Mercury in the Arctic Ocean: Stopover in the tundra

The Arctic Ocean and its fauna are far from major sources of pollution. So why are they so contaminated with mercury? This mystery has just been solved by an international team including researchers from the CNRS, the Desert Research Institute, and the University of Colorado.¹ They have shown that tundra vegetation and soils sequester atmospheric mercury originating from industrial activities in the mid-latitudes. In the spring, when surface snow melts and the top layer of the soil thaws, trapped mercury is released in large quantities and makes its way to the Arctic Ocean, where it is concentrated in the marine fauna. Each year, coal-fired power plants, mining operations, and other industrial activities emit thousands of metric tons of mercury into the atmosphere. In the aquatic environment, mercury accumulates in the food chain. Concentrations are especially high at the top of the chain, among large predators—including walruses, belugas, and certain fish. Their consumption by humans may lead to neurotoxicity in children and cardiovascular disease in adults.