SEA SURFACE pCO2 IN THE INDIAN SECTOR OF THE SOUTHERN OCEAN DURING AUSTRAL SUMMER OF 2009

This Southern Ocean plays a key role in removing carbon dioxide from the Earth's atmosphere by physical, chemical, and biological processes. The present study attempts to understand: the spatio-temporal variations in pCO(2) and its relationship with nutrients and biological production in the Indian sector of the Southern Ocean during the late austral summer of 2009. The partial pressure of carbon dioxide (pCO(2)) showed high spatio-temporal variability in the study area. The highest pCO(2) that was recorded along the Polar Front (PF) the two transects is attributed to low productivity in the PF. From 57 degrees 30' E(T-E) towards 48 degrees E, the average sea surface pCO(2), chlorophyll and Total organic carbon (TOC) increased by 24 mu atm, 0.3mg/m(3), and 3 mu M, respectively, suggesting that the physical processes are predominantly active along 48 degrees E. Enhanced vertical mixing along 48 degrees E supports the corresponding increase in the average NO3, PO4, and SiO4 concentrations by 2 mu M, 0.4 mu M, and 1.7 mu M, respectively. pCO(2) and chlorophyll a are negative correlated along 57. 30' E(TE), however, positively correlated along 48 degrees E'(T-W), which suggests that the biological processes control the pCO(2) along 57 degrees 30'E. The average air-sea fluxes recorded were about -28 and -33 mmol m(-2)d(-1), on T-W and T-E, respectively. A significant finding of this study is that although the Southern Ocean is a known sink of carbon dioxide, the vicinity of the Crozet Island, where oceanic fronts are known to merge, suggests to act as a source of atmospheric CO2. It is attributed that "The island mass effect" could also be a factor that generates elevated CO2 in the vicinity of the study area. In the last one decade the oceanic pCO(2) increased at a rate 0.77 mu atm/year in the region south of the Polar front; but is not associated with the Southern Annular Mode effect.