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Nitrate δ15N and δ18O evidence for active biological transformation in the Changjiang Estuary and the adjacent East China Sea 总被引:1,自引:0,他引:1
CHEN Fajin CHEN Jianfang JIA Guodong JIN Haiyan XU Jie YANG Zhi ZHUANG Yanpei LIU Xizhen ZHANG Haisheng 《海洋学报(英文版)》2013,32(4):11-17
The Changjiang Estuary has been considered as one of the most polluted estuaries in the world due to high nitrate (NO-3) input, especially in spring and summer. In this study, δ15N and δ18O of NO-3 , along with other chemical parameters in this area, were measured in spring to evaluate NO-3 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-3 sources in the Changjiang Estuary and the adjacent East China Sea. The isotopic signals show that NO-3 behaved relatively and conservatively in Transect F and Transect P where assimilation was weak possibly due to vertical mixing, while active assimilation and weak nitrification occurred in Transect D. Spatial difference in assimilation was indicated by the~1:1 enrichment of δ15N and δ18O in the three transects, while spatial difference in nitrification was reflected by deviations of δ15 N and δ18O from assimilation line. Our results suggest that the input of the Changjiang River Diluted Water promoted NO-3 assimilation possibly by stratifying the water column which favored the phytoplankton growth. 相似文献