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.

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.

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).

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 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.

This dataset includes mercury and other constituent concentration and physical properties data for surface sediment, pore water and surface water collected as part of the South San Francisco Bay Salt Pond Restoration Phase 1 (2010 to 2018) studies. The overarching focus of these studies was to monitor mercury (Hg) biogeochemistry in both sediment and water in response to management actions associated with the conversion of former salt producing ponds to contemporary wetland habitat. The two primary management actions included the breaching of Pond A6 during December 2010, and the construction and operation of an adjustable tidal control structure (TCS) associated with the Pond A5/A7/A8 Complex beginning in June 2011. The TSC that reconnects the Complex to Alviso Slough (specifically referred to as the A8-TCS), a historically Hg contaminated waterway that represents the terminus of watershed drainage that includes the New Almaden mercury mining district. The A8-TCS consists of eight gates, each five feet wide. During the initial testing period (starting in June 2011) only one gate was opened, and the structure was closed again during the winter-spring months (from December until the following June). Over the subsequent seven years, the number of gates open was increased to three (15 feet, June 2012), to five (25 feet, September 2014), and eventually to all eight (40 feet, June 2017). Beginning in 2014 the A8-TCS was opened year-round. Field sampling occurred in both ponds and sloughs. In addition to sampling within the Complex ponds, two control ponds (A3N and A16) were also sampled. Similarly, in addition to sampling within Alviso Slough, two nearby control sloughs (Mallard Slough a.k.a Artesian Slough and Guadalupe Slough) were sampled (beginning in 2014 for Guadalupe Slough). Sediment sampling was conducted for the period of May 2010 through August 2011, which represents the period immediately prior to and immediately after the two above mentioned management actions. Additional sediment sampling was conducted in Mallard Slough exclusively during the August- September period 2011-2013, 2015, and 2017. Surface water sampling was conducted during three periods. The first period was in conjunction with the sediment sampling (May 2010 through August 2011). The second period involved a unique series of high temporal resolution sampling events conducted at a single site in mid-Alviso Slough, when water samples were collected hourly over a 25-hour period to capture the Hg dynamics associated with two full tidal cycles. A total of five such high-resolution ‘diel’ sampling events were conducted between May 2012 and February 2013, which included each of the four seasons and the annual ‘first flush’ event associated with the initiation of the 2012-13 rainy season. The third period, from February 2014 through February 2018, represents when all ponds and sloughs were again sampled (akin to the first period). This third period also represents when the A8-TCS was sequentially opened from 15 feet (3 gates open) to 40 feet (all 8 gates open), and when the A8-TCS management transitioned from being closed during the winter months to being opened year-round, beginning in 2014. This data release includes five data tables given both as Excel (*.xlxs) and machine readable 'comma-separated values' format (*.csv): 1) ‘SBSP.Data.Dictionary_2010-18’, the Data Dictionary, which provides definitions and details related to the other four data tables and includes analytical methods citations; 2) ‘SBSP.SED_2010-17’, the surface sediment analytical dataset; 3) ‘SBSP.SW_2010-18’, the primary surface water analytical dataset; 4) ‘SBSP.SW_Diel_2012-13’, the surface water diel sampling dataset; 5) ‘SBSP.QA_2010-18’, quality assurance data summary for the sediment and water datasets.

This dataset includes the field measurements and laboratory analyses of surface water, seston, and sediment collected from Lake Powell, within Glen Canyon National Recreation area (GLCA), during high flow (May-June 2014) and low flow (August 2015) conditions. The study area includes 12-13 sampling sites that follow a transect spanning the entire length of the reservoir from the Colorado River inflow to the Glen Canyon dam, as well as the San Juan River arm, the Escalante River arm and West Canyon. Bed sediment samples were analyzed for mercury speciation, methylmercury production and degradation rates, total reduced sulfur, iron speciation, organic content, and 16S rRNA gene templates as a proxy for microbial abundances. Water samples were collected from 3-5 depths at each site and analyzed for: total mercury (filtered and particulate), methylmercury (filtered and particulate), dissolved organic and inorganic carbon with 13C isotopic ratios, nutrients, anions, cations, trace metals, particulate carbon (with 13C isotopic ratios) and particulate nitrogen (with 15N isotopic ratios). Water quality sonde (EXO) field measurements included specific conductivity, temperature, pH, dissolved oxygen, fluorescent dissolved organic matter, chlorophyll, and turbidity. Fish samples were also collected during November 2014 from Good Hope Bay (upper reservoir), Wahweap Bay (lower reservoir), and the San Juan arm and assayed for total mercury for comparison with previous striped bass samples collected by the state of Utah. There are nine files (*.csv) in this dataset: 1) data dictionary ; 2) sediment data; 3) water data; 4) seston data; 5) fish data; 6) EXO main channel profile data ; 7) EXO off channel profile data; 8) quality assurance data; and 9) molecular data.

Comma-separated values (.csv) file containing data related to amphibian sampling across the United States between 2016 and 2021. Data files contain mercury concentrations in amphibian and dragonfly tissues, mercury concentrations in sediment, as well as amphibian morphometrics, and habitat and climate characteristics where the samples were collected.