氮和氧同位素示踪云台山地表水硝酸盐来源  

Tracking nitrate sources of the surface water in the Yuntai Mountain scenic area by nitrogen and oxygen isotopes

作　　者：李艳利[1] 任世航 闫瑞敏 朱庆会 崔鹏煜 马梦杰 LI Yanli;REN Shihang;YAN Ruimin;ZHU Qinghui;CUI Pengyu;MA Mengjie(Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo 454000;Mornitoring Center of Ecology and Environment of Jiaozuo,Henan Province,Jiaozuo 454000)

机构地区：[1]河南理工大学资源环境学院,焦作454000 [2]河南省焦作生态环境监测中心,焦作454000

出　　处：《环境科学学报》2024年第4期106-115,共10页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.U1704241);河南省科技攻关项目(No.232102320141);水资源与水电工程科学国家重点实验室开放基金(No.2022SWG01);马鞍石水库水质超标调查研究项目(No.15210491)。

摘　　要：多年监测发现,5A级风景旅游区云台山水中总氮超标.为了摸清其不同形态氮含量水平并识别氮污染来源,本研究分别于丰水期(2021年9月、2022年6、7月)、平水期(2021年11月)和枯水期(2021年12月、2022年2月)采集云台山马鞍石水库表层和深层水及其上游河流表层水样品共58个,测定并分析了水化学参数(TN、NO_(3)^(-)-N、NH_(4)^(+)-N和Cl^(-))的浓度和硝酸盐氮氧稳定同位素(δ^(15)N-NO_(3)^(-)、δ^(18)O-NO_(3)^(-)),同时利用SIAR同位素模型定量解析了水库及其上游河流中NO_(3)^(-)源的贡献.结果表明,马鞍石水库及其上游河流水中ρ(TN)、ρ(NO_(3)^(-)-N)、ρ(NH_(4)^(+)-N)变化范围分别为1.86~6.4、1.40~4.19、0~0.45 mg·L^(-1),ρ(NO_(3)^(-)-N)/ρ(TN)变化范围为44.08%~99.3%,均值为79.84%,硝态氮是氮的主要存在形态.δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)变化范围分别为-9.12‰~8.49‰和-0.58‰~13.62‰,水库δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)值在平水期最高.δ^(15)N-NO_(3)^(-)、δ^(18)O-NO_(3)^(-)值和n(NO_(3)^(-))/n(Cl^(-))与Cl^(-)物质的量浓度的关系指示水库及其上游河流NO_(3)^(-)主要来源于化肥和土壤氮.SIAR同位素模型结果表明,丰水期、平水期和枯水期土壤氮的贡献分别为48.5%、41.5%和22.4%,化肥的贡献分别为25.8%、22.9%和62.7%.The surface water of the 5A scenic tourist area of Yuntai Mountain has been heavily affected by nitrogen pollution,in accordance with the Environmental Quality Standard for surface water in China.To determine the types and concentrations of nitrogen species and identify their sources,we collected a total of 58 surface and deep water samples from the reservoir and its upper rivers during the high flow season (September in 2021,June and July 2022),usual flow season (November 2021) and low flow season (December 2021 and February 2022) in this study.The concentrations of some chemical ions (TN、NO_(3)^(-)-N、NH_(4)^(+)-N and Cl^(-)) and nitrogen and oxygen stable isotopes of nitrate (δ^(15)N-NO_(3)^(-)and δ^(18)O-NO_(3)^(-)) were measured and analyzed.Quantitative identification of nitrate sources was performed using a Bayesian mixing model.The results are as follows:The concentrations of total nitrogen,ammonia nitrogen and nitrate nitrogen ranged from 1.86 to 6.4 mg·L^(-1),1.40 to 4.19 mg·L^(-1),0 to 0.45 mg·L^(-1),respectively.Nitrate nitrogen accounted for 44.08%to 99.33%of total nitrogen,with a mean value of 79.84%,indicating that nitrate nitrogen is the dominant species of total nitrogen.The ranges of δ^(15)N-NO_(3)^(-)and δ^(18)O-NO_(3)^(-)were-9.12‰to 8.49‰and-0.58‰to 13.62‰,respectively,with the highest values during the usual flow season.The relationship between NO_(3)^(-)/Cl^(-)molar ratios and Cl^(-)molar concentrations,as well as nitrate dual isotopes,indicated that nitrate mainly from chemical fertilizer and soil nitrogen.According to the results of SIAR stable isotopes model,the fractional contributions from soil nitrogen during the high,usual and low flow seasons were 48.5%,41.5%and 22.4%,respectively,while contributions from chemical fertilizer were 25.8%,22.9%and 62.7%,respectively.

关 键 词：硝酸盐 稳定同位素 贝叶斯混合模型 来源示踪 SIAR同位素模型 云台山 

分 类 号：X524[环境科学与工程—环境工程] X832