CO2 CYCLING IN THE COASTAL OCEAN .2. SEASONAL ORGANIC LOADING OF THE ARCTIC-OCEAN FROM SOURCE WATERS IN THE BERING SEA

A Lagrangian model of water parcel transit along a 2850-km trajectory from the 80-m isobath of the southeastern Bering Sea to the same depth of the northwestern Chukchi Sea replicates the major seasonal feature s of nitrogen and carbon cycling on these shelves. Spring-summer extra ction of nitrate from the Bering and Chukchi water columns and of CO2 from the atmosphere is followed by fall-winter storage of ammonium and DOC near the shelf-break of the Canadian Basin. Here, the memory of a simulated seasonal range in water parcel contents of 0.2-13.0 mu g-at NO3 1(-1), 2056-2125 mu g-at Sigma CO2 1(-1), 0.3-3.3 mu g-at NH4 1(- 1), and 67-134 mu g-at total marine DOC 1(-1), exiting the Chukchi Sea , is evidently maintained in the halocline of the adjacent Canadian Ba sin at depths of similar to 75 m during summer and similar to 125 m du ring winter. Based on these properties of imported water parcels, esti mated rates of nitrification, DOC oxidation, and Sigma CO2 evolution i n the Canadian Basin suggest (I) a residence time of similar to 10 y f or shelf waters of Pacific origin in the halocline, (2) production of POC within the overlying ice-covered slope waters may indeed be 10-fol d larger than first estimates made in the deeper Basin during the 1950 s, (3) similar to 81% of all of the DOC within Bering Strait is of mar ine origin from prior production cycles In the SBS, and (4) over 50% o f the color signal seen by satellite above these waters is of DOC orig in, rather than from phytoplankton pigments. Copyright (C) 1996 Elsevi er Science Ltd