Key nitrogen biogeochemical processes revealed by the nitrogen isotopic composition of dissolved nitrate in the Changjiang River estuary, China  

作　　者：于海燕 俞志明 宋秀贤 曹西华 袁涌铨 卢光远 刘丽丽 

机构地区：[1]Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences [2]University of Chinese Academy of Sciences

出　　处：《Chinese Journal of Oceanology and Limnology》2014年第1期162-173,共12页中国海洋湖沼学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(No.41276116);the Fund for Creative Research Groups by NSFC(No.41121064);the National Basic Research Program of China(973 Program)(No.2010CB428706)

摘　　要：Seasonal variations in the nitrogen isotopic composition of dissolved nitrate （δ15NO3） were investigated in the surface waters of the Changjiang River estuary in 2009 and 2010. δ15NO3 varied between -4.6‰ and 8.9%0 with changes in temperature, salinity, dissolved oxygen concentrations, and the composition of the dissolved inorganic nitrogen pool. In February, biological processes decreased because of low temperature, and the mean δ15NO3 near the river mouth was 2.4%0. In May, δ15NO3 was the highest in the surface waters among all seasons. Analysis on the conservative mixing revealed assimilation, and this finding is supported by positive relationship between Chl a and δ15NO3. The fractionation factor of assimilation was estimated to be 2.0‰ by the Rayleigh equation. Nitrification was supported based on the mixing behaviors in November 2010 and the low δ15NO3 values in May and November 2009. The high ammonium concentrations in the adjacent marine area and positive relationships between total organic nitrogen and δ15NO3 in November 2010 indicated that mineralization was taking place.Seasonal variations in the nitrogen isotopic composition of dissolved nitrate(δ 15 NO 3) were investigated in the surface waters of the Changjiang River estuary in 2009 and 2010. δ 15 NO 3 varied between-4.6‰ and 8.9‰ with changes in temperature, salinity, dissolved oxygen concentrations, and the composition of the dissolved inorganic nitrogen pool. In February, biological processes decreased because of low temperature, and the mean δ 15 NO 3 near the river mouth was 2.4‰. In May, δ 15 NO 3 was the highest in the surface waters among all seasons. Analysis on the conservative mixing revealed assimilation, and this fi nding is supported by positive relationship between Chl a and δ 15 NO 3. The fractionation factor of assimilation was estimated to be 2.0‰ by the Rayleigh equation. Nitrifi cation was supported based on the mixing behaviors in November 2010 and the low δ 15 NO 3 values in May and November 2009. The high ammonium concentrations in the adjacent marine area and positive relationships between total organic nitrogen and δ 15 NO 3 in November 2010 indicated that mineralization was taking place.

关 键 词：ASSIMILATION NITRIFICATION MINERALIZATION EUTROPHICATION 

分 类 号：X55[环境科学与工程—环境工程]