The imprint of anthropogenic CO2 in the Arctic Ocean: evidence from planktic delta C-13 data from watercolumn and sediment surfaces

delta(13)C values of N. pachyderma (sin.) from the water column and from co re top sediments are compared in order to determine the C-13 decrease cause d by the addition of anthropogenic CO2 to the atmosphere. This effect, whic h is referred to as the surface ocean Suess effect, is estimated to be abou t - 0.9 parts per thousand (+/- 0.2 parts per thousand) within the Arctic O cean halocline waters and to about - 0.6 parts per thousand (+/- 0.1 parts per thousand) in the Atlantic-derived waters of the southern Nansen Basin. This means that the area where the Arctic Ocean halocline waters are formed , the Arctic shelf regions, are relatively well ventilated with respect to CO2. Nevertheless, delta(13)C Of dissolved inorganic carbon (delta(13)C(DIC )) in the Arctic Ocean halocline waters is far from isotopic equilibrium. A bsolute values of delta(13)C of N, pachyderma (sin.) covary with the surfac e ocean Suess effect, and we interprete changes in both parameters as a ref lection of the degree of ventilation of the waters on the shelf sea. Measur ements of delta(13)C of N. pachyderma (sin.) in the Arctic Ocean from plank ton tows reveal a "vital effect" of about - 2 parts per thousand, significa ntly different from other published values. A first-order estimate of the t otal anthropogenic carbon inventory shows, that despite of its permanent se a-ice cover, the Arctic Ocean, with 2% of the global ocean area, is respons ible for about 4-6% of the global ocean's CO2 uptake. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.