Climate Induced Mobilization of Persistent Organic Pollutants (POPs) in Rivers in India (INDNOPOP)

The overall goal of the project was to assess the climatic controls on the environmental exposure of diffuse chemical micropollutants in the hydrological system of the Ganges river basin. The Ganges catchment is one of the largest on earth, hosting about 7% of the world's population. Despite the fact that India is generally considered a hotspot for chemical pollution, data on water resources contamination are very scarce. This has been hampering any attempt of understanding drivers controlling environmental and human exposure to chemical pollution in such a large and complex system. The ambition of our work has been to reduce this gap and use the Ganges scenario to collect information on anthropogenic and environmental controls on chemical contaminant levels in surface and drinking water resources over a large and complex scenario. The project assessed the role of glacial meltwater as a source of legacy contaminants for the water resources in the large regional context, which had not previously been done in India or in a large catchment. We found that that melting Himalayan glaciers can be major contributors of micropollutants for surface water in the Gangetic plain, and thus can impact the river's water quality significantly. Particularly interesting was the finding that a group of chemicals, PCB, to a large extent originated from glacial meltwater, meaning that long range atmospheric transport in earlier decades is important for the current pollution pressure. The melting glaciers' impacts on the river water quality are thus important, and illustrate the link between climate change and chemical pollution. The project also included a comprehensive, large-scale survey which provides the first dataset on flourinated organic compounds (PFAS) in river and drinking water in India, providing important data to fill knowledge gaps and enable comparative studies in the future.

Data reveals that many regions of India are hotspots of POP exposure. Beyond the presence of active primary sources the Indian environment may be sensitive to the influence of releases from environmental repositories. POP outflow from glacier, for example , has been pointed out as a relevant source for freshwater ecosystems. Although it is espected that climate change have an effect on environmental exposure and remobilization of diffuse chemical pollution from environmental repositories (including soil, v egetation and glaciers), very little is known on the modality and relevance of this relationship. Furthermore, lack of baseline studies, hampers a sounding forecasting of future regional exposure scenarios under climate change conditions. INDNOPOP will co ntribute to fill these gaps by developing a research in a particularly informative scenario: the Ganges river catchment. In average 30 to 40% of the Ganges waters derive from glacier melting. Monsoon inputs and water withdrawal for human use represents th e other major drivers controlling seasonality of the Ganges hydrology. The variability expressed here along the spatial and seasonal scale represents an ideal scenario to investigate the potential effects of climate on the environmental exposure to POPs. We will exploit this in order to characterize and assess the effectiveness of climatic controls on ecosystem and potential human exposure to POPs over a large regional scale. We will establish infrastructures for POP monitoring in 9 sites along the Ganges main stream and its Himalayan headwaters. We will perform a seasonally resolved assessment of the contribution of selected sources of POPs to the water ecosystem (namely glacier melting, atmospheric depositions and primary sources). We will also investig ate the potential implications for human exposure through the water ecosystem by consistently monitoring drinking water and water resources used in food production.