Swiss researchers from several national institutes have discovered long-banned chemicals turning up in glacial lake sediments at levels not seen since they were in use more than 50 years ago.

A new report published jointly by researchers from the Swiss Institute for Chemical and Bioengineering (ETH Zurich), the Swiss Federal Laboratories for Materials Testing and Research (EMPA) and the Swiss Federal Institute of Aquatic Science and Technology (EAWAG) has found that receding glaciers in the Swiss Alps are releasing high levels of 'legacy pollutants', chemicals that exist in ecosystems for a long time.

Substances such as persistent organic pollutants, organochlorine pesticides and synthetic musk fragrances have been leaching into nearby lakes and ecosystems for the last two decades as the glaciers give in to warmer temperatures.

It is not clear whether the chemicals could travel out of the alpine area, following meltwater into the North Sea or evaporating into the air. Nor is it clear whether the same problem persists in other glacial regions around the globe but it seems likely the problem could get worse.

"Considering ongoing global warming and accelerated massive glacier melting predicted for the future, our study indicates the potential for dire environmental impacts due to pollutants delivered into pristine environments," warns the report.

The researchers say more research on the topic is needed to protect the environment from future leakage: "The coupling of glacier dynamics and pollutant cycling is a complex topic and represents a poorly studied research field. Ongoing work in this field may provide additional insight into the fate of persistent organic pollutants in the Alpine environment," the report concludes.

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