黑龙江省海伦地区浅层地下水中“三氮”分布特征及来源解析

Distribution Characteristics and Source Analysis of“Three Nitrogen”in Shallow Groundwater in Hailun Area of Heilongjiang Province

近年来随着人类活动增加、工业废水的大量排放以及农业氮肥过量施用,使得地下水中“三氮”(即硝酸盐氮、氨氮、亚硝酸盐氮)污染问题愈加严重,对人体带来潜在健康风险。通过地下水“三氮”污染分布及来源作出解析,对于开展污染源头防控具有重要的现实意义。本文以黑龙江省海伦地区浅层地下水作为研究对象,采用气相分子吸收光谱法(GMA)及电感耦合等离子体质谱法(ICP-MS)测定了地下水中“三氮”及其他金属元素的检出情况,应用内梅罗综合污染指数法对地下水中“三氮”划分水质污染等级,综合运用Pearson相关性分析、正定矩阵因子分析法(PMF)等方法,识别和定量解析污染源及贡献。结果表明:①研究区地下水中硝酸盐氮含量范围在0.021~123.05mg/L之间,平均浓度为15.27mg/L;氨氮含量范围在ND~3.91mg/L之间,平均浓度为0.33mg/L;亚硝酸盐含量范围在ND~0.65mg/L之间。与《地下水质量标准》(GB/T 14848—2017)Ⅲ类水指标对比,硝酸盐氮超标率为20.0%,氨氮超标率为12.5%。②内梅罗综合污染指数评价结果表明,研究区地下水水质污染等级一级至三级中度污染地下水占比为92.5%,整体上水质“三氮”污染较轻。海伦地区“三氮”空间分布整体上呈现出氨氮、硝酸盐氮流域中心区近端含量高、远端含量低的趋势。硝酸盐氮及氨氮超标点主要分布在研究区中部的人类活动密集区域。亚硝酸盐氮在空间分布上沿海伦河流向呈现出北高南低的趋势。③正定矩阵因子分析模型(PMF)源解析结果表明,硝酸盐氮主要来源于生活与工业复合源;亚硝酸盐氮主要来源于自然源;氨氮主要来源于生活与农业复合源。与中南部长三角武进地区太湖平原、西南部成都平原及东南部广花盆地地下水相比,海伦地区氨氮含量偏低,硝酸盐氮均值则均高于中南部地区。“三氮”的源解析结果呼应了东三省尤其是黑龙江部分地区“三氮”含量较高的分布特征。海伦地区地下水“三氮”污染程度整体上相对较轻,人类活动对地下水中“三氮”分布的影响较大。

BACKGROUND:With the increase of population,urbanization development,the large discharge of industrial wastewater and the excessive application of agricultural nitrogen fertilizer,the problem of“three nitrogen”(nitrate nitrogen,ammonia nitrogen,and nitrite nitrogen)pollution in groundwater has become increasingly serious.Due to the slow flow,weak alternation degree and poor self-purification ability,the nitrogen polluted groundwater is difficult to rehabilitate and the repair cost is high.It is of great practical significance to carry out prevention and control from the pollution source.With the concealment,complexity and hysteretic groundwater pollution property,it is difficult to conduct the source analysis of nitrate in groundwater.Positive matrix factorization(PMF)model,as a new type of source analysis model,has more interpretable and clear physical significance in terms of factor load and source factor score.At present,the application of the PMF model in the source analysis of“three nitrogen”in groundwater media is rarely reported,and the research in this field needs to be deepened.Gas-phase molecular absorption spectrometry is a practical analytical method for nitrogen compounds with high accuracy,wide linear range without color and turbidity interference.This method does not require chemical separation,and uses few chemical reagents and innoxious reagents.At present,this method has been widely used in the analysis and determination of water quality,nitrite nitrogen,ammonia nitrogen,nitrate nitrogen,total nitrogen,and other substances.OBJECTIVES:To identify the source and distribution characteristics of the“three nitrogen”in shallow groundwater in the Hailun area.METHODS:(1)Determination of“three nitrogen”and other elements in groundwater samples.With GPS coordinates,the 40 shallow groundwater samples were collected in Helen River Basin and Zaying River Basin.The collection and preservation of groundwater samples were performed in accordance with the environmental standards HJ/T 164-2004,HJ/T 195-2005,HJ/T 197-2005 and the ecological industry standards DZ/T 0064-2021.The quality control of the“three nitrogen”test in groundwater was based on the requirements of the national standard GB/T 14848-2017,the technical requirements for analytical quality control of groundwater pollution investigation(DD 2014-15),and the specification of testing quality management for geological laboratories(DZ/T 0130-2006).Each batch contained twenty samples and the test process of each batch was equipped with laboratory blank,reference materials,laboratory duplicate samples and quality control of external monitoring samples.All of the laboratory blank results were less than 2 times the detection limit of the method.The added standard recovery rate of the sample matrix was between 80%-120%,with the relative deviation(RD)of the laboratory repeat samples under 15%.The qualified rate of external quality control sample was 100%.(2)Analysis of detection data.Statistics and analysis of“three nitrogen”,heavy metal content correlation and principal components in groundwater were carried out using WPS Office 2016 and SPSS 22.0.The spatial distribution map of“three nitrogen”content in groundwater was obtained by CoreDRAW X5.0 software.TheⅢclass water criterion in Standard for Groundwater Quality(GB/T 14848-2017)was used as the criterion for drinking water source and industrial and agricultural water.The Nemerow pollution index was calculated and compared with the corresponding grade standard index.The PMF model was used to identify and quantify the contribution rate of each nitrogen source to comprehensively judge the source of“three nitrogen”.