Early- to late-Holocene contrast in productivity, OMZ intensity and calcite dissolution in the eastern Arabian Sea

Abstract

The Oxygen Minimum Zone (OMZ) is a potential source of CO2 to the atmosphere, and the extensive OMZ spread to 1.37 × 106 km2 in the Northern Arabian Sea would be an important contributor to the CO2 budget. In this perspective, we report here that the Eastern Arabian Sea experienced coeval increase in productivity and denitrification from ~7 to 0 kyr, which coincides with minimum dissolved oxygen levels in bottom waters. In addition, during the same period, an increased calcium carbonate dissolution occurred as evidenced by low CaCO3 content, decreasing shell weights of planktonic foraminifer species Globigerinoides ruber with well-marked dissolution features on their shells. Therefore, this study has implications on the role of OMZ in governing CaCO3 dissolution and contributing to an increase in atmospheric CO2.