摘要 : Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO_2 and the subsequent effect on air–sea CO_2 exchange have received little attention. We review the m... 展开 Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO_2 and the subsequent effect on air–sea CO_2 exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air–sea CO_2 exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO_2 uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO_2 uptake in ice-free polar seas. This sea-ice driven CO_2 uptake has not been considered so far in estimates of global oceanic CO_2 uptake. Net CO_2 uptake in sea-ice–covered oceans can be driven by; (1) rejection during sea–ice formation and sinking of CO_2-rich brine into intermediate and abyssal oceanic water masses, (2) blocking of air–sea CO_2 exchange during winter, and (3) release of CO_2-depleted melt water with excess total alkalinity during sea-ice decay and (4) biological CO_2 drawdown during primary production in sea ice and surface oceanic waters. 收起