Arctic Ice Traces Widespread Pollution to Montana Mine

Ice-core records from Greenland, the Russian Arctic and northern Canada show that emissions from Montana’s Anaconda Copper Mine drove a roughly 15-fold rise in arsenic and other toxic metals in the Arctic from about 1886 to 1918. Researchers combined the ice data with atmospheric modeling and mine records to estimate peak annual emissions of about 11,000 tons of arsenic and 4,400 tons of lead. They estimate that pollution from the operation exposed 55% of Americans and 11% of Canadians living downwind to years of contaminated air, with potential health effects including increased cancer risks. The decline in pollution after 1919, despite the mine’s continued operation, was likely due to the installation of electrostatic precipitators at its smelter. An independent scientist described the use of arsenic to trace the pollution to a single major source as convincing detective work.