Aragonite undersaturation in Gwangyang Bay, South Korea: Effects of fresh water input

Abstract

Dissolved inorganic carbon (DIC) and alkalinity were precisely measured for surface and bottom waters in Gwangyang Bay, Korea, during the four seasons to assess seasonal variations of aragonite saturation state (Omega(arag)). Both the surface and bottom waters were undersaturated with respect to aragonite during summer but were supersaturated during the other seasons. The summertime undersaturation of the surface waters with respect to aragonite may have been a result of the dilution effect caused by higher seasonal river runoff. In the bottom waters, the average DIC concentration increased by 40.6 mu mol kg((TM) 1) from spring to summer, while the average alkalinity decreased by 74.7 mu eq kg((TM) 1). As a result, the alkalinity/DIC ratio decreased from 1.07 in spring to 1.01 in summer and pH also decreased from 7.91 to 7.48, which resulted in the summertime undersaturation of the bottom waters.