A study on inorganic carbon components in the Andaman Sea during the post monsoon season

Abstract

Extensive data have been collected on the carbon dioxide system during the post monsoon season in the eastern Bay of Bengal and the Andaman Sea of the northeastern Indian Ocean. The vertical distribution of temperature and salinity in the eastern Bay of Bengal were similar to that in the Andaman Sea down to 700–800 m. Below 1200 m depth the salinity remained constant at 34.90 in the Andaman Sea whereas it decreased to 34.80 in the eastern Bay of Bengal. On the other hand, deep waters (> 1200 m) of the Andaman Sea were warmer than those of the Bay of Bengal by approximately 2°C. Dissolved oxygen concentrations in the subsurface waters were higher in the Andaman Sea than in the central Bay of Bengal and Arabian Sea due to lower rates of regeneration. Total alkalinity, and pCO₂ showed similar distribution patterns both in the eastern Bay of Bengal and the Andaman Sea up to a depth of 1000–1200 m. Below this depth, their concentrations were higher in the latter than compared to former due to warmer waters. Carbonate saturation depth with respect to aragonite was shallow (approximately 300 m) in the Andaman Sea whereas deeper waters were found to be under saturated with respect to calcite.