Because the Bering/Chukchi region is likely to be the site of net carbon sequestration,and because the region has experienced rapid change,it is important to improve our understanding of carbon cycling in this region.In the summers of 1999 and 2003,the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO2 in the air and surface waters (pCO2) of the Bering Sea and the western Arctic Ocean.Distributions of pCO2 in the Bering and Chukchi seas during July-Sept 1999 and 2003 displayed obvious geographic differences,with the lowest values being found in continental shelf waters,increased values over the Bering Sea shelf slope,and the highest values in the waters of the Bering Abyssal Plain(BAP) and the Canadian Basin.