Mercury Concentrations in Waters, Seston, Mussels, Sediment, and Prey Fish from Lake Ontario, 2023

As part of the larger Great Lakes Cooperative Science and Monitoring Initiative (CSMI) , the U.S. Geological Survey Mercury, Metals, and Microplastics Research Laboratory (USGS M3RL) completed a binational assessment partnering with the U.S. Environmental Protection Agency (US EPA), Environmental Climate Change Canada (ECCC), Ontario Ministry of Natural Resources and Forestry (ONRF), Ontario Ministry of the Environment, Conservation & Parks (OECP), University of Minnesota-Duluth Natural Resources Research Institute (UM NRRI), and the National Oceanographic and Atmospheric Association Great Lakes Environmental Research Laboratory (NOAA-GLERL), to assess contaminant concentrations within surface waters, surface sediment, seston, mussels, and prey fish within Lake Ontario. All matrices were assessed for mercury and methylmercury concentrations to examine spatial trends of mercury within the lakes. Sediment samples were also analyzed for total mercury stable isotope composition to approximate sources of mercury contamination to the lake.