Does Changjiang Diluted Water influence the Yellow Sea Ecosystem?

Abstract

There is a growing interest in the eutrophication bring about radical changes to the ecosystem of the East China Sea. The inflowing nutrients from the Changjiang River are characterized by high concentration and lofty N/P ratio. The eutrophication occurs frequently in the nearby sea of the Changjiang River. The distribution of the Changjiang Diluted Water(CDW), characterized as water with relatively low salinity (< 30~32) in general, have seasonal variation with flowing southward along the coastline of China in winter while the northeast towards Cheju Island in summer. In this study, the effect of the CDW on the lower trophic ecosystem of the central Yellow Sea has been investigated based on the POLCOMS-ERSEM coupled physico-biogeochemical ecosystem model.The physical and biogeochemical borderlines of the CDW are defined by the distribution of the salinity and nitrate concentration at the surface. The extension region of both CDW borderlines has maximum in August and the borderlines don’t reach to the center of the Yellow Sea and usually propagate toward the Korea Strait. The variation of the lower trophic ecosystem was investigated by comparing the Changjiang Estuary located inside the CDW and the center of YS outside of it. The nutrients have mostly high concentration in winter on account of vertical mixing derived by strong wind while the nitrate in the Changjiang Estuary shows high concentration in summer at tication occurs frequently in the nearby sea of the Changjiang River. The distribution of the Changjiang Diluted Water(CDW), characterized as water with relatively low salinity (< 30~32) in general, have seasonal variation with flowing southward along the coastline of China in winter while the northeast towards Cheju Island in summer. In this study, the effect of the CDW on the lower trophic ecosystem of the central Yellow Sea has been investigated based on the POLCOMS-ERSEM coupled physico-biogeochemical ecosystem model.The physical and biogeochemical borderlines of the CDW are defined by the distribution of the salinity and nitrate concentration at the surface. The extension region of both CDW borderlines has maximum in August and the borderlines don’t reach to the center of the Yellow Sea and usually propagate toward the Korea Strait. The variation of the lower trophic ecosystem was investigated by comparing the Changjiang Estuary located inside the CDW and the center of YS outside of it. The nutrients have mostly high concentration in winter on account of vertical mixing derived by strong wind while the nitrate in the Changjiang Estuary shows high concentration in summer at t