【摘要】 河套平原是我国地方性砷中毒最为严重的地区之一。基于河套平原浅层地下水的砷含量数据,利用地统计学中半变异函数分析法,对地下水砷含量的空间分布及其异质性特征进行了分析,并探讨其空间变异性的影响因素。结果显示,河套平原地下水砷含量整体上呈由南向北递增的趋势,在假设各向同性条件下,砷含量残差项的空间分布符合纯块金效应模型,在所测尺度上(2～4 km)为随机分布,不存在空间自相关性,短距离内变异较大;地下水砷含量的分维数较大(D=1.999),进一步说明该尺度上变异显著。地下水砷含量与沉积物中有机质关系密切。晚第四纪以来,河套平原北部山区的新构造运动和盆地沉积环境变迁形成多种成因、形态复杂的沉积相,导致有机质埋藏条件的高度空间变异性,进而导致地下水砷含量的高度空间变异。河套平原缓慢的地下水径流条件有利于砷元素空间变异性的维持。河套地区地下水砷的空间异质性研究,对有效预测未知地区饮水型砷暴露潜在风险、精准防控地方病和保障供水安全具有重要的科学意义。更多还原

【Abstract】 Hetao Plain is one of the most serious area of local arsenic poisoning in China.Based on shallow groundwater arsenic samples,the paper used the semivariogram to reveal the spatial distribution and heterogeneity of groundwater arsenic concentration,and further discussed the influencing factors.The results show that the arsenic concentration in groundwater generally increases from south to north in the Hetao Plain.The residual groundwater arsenic concentration is fitted to the pure nugget effect model under the assumption of isotropic conditions,which means it is random on the measured scale,so there is no spatial autocorrelation and the variance is great in short distances.The fractal dimension value is large(D=1.999),further indicating the distinct variation of groundwater arsenic concentration within the measured scale.Groundwater arsenic is closely related to organic matters in sediments.Since the Late Quaternary,the tectonic movements of the northern mountains and changes in the sedimentary environment of the basin has caused multiple sedimentary facies,resulting in a high degree of spatial variability in burial conditions of organic matters.The high spatial variability of organic matters characteristics further leads to high spatial variability of groundwater arsenic concentration.The slow groundwater flow plays an important role in maintaining this pattern.This article focuses on the spatial heterogeneity of groundwater arsenic in the Hetao area,which has scientific significance for effectively predicting the potential risk of arsenic exposure in drinking water in unknown areas,accurately preventing endemic diseases and ensuring water supply safety.更多还原