The dynamic nature of the annual volume of water discharged down the Carson River over a 10-year period, which included a century flood and drought, was examined in order to gain a better understanding of mercury movement, biological availability, and exposure to waterbirds nesting at Lahontan Reservoir. Total annual water discharge directly influenced total mercury (THg) in unfiltered water above the reservoir and downstream of a mining area, whereas methyl mercury (MeHg) at the same site was negatively related to annual discharge. Annual water storage at Lahontan Reservoir in the spring and early summer, as expected, was directly related to annual Carson River discharge. In contrast to the findings from above the reservoir, annual MeHg concentrations in water sampled below the reservoir were positively correlated with the total discharge and the amount of water stored in the reservoir on 1 July; that is, the reservoir is an important location for mercury methylation, which agrees with earlier findings. However, unfiltered water MeHg concentrations were about 10-fold higher above than below the reservoir, which indicated that much MeHg that entered as well as that produced in the reservoir settled out in the reservoir. Avian exposure to mercury at Lahontan Reservoir was evaluated in both eggs and blood of young snowy egrets (Egretta thula) and black-crowned night-herons (Nycticorax nycticorax). Annual MeHg concentrations in unfiltered water below the reservoir, during the time period (days 90–190) when birds were present, correlated significantly with mercury concentrations in night-heron blood, snowy egret blood, and night-heron eggs, but not snowy egret eggs. A possible reason for lack of an MeHg water correlation with snowy egret eggs is discussed and relates to potential exposure differences associated with the food habits of both species. THg concentrations in water collected below the reservoir were not related to egg or blood mercury concentrations for either species. The initial phase of this study was a 2-year evaluation of the effects of Hg on fish-eating birds nesting at Lahontan Reservoir and Carson Lake and at reference areas in northeastern Nevada (Henny et al. 2002). In the first year (1997), reproduction of snowy egrets (Egretta thula) and black-crowned night-herons (Nycticorax nycticorax) was studied via the ‘‘sample egg’’ technique (Blus 1984) (i.e., evaluate reproductive success of each clutch in relationship to the total Hg [THg] concentrations in the sample egg collected from that clutch). Both species laid eggs with comparatively low THg concentrations (Henny et al. 2002). Most eggs had THg concentrations below 0.80 lg/g wet weight (ww), the putative threshold concentration at which reproductive problems might be expected (Heinz 1979; Newton and Haas 1988). The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU2 Remedial Investigation Report (EPA, 2017), which describes the nature and extent of contamination from the Site. The report contains the Human Health Risk Assessment and Ecological Risk Assessment. Literature and other source Hg data are summarized in the RI for surface waters, sediments, and biological tissues.

As a component of the ecological assessment for the Carson River Mercury Site, EPA conducted a survey of lizard samples collected from historic mill sites in the Carson River upstream from Lahontan Reservoir to evaluate the potential uptake of mercury in terrestrial food chains. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU1 Remedial Investigation Report (EPA, 1994) as well as the OU2 Remedial Investigation Report (EPA, 2017), describing the nature and extent of contamination from the Site, primarily the Ecological Risk Assessment Report. The RI report also contains the Human Health Risk Assessment. Literature and other source Hg data are summarized in the RI for surface waters, sediments, and biological tissues.

This is a summary of mercury (Hg) data from the Lahontan spillway area of the Carson River Basin. USBR provided an information overview and reference source on mercury (Hg) in soils for water resources managers and researchers working in the Carson River Basin. These data and the data tables provide results of the Lahontan spillway area, focused on the wetlands used by recreationalists and hunters, in order to measure concentrations of Hg to evaluate potential human health exposure pathways. The original sources of Hg contamination in the Carson River Basin are from historic gold and silver mining and associated milling of the Comstock Lode near Virginia City, Nevada. Runoff and erosion from an estimated 236 'stamp mills', driven by flumes, resulted in a cummulative release of an estimated 7,500 Tons of elemental mercury into the Carson River Basin. The elemental mercury, imported from mines in California and used to almalgamate the ore at the stamp mills, contaminated sediments throughout the Basin from the source area situated approximately between Carson City and Dayton, to the closed terminal wetlands in the Carson Sink. This area is the primary source of Hg pollution in the Basin, considering the naturally occurring mercury concentrations are close to the crustal average. During runoff and flood events, the River laterally cuts through the contaminated sediments in the overbanks and transports Hg with suspended sediments, and with concentrations rising with higher flow. When Lahontan Reservoir was built in 1915, it became a settling basin for suspended Hg from the Carson River, and while it retains up to 90 percent of influent sediments, the reservoir continues to pass significant concentrations of suspended and dissolved inorganic Hg and methylmercury (Me-Hg) downstream to the Carson Sink. This data was collected to help achieve goals set by the CWA that requires individual States to identify impaired water bodies and create enforceable WQ objectives to protect surface water quality within State bounds (CWA Sections 303d and 305 b). These objectives were to focus on priority toxic pollutants, pursuant to CWA Section 307a. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU2 Remedial Investigation Report (EPA, 2017), which describes the nature and extent of contamination from the Site. Literature and other source Hg data are summarized in the RI, for surface waters, sediments, and biological tissues. The report contains the Human Health Risk Assessment and Ecological Risk Assessment.

As a component of the ecological assessment for the Carson River Mercury Site, EPA conducted a survey of lizard samples collected from historic mill sites in the Carson River upstream from Lahontan Reservoir to evaluate the potential uptake of mercury in terrestrial food chains. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU1 Remedial Investigation Report (EPA, 1994) as well as the OU2 Remedial Investigation Report (EPA, 2017), describing the nature and extent of contamination from the Site, primarily the Ecological Risk Assessment Report. The RI report also contains the Human Health Risk Assessment. Literature and other source Hg data are summarized in the RI for surface waters, sediments, and biological tissues.

This is a summary of mercury (Hg) data from fish collected in the Lahontan Reservoir area of the Carson River Basin. NDOW collected the fish and the EPA Region 9 Laboratory analyzed the tissue for mercury (Hg) for EPA's Impaired Waters Program, water resources managers and researchers working in the Carson River Basin. These data and the data tables provide results of the Lahontan Reservoir area, used by recreationalists and fishermen, in order to measure concentrations of Hg to evaluate potential human health exposure pathways. The original sources of Hg contamination in the Carson River Basin are from historic gold and silver mining and associated milling of the Comstock Lode near Virginia City, Nevada. Runoff and erosion from an estimated 236 'stamp mills', driven by flumes, resulted in a cummulative release of an estimated 7,500 Tons of elemental mercury into the Carson River Basin. The elemental mercury, imported from mines in California and used to almalgamate the ore at the stamp mills, contaminated sediments throughout the Basin from the source area situated approximately between Carson City and Dayton, to the terminal wetlands in the Carson Sink. This area is the primary source of Hg pollution in the Basin, considering the naturally occurring mercury concentrations are close to the crustal average. During runoff and flood events, the River laterally cuts through the contaminated sediments in the overbanks and transports Hg with suspended sediments, and with concentrations rising with higher flow. When Lahontan Reservoir was built in 1915, it became a settling basin for suspended Hg from the Carson River, and while it retains up to 90 percent of influent sediments, the reservoir continues to pass significant concentrations of suspended and dissolved inorganic Hg and methylmercury (Me-Hg) downstream to the Carson Sink. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU2 Remedial Investigation Report (EPA, 2017), which describes the nature and extent of contamination from the Site. The report contains the Human Health Risk Assessment and Ecological Risk Assessment. Literature and other source Hg data are summarized in the RI for surface waters, sediments, and biological tissues.

This is a summary of mercury (Hg) data from the Lahontan Reservoir area of the Carson River Basin. USBR provided an information overview and reference source on mercury (Hg) in soils for water resources managers and researchers working in the Carson River Basin. These data and the data tables provide results of the Lahontan Reservoir area, focused on the camp sites and the beaches, in order to measure concentrations of Hg to evaluate potential human health exposure pathways. The original sources of Hg contamination in the Carson River Basin are from historic gold and silver mining and associated milling of the Comstock Lode near Virginia City, Nevada. Runoff and erosion from an estimated 236 'stamp mills', driven by flumes, resulted in a cummulative release of an estimated 7,500 Tons of elemental mercury into the Carson River Basin. The elemental mercury, imported from mines in California and used to almalgamate the ore at the stamp mills, contaminated sediments throughout the Basin from the source area situated approximately between Carson City and Dayton, to the terminal wetlands in the Carson Sink. This area is the primary source of Hg pollution in the Basin, considering the naturally occurring mercury concentrations are close to the crustal average. During runoff and flood events, the River laterally cuts through the contaminated sediments in the overbanks and transports Hg with suspended sediments, and with concentrations rising with higher flow. When Lahontan Reservoir was built in 1915, it became a settling basin for suspended Hg from the Carson River, and while it retains up to 90 percent of influent sediments, the reservoir continues to pass significant concentrations of suspended and dissolved inorganic Hg and methylmercury (Me-Hg) downstream to the Carson Sink. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU2 Remedial Investigation Report (EPA, 2017), which describes the nature and extent of contamination from the Site. Literature and other source Hg data are summarized in the RI, for surface waters, sediments, and biological tissues. The report contains the Human Health Risk Assessment and Ecological Risk Assessment.

This is a summary of mercury (Hg) data from the Lahontan Reservoir area of the Carson River Basin. USBR provided an information overview and reference source on mercury (Hg) in soils for water resources managers and researchers working in the Carson River Basin. These data and the data tables provide results of the Lahontan Reservoir area, focused on the camp sites and the beaches, in order to measure concentrations of Hg to evaluate potential human health exposure pathways. The original sources of Hg contamination in the Carson River Basin are from historic gold and silver mining and associated milling of the Comstock Lode near Virginia City, Nevada. Runoff and erosion from an estimated 236 'stamp mills', driven by flumes, resulted in a cummulative release of an estimated 7,500 Tons of elemental mercury into the Carson River Basin. The elemental mercury, imported from mines in California and used to almalgamate the ore at the stamp mills, contaminated sediments throughout the Basin from the source area situated approximately between Carson City and Dayton, to the terminal wetlands in the Carson Sink. This area is the primary source of Hg pollution in the Basin, considering the naturally occurring mercury concentrations are close to the crustal average. During runoff and flood events, the River laterally cuts through the contaminated sediments in the overbanks and transports Hg with suspended sediments, and with concentrations rising with higher flow. When Lahontan Reservoir was built in 1915, it became a settling basin for suspended Hg from the Carson River, and while it retains up to 90 percent of influent sediments, the reservoir continues to pass significant concentrations of suspended and dissolved inorganic Hg and methylmercury (Me-Hg) downstream to the Carson Sink. The EPA is publishing this data in support of the Carson River Mercury NPL Site in Nevada. Data was compiled and evaluated for the OU2 Remedial Investigation Report (EPA, 2017), which describes the nature and extent of contamination from the Site. Literature and other source Hg data are summarized in the RI, for surface waters, sediments, and biological tissues. The report contains the Human Health Risk Assessment and Ecological Risk Assessment.

We examined the role of wetland water-management on mercury bioaccumulation in songbirds and ducks. This database contains records of mercury concentrations in blood of wetland-foraging songbirds (80 common yellowthroats [Geothlypis trichas] and 14 Nelson’s sparrows [Ammospiza nelsoni]) and eggs of upland-nesting ducks (28 gadwall [Mareca strepera], 19 blue-winged teal [Spatula discors], and 13 northern shoveler [S. clypeta]) across four wetland water-management classifications at Kellys Slough National Wildlife Refuge Complex, near Grand Forks, North Dakota USA.

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.

An ecological study on mercury contamination in the wetland of West Dongting Lake in China. This study measured the total mercury concentration in the soil and compared it to the measured total concentration of mercury in the above and below ground tissue of different plant species on the floodplain of West Dongting Lake. Bioconcentration, bioaccumulation, and translocation factors were determined for each plant species at the nine study sites. Soil data on mercury concentration as well as moisture and bulk density was collected. Measurements of species richness, evenness and biodiversity were also calculated.