The Changjiang Estuary has been considered as one of the most polluted estuaries in the world due to high nitrate （NO3） input, especially in spring and summer. In this study, 6~5N and t^180 of NO3, along with other ...The Changjiang Estuary has been considered as one of the most polluted estuaries in the world due to high nitrate （NO3） input, especially in spring and summer. In this study, 6~5N and t^180 of NO3, along with other chemical parameters in this area, were measured in spring to evaluate NO3 biogeochemical processes. A simple two end-members mixing model was used to examine the relative contribution of the Changjiang River Diluted Water and marine water to NO~ sources in the Changjiang Estuary and the adjacent East Chi- na Sea. The isotopic signals show that NO3 behaved relatively and conservatively in Transect F and Transect P where assimilation was weak possibly due to vertical mixing, while active assimilation and weak nitrifi- cation occurred in Transect D. Spatial difference in assimilation was indicated by the ~ 1：1 enrichment of S 15N and 6180 in the three transects, while spatial difference in nitrification was reflected by deviations of 15N and 6180 from assimilation line. Our results suggest that the input of the Changjiang River Diluted Wa- ter promoted NO3 assimilation possibly by stratifying the water column which favored the phytoplankton growth.展开更多
基金The National Basic Research Program of China (973Program) under contract No.2010CB428903the National Natural Science Foundation of China under contract Nos 41006045 and 91128212+2 种基金National Science and Technology Pillar Program under contract No.2008BAC42B01China Postdoctoral Science Foundation under contract No.20100471690SIOSOA Project under contract Nos JT0707 and GCMAC1103
文摘The Changjiang Estuary has been considered as one of the most polluted estuaries in the world due to high nitrate （NO3） input, especially in spring and summer. In this study, 6~5N and t^180 of NO3, along with other chemical parameters in this area, were measured in spring to evaluate NO3 biogeochemical processes. A simple two end-members mixing model was used to examine the relative contribution of the Changjiang River Diluted Water and marine water to NO~ sources in the Changjiang Estuary and the adjacent East Chi- na Sea. The isotopic signals show that NO3 behaved relatively and conservatively in Transect F and Transect P where assimilation was weak possibly due to vertical mixing, while active assimilation and weak nitrifi- cation occurred in Transect D. Spatial difference in assimilation was indicated by the ~ 1：1 enrichment of S 15N and 6180 in the three transects, while spatial difference in nitrification was reflected by deviations of 15N and 6180 from assimilation line. Our results suggest that the input of the Changjiang River Diluted Wa- ter promoted NO3 assimilation possibly by stratifying the water column which favored the phytoplankton growth.
