High-resolution measurements of dissolved organic carbon in the Arctic Ocean by in situ fiber-optic spectrometry

Here we report results from an extensive survey of dissolved organic carbon (DOC) in the Arctic Ocean, which was achieved by means of a high-resolutio n, in situ UV fluorometer deployed on a nuclear submarine. Based on a stron g linear correlation observed between fluorescence (320 nm excitation, 420 nm emission) and organic carbon concentrations determined directly by high- temperature combustion, a continuous record of DOC was produced at a keel d epth of 58 m along a 2900-km transect north of the Beaufort, Chukchi, East Siberian and Laptev seas. The DOC record, combined with other physical and chemical measurements, identifies areas where river waters cross the shelve s and enter the circulation of the Arctic interior. Fluvial sources were fo und to account for 12-56% of the total DOC in parts of the upper Makarov an d Amundsen basins.