As part of the larger Great Lakes Cooperative Science and Monitoring Initiative (CSMI) , the U.S. Geological Survey Mercury Research Laboratory (MRL) completed a binational assessment partnering with the U.S. Environmental Protection Agency (US EPA), Environmental Climate Change Canada (ECCC), Michigan-DNR (MI-DNR), University of Minnesota-Duluth Natural Resources Research Institute (UM-NRRI), and the National Oceanographic and Atmospheric Association (NOAA), to assess contaminant concentrations within seston, mussels, preyfish, waters, and surface sediments within Lake Huron. All matrices were assessed for mercury and methylmercury concentrations to examine spatial trends of mercury within the lakes. Sediments were also analyzed for total mercury stable isotope composition to approximate sources of mercury contamination to the lake.

In 2021, the U.S. Geological Survey (USGS) Mercury Research Laboratory (MRL) conducted a large-scale assessment of mercury (Hg) concentrations and Hg stable isotope values in tributaries of Lake Superior in order to define the sources and amounts of Hg entering the lake. Water samples were collected monthly from 18 tributaries in the United States from April through October in 2021 and during 2022 spring melt (May 2022). As a complement, 10 tributaries on the Lake Superior Northshore were sampled three times a year (spring, summer, and fall) by Lakehead University and Lakehead Region Conservation Authority. Nine tributaries were also sampled twice per year (spring and summer) in Pukaskwa National Park by Parks Canada. Filtered total Hg (THg) concentrations from United States and Canadian Northshore ranged from 0.2 to 8.8 nanograms per liter (ng L-1), with a median value of 1.2 ng L-1. Unfiltered THg in Pukaskwa National Park ranged from 0.6 to 5.0 ng L-1 with a median of 3.2 ng L-1, but encompassed both the filtered and particulate bound Hg. Median methylmercury (MeHg) values were approximately 0.1 ng L-1 for both filtered and unfiltered waters, but could reach levels greater than 1 ng L-1 during higher flow events. THg and MeHg concentrations were positively correlated to dissolved organic carbon (DOC) concentrations for most tributaries. Hg loads to Lake Superior were calculated for U.S. tributaries using the R package loadflex ( http://dx.doi.org/10.1890/ES14-00517.1 ), median loads for THg were 18 grams per day, but could increase to 590 grams per day under high flow and snow melt conditions.

In 2021, the U.S. Geological Survey (USGS) Mercury Research Laboratory (MRL) conducted a large-scale assessment of mercury (Hg) concentrations and Hg stable isotope values in tributaries of Lake Superior in order to define the sources and amounts of Hg entering the lake. Water samples were collected monthly from 18 tributaries in the United States from April through October in 2021 and during 2022 spring melt (May 2022). As a complement, 10 tributaries on the Lake Superior Northshore were sampled three times a year (spring, summer, and fall) by Lakehead University and Lakehead Region Conservation Authority. Nine tributaries were also sampled twice per year (spring and summer) in Pukaskwa National Park by Parks Canada. Filtered total Hg (THg) concentrations from United States and Canadian Northshore ranged from 0.2 to 8.8 nanograms per liter (ng L-1), with a median value of 1.2 ng L-1. Unfiltered THg in Pukaskwa National Park ranged from 0.6 to 5.0 ng L-1 with a median of 3.2 ng L-1, but encompassed both the filtered and particulate bound Hg. Median methylmercury (MeHg) values were approximately 0.1 ng L-1 for both filtered and unfiltered waters, but could reach levels greater than 1 ng L-1 during higher flow events. THg and MeHg concentrations were positively correlated to dissolved organic carbon (DOC) concentrations for most tributaries. Hg loads to Lake Superior were calculated for U.S. tributaries using the R package loadflex ( http://dx.doi.org/10.1890/ES14-00517.1 ), median loads for THg were 18 grams per day, but could increase to 590 grams per day under high flow and snow melt conditions.

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.

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

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

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.

These data were collected as part of the Southwest Alaska Inventory and Monitoring Network (SWAN) freshwater contaminants protocol. The protocol outlines a framework for monitoring mercury (Hg) concentrations in resident lake fish within SWAN parks. The primary goal of this monitoring is to understand the spatial differences, temporal trends, and health ramifications of Hg contamination in resident lake fish. Monitoring relies on total Hg in fish axial muscle as an indicator of methyl Hg exposure. It targets four high-priority lakes which vary in size, depth, wetland cover, glacial influence, and Hg concentration. These lakes are in Katmai National Park and Preserve (KATM). The focal species is lake trout (Salvelinus namaycush), a widespread, long lived, top predator in SWAN lakes. However, if other species are sampled as bycatch, they may be retained and analyzed if they represent species-specific data gaps in Hg concentration. Two broad types of data are generated from this protocol. The first type includes observations and measurements that are recorded while sampling and processing fish (e.g., length, weight, sex). The second type includes results of analyses performed by contract laboratories (e.g., age, total Hg). This particular dataset includes those two broad types of data for 40 fish sampled in 2021. Of those fish, all 40 were lake trout.