基于随机模拟的地下水铬污染健康风险动态评价

Dynamic health risk assessment of chromium pollution in groundwater based on the stochastic simulation

在考虑污染场地水文地质参数的空间变异性以及浓度随时间变化的基础上,构建了污染场地健康风险动态评价模型。通过灵敏度分析选取空间变异对数值模拟影响较大的随机参数,运用地下水模拟系统(Groundwater Modeling System,GMS)中的蒙特卡罗随机模拟得到敏感点污染物任意时刻的概率浓度分布特征,进而选取50%和95%分位点分别代表正常情况和最不利情况,预测敏感点健康风险历时变化特征。以石家庄市藁城区某铬化工污染场地为案例进行分析,结果表明,敏感点初始时健康风险值为0.81,在可以接受的风险范围内,污染羽运移1a后,在正常情况和最不利情况下,风险值分别为1.28、1.52,均大于1,即存在非致癌风险,随后逐渐增大,正常情况下,直到第13年才达到风险可接受水平,说明敏感点未来一段时间都存在较大的健康风险,因此需要对污染场地地下水进行修复。

Based on the spatial variability of hydrogeological parameters of a contaminated site and the change of concentration with time,a dynamic evaluation model of health risk assessment was constructed.Through a sensitivity analysis,stochastic parameters that had great influence on numerical simulations by spatial variability were selected.Two percentiles(50% and95%)were selected to represent normal and most unfavorable condition,respectively,to predict the variation in duration of the health risk at the sensitive spot.A chromium-contaminated site in Gaocheng City,China,was selected as a case study.The results showed that the initial health risk value of sensitive spot was 0.81,while removing the contaminant plume after one year,under the normal and the most unfavorable conditions the risk values were 1.28 and 1.52,respectively.Accordingly,there was a gradually increasing non-carcinogenic risk.Under normal conditions,the risk value was not reach to acceptable level until13 th year,indicating the sensitive point.