Factors Controlling Acidification in Intermediate and Deep/Bottom Layers of the Japan/East Sea

Abstract

AbstractMuch effort has been devoted to studying the absorption of anthropogenic CO2 by the surface and subsurface ocean, where surface seawater acidifies rapidly while the deep ocean was thought to respond to CO2 intrusion at longer time scales. However, recent studies have revealed rapid acidification of the deep Japan/East Sea, implying that ongoing changes in ocean dynamics are accelerating acidification at depth, and the controlling mechanisms have not been fully addressed. Using a multibox model of ocean circulation and carbonate chemistry, we demonstrate that a combination of reduced deep/bottom water formation and an increase in organic matter remineralization can best explain the observed pattern of rapid acidification in deep waters. In contrast, acidification in the intermediate layer is controlled by increased particulate organic carbon remineralization accompanied by intensified intermediate ventilation. Variations of ventilation and remineralization of particulate organic carbon dominating acidification in different layers of the water column need to be considered in future investigations.