基于氮氧同位素的南四湖硝酸盐来源解析  

An analysis of nitrate sources in Nansi Lake based on nitrogen and oxygen isotopes

作　　者：凌郡鸿 张依章[1,2] 曹英杰 李旭 赵光磊 LING Jun-hong;ZHANG Yi-zhang;CAO Ying-jie;LI Xu;ZHAO Guang-lei(Chinese Research Academy of Environmental Sciences,Beijing 100012,China;Research Institute for Environmental Innovation(Tianjin Binhai),Tianjin 300457,China;School of Environmental Science and Engineering,Sun Yat-sen University,Guangdong 510275,China)

机构地区：[1]中国环境科学研究院,北京100012 [2]天津市滨海新区环境创新研究院,天津300457 [3]中山大学环境科学与工程学院,广东510275

出　　处：《中国环境科学》2023年第6期3100-3106,共7页China Environmental Science

摘　　要：选取南水北调东线受水湖南四湖为研究对象,运用δ^(15)N-NO_(3)^(-)、δ^(18)O-NO_(3)^(-)同位素示踪技术和水化学分析方法,阐明了研究区水化学及不同形态氮分布特征,揭示了氮的转化过程,分析了硝酸盐来源,基于MixSIAR模型,对研究区水体中各硝酸盐来源贡献比例进行了定量识别.结果表明:南四湖无明显温跃层,水体呈碱性,水化学类型以SO_(4)^(2-)-Na^(+)型为主.下级湖中的氮以硝态氮为主,随着水体自净及沉积物吸附,浓度逐渐降低,入湖河流污染特征与湖水一致.研究区湖水硝酸盐形成过程以硝化作用为主,水体中的硝酸盐来源生活污水>土壤有机氮>合成化肥>大气沉降,基于MixSIAR源解析模型分析,贡献比例分别为51.3%、23.7%、16.4%、8.5%.The Nansi Lake of the eastern route of the South-to-North Water Diversion Project was selected as the research object.The water chemistry and distribution characteristics of different forms of nitrogen in the study area were elucidated by usingδ^(15)N-NO_(3)^(-)andδ^(18)O-NO_(3)^(-)isotope tracing techniques and water chemistry analysis,revealing the transformation process of nitrogen and analyzing the source of nitrate.Meanwhile,according to the MixSIAR model,the contribution rates of different nitrate sources in were also identified quantitatively.There was no obvious thermocline in Nansi Lake and the water here was alkaline,the SO_(4)^(2-)-Na^(+)type was main hydrochemical type.Nitrate nitrogen was the main form of nitrogen in the subordinate lake.The concentration gradually decreased with the self-purification of water and the adsorption of sediment.The pollution characteristics of the rivers were consistent with that of the lake.Nitrification occurred in the process of nitrate formation,and the nitrate in the lake mainly came from domestic sewage>soil organic nitrogen>synthetic fertilizer>atmospheric deposition.Based on the MixSIAR model,the contribution ratios were 51.3%,23.7%,16.4%and 8.5%,respectively.

关 键 词：氮氧同位素 硝酸盐 源解析 南四湖 MixSIAR 

分 类 号：X524[环境科学与工程—环境工程]