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.