The Hannibal Pool of the Ohio River is heavily industrialized and receives direct effluent discharges from coal power plants, chlor-alkali plants, and sewage treatment facilities. Mercury (Hg) is a contaminant of concern due to the risk of bioaccumulation at wildlife refuges also located within this region. Mercury concentrations and isotopes compositions were measured to assess the levels and source of Hg contamination, respectively within the system. Sediments and waters were measured to define isotopic end members within Hannibal Pool. Heelsplitter mussels, zebra mussels, and prey fish were also analyzed to determine if Hg source signatures were conserved within the food web. These data are a part of a larger study and an associated journal article documented in Integrated Environmental Assessment and Management (https://doi/10.1002/ieam.4308).

Mercury (Hg) is a persistent environmental contaminant and can accumulate and concentrate in food webs as methylmercury (MeHg), presenting a health risk to humans and wildlife. Multiyear monitoring and modeling studies have shown that atmospheric Hg in litterfall is an important form of Hg deposition to forests. Annual litterfall consists primarily of leaves with some amounts of needles, twigs, bark, flowers, seeds, fruits, and nuts. Atmospheric Hg accumulates in leaves and reaches an annual maximum concentration at autumn leaf drop. This data set is derived from ambient autumn litterfall samples collected at 23 selected National Atmospheric Deposition Program (NADP) Litterfall Mercury Monitoring Initiative (LMMI) sites located near NADP Mercury Deposition Network sites in deciduous and mixed deciduous-coniferous forests in 11 states in the eastern United States during 2016. The NADP administered litterfall collection at the LMMI sites. The U.S. Geological Survey (USGS) distributed sets of passive litterfall sample collectors to LMMI site operators for systematic retrieval of samples during the 4 to 24 weeks of autumn leaf drop at each site. Samples were processed and analyzed at the USGS Mercury Research Laboratory where concentrations of Hg and MeHg and litterfall dry mass and sample moisture were determined. Hg concentrations were measured in 4 samples collected from each site and MeHg concentrations were measured in one composite sample per site. Litterfall mass and sample moisture were determined for 8 samples per site. Duplicate sets of these sample data were determined for 3 sites in 2016.

Mercury (Hg) is a persistent environmental contaminant and can accumulate and concentrate in food webs as methylmercury (MeHg), presenting a health risk to humans and wildlife. Multiyear monitoring and modeling studies have shown that atmospheric Hg in litterfall is an important form of Hg deposition to forests. Annual litterfall consists primarily of leaves with some amounts of needles, twigs, bark, flowers, seeds, fruits, and nuts. Atmospheric Hg accumulates in leaves and reaches an annual maximum concentration at autumn leaf drop. This data set is derived from ambient autumn litterfall samples collected at 23 selected National Atmospheric Deposition Program (NADP) Litterfall Mercury Monitoring Initiative (LMMI) sites located near NADP Mercury Deposition Network sites in deciduous and mixed deciduous-coniferous forests in 11 states in the eastern United States during 2016. The NADP administered litterfall collection at the LMMI sites. The U.S. Geological Survey (USGS) distributed sets of passive litterfall sample collectors to LMMI site operators for systematic retrieval of samples during the 4 to 24 weeks of autumn leaf drop at each site. Samples were processed and analyzed at the USGS Mercury Research Laboratory where concentrations of Hg and MeHg and litterfall dry mass and sample moisture were determined. Hg concentrations were measured in 4 samples collected from each site and MeHg concentrations were measured in one composite sample per site. Litterfall mass and sample moisture were determined for 8 samples per site. Duplicate sets of these sample data were determined for 3 sites in 2016.

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.

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.

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.

Annual litterfall samples were collected and analyzed for THg (total mercury) and MHg (methyl mercury) at a site (WI95) on Bad River tribal lands during 2012 to 2018. Litterfall was collected at a second site, WI01, during 2012 only. Litterfall was sampled in eight collectors, from which annual mass was determined. Total mercury analyses were performed on only four samples from the collectors with the lowest numbers in the sequence. A mass weighted sample based on the four THg samples was analyzed for MHg. Neither the collection of litterfall samples nor the Hg analyses were performed by the U.S. Geological Survey, New York Water Science Center.

Annual litterfall samples were collected and analyzed for THg (total mercury) and MHg (methyl mercury) at a site (WI95) on Bad River tribal lands during 2012 to 2018. Litterfall was collected at a second site, WI01, during 2012 only. Litterfall was sampled in eight collectors, from which annual mass was determined. Total mercury analyses were performed on only four samples from the collectors with the lowest numbers in the sequence. A mass weighted sample based on the four THg samples was analyzed for MHg. Neither the collection of litterfall samples nor the Hg analyses were performed by the U.S. Geological Survey, New York Water Science Center.

The lower Fox River in Wisconsin is a heavily industrialized system and the major tributary to Green Bay within Lake Michigan. The region has been a listed as Area of Concern by the United States Environmental Protection Agency (USEPA), indicating severe impairment of the ecological health of the system. Remedial action has taken place along the river to remove extensive polychlorinated biphenyl (PCB) contamination. However, it was unknown if mercury (Hg), also derived from industrial activity, remained within sediments and actively bioaccumulated within the food web. Mercury stable isotopes were analyzed in sediments and waters collected below the DePere Dam and upstream at Lake Winnebago to compare if Hg sources within the Fox River and determine the extent of industrial contamination. Speciation, methylmercury (MeHg), and isotope measurements were made within biota (prey fish and invertebrates) below DePere Dam to determine if industrial Hg was bioavailable for methylation and bioaccumulation. The interpretation of these results can be found in a companion journal articles published in Environmental Science and Technology (https://doi.org/10.1021/acsestwater.1c00285)