华北典型丘陵地区地下水水质特征及污染成因分析—以河南省安阳市龙安区为例

为探明华北典型丘陵地区——安阳市龙安区的地下水水质状况，共检测了龙安区内127个监测井的24项水质指标，开展区域地下水水质特征及污染成因研究；在水化学统计和水质评价的基础上，应用反距离权重空间插值法对污染物进行空间分布特征解析，并通过主成分分析法识别污染源。结果表明：龙安区浅层地下水化学类型多为HCO₃-Ca型，区域内93.0%的地下水样品中NO₃ ⁻浓度超过GB/T 14848—2017《地下水质量标准》中Ⅲ类标准限值，最大超标倍数为47.1倍。单因子污染指数评价结果显示，研究区地下水样品中NO₃ ⁻污染指数最大值为48.10，其中27%的样品处于较重污染状态，19%处于严重至极重污染状态；SO₄ ²⁻处于中度污染状态，Cl⁻、NH₄ ⁺、F⁻处于轻度污染状态。内梅罗综合污染指数评价结果显示，研究区地下水综合污染指数为0.01~34.69，地下水水质整体处于良好水平，但有4%的样品处于极差状态，主要分布于研究区中部。NO₃ ⁻、NH₄ ⁺、SO₄ ²⁻、Cl⁻浓度高值区主要分布于区域中部，且呈现中部高、东西低的分布特征；F⁻浓度高值区分布于地下水滞留区，且呈现西低东高的分布特征。污染成因分析结果表明，研究区地下水水质状况主要受区域水文地质条件、地下水地球化学特征和农业面源污染影响。

Groundwater quality characteristics and pollution causes in typical hilly areas of North China: the case of Longan District,Anyang City,Henan Province

In order to ascertain the groundwater quality in Longan District, Anyang City, a typical hilly area in North China, the data of 24 water quality indicators from 127 monitored well samples were obtained, and the groundwater quality characteristics and pollution causes were analyzed. On the basis of hydrochemical statistics and water quality evaluation, the inverse distance weighting (IDW) spatial interpolation method was used to analyze the spatial distribution of different pollutants, and the principal component analysis was used to identify pollution sources. The results showed that HCO3-Ca type was the typical chemical type of shallow groundwater in Longan District. The NO3 − concentration at 93.0% of samples exceeded the class Ⅲ standard defined in Standard for Groundwater Quantity (GB/T 14848-2017), whose maximum exceeding multiples was 47.1. The single factor evaluation showed that the NO3 − pollution index of groundwater monitoring well samples in Longan District reached a maximum value of 48.10, among which 27% were heavy pollution level, and 19% were serious to extremely heavy pollution levels. The concentration of SO4 2− reached moderate pollution level, while Cl−, NH4 +, and F− reached mild pollution level. Nemero comprehensive evaluation results showed that the comprehensive groundwater pollution index was between 0.01 and 34.69, and the groundwater quality was generally at good condition. Among them, 4% of the monitored well samples were at extremely poor pollution level, which were mainly distributed in the middle of Longan District. The highest concentrations of NO3 −, NH4 +, SO4 2−, Cl− were mainly located in the middle, presenting the spatial distribution characteristics of higher concentration in the middle than that in the east and west. The concentration of F− was higher in the east and lower in the west, and the highest was mainly distributed in the groundwater retention area. Source analysis showed that the groundwater quality was mainly affected by regional geohydrologic conditions, groundwater geochemical characteristics, and agricultural non-point source pollution.