Contrasting chemistry in the Central Arctic Ocean in a pan-Arctic and climate change perspective

Abstract

The Arctic Ocean is changing, with less sea ice, increased meltwater and increased ocean CO2 uptake. Data from two central Arctic Ocean cruises in late summer of 2021 and 2022 show contrasting hydrography and chemistry in the water column between the deep Amundsen and Nansen basins. The chemical characteristics are affected by different hydrography in the two basins; the Transpolar Drift (TPD) current carries freshwater and carbon from the Siberian shelves to the western Amundsen Basin and the Atlantic water on the other hand carries heat, salt, and nutrients to the western Nansen Basin. We present carbon and nutrient data from the two years and examine the differences between the two basins and put this into a pan-Arctic perspective. We observed higher concentrations of inorganic (CO2) and organic (CDOM) carbon and silicic acid in the polar mixed layer in the Amundsen Basin compared to the Nansen Basin, indicating impacts of river water transported with the TPD from the shelves into the Amundsen Basin.