This dataset consists of concentration and isotopic data for a method designed to isolate and analyze methylmercury. Several matrices (lab-based, and natural) were tested to ensure that the method was capable of recovering methylmercury amendments. Additionally, natural matrices (plankton and sediment) with ambient methylmercury were also analyzed to ensure that the method could be successfully applied to natural matrices. Separation tests for sediment, water, and biotic matrices showed acceptable recoveries (98 ± 5%, n = 54) and reproducible δ202Hg isotope results (2SD < 0.15 ‰) down to 5 ng of MeHg. This dataset is part of a complimentary paper published in Analytical and Bioanalytical Chemistry (link).

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)

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)

Macroinvertebrate samples were collected from streams tributary to Honnedaga Lake and from the Middle Branch of the Black River during 2012-2016 and analyzed for methylmercury concentrations and for stable isotope ratios of nitrogen and carbon. Macroinvertebrates were identified in the field, and the level of taxonomic resolution varied from order to species; most taxa were identified to the family level. Specimens were field-processed into composite samples, field-frozen, and submitted to the mercury laboratory for freeze-drying and analysis. Subsamples were then submitted to the stable isotope laboratory for analysis of nitrogen and carbon isotope ratios. This database contains the resulting data and associated information for these composite samples of whole macroinvertebrates.

Macroinvertebrate samples were collected from streams tributary to Honnedaga Lake and from the Middle Branch of the Black River during 2012-2016 and analyzed for methylmercury concentrations and for stable isotope ratios of nitrogen and carbon. Macroinvertebrates were identified in the field, and the level of taxonomic resolution varied from order to species; most taxa were identified to the family level. Specimens were field-processed into composite samples, field-frozen, and submitted to the mercury laboratory for freeze-drying and analysis. Subsamples were then submitted to the stable isotope laboratory for analysis of nitrogen and carbon isotope ratios. This database contains the resulting data and associated information for these composite samples of whole macroinvertebrates.

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 from Cottage Grove Reservoir, and the rivers upstream of Cottage Grove Reservoir, Oregon.

Laboratory experiments were performed between 2019 and 2020 to examine how dissolved organic matter (DOM) and phytoplankton (Raphidocelis subcapitata) cells alter mercury (Hg) uptake and isotope fractionation. Experiments were performed at ambient Hg to thiol ratios using natural organic matter isolates received from collaborators at the University of California-Davis. Two types of experiments were performed: (1) one set with SRFA isolates at two concentrations and Hg, termed uptake experiment, and (2) one set with DOM isolates, Hg, and cultured Raphidocelis subcapitata cells, termed sunlight exposure experiment. For additional experimental details, including culturing conditions, experimental set-up, and analysis, refer to the companion publication (Armstrong and others, 2023, TBD).

Laboratory experiments were performed between 2019 and 2020 to examine how dissolved organic matter (DOM) and phytoplankton (Raphidocelis subcapitata) cells alter mercury (Hg) uptake and isotope fractionation. Experiments were performed at ambient Hg to thiol ratios using natural organic matter isolates received from collaborators at the University of California-Davis. Two types of experiments were performed: (1) one set with SRFA isolates at two concentrations and Hg, termed uptake experiment, and (2) one set with DOM isolates, Hg, and cultured Raphidocelis subcapitata cells, termed sunlight exposure experiment. For additional experimental details, including culturing conditions, experimental set-up, and analysis, refer to the companion publication (Armstrong and others, 2023, TBD).

This dataset describes mercury (Hg) and methylmercury (MeHg) concentration data and Hg and MeHg stable isotope values in plankton, waters, and sediments that were collected from two inland freshwater lakes in Madison, Wisconsin. Plankton and waters were collected monthly from May-October in 2021 and 2022 from Lake Mendota and Lake Monona and sediments were sampled in 2017. Samples were processed and analyzed at the U.S. Geological Survey Mercury Research Laboratory in collaboration with the University of Wisconsin for mercury species concentration and stable isotope analysis.