Melting Glaciers Releasing Trapped Pollutants

New research shows that concentrations of pollutants in the environment and atmosphere may increase with global warming, as melting glaciers release pollutants which became trapped in their ice at the end of the twentieth century.

A team of researchers working in Switzerland has found that the concentration of pollutants, including DDT and PCBs (polychlorinated biphenols) in a glacier-fed lake – Lake Oberaar – is higher than in lakes which do not receive meltwater from glaciers, indicating that the pollutants are entering the lake from the glacier, rather than from direct deposition from the atmosphere.

From the 1950s – 70s remote glaciers in the Swiss alps were affected by atmospheric deposition of pollutants. Persistent pollutants such as PCBs and DDT can travel long distances in the atmosphere and can persist for many years in the environment, accumulating in food chains. Analysis shows that from the 1960s – 70s, the accumulation of pollutants in the sediment of Lake Oberaar was rapid, whilst this dropped in the 1980s – 90s due to tighter regulation and the banning of particular products, such as DDT. Now, the researchers have shown, the input of organic chlorines into the lake is as high as the peaks in the 60s and 70s.

The researchers conclude that increased warming will cause the further release of pollutants, leading to the increased exposure of wildlife and fisherman to these compounds, and contamination of water used for drinking and irrigation.

Original research: Bogdal, C., Schmid, P., Zennegg, M. et al. (2009). Blast from the Past: Melting Glaciers as a Relevant Source for Persistent Organic Pollutants. Environmental Science and Technology. 43: 8173-8177.

Source: EU Science for Environment Policy