德阳市平原区浅层地下水水化学特征与健康风险评价

Hydrochemical Characteristics and Health Risk Assessment of Shallow Groundwater in the Plain Zone of Deyang City

地下水是德阳市的重要供水水源,了解其水化学特征及生态风险状况对可持续发展至关重要.以德阳市平原区为研究对象,采集78个地下水样,分析其水化学特征及其影响因素,运用绝对主成分-多元线性回归模型(APCS-MLR)进行水化学组分来源解析,并综合运用熵权水质指数(EWQI)和人类健康风险评价模型(HHRA)进行地下水水质及健康风险评价.结果表明,地下水中Ca^(2+)、HCO_(3)^(-)、Mn^(2+)和TFe浓度均值超过国家Ⅲ类水质标准;Na^(+)、K^(+)、Cl^(-)、NO_(3)^(-)、Mn^(2+)和TFe变异系数介于1.11~3.72,含量起伏变化大,局部富集程度高;区内地下水化学类型以HCO_(3)·SO_(4)-Ca、HCO_(3)-Ca·Mg、HCO_(3)·SO_(4)-Ca·Mg和HCO_(3)-Ca型为主,分别占比33.33%、25.64%、19.23%和14.10%.APCS-MLR模型源解析结果表明,地下水水化学组分主要来源为:水岩作用源(32.87%)、农业活动源(12.75%)、生活污水和工业废水排放源(12.40%)、原生地质环境和水岩作用复合源(9.86%)、农业与工业复合源(9.44%)和未识别源(22.69%).熵权水质指数(EWQI)结果显示,地下水质量Ⅰ级和Ⅱ级占比分别为6.41%和74.36%,达到优良和良好程度;地下水质量为Ⅲ级占比11.54%,质量中等;地下水质量为Ⅳ级和Ⅴ级占比分别为6.41%和1.28%,地下水质量差或极差;影响地下水水质等级的主要指标依次为:TFe>Ca^(2+)>Mn^(2+)>HCO_(3)^(-).HHRA模型结果显示区内潜在非致癌风险较低,均未超过1;与皮肤接触相比,直接摄入是这些指标危害人类的主要途径;在相同环境下儿童比成人暴露更容易受到伤害.整体而言,区内地下水水质状况良好,研究区东南部存在一定的潜在风险,在地下水资源利用中应加强对该地区的地下水资源管理和污染防治.

Taking the plain area of Deyang City as the research object,78 groundwater samples were collected to analyze their hydrochemical characteristics and influencing factors.The absolute principal component-multiple linear regression model(APCS-MLR)was used to analyze the sources of hydrochemical components,the entropy-weight water quality index(EWQI)was used to evaluate groundwater quality,and the human health risk assessment model(HHRA)was used to evaluate health risk.The results showed that the average concentration values of Ca^(2+),HCO_(3)^(−),Mn^(2+),and TFe in groundwater exceeded the national grade groundwater quality standards of Class III.The variation coefficients of Na^(+),K^(+),Cl^(−),NO_(3)−,Mn^(2+),and TFe ranged from 1.11 to 3.72,with large fluctuations in content and a high degree of local enrichment.The chemical types of groundwater in the area were dominated by HCO_(3)·SO_(4)-Ca,HCO_(3)-Ca·Mg,HCO_(3)·SO_(4)-Ca·Mg,and HCO_(3)-Ca,accounting for 33.33%,25.64%,19.23%,and 14.10%,respectively.The source apportionment results of the APCS-MLR model showed that the main sources of hydrochemical components in groundwater were water-rock interaction sources(32.87%),agricultural activities sources(12.75%),domestic sewage and industrial wastewater discharge sources(12.40%),the mixed source of primary geological environment and waterrock interaction(9.86%),mixed agricultural and industrial sources(9.44%),and unidentified sources(22.69%).The results of the entropy-weight water quality index(EWQI)showed that the groundwater quality of GradeⅠand GradeⅡaccounted for 6.41%and 74.36%,respectively,which reached the excellent and good degrees.The groundwater quality of GradeⅢaccounted for 11.54%and reached medium degree.The groundwater quality of GradeⅣand GradeⅤaccounted for 6.41%and 1.28%,respectively,indicating poor or extremely poor groundwater quality.The main indexes affecting groundwater quality grade were:TFe>Ca^(2+)>Mn^(2+)>HCO_(3)^(−).The HHRA model results showed that the potential non-carcinogenic risk in the region was low and did not exceed 1.Compared with skin contact,these indicators mainly harmed humans through direct ingestion.Children were more vulnerable to exposure than adults in the same environment.Overall,the groundwater quality in the area was good,and there was a certain potential risk in the southeast of the study area.Thus,the resource management and pollution prevention of local groundwater should be strengthened in future water resource utilization.