Biological and physical controls on surface gas distributions along the Antarctic continental shelf

• Main Authors: Tortell, P. D., Bittig, H.C., Körtzinger, A., Jones, Elizabeth M., Hoppema, Mario
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Antarctic; Southern Ocean; The Antarctic; Austral; Antarc*; Sea ice
• Online Access: https://epic.awi.de/id/eprint/37450/; https://hdl.handle.net/10013/epic.45091

We present measurements of pCO2, O2, biological oxygen saturation (ΔO2/Ar) and N2 saturation in surface waters of the Antarctic continental shelf during austral summer, 2010–2011. pCO2 and ΔO2/Ar exhibited large spatial gradients and co-varied strongly with Chla. However, differential gas exchange led to an uncoupling of biological O2 accumulation and dissolved inorganic carbon drawdown. Computed sea-air CO2 fluxes significantly exceeded regional climatological values, suggesting that CO2 sink along the Southern Ocean continental shelf may be currently underestimated. Whereas N2 was mostly supersaturated in surface waters, atmospheric processes and mixed layer entrainment resulted in super-saturation and under-saturation of mixed layer O2. Net community production derived from entrainment-corrected surface ΔO2/Ar data showed good coherence with independent estimates based on seasonal mixed layer DIC deficits, with the highest values (~200 mmol O2 m-2 d-1) observed in frontal mixing zones and stratified regions of sea-ice melt. Our results demonstrate the utility of various gas tracers in examining the impact of physical and biological forcing on surface water biogeochemistry in oceanographic complex waters of the Antarctic continental shelf.