Determining the Impact of Nutrient, Organic Matter and Contaminant Fluxes From Melting Himalaya Glaciers on Downstream Ecosystems

Around 75 % of the Earth's freshwater is locked up in mountain glaciers and ice sheets and is highly sensitive to changes in future climate. Glaciers located within the Hindu-Kush Himalayan region represent the largest store of freshwater held in mountain glaciers globally, and many are predicted to either retreat or disappear this century. The impacts of these changes upon the flow regimes major Asian rivers, which supply > 1.4 billion people, are becoming better studied. However, a major research gap is the impact of Himalayan glacier melting upon on the quality of water in these rivers, and thus on downstream ecosystem health. This is important for two main reasons. First, glacier runoff is often found to be enriched in nutrient and bioavailable organic matter, which may be important in sustaining downstream ecosystems and ecosystem services (e.g. fisheries). However, glacial catchments also sequester pollutants from the atmosphere in snowfall and release trace metals from bedrock via erosion, which are released to downstream aquatic ecosystems. While these impacts are well researched elsewhere (e.g. Alaska, European Alps, Greenland), the role of glacial meltwater in shaping the form and function of Himalayan aquatic ecosystems is a new field. It requires close cooperation with Himalayan host nations because of the remote nature of the field sites and requirement for governmental permission.

This PhD project aims to employ novel in situ chemical sensing technologies developed via previous NERC funding (Discovery Grant "DELVE", Dr Liz Bagshaw, University of Cardiff and Dr Alex Beaton, National Oceanography Centre), in combination with chemical profiling of Himalayan glacier runoff for organic matter, inorganic nutrients (Profs. Jemma Wadham, Richard Evershed) and contaminants (Prof. Laura Robinson). It will be complemented by in situ biological measurements and bio-assays in the study river catchments to infer the bioavailability of exported nutrients/organic matter to planktonic communities and any incorporation of contaminants into biota (Prof. Alex Anesio).

The project will be undertaken in collaboration with Prof. Al. Ramanathan at Jawaharlal Nehru University (JNU: New Delhi) who has developed several glacier field sites in the Indian Himalaya over the last 15 years. The project will specifically aim to determine the controls upon the fluxes of nutrient and organic matter (Objective 1) and of toxins (e.g. metals, micro plastics) (Objective 2) in runoff from Himalayan river catchments with contrasting glacial cover. It will go on to determine the impact of Himalayan river water quality upon downstream planktonic communities (Objective 3). This will result in a ground-breaking assessment of the impact of a deglaciating Himalaya upon downstream river water quality and aquatic ecosystems in warming world.