SEASONAL NUTRIENT AND IRON FLUXES FROM A GLACIER ALONG THE GULF OF ALASKA: INSIGHT INTO MATERIAL EXPORT INTO COASTAL ESTUARIES

Glaciated watersheds across the globe are experiencing increased melting in response to climate warming. Along the Gulf of Alaska (GOA), runoff from glaciers within the Coast Mountains represents over 47% of the total freshwater discharge to the GOA. This glacier discharge also delivers a unique suite of nutrients (e.g., N, P, C, Fe) to the coastal estuaries. However, few studies have quantified nutrient fluxes from glacier ecosystems. Here, we directly measured nutrients from the outflow of the Mendenhall Glacier, which is part of the Juneau Icefield. Using these measurements and estimated glacier discharge, we calculated daily, seasonal, and annual average nutrient fluxes from the Mendenhall glacier. Our results highlight the magnitude of nutrient fluxes from glaciated landscapes. For example, from July – September, glacier fluxes contribute up to 50 kg/km2/day of DOC to the coastal estuaries. Ultimately, these fluxes provide new insights into the role that glacier ecosystems play in exporting organic matter and limiting nutrients and micronutrients to downstream freshwater and marine ecosystems.