基于空间分析构建环境背景值—以宿州市城区浅层地下水Cu含量为例

Establishment of the Environmental Background Based on Spatial Analysis—A Case Study of Cu in the Groundwater of the Urban Area of Suzhou

摘要: 环境背景值对于区域环境管理意义重大。本研究以宿州市城区浅层地下水为例，在系统采样并测试其Cu元素含量的基础上，结合数理统计和空间分析方法构建了其环境背景值。结果表明，地下水中的Cu元素含量较低，所有样品均达到I、II类水质标准。但其变异系数和正态分布检验结果表明依然可能存在人为影响，且从Cu含量的空间分布所发现的高含量集中区与人流和交通密集区的一致性也可以证明这一点。基于箱线图方法，在剔除掉异常值后计算出的环境背景值为1.68~11.9 μg/L，而利用空间分布的方法(数据先进行Box-Cox转换)，在剔除掉异常值后计算出的环境背景值为0~22.1 μg/L。虽然存在一定差距，但二者在理论基础和实用性上存在区别，前者基于环境背景值符合正态分布的假设，而后者则不需要基于这一点。

Abstract: Environmental background is important for the local environmental management. In this study, the groundwater in the urban area of Suzhou has been taken as research object, and the environmental background of Cu has been established through the statistical and spatial methods, based on the analyzing of Cu contents in the systematically collected water samples. The results suggested that the Cu concentrations in the water were low, and all of the samples can meet the requirement of the class I and II water quality. However, the coefficient of variation and the result of normal distribution test indicated the anthropogenic influence, which was further demonstrated by the consistent of the distributions of high Cu areas and the areas with high density of people and transportation. Based on the box plot, the environmental background was calculated to be 1.68 - 11.9 μg/L after outlier removal, whereas it was calculated to be 0 - 22.1 μg/L with spatial analysis (all of the data was firstly transformed by Box-Cox). The results were different because they based on different hypothesis, the former based on the normal distribution whereas the latter did not.