Transboundary Atmospheric Pollution from Mountaintop Coal Mining

Mountaintop removal coal mining impairs down-stream ecosystems through the delivery of nutrients, ions, and heavy-metals. Here, we show that this mining also impacts ecosystems downwind, and that the suite of environmental contaminants released includes polycyclic aromatic compounds (PACs). We recovered a sediment core from Window Mountain Lake, located along the eastern slopes of Canada's Rocky Mountains. The sediment core records a similar to 30-fold increase in PAC concentrations, and a compositional profile that matches closely with coal mined in the Elk Valley, British Columbia, on the other side of the continental divide. Selenium concentrations have also increased, paralleling a rise in the Elk River, which drains the coal mines. The source of these contaminants is fugitive coal dust, emitted during mining and carried atmospherically from Pacific to Atlantic drainage basins. Atmospheric PAC emissions will increase as mines expand unless mitigation measures are implemented, and our results likely apply at similar mountaintop removal coal operations around the world.