Melting glaciers are natural redistributors of legacy airborne pollutants, affecting exposure of pristine proglacial environments. Our data shows that melting Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic Plain during the dry season. Glacial emissions can exceed in some cases inputs from diffuse sources within the catchment. We analyzed air, deposition and river water in several sections along the Ganges River and its major headwaters. The predominant glacial origin of these contaminants in the Himalayan reach was demonstrated using air-water fugacity ratios and mass balance analysis. The proportion of meltwater emissions compared to pollutant discharge at downstream sections in the central part of the Gangetic Plain was between 2 and 200%. By remobilizing legacy pollutants from melting glaciers, climate change can enhance exposure levels over large and already heavily impacted regions of Northern India.

Norwegian Institute for Water Research Gaustadalleen 21 Oslo 0349 Norway

Norwegian Institute for Water Research Masaryk University Brno 62500 Czech Republic

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

TERI University 10 Institutional Area Vasant Kunj New Delhi 110070 India

TERI University 10 Institutional Area Vasant Kunj New Delhi 110070 India; The Energy and Resources Institute Darbari Seth Block India Habitat Centre Lodhi Road New Delhi 110003 India

The Energy and Resources Institute Darbari Seth Block India Habitat Centre Lodhi Road New Delhi 110003 India

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