Spatial variability in the partial pressures of CO_2 in the northern Bering and Chukchi seas

摘要

In the summers of 1999 and 2003, the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO_2 in the air and surface waters (pCO_2) of the Bering Sea and the western Arctic Ocean. The lowest pCO_2 values were 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. These differences arise from a combination of various source waters, biological uptake, and seasonal warming. The Chukchi Sea was found to be a carbon dioxide sink, a result of the increased open water due to rapid sea-ice melting, high primary production over the shelf and in marginal ice zones (MIZ), and transport of low pCO_2 waters from the Bering Sea. As a consequence of differences in inflow water masses, relatively low pCO_2 concentrations occurred in the Anadyr waters that dominate the western Bering Strait, and relatively high values in the waters of the Alaskan Coastal Current (ACC) in the eastern strait. The generally lower pCO_2 values found in mid-August compared to at the end of July in the Bering Strait region (66-69°N) are attributed to the presence of phytoplankton blooms. In August, higher pCO_2 than in July between 68.5 and 69°N along 169°W was associated with higher sea-surface temperatures (SST), possibly as an influence of the ACC. In August in the MIZ, pCO_2 was observed to increase along with the temperature, indicating that SST plays an important role when the pack ice melts and recedes.