Particulate organic carbon export fluxes on Chukchi Shelf, western Arctic Ocean, derived from 210Po/210Pb disequilibrium

Fluxes of particulate organic carbon (POC) were derived from Po-210/Pb-210 disequilibrium during the 4th Chinese National Arctic Research Expedition (CHINARE-4) from July 1 to September 28, 2010. Average residence times of particulate Po-210 in the euphotic zone were -16.00 a to 1.54 a, which are higher than those of dissolved Po-210 (-6.89 a to -0.70 a). Great excesses of dissolved Po-210 were observed at all stations, with an average Po-210/Pb-210 ratio of 1.91 +/- 0.20, resulting from Pb-210 atmospheric deposition after sea ice melt. POC fluxes from the euphotic zone were estimated by two methods (E and B) in the irreversible scavenging model. Estimated POC fluxes were 945-126 mmol C/(m(2)center dot a) and 1 848-109 mmol C/(m(2)center dot a) by methods E and B, respectively, both decreasing from low to high latitude. The results are comparable to previous works for the same region, indicating efficient biological pumping in the Chukchi Sea. The results can improve understanding of the carbon cycle in the western Arctic Ocean.