Carbon cycling components in the Arctic seas of Russia: Carbon fluxes fromland, carbon in the bottom sediments, elements of balance

Balance estimates of the organic carbon (C-org) cycling in the Arctic seas of Russia are made using the "Uglerod" database created at the Shirshov Ins titute of Oceanology, Russian Academy of Sciences, containing the materials of 1952-1998, previously published materials of the 1950s-1980s, and new d ata obtained in the expeditions of 1997-1998. The principal sources for C-o rg in the Arctic seas of Russia are the primary production of phytoplankton of 140-150 t C-org per year, riverine runoff of 20.7 x 10(6) t C-org per y ear (dissolved organic matter), and 2.3 x 10(6) t C-org per year (suspended organic matter), as well coastal abrasion of 4-5 x 10(6) t C-org per year. The contributions of subsurface runoff bypassing the rivers (0.3 x 10(6) t C-org per year) and eolian supply (0.2 x 10(6) t C-org per year) are signi ficantly smaller. The overall runoff of C-org from land makes up about 20% of the volume of the primary production of photosynthesis; however, it is p resented by the organic matter most resistant to degradation and assimilati on, which provides the basic contribution to the C-org accumulation in the ;bottom sediments. New maps of C-org and C-inorg distribution in the bottom sediments of the Arctic Seas of Russia are presented together with the map s of the rates of their accumulation in the sediments of the Barents and Ka ra seas. Integration of the absolute masses of C-org over the area shows th at 3.3 x 10(6) and 1.8 x 10(6) t C-org per year are accumulated in the Bare nts and Kara seas, respectively. Calculations showed that the amount of C-o rg accumulated within the area of all the Arctic seas of Russia (4.48 x 10( 6) km(2)) is equal to that accumulated over the entire pelagic zone of the World's ocean (9 x 10(6) t C-org per year over an area of 290 x 10(6) km(2) ). The accumulation of great absolute masses of C-org in the Arctic seas of Russia at relatively low mean annual production of plankton is caused by s ignificant terrigenous supply, high values of the burial coefficient relate d to the shallowness of the water areas, low temperature, and resistance of the bulk of organic matter to bacterial destruction.