The global carbon cycle has played a key role in mitigating global warming and climate change.Long-term natural and anthropogenic processes influence the composition,sources,burial rates,and fluxes of carbon in sedime...The global carbon cycle has played a key role in mitigating global warming and climate change.Long-term natural and anthropogenic processes influence the composition,sources,burial rates,and fluxes of carbon in sediments on the continental shelf of China.In this study,the rates,fluxes,and amounts of carbon storage at the centennial scale were estimated and demonstrated using the case study of three fine-grained sediment cores from the central South Yellow Sea area(SYSA) and Min-Zhe belt(MZB),East China Sea.Based on the high-resolution temporal sequences of total carbon(TC)and total organic carbon(TOC)contents,we reconstructed the annual variations of historical marine carbon storage,and explored the influence of terrestrial and marine sources on carbon burial at the centennial scale.The estimated TC storage over 100 years was 1.18×10~8 t in the SYSA and 1.45×10~9 t in the MZB.The corrected TOC storage fluxes at the centennial scale ranged from 17 to 28 t/(km^2·a)in the SYSA and from 56 to 148 t/(km^2·a)in the MZB.The decrease of terrestrial materials and the increase of marine primary production suggest that the TOC buried in the sediments in the SYSA and MZB was mainly derived from the marine autogenetic source.In the MZB,two depletion events occurred in TC and TOC storage from 1985 to 1987 and 2003 to 2006,which were coeval with the water impoundment in the Gezhouba and Three Gorges dams,respectively.The high-resolution records of the carbon storage rates and fluxes in the SYSA and MZB reflect the synchronous responses to human activities and provide an important reference for assessing the carbon sequestration capacity of the marginal seas of China.展开更多
Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate chan...Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores（#34： 28.5°N, 122.272°E; CJ12-1269： 28.861 9°N, 122.515 3°E） from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B（dinosterol/brassicasterol） ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.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The global carbon cycle has played a key role in mitigating global warming and climate change.Long-term natural and anthropogenic processes influence the composition,sources,burial rates,and fluxes of carbon in sediments on the continental shelf of China.In this study,the rates,fluxes,and amounts of carbon storage at the centennial scale were estimated and demonstrated using the case study of three fine-grained sediment cores from the central South Yellow Sea area(SYSA) and Min-Zhe belt(MZB),East China Sea.Based on the high-resolution temporal sequences of total carbon(TC)and total organic carbon(TOC)contents,we reconstructed the annual variations of historical marine carbon storage,and explored the influence of terrestrial and marine sources on carbon burial at the centennial scale.The estimated TC storage over 100 years was 1.18×10~8 t in the SYSA and 1.45×10~9 t in the MZB.The corrected TOC storage fluxes at the centennial scale ranged from 17 to 28 t/(km^2·a)in the SYSA and from 56 to 148 t/(km^2·a)in the MZB.The decrease of terrestrial materials and the increase of marine primary production suggest that the TOC buried in the sediments in the SYSA and MZB was mainly derived from the marine autogenetic source.In the MZB,two depletion events occurred in TC and TOC storage from 1985 to 1987 and 2003 to 2006,which were coeval with the water impoundment in the Gezhouba and Three Gorges dams,respectively.The high-resolution records of the carbon storage rates and fluxes in the SYSA and MZB reflect the synchronous responses to human activities and provide an important reference for assessing the carbon sequestration capacity of the marginal seas of China.
基金The National Basic Research Program of China(973 Program)under contract No.2010CB428901the National Natural Science Foundation of China under contract Nos 41020164005,40976042 and 41076036
文摘Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores（#34： 28.5°N, 122.272°E; CJ12-1269： 28.861 9°N, 122.515 3°E） from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B（dinosterol/brassicasterol） ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.
