019. The sites sampled in Water Conservation Areas 2 and 3 follow hydrologic flow paths. Field measurements reported for surface and pore waters include specific conductance, pH, dissolved oxygen (DO) concentration, and oxidation-reduction potential (ORP). Pore waters were filtered (quartz fiber filter) and measured for major cations, inorganic anions, inorganic sulfide, dissolved organic carbon (DOC) concentration, dissolved organic matter (DOM) ultraviolet and visible light (UV-Vis) absorption and fluorescence, total mercury (HgT), and methylmercury (MeHg)concentrations. Surface water samples were collected and filtered (quartz fiber filter); particulate concentrations of MeHg and HgT were measured, and filtered aliquots were measured for major cations, inorganic anions, inorganic sulfide, DOC concentration, DOM UV-Vis and fluorescence, HgT and MeHg. Sediments were collected by push-core and measured for HgT, MeHg, organic matter content by loss on ignition (LOI), and percent dry weight. Resident mosquitofish (Gambusia holbrooki) were collected and measured for HgT and MeHg.

The data in this data release includes results from the analysis of water and fish from 76 sites in the Everglades National Park (ENP). Water and particulate matter samples were collected from 2008 to 2018 and analyzed for total mercury (THg) and methylmercury (MeHg). Filtered water samples were also analyzed for dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA), and major anions. Fish samples (Eastern Mosquitofish, Flagfish, African Jewelfish, Golden Topminnow, and Mayan Cichlid species) were collected from 2007 to 2018 and analyzed for THg and MeHg and carbon and nitrogen stable isotopes. These data are important for analyzing hydrologic and geochemical controls on MeHg distribution and production in the ENP.

The data in this data release includes results from the analysis of water and fish from 76 sites in the Everglades National Park (ENP). Water and particulate matter samples were collected from 2008 to 2018 and analyzed for total mercury (THg) and methylmercury (MeHg). Filtered water samples were also analyzed for dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA), and major anions. Fish samples (Eastern Mosquitofish, Flagfish, African Jewelfish, Golden Topminnow, and Mayan Cichlid species) were collected from 2007 to 2018 and analyzed for THg and MeHg and carbon and nitrogen stable isotopes. These data are important for analyzing hydrologic and geochemical controls on MeHg distribution and production in the ENP.

This data was collected as part of a laboratory study examining the effects of sea level rise on mercury (Hg) methylation and demethylation rates in peat cores collected from the Florida Everglades. Peat cores were collected from a freshwater region of the Everglades, Water Conservation Area 3, in 2022 and taken to the University of California-Davis for methylation and demethylation studies. Prior to the incubations peat cores were inundated with water of different salinities (0.16 parts-per-thousand (ppt), 0.25 ppt, 0.50 ppt, 1.0 ppt, 6.0 ppt) to simulate saltwater intrusion in coastal regions of Everglades National Park. Incubations were run for 20 days. An enriched isotope tracer of inorganic Hg (201Hg) was added to the cores to track the methylation process. In tandem isotopically enriched methylmercury (204MeHg) was tracked to examine demethylation. Porewater and peat material were collected from the incubations and analyzed for Hg and MeHg. Additional parameters such as dissolved organic carbon concentration and quality, reduction-oxidation potential, major cation and anions, and other metals were monitored during the incubations to examine the controlling variables dictating Hg methylation. Across all salinity treatments, porewaters became increasingly anoxic, sulfate concentrations decreased, and MeHg concentrations increased over the course of 20 days. The findings highlight the potential for enhanced production and mobilization of MeHg in coastal wetlands of the Florida Everglades due to the onset of saltwater intrusion.

This data was collected as part of a laboratory study examining the effects of sea level rise on mercury (Hg) methylation and demethylation rates in peat cores collected from the Florida Everglades. Peat cores were collected from a freshwater region of the Everglades, Water Conservation Area 3, in 2022 and taken to the University of California-Davis for methylation and demethylation studies. Prior to the incubations peat cores were inundated with water of different salinities (0.16 parts-per-thousand (ppt), 0.25 ppt, 0.50 ppt, 1.0 ppt, 6.0 ppt) to simulate saltwater intrusion in coastal regions of Everglades National Park. Incubations were run for 20 days. An enriched isotope tracer of inorganic Hg (201Hg) was added to the cores to track the methylation process. In tandem isotopically enriched methylmercury (204MeHg) was tracked to examine demethylation. Porewater and peat material were collected from the incubations and analyzed for Hg and MeHg. Additional parameters such as dissolved organic carbon concentration and quality, reduction-oxidation potential, major cation and anions, and other metals were monitored during the incubations to examine the controlling variables dictating Hg methylation. Across all salinity treatments, porewaters became increasingly anoxic, sulfate concentrations decreased, and MeHg concentrations increased over the course of 20 days. The findings highlight the potential for enhanced production and mobilization of MeHg in coastal wetlands of the Florida Everglades due to the onset of saltwater intrusion.

Mercury concentrations in various environmental media, as well as water quality characteristics, from survey samples taken in the Florida Everglades. Portions of this dataset are inaccessible because: will add after peer review. They can be accessed through the following means: will add after peer review. Format: will add after peer review. This dataset is associated with the following publication: Kalla, P., M. Cyterski, D. Scheidt, and J. Minucci. Spatiotemporal effects of interacting water quality constituents on mercury in a common prey fish in a large, perturbed, subtropical wetland. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 792: 148321, (2021).

Mercury concentrations in various environmental media, as well as water quality characteristics, from survey samples taken in the Florida Everglades. Portions of this dataset are inaccessible because: will add after peer review. They can be accessed through the following means: will add after peer review. Format: will add after peer review. This dataset is associated with the following publication: Kalla, P., M. Cyterski, D. Scheidt, and J. Minucci. Spatiotemporal effects of interacting water quality constituents on mercury in a common prey fish in a large, perturbed, subtropical wetland. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 792: 148321, (2021).

This data release provides data for filter-passing total mercury, filter-passing methylmercury, particulate total mercury, particulate methylmercury, and dissolved organic carbon concentrations calculated for USGS station 254543080405401: Tamiami Canal at S-12D Near Miami, FL. Five site-specific regression models were developed using continuously measured temperature, turbidity, specific conductance and or fluorescence of chromophoric dissolved organic matter and concomitant discretely collected dissolved organic carbon samples to calculate continuous concentrations of mercury and carbon.