Surface seawater partial pressure of CO2 variability and air-sea CO2 fluxes in the Bering Sea in July 2010

Abstract

Prior studies of surface seawater CO2 partial pressure (pCO2) and air-sea CO2 fluxes have primarily been conducted on the eastern Bering Sea shelf area, with a paucity of data in the Bering Sea basin. In order to assess the surface variability and the air-sea CO2 fluxes for a more complete set of different regions, underway surface seawater pCO2 and related parameters were investigated across the Bering Sea basin, slope and shelf in July 2010 during the 4th Chinese National Arctic Research Expedition (CHINARE). The surface pCO2 exhibited large spatial variability and was observed to vary from 137 μatm in the central Bering Strait to 481 μatm in the western Bering Strait. In the central Bering Strait, the high supersaturation with respect to the atmospheric pCO2 (378 ± 2 μatm) was driven by the upwelling event. The neutral or weak CO2 sink in the Bering Sea basin and eastern nearshore region were related to high nutrient low chlorophyll status and riverine input, respectively. Biological process maintained the most shelf and slope areas as a strong CO2 sink. Overall, despite a small CO2 outgassing area the whole Bering Sea still acted as a net ocean CO2 sink of −6.4 ± 0.9 mmol m−2 d−1 in summer.