Is particulate organic carbon transported to the deep-ocean increasing with the growing ocean carbon sink

Abstract

In recent years, the ocean carbon sink has been increasing due to the rising atmospheric CO2 concentration, and the oceanic oxygen minimum zone (OMZ, 0-200m) is expanding due to ocean warming and strengthened ocean stratification. So, will the strengthening of ocean carbon sink and the expansion of the OMZ lead to more POC being transported to the deep ocean? On the basis of 16208 POC data in 547 stations obtained from sediment traps since the 1970s worldwide, the POC fluxes in the OMZ increase, however, that in the deep ocean tended to decrease over recent decades, which means that the growing ocean carbon sink and the OMZ expansion didn’t lead to more POC being transported to the deep ocean. In addition, the remineralization of POC in the OMZ consumes large amounts of dissolved oxygen (DO), in turn contributing to the expansion of the OMZ.