奎屯河流域高砷地下水砷含量空间分布异常的影响因素

Factors Influencing the Abnormal Spatial Distribution of Arsenic Content in Groundwater in Kuitun River Basin

新疆奎屯河流域是我国地下水受砷影响较为严重的一个区域,为了查明该区地下水中砷的空间分布特征及砷含量异常的原因,于2017年在研究区采集地表水、潜水和承压水样品51组,2019年在典型高砷区采集承压水样品16组,2个钻孔沉积物样品45组。通过地下水及沉积物的测试分析、数理统计等方法对研究区高砷地下水的空间分布特征及砷含量异常的影响因素进行分析,结果表明:水平方向上,砷浓度从南向北逐渐升高,与海拔呈负相关;垂直方向上,高砷地下水主要分布在>80 m深层含水层中。地下水中砷含量空间分布与古地理环境、地形地貌、封闭的地质、干旱的气候等自然地理条件有关;地下水砷含量分布异常主要有3个原因,即高pH值、高HCO_(3)^(-)、低Eh的地下水环境,沉积物的粒径、色度、局部沉积环境,施用含砷农药、化肥的人为活动。研究成果可为奎屯河流域地下水砷富集机制的研究奠定基础。

Kuitun River Basin in Xinjiang is an area where groundwater is seriously affected by arsenic.To find out the spatial distribution characteristics of arsenic in groundwater and the causes of abnormal arsenic content in the area,we collected 51 groups of surface water,underflow and confined groundwater samples in the study area in 2017,16 groups of confined groundwater samples and 45 groups of borehole sediment samples in typical high-arsenic-content area in 2019.By test analysis and mathematical statistical analysis on the groundwater and sediment samples,we obtained the spatial distribution characteristics of high-arsenic groundwater in the study area and the influencing factors of abnormal arsenic content.Results manifest that in horizontal direction,arsenic concentration is correlated negatively with topography,increasing gradually from south to north;in vertical direction,high-arsenic groundwater is mainly distributed in aquifers greater than 80 meters deep.The spatial distribution of arsenic content in groundwater is related to natural geographical conditions such as paleogeographic environment,topography,closed geology,and arid climate.The causes of abnormal arsenic content in groundwater are concluded as:groundwater environment with high pH value,high HCO^(-)_(3) concentration and low Eh;particle size,chromaticity,and local deposition environment of sediments;and human activities using arsenic-containing pesticides and fertilizers.