동해 울릉분지 표층 해수의 이산화탄소 장기 변동과 해양 산성화

Abstract

Since the Industrial Revolution, carbon dioxide emitted by humans has been perturbing the carbon cycle of the Earth, and both global warming and ocean acidification have accelerated. In this study, increasing CO2 and ocean acidification in the surface of the Ulleung Basin (UB) of the East/Japan Sea are discussed. It was revealed by means of twelve direct observations of surface fCO2 from 1995 to 2004 that the UB acts as a sink for atmospheric CO2, depending on the season. The seasonal variability of fCO2 is almost balanced between thermal and non-thermal effects. The long-term increasing trend of fCO2 was estimated, considering the seasonal variability by harmonic analysis, which fit well to the in-situ fCO2 observation data. The estimated rates of increase of fCO2 were 1.97 μatm yr-1 for the atmosphere and 3.36 μatm yr-1 for the surface ocean, exceeding the global mean of 1.5 μatm yr-1. The ocean acidification trend, which was calculated from total alkalinity and fCO2, is estimated to be 0.04 pH unit decade-1. Surface seawater of the UB has been acidifying rapidly comparing with the global ocean (0.02 pH unit decade-1). This study provides clues to the impacts of climate change and ocean acidification on a regional scale. in the surface of the Ulleung Basin (UB) of the East/Japan Sea are discussed. It was revealed by means of twelve direct observations of surface fCO2 from 1995 to 2004 that the UB acts as a sink for atmospheric CO2, depending on the season. The seasonal variability of fCO2 is almost balanced between thermal and non-thermal effects. The long-term increasing trend of fCO2 was estimated, considering the seasonal variability by harmonic analysis, which fit well to the in-situ fCO2 observation data. The estimated rates of increase of fCO2 were 1.97 μatm yr-1 for the atmosphere and 3.36 μatm yr-1 for the surface ocean, exceeding the global mean of 1.5 μatm yr-1. The ocean acidification trend, which was calculated from total alkalinity and fCO2,