我国地下水硝酸盐污染及源解析研究进展

Research Advances of Groundwater Nitrate Pollution and Source Apportionment in China

我国地下水中硝酸盐污染问题严峻,尤其农业产区地下水硝酸盐污染日益突出,严重影响了地下饮用水安全,急需引起重视.通过综述发现,我国地下水中硝酸盐的主要来源为大气沉降、土壤氮、农业施肥和粪便污水等,其中粪便污水和农业施肥是地下水硝酸盐超标的主要原因.总结了水化学分析法、多元统计分析法、稳定同位素示踪法和微生物源追踪等技术在地下水硝酸盐溯源中的应用.各种溯源方法均有一定的局限性,建议采用多种方法联合识别地下水中硝酸盐来源,并通过多元统计分析和同位素定量解析模型计算不同污染来源贡献率.硝酸盐污染溯源经历了从定性到定量的研究过程,目前基于δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)解析硝酸盐来源的SIAR和Mix SIAR模型已经相当成熟,但由于不同输入端元同位素特征值范围相互重叠,不同时空变化等条件下δ^(15)N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)值具有一定差异,以及氮迁移转化过程中的同位素分馏等的影响,导致模型计算得出的结果还存在不确定性,需要进一步优化模型的解析方法,以更精准地获取硝酸盐污染来源及其贡献率,服务于地下水资源的科学管理.

Groundwater nitrate(NO_(3)^(-))contamination in China has become a serious environmental problem,especially in agricultural production areas,which greatly affects the safety of drinking groundwater and requires urgent attention.In this study,the main sources of groundwater nitrate in China were reviewed,including atmospheric deposition,soil nitrogen,agricultural fertilization,and fecal sewage,among which fecal sewage and agricultural fertilization were the main reasons for the excessive groundwater nitrate.The application of hydrochemical analysis,multivariate statistical analysis,stable isotope tracer method,and microbial source tracking in the source apportionment of groundwater nitrate was summarized.All types of source apportionment methods had certain limitations.It is suggested that a variety of methods should be used to identify the source of groundwater nitrate,and the contribution rate of different pollution sources should be calculated using multivariate statistical analysis and isotope quantitative analysis models.The source apportionment of nitrate pollution has undergone a process from qualitative to quantitative research.At present,the SIAR and MixSIAR models based onδ^(15)N-NO_(3)^(-)andδ^(18)O-NO_(3)^(-)have been used widely to analyze the source of nitrate.However,due to the overlap of isotope characteristic values of different input end-members,the difference inδ^(15)N-NO_(3)^(-)andδ^(18)O-NO_(3)^(-)values under different spatial and temporal changes,and the influence of isotope fractionation in the process of nitrogen migration and transformation,the results calculated by the model remain uncertain.It is necessary to further optimize the analytical method of the model to obtain the source of nitrate pollution and its contribution rate more accurately to further aid in the scientific management of groundwater resources.