Impacts of anthropogenic SO_x, NO_x and NH₃ on acidification of coastal waters and shipping lanes

Abstract

The acidification of the ocean by anthropogenic CO₂ absorbed from the atmosphere is now well-recognized and is considered to have lowered surface ocean pH by 0.1 since the mid-18th century. Future acidification may lead to undersaturation of CaCO₃ making growth of calcifying organisms difficult. However, other anthropogenic gases also have the potential to alter ocean pH and CO₂ chemistry, specifically SO_x and NO_x and NH₃. We demonstrate using a simple chemical model that in coastal water regions with high atmospheric inputs of these gases, their pH reduction is almost completely canceled out by buffering reactions involving seawater HCO₃- and CO₃^2- ions. However, a consequence of this buffering is a significant decrease in the uptake of anthropogenic CO₂ by the atmosphere in these areas.