Comma-separated values (.csv) file containing data related to mercury in biota from Cottage Grove Reservoir, and the rivers upstream of Cottage Grove Reservoir, Oregon.

Comma-separated values (.csv) file containing data related to mercury in biota collected from the Hells Canyon Reservoir Complex on the Snake River, Idaho and Oregon.

Comma-separated values (.csv) file containing data related to mercury in biota collected from the Hells Canyon Reservoir Complex on the Snake River, Idaho and Oregon.

Under the Great Lakes Restoration Initiative, the U.S. Geological Survey Mercury Research Lab (USGS MRL) conducted a multiyear assessment of mercury across the Laurentian Great Lakes. Biannual sampling was conducted across all five lakes onboard the U.S. Environmental Protection Agency (US EPA) research vessel Lake Guardian (in years 2010–2014, 2018) at pelagic sampling locations established by the long-term US EPA Great Lakes monitoring program. In addition to the regularly scheduled biannual sampling, in September 2013 and 2014 Lake Michigan and Lake Erie (respectively) were sampled with increased focus on shallow nearshore locations. Throughout these sampling efforts, sediments, mussels, surface water, and plankton were collected from open-water locations within all five of the Great Lakes. Additionally, surface water from Great Lake tributaries were sampled by the USGS MRL and preceded (2005 or 2006) or overlapped (2010-2015) with the open lake sampling efforts. All surface water samples were analyzed for methylmercury, total mercury, and dissolved organic carbon. Plankton and mussel tissue were analyzed for methylmercury, total mercury, and carbon/nitrogen stable isotopes and concentrations (plankton only). Sediments were analyzed for methylmercury, total mercury, and carbon content.

Under the Great Lakes Restoration Initiative, the U.S. Geological Survey Mercury Research Lab (USGS MRL) conducted a multiyear assessment of mercury across the Laurentian Great Lakes. Biannual sampling was conducted across all five lakes onboard the U.S. Environmental Protection Agency (US EPA) research vessel Lake Guardian (in years 2010–2014, 2018) at pelagic sampling locations established by the long-term US EPA Great Lakes monitoring program. In addition to the regularly scheduled biannual sampling, in September 2013 and 2014 Lake Michigan and Lake Erie (respectively) were sampled with increased focus on shallow nearshore locations. Throughout these sampling efforts, sediments, mussels, surface water, and plankton were collected from open-water locations within all five of the Great Lakes. Additionally, surface water from Great Lake tributaries were sampled by the USGS MRL and preceded (2005 or 2006) or overlapped (2010-2015) with the open lake sampling efforts. All surface water samples were analyzed for methylmercury, total mercury, and dissolved organic carbon. Plankton and mussel tissue were analyzed for methylmercury, total mercury, and carbon/nitrogen stable isotopes and concentrations (plankton only). Sediments were analyzed for methylmercury, total mercury, and carbon content.

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.

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.

Data includes fine‑scale (1.5 cm minimum resolution) vertical solute concentrations for filtered methylmercury (ng/L), filtered total mercury (ng/L), dissolved organic carbon (mg/L), and dissolved chloride (micromole/L) in SixMile Brook, New York and McTier Creek, South Carolina. Vertical solute data were assessed one time at one site in each stream in 2009, at edge-of-water (margin) and center-of-channel (channel) using two mini-piezometer (USGS MINIPOINT) devices (seven 0.325 cm stainless steel tubes, 0.8 cm screened interval). Each MINIPOINT device was installed with sampling points in surface water and at approximately 1.5, 4.5, 7.5, 12.5, 17.5, 30, and 60 cm below the bed-sediment/surface-water interface.

Data includes fine‑scale (1.5 cm minimum resolution) vertical solute concentrations for filtered methylmercury (ng/L), filtered total mercury (ng/L), dissolved organic carbon (mg/L), and dissolved chloride (micromole/L) in SixMile Brook, New York and McTier Creek, South Carolina. Vertical solute data were assessed one time at one site in each stream in 2009, at edge-of-water (margin) and center-of-channel (channel) using two mini-piezometer (USGS MINIPOINT) devices (seven 0.325 cm stainless steel tubes, 0.8 cm screened interval). Each MINIPOINT device was installed with sampling points in surface water and at approximately 1.5, 4.5, 7.5, 12.5, 17.5, 30, and 60 cm below the bed-sediment/surface-water interface.

Comma-separated values (.csv) file containing data related to mercury in biota collected from Clear Lake California.