安全填埋场地下水环境影响评价情景优化设置

摘要

在安全填埋场的地下水环境影响评价中，污染途径、边界条件、控制方程等均存在不确定性。本文首先对这些造成环境影响评价结果不确定性的来源进行了定性识别。随后以某安全填埋场为例，采用多参数序列表达不确定性来源及程度，通过构建多套模拟情景，采用MODFLOW和MT3DMS进行数值模拟。计算结果表明：对以垂向运动为主的地下水系统，丰、平、枯等地下水流场对地下水中污染物的浓度增量、空间分布范围影响较小，地下水流场情景设置可简化，仅设丰、平两组；污染负荷是控制地下水污染物浓度的关键因素，其中地下水中有机物受污染范围由渗滤液负荷范围决定，且受污染物吸附-降解特性等反应项参数影响，渗滤液中重金属的影响范围由水力弥散度等弥散项参数决定。%The EIA of secure landfill is confronted with uncertainties caused by pollution way,boundarycon-ditionand controlling equation. With the secure landfilllocated in Hangzhou Bay as an example, this paper established several models with inputparameters expressing the source and degree of uncertainties. MOD-FLOW and MT3DMS were used for numerically solving the models. In the place where the groundwater flow is vertical-dominated, flow fieldscenariosaffect pollutant concentrationsin the groundwater and areas im-pacted by the landfill to some degree. Therefore, flow fieldscenarios of such landfill EIA could be simpli-fied into two scenarios:high flow year and normal year.The pollutant concentration in the groundwater is up to the leachateload of the landfill. Meanwhile,the organic matter’s concentration is influenced by adsorp-tion reaction items, while the heavy metal’sconcentration is affected by hydraulic dispersion parameters sig-nificantly.