Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is simil...Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is similarto that of the Huanghe River. The annual weighted mean of POC 13 C values of the Changjiang River is almost the same as that of the Huanghe River. Based on the data of runoff and sediment load measured daily and POC concentra-tion measured monthly the POC flux at Sta. Datong was estimated. The flux value at Datong may be considered ap-proximately to be the M flux of the Changjiang River discharging into the sea. The M flux of the Changjiang Riv-er is slightly larger than that of the Huanghe River.展开更多
The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-...The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm （1 atm=101 325 Pa） in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/（m2.d） [61 mmol/（m2.d） on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.展开更多
A modified inverse method is ed to compute the volume transport (VT), the heat transport (HT) andthe horizontal meterial fluxes in the East China Sea with data of CTD, T2, DOC, PCO, etc. Obtained in April1994. In Apri...A modified inverse method is ed to compute the volume transport (VT), the heat transport (HT) andthe horizontal meterial fluxes in the East China Sea with data of CTD, T2, DOC, PCO, etc. Obtained in April1994. In April 1994 VT and HT through Section PN in the East China As are 30.6×106 m3/s and 2.42× 1015 Wrespectively, and the horizontal fluxes of T2, DOC and POC through Section PN are 65× 106,2. 2×106 and 0. 17×106 mol/s respectively. This means that the Percentages of fluxes of T2 , DOC and POC in total C flux are about96.5%, 3.3% and 0.2% respectively. VT and HT through betion Ss(near the Tokara Strait) are 26. 7×106m3/sand 2. 14× 1015 W respectively, which are about 87% and 88% of VT and HT through Section PN respectively. Thehorizontal flux of T2 through sation % is 61×106 mol/s, which is about 93. 8 % of the flux of T2 through SectionPN, i. e., its percentage is close to that of VT and HT of betions S5 and PN. The horizontal fluxes of DOC and POCthrough Section S5 are 2. 5× 106 and 0.08×106 mol/s respectively. The sum of the horizontal influx and outflux ofTop through the boundaries of Box-2 is about-2×106 mol/s (outflux), which is about 3% of the flux of T2 through Section PN. This value is the same order of magnitude of the vertical flux caused by the downwelling or theupwelling. Tins means that the horizontal flux of T2 must be considered, when the vertical flux of T2 is computed,and so are the other material vertical fluxes (DOC, etc. ). Finally, the vertical velocity component is computed with adiagnostic model.展开更多
A major flood event occurred within the drainage basin of the Changjiang River in June-August, 1998. Survey over the East China Sea adjacent to the Changjiang River estuary shows that during the flood the turbid water...A major flood event occurred within the drainage basin of the Changjiang River in June-August, 1998. Survey over the East China Sea adjacent to the Changjiang River estuary shows that during the flood the turbid water (with a suspended sediment concentration of higher than 10 mg l-1) °°′reached 123E. Stratification of the concentration layers was present near 12215E, with the concentration in the bottom layer being 3 times that in the upper layer, in response to sediment °°settling processes. The concentration is the lowest in the area of 126E^127E, representing a characteristic of the Kuroshio water. Although there was some expansion of the turbid water extension compared with the winter situations with low freshwater discharges, the suspended sediment does not appear to disperse towards the northeast from the Changjiang River. Further, several secondary high suspended sediment concentration centers were present on the East China Sea continental shelf, which may result from resuspension of the seabed sediment or advection of seawater containing suspended matter. In order to understand the processes of fine-grained sediment transport/deposition and their impact on the flux of chemical constituents on the shelf, further studies on the hydrodynamics, temperature, salinity and nutrient characteristics are required.展开更多
Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in t...Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions.The first,the sediment load/yield of the islands has the same pattern as the adjacent small,mountainous rivers along the coastline;and the second,each of the islands was treated as a single catchment.The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a,which is comparable to the supply from the local smaller rivers.A sensitivity analysis indicates that this value represents the lower limit of estimate;if the accurate amount of sub-catchments of any island is considered,then this value will be enhanced slightly.This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and,therefore,should be paid with attention.展开更多
The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East Chin...The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.展开更多
文摘Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is similarto that of the Huanghe River. The annual weighted mean of POC 13 C values of the Changjiang River is almost the same as that of the Huanghe River. Based on the data of runoff and sediment load measured daily and POC concentra-tion measured monthly the POC flux at Sta. Datong was estimated. The flux value at Datong may be considered ap-proximately to be the M flux of the Changjiang River discharging into the sea. The M flux of the Changjiang Riv-er is slightly larger than that of the Huanghe River.
基金The Marine Public Welfare Project of China under contract Nos200805029,200905012,200905025,and 201005034the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract Nos JG0821 and JG1021
文摘The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm （1 atm=101 325 Pa） in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/（m2.d） [61 mmol/（m2.d） on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.
文摘A modified inverse method is ed to compute the volume transport (VT), the heat transport (HT) andthe horizontal meterial fluxes in the East China Sea with data of CTD, T2, DOC, PCO, etc. Obtained in April1994. In April 1994 VT and HT through Section PN in the East China As are 30.6×106 m3/s and 2.42× 1015 Wrespectively, and the horizontal fluxes of T2, DOC and POC through Section PN are 65× 106,2. 2×106 and 0. 17×106 mol/s respectively. This means that the Percentages of fluxes of T2 , DOC and POC in total C flux are about96.5%, 3.3% and 0.2% respectively. VT and HT through betion Ss(near the Tokara Strait) are 26. 7×106m3/sand 2. 14× 1015 W respectively, which are about 87% and 88% of VT and HT through Section PN respectively. Thehorizontal flux of T2 through sation % is 61×106 mol/s, which is about 93. 8 % of the flux of T2 through SectionPN, i. e., its percentage is close to that of VT and HT of betions S5 and PN. The horizontal fluxes of DOC and POCthrough Section S5 are 2. 5× 106 and 0.08×106 mol/s respectively. The sum of the horizontal influx and outflux ofTop through the boundaries of Box-2 is about-2×106 mol/s (outflux), which is about 3% of the flux of T2 through Section PN. This value is the same order of magnitude of the vertical flux caused by the downwelling or theupwelling. Tins means that the horizontal flux of T2 must be considered, when the vertical flux of T2 is computed,and so are the other material vertical fluxes (DOC, etc. ). Finally, the vertical velocity component is computed with adiagnostic model.
文摘A major flood event occurred within the drainage basin of the Changjiang River in June-August, 1998. Survey over the East China Sea adjacent to the Changjiang River estuary shows that during the flood the turbid water (with a suspended sediment concentration of higher than 10 mg l-1) °°′reached 123E. Stratification of the concentration layers was present near 12215E, with the concentration in the bottom layer being 3 times that in the upper layer, in response to sediment °°settling processes. The concentration is the lowest in the area of 126E^127E, representing a characteristic of the Kuroshio water. Although there was some expansion of the turbid water extension compared with the winter situations with low freshwater discharges, the suspended sediment does not appear to disperse towards the northeast from the Changjiang River. Further, several secondary high suspended sediment concentration centers were present on the East China Sea continental shelf, which may result from resuspension of the seabed sediment or advection of seawater containing suspended matter. In order to understand the processes of fine-grained sediment transport/deposition and their impact on the flux of chemical constituents on the shelf, further studies on the hydrodynamics, temperature, salinity and nutrient characteristics are required.
基金Supported by the National Natural Science Foundation of China(Nos.41625021,41876092,41576095,41906021)。
文摘Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions.The first,the sediment load/yield of the islands has the same pattern as the adjacent small,mountainous rivers along the coastline;and the second,each of the islands was treated as a single catchment.The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a,which is comparable to the supply from the local smaller rivers.A sensitivity analysis indicates that this value represents the lower limit of estimate;if the accurate amount of sub-catchments of any island is considered,then this value will be enhanced slightly.This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and,therefore,should be paid with attention.
基金The National Key Basic Research Program of Ministry of Science and Technology of China under contract No.2001CB4097the Foundation of Key Laboratory of Marine Ecosystem and Biogeochemistry of State Oceanic Administration of China under contract No.LMEB200603.
文摘The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.
