Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerf...Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerful proxy for tracing natural processes and human activities.In this study,one fine-grained sediment core(DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon(BC) contents and TOC stable carbon isotope ratios(d13 C).By combining these data with 210~Pb dating,an improved carbon correction model and a two end-member mixing model,we reconstructed century-scale high-resolution sequences of corrected TOC,terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record.The two events,shown as two minima in the TOC profiles,correspond temporally to 1985-1987 AD and 2003-2006 AD,which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam,respectively.In addition,the variations in TOC contents and δ^(13)C values before,during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River.The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological ef fects on the inner shelf of the East China Sea to the water impoundment of the dams.These new TOC records reflect the interaction between natural and anthropogenic processes and,accordingly,provide a deep insight and important references for assessing marine ecological ef fects resulting from water impoundment of largescale dams.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(No.2012CB956004)the Fundamental Research Funds for the Central Universities(No.16lgjc22)
文摘Coastal seas,located between continents and the open ocean,are an important active carbon pool.The sedimentary total organic carbon(TOC)in these areas is a mixture of terrestrial and marine sources,and can be a powerful proxy for tracing natural processes and human activities.In this study,one fine-grained sediment core(DH5-1) from the inner shelf of the East China Sea was systematically analyzed for TOC and black carbon(BC) contents and TOC stable carbon isotope ratios(d13 C).By combining these data with 210~Pb dating,an improved carbon correction model and a two end-member mixing model,we reconstructed century-scale high-resolution sequences of corrected TOC,terrestrial TOC and marine TOC contents and identified two carbon depletion events in the DH5-1 record.The two events,shown as two minima in the TOC profiles,correspond temporally to 1985-1987 AD and 2003-2006 AD,which exactly matches the water impoundment of the Gezhouba Dam and Three Gorges Dam,respectively.In addition,the variations in TOC contents and δ^(13)C values before,during or after the minima demonstrate a relationship between the depletion events and water impoundment of the dams on the Changjiang River.The TOC reductions may represent synchronous responses of sedimentary TOC and resultant ecological ef fects on the inner shelf of the East China Sea to the water impoundment of the dams.These new TOC records reflect the interaction between natural and anthropogenic processes and,accordingly,provide a deep insight and important references for assessing marine ecological ef fects resulting from water impoundment of largescale dams.
