동해 울릉분지 표층 pCO2의 시.공간적 분포에 관한 연구

Abstract

To clarify the temporal and spatial distribution of partial pressure of CO2 (pCO2) in surface seawater and of which major factors in the Ulleung Basin of the East Sea/Sea of Japan, we measured surface pCO2, sea surface temperature (SST), sea surface salinity (SSS) by underway measurement system and nutrients, alkalinity and chlorophyll-a of surface seawater by hydrocasting in April 2006 (spring), August 2007 (summer), February 2008 (winter) and October 2008 (autumn). SST showed a typical seasonal variation as a mid-latitude temperate ocean in the north hemisphere with high in summer and low in winter, while SSS showed an opposite seasonal trend with SST due to the concentrated rain in summer by seasonal monsoon. Temporal distribution of surface pCO2 showed a similar tendency with SST variations, but its magnitude of change was less than that the estimate by thermal effect due to the SST changes. In summer, the lower surface pCO2, which was less than expected by the SST, probably arose from the dilution effect of less saline, low pCO2 surface water by increased seasonal rainfall and river discharges. In winter, the higher surface pCO2 was likely due to the strong vertical mixing derived by the deep surface mixed layer. The Ulleung Basin of the East Sea acted as a CO2 sink, except summer when it acted as a weak CO2 source.