莱州湾入海河流河口氮来源及转化过程的同位素解析  

Isotopic analysis of nitrogen sources and transformation processes in the coastal river estuaries of Laizhou Bay

作　　者：张璐瑶 岳甫均 李军[2,5] 简锐风 马卓妮 弓耀奇 刘小龙[2] ZHANG Lu-yao;YUE Fu-jun;LI Jun;JIAN Rui-feng;MA Zhuo-ni;GONG Yao-qi;LIU Xiao-long(Department of Geography,Tianjin Normal University,Tianjin 300387,China;Tianjin Key Laboratory of Water Resources and Environment,Tianjin Normal University,Tianjin 300387,China;School of Earth System Science,Tianjin University,Tianjin 300072,China;Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development around Bohai Sea,Tianjin 300450,China;Academy of Eco-civilization Development for Jing-Jin-Ji Megalopolis,Tianjin Normal University,Tianjin 300387,China)

机构地区：[1]天津师范大学地理学部,天津300387 [2]天津师范大学,天津市水资源与水环境重点实验室,天津300387 [3]天津大学地球系统科学学院,天津300072 [4]天津环渤海滨海地球关键带国家野外科学观测研究站,天津300450 [5]天津师范大学,京津冀生态文明发展研究院,天津300387

出　　处：《中国环境科学》2025年第2期981-990,共10页China Environmental Science

基　　金：国家自然科学基金资助项目(42293262);国家科技基础资源调查专项项目(2021FY101001)。

摘　　要：为解决莱州湾氮污染问题,本文开展了莱州湾入海河流氮来源及转化过程研究.通过分析水质参数、氮含量、水和硝酸盐的稳定同位素,以明确河流河口水体氮来源及其关键过程.结果表明:水的δD和δ^(18)O与盐度之间具有较好的时空变化一致性,表明入海河口受到较强的海水混合作用影响,并向河流上游显著减弱.丰水期和枯水期NO_(3)^(-)-N占TN比例除个别点较低外,大部分都在37.2%~81.7%和29.5%~95.9%内,表明在大部分河段NO_(3)^(-)-N是主要的无机氮形态;枯水期ρ(TN)和ρ(NH_(4)^(+)-N)在部分样点出现极值,显著高于丰水期,部分水体ρ(NH_(4)^(+)-N)在2mg/L以上,属劣V类水质.2005-2023年间的ρ(NO_(3)^(-)-N)的变化表明,莱州湾入海河流NO_(3)^(-)-N浓度呈“先上升,后下降”趋势.总体上,水体中δ^(15)N-NO_(3)^(-)在丰水期和枯水期的变化范围分别为+5.7‰~+18.6‰和+4.5‰~+20.0‰;δ^(18)O-NO_(3)^(-)为+4.2‰~+13.8‰和-0.5‰~+20.1‰,均无明显季节变化.硝酸盐同位素结果表明莱州湾入海河流主要受硝化作用影响,同时部分河段样点受到反硝化作用影响.枯水期低盐度采样点NO_(3)^(-)-N主要来自于粪肥和污水,丰水期河口大部分采样点受咸潮回溯的影响,并且大部分河段水体受农业施肥影响明显.本研究明确了莱州湾海岸带入海河流河口氮污染源的排放特征和时空差异性,所取得的认识可以为未来环渤海入海河流氮污染的防控和治理提供研究示范和数据参考.To understand nitrogen pollution and sources of Laizhou Bay,nitrogen sources and transformation processes in the coastal rivers entering the sea of Laizhou Bay were studied.Water quality parameters,nitrogen content,and stable isotopes were used to clarify the sources and key processes in river estuary.The results indicate strong temporal and spatial consistency betweenδD andδ^(18)O of water,EC,and salinity,suggesting significant seawater mixing effects in the estuary,which was significantly weakened upstream of the river.NO_(3)^(-)-N was found to be the dominant form to inorganic nitrogen in most reaches of the river during high flow and low flow seasons,ranging from 37.2%to 81.7%and 29.5%to 95.9%,respectively,except for a few sites.Furthermore,extreme values ofρ(TN)andρ(NH_(4)^(+)-N)values were observed at some sample sites during low flow season,which were significantly higher than those during the high flow season.Some water samples hadρ(NH_(4)^(+)-N)values exceeding 2mg/L,resulting in an inferior Category V water quality.The long-term variation ofρ(NO_(3)^(-)-N)from 2005 to 2023 showed an initial increase followed by a decrease in rivers entering Laizhou Bay.Theδ^(15)N-NO_(3)^(-)varied from+5.7‰to+18.6‰and from+4.5‰to+20.0‰during the high flow and low flow seasons,respectively,while theδ^(18)O-NO_(3)^(-)varied from+4.2‰to+13.8‰and from-0.5‰to+20.1‰,with no obvious seasonal variations.The nitrate isotope results showed that nitrification was major process affecting riverine nitrogen entering Lanzhou Bay,and that some river samples were also influenced by denitrification.During low flow season,NO_(3)^(-)-N at the low salinity sampling sites was mainly sourced from manure and sewage,while most estuary sites during the high flow season were affected by the salty tide backflow,and agricultural fertilization impacted most river sections.This study provides insights into the emission characteristics of nitrogen pollution sources and spatial and temporal variability in Laizhou Bay’s coastal

关 键 词：同位素 氮来源 莱州湾 入海河流 

分 类 号：X52[环境科学与工程—环境工程]