Atmospheric deposition: It’s not just acid rain anymore.

Acid rain was one of the big environmental issues of the 1980’s, and it made us aware of the importance of atmospheric transport as a source of pollutants to sensitive ecosystems. Since then, controls on emissions of sulfur dioxide have resulted in substantially less acidic precipitation in North America and Europe, and many ecosystems are recovering from acid rain. Meanwhile, concerns about deposition of nutrients, mercury, and organic contaminants have increased. These pollutants are found in air emissions from many different sources including transportation, industry, energy production, and agriculture. They can be transported over great distances, their fate in both the atmosphere and in ecosystems is controlled by complex biogeochemical processes, and their impacts are far more ubiquitous than those of acid rain. Organic compounds and trace metals can be potent at very low concentrations, and they can bioaccumulate in the ecosystem. New methods for measuring atmospheric pollutant inputs, identifying their sources, and tracking their fate in the ecosystem are improving our understanding of the relation between air and water quality. USGS studies are contributing to the science and helping shape cost-effective policies that protect human health and ecosystems from adverse impacts of atmospheric deposition.

Don Campbell of the Colorado Water Science Center has studied atmospheric deposition since back when sulfur was the big deal. He conducts basic and applied research with scientists and resource managers from USGS, other federal agencies, state and local government, and universities.