Following the water.: The thawing and erosion of permafrost increase input of reactive nitrogen and carbon to the coastal water at the Baldwin Peninsula, Alaska

Permafrost affected soils and especially Yedoma deposits contain a huge amount of carbon and nitrogen, which can be released and become available after thawing. Coastal and thermal erosion, e.g. in drain lake basins, are important processes for the release and transport of reactive nitrogen and carbon from soils to the aquatic environment and consequently to the coastal waters and the Ocean. The faster warming of the Arctic in relation to the rest of the world will amplify the rate of release of nitrogen and carbon.

To understand the hydrological conditions and release pathways of the thawing nitrogen and carbon, we investigated a drained lake basin (Schaeffers Lake) and a Yedoma Cliff (Cape Blossom) at the Baldwin Peninsula, Alaska. Samples from rain, snow, ice wedges, outflow water, basin water, pore water and soil were taken. By measuring biogeochemical properties (dissolved inorganic (DIN)and organic nitrogen (DON) plus ¹⁵N stable isotopes, DI¹³C/TA, ¹⁸OH₂O, dissolved gases (CO₂, methane and N₂O) et al.), we want to unravel the path of the water and how carbon and nitrogen are enriched and transported.

First results show that the out-flowing water contained a considerable amount of DIN and DON, the 15N stable isotopes of nitrate were significantly enriched and the water was oversaturated with methane and N2O. This indicates that not only reactive nitrogen is released by the thawing and erosion, but also quickly processed by microbial activity that is stimulated by the nutrient input.