北京密怀顺地区地下水污染风险评价方法探究

Study on risk assessment method of groundwater pollution in Beijing Mi-HuaiShun area

地下水污染风险评价通常由地下水污染荷载评价与固有脆弱性评价叠加得到,但叠加方法众多,且缺乏各个方法之间的对比验证.本研究选取北京密怀顺地区作为示例,利用GIS平台进行构图表征,对比了相加法、矩阵法和计算法3种地下水污染风险的叠加方法,并利用硝酸盐浓度等级与地下水污染风险评价等级的差值和Spearman等级相关因子两种指标,对以上3种叠加方法所获得的地下水污染风险评价结果进行验证,旨在探究最优的地下水污染风险方法.结果表明,从硝酸盐浓度等级与地下水污染风险评价等级差值为0的区域占比来看,矩阵法(51.12%)>相加法(32.29%)>计算法(21.71%);从Spearman等级相关因子来看,矩阵法(ρ=93.19%)>计算法(ρ=90.33%)>相加法(ρ=89.23%).故研究区内地下水污染风险评价采用矩阵法得到的结果更准确、更可行,其评价结果比较真实地反映了北京密怀顺水源地污染风险状况,对城市规划建设和地下水资源的可持续利用具有指导意义.

Groundwater pollution risk assessment is usually obtained by adding groundwater pollution load assessment and inherent vulnerability,but there are many superposition methods,but there is a lack of comparison and verification between various methods. This study selects the Beijing Mi-Huai-Shun area as an example,uses the GIS platform for the composition characterization,and compares the three groundwater pollution risk superposition methods：additive method,matrix method,and calculation method. And using the difference between the nitrate concentration level and groundwater pollution risk assessment level and the spearman rank correlation factor. The groundwater pollution risk assessment results obtained by the above three superposition methods are verified to explore the optimal groundwater pollution risk method. The results showed that from the ratio of nitrate concentration class and groundwater pollution risk assessment grade difference to 0,matrix method（ 51. 12%） 〉additive method（ 32. 29%） 〉calculation method（ 21. 71%）.From the Spearman rank correlation factor,matrix method（ ρ = 93.19%） calculation method（ ρ = 90.33%） 〉additive method（ ρ = 89.23%）. Therefore,the results of the matrix method used in the risk assessment of groundwater pollution in the study area are more accurate and feasible,and their evaluation results truly reflect the pollution risk status of the Mi-Huai-Shun water source in Beijing. It has guiding significance for urban planning and construction and sustainable use of groundwater resources.