In previous studies, the incorporation of polychlorinated biphenyls (PCBs) has been quantified in the accumulation areas of Alpine glaciers. Here, we introduce a model framework that quantifies mass fluxes of PCBs in glaciers and apply it to the Silvretta glacier (Switzerland). The models include PCB incorporation into the entire surface of the glacier, downhill transport with the flow of the glacier ice, and chemical fate in the glacial lake. The models are run for the years 1900-2100 and validated by comparing modeled and measured PCB concentrations in an ice core, a lake sediment core, and the glacial streamwater. The incorporation and release fluxes, as well as the storage of PCBs in the glacier increase until the 1980s and decrease thereafter. After a temporary increase in the 2000s, the future PCB release and the PCB concentrations in the glacial stream are estimated to be small but persistent throughout the 21st century. This study quantifies all relevant PCB fluxes in and from a temperate Alpine glacier over two centuries, and concludes that Alpine glaciers are a small secondary source of PCBs, but that the aftermath of environmental pollution by persistent and toxic chemicals can endure for decades.

Agroscope Institute for Sustainability Sciences ISS CH 8046 Zurich Switzerland

Department of Chemistry and Biochemistry University of Berne CH 3012 Berne Switzerland

Department of Geography University of Zurich CH 8057 Zurich Switzerland

Institute for Chemical and Bioengineering Swiss Federal Institute of Technology ETH Zurich CH 8093 Zurich Switzerland

Laboratory of Hydraulics Hydrology and Glaciology Swiss Federal Institute of Technology ETH Zurich CH 8093 Zurich Switzerland

Oeschger Centre for Climate Change Research University of Berne CH 3012 Berne Switzerland

Paul Scherrer Institute CH 5232 Villigen Switzerland

Research Centre for Toxic Compounds in the Environment Masaryk University 62500 Brno Czech Republic

Swiss Federal Laboratories for Materials Science and Technology CH 8600 Dübendorf Switzerland

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