Air-sea CO2 exchange of beach and near-coastal waters of the Chukchi Sea near Barrow, Alaska

Authors: Ikawa, H.; Oechel, WC
Source: CONTINENTAL SHELF RESEARCH  Volume: 31   Issue: 13   Pages: 1357-1364   DOI: 10.1016/j.csr.2011.05.012   Published: SEP 1 2011

Abstract: Partial pressure of CO₂ in equilibrium with sample water (pCO₂) for the coastal water in the Chukchi Sea was continuously observed in summer, 2008. Average daily CO₂ flux calculated from the pCO₂ and gas transfer coefficients ranged from -0.144 to -0.0701 g C m^-2 day^-1 depending on which gas transfer coefficient was used. The pCO₂ before the landfast ice sheets melted appeared to be highly biologically controlled based on the following information: (1) the diurnal pattern of pCO₂ was strongly correlated with Photosynthetic Photon Flux Density (PPFD); (2) high chlorophyll density was observed during periods of peak uptake; and (3) the day-to-day variation in the pCO₂ strongly correlated with the presence or absence of near-shore ice sheets. The lowest pCO₂ of 35 ppm together with the highest PPFD of 1362 mu mol E m(-2) s(-1) observed in the afternoon on June 28 in the presence of sea ice. The very low pCO₂ observed in late June was likely caused by high photosynthetic rates related to high phytoplankton densities typically observed from spring to early summer near the ice edge, and by water low in salinity and CO_{2 released by melting sea ice early in the season.}