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MEltwater release of heavy meTALs from gLacIer to ocean in a Changing Arctic

Alternative title: Metalltoksisitetseffekter av tilbaketrekning av arktiske isbreer

Awarded: NOK 12.0 mill.

Glaciers are moving rivers of ice, which trap water as snow in winter and release it in summer as meltwater to fjords and oceans. The recent warming of the Arctic, four times the global average, is causing them to shrink and to release more meltwater into fjords. Once thought to be sterile and inhospitable wastelands, glaciers are now known to be homes for tiny microbial life forms, which get their energy and nutrition from rocks buried beneath the ice, which is ground to a fine powder by the glacier´s continual flow downslope. Hidden in this rock powder are minerals which contain heavy metals; some like mercury and arsenic can be toxic. The type and amounts of heavy metals released in glacial meltwaters depends on the local geology, along with the pathways that meltwaters follow as they journey through the glacier and over bare rock and tundra land fringes. A huge gap in our understanding is how the accelerating melting of Arctic glaciers might liberate toxic heavy metals from glaciers into valuable coastal food webs. METALLICA aims first, to measure heavy metals in rivers draining from glaciers sitting on vastly different geological formations in Norway and Svalbard, from soft rocks once formed from ancient layers of sediments on the sea floor, to hard rocks formed from the Earth´s crust. It will go on to study how virgin land surfaces, uncovered by glacier retreat and slowly colonized by plants, might alter heavy metals released from glacial rivers to fjords. Finally, it will trace the movement of heavy metals in glacial rivers into the fjord food webs on which human livelihoods depend, including fish and seabirds. In doing so, METALLICA seeks to work out – where and why does glacier retreat cause heavy metal toxicity in fjords and how does this affect the seafood that we and other organisms eat, or put simply – is glacier melting a heavy metal toxicity time bomb?

The Arctic is an epicenter for 21st century climate change, with amplified warming four times the global average. This has profound impacts on Arctic glaciers, driving rapid retreat of marine-terminating glaciers, expansion of glacier forefields, and shifts in river freshwater and sediment discharge. Implicated in these dramatic changes are extensive Arctic fjords and coasts which receive freshwaters, sediments and chemical species associated with glacial runoff and icebergs, with potential impacts on the health, structure and productivity of invaluable food webs. The recent discovery of glaciers as hot spots for biogeochemical cycling, with chemical export from ice to ocean represents a paradigm shift in ice-ocean interactions. Central to this is the liberation of metal species from rocks beneath glaciers by intense physical and biogeochemical weathering, including high concentrations of some heavy species (e.g. mercury) which cause bio-accumulation and toxicity in marine ecosystems. Glacial rivers in Greenland display some of the highest recorded concentrations of mercury on the planet, and elevated concentrations of several heavy species, including mercury, in marine organisms in Norwegian, Svalbard and Antarctic fjords are linked to a terrestrial, and likely glacial source. Despite the potency of glacial heavy metal export for Arctic marine ecosystems, little is known about the controls on their release, nor their fate in fjords and marine food webs. METALLICA unites an international interdisciplinary team to provide transformational understanding of the glacial drivers, transport routes and fjord ecosystem impacts of toxic heavy metal species in a changing Arctic, drawing upon excellent Norwegian infrastructure and glaciers in Norway and Svalbard as a natural laboratory. Its findings will feed novel tools and models directly to policy-makers, with potential for high societal impact.

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