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Long-term monitoring of stream-bed sediments reveals spatial and temporal trends in metal concentrations. Here we use concentration gradient “heat maps” as a visualization tool to report annual mean arsenic, cadmium and copper concentrations along a contamination gradient in the Clark Fork River (CFR) in Western Montana. The CFR has been heavily impacted by large-scale mining operations since the 19th century. Legacy mine waste and tailings have been deposited within the streambed, banks, and floodplains more than 200 kilometers downstream. Sieved sediment samples (<63µm) have been collected at 10 stations along a 200 kilometer contamination gradient annually since 1996. Ongoing remediation activities in the upper...
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Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the form of metal-enriched particulate matter or seston, comprising a mixture of organic and inorganic materials (J.N. Moore and S.N. Luoma, Hazardous wastes from large-scale metal extraction: A case study. Environmental Science and Technology, v.24:1278-1285, 1990). Metal enriched seston poses a dietary exposure risk to filter-feeding...
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The U.S. Geological Survey monitored algal biomass accrual and concentrations of metals and other trace elements in stream water and periphytic algae at 3-4 day intervals over a 2-week period at 3 locations within the upper and middle portions of the mining-impacted Clark Fork River, Montana, and at one location on the relatively unimpacted Blackfoot River tributary. This data release makes available trends in major and minor trace element concentrations in surface water and periphytic algae, and corresponding trends in concentrations of autotrophic (chlorophyll a) and heterotrophic (ash-free dry mass) algal biomass collected in late July and early August 2015.


    map background search result map search result map Biomass accrual and trace-element concentrations in water and periphytic algae at select locations in the Clark Fork and Blackfoot Rivers, Montana, 2015 Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020 Metal concentrations in seston and water in the Clark Fork River, MT Biomass accrual and trace-element concentrations in water and periphytic algae at select locations in the Clark Fork and Blackfoot Rivers, Montana, 2015 Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020 Metal concentrations in seston and water in the Clark Fork River, MT