Processes regulating oxygen and carbon dioxide in surface waters west of the Antarctic Peninsula

Abstract

Geographic surveys of oxygen (O 2) and carbon dioxide (CO 2) concentrations in surface waters west of the Antarctic Peninsula show the large temporal and spatial variability predicted for polar regions with winter ice cover and vernal phytoplankton blooms. The saturation states of surface seawater fugacity of carbon dioxide (fCO 2{Sat}) ranged from 27% to 112% relative to the atmosphere and oxygen saturation states (O 2{Sat}) ranged from 81% to 157% of the corresponding air-saturated values. Areas of O 2 supersaturation and fCO 2 undersaturation occurred mostly in coastal waters and were correlated with increases in chlorophyll a indicating a biological influence. Net community production (NCP) showed offshore to onshore gradients with O 2 production as high as 23.8 mmol O 2 m −3 day −1 and CO 2 consumption as high as 19.2 mmol C m −3 day −1 within coastal areas. Areas of surface water O 2 and fCO 2 supersaturation were found further offshore, suggesting heating as a locally significant process. Areas of fCO 2 supersaturation and O 2 undersaturation were also found further offshore suggesting upwelling as a source of the CO 2-enriched waters. Finally, within selected coastal areas, O 2 and fCO 2 were undersaturated suggesting cooling as a locally significant process. The seasonal phasing of biological, chemical and physical processes can help explain the temporal and regional variability that was observed in the saturation states of O 2 and fCO 2.