The importance of shelf processes for the modification of chemical constituents in the waters of the Eurasian Arctic Ocean: implication for carbon fluxes

Carbon transformation along the Eurasian shelves in water of Atlantic origi n is estimated. Nutrient, oxygen, and inorganic and organic carbon data wer e used in the evaluation. By comparing the relative deficit of the differen t chemical constituents it is possible to evaluate the transformation of ca rbon. It can be seen that the chemical signature in the shelf seas was modi fied extensively, corresponding to an export production from the upper 50 m in the Barents Sea of 28-32 g C m(-2), which is five times higher than tha t in the Kara-Laptev Seas and over the deep Eurasian basin. The difference in the export production, computed from the nutrient deficit, and the obser ved deficit of dissolved inorganic carbon is attributed air-sea exchange of CO2. With this approach the relative oceanic uptake of CO2 from the atmosp here was estimated to be 70% (44 g C m(-2)) in the Barents Sea and 15% (1 g C m(-2)) in the Kara-Laptev Seas, relative to the export production. Of th e export production in the Barents Sea, about a quarter is found as DOC. Th e difference between the chemical signature at the Laptev Sea shelf slope a nd over the Lomonosov Ridge is negligible, which shows that the transformat ion of carbon is very small in the surface layers of the Eurasian basin. Co mbining the chemical transformation with reported volume transports gives a n annual export production of 9.6 x 10(12) g C yr(-1) in the Barents Sea. T he oceanic uptake of CO2 for the same area is 9.2 x 10(12) g C yr(-1). (C) 2001 Elsevier Science Ltd. All rights reserved.