典型潜水层苯系物污染羽稳定性主控因子及统计建模

Primary Controlling Factors and Statistical Modeling of Plume Stability for BTEX in Typical Phreatic Aquifers

场地或区域地下水污染羽能否达到稳定及其稳定性特征直接决定自然衰减修复的可行性.本文构建了从上到下依次为潜水层、弱透水层、承压层的典型含水结构,模拟量化潜水层恒定源地下水污染羽迁移扩散,以污染羽稳定面积、稳定浓度和稳定所需时间为特征因子,充分考虑可能影响污染羽迁移扩散的水文地质和水化学参数.首先通过敏感性分析筛选出较敏感因子,然后利用正交试验进行主控因子识别,最后采用多元回归模型构建特征因子与主控因子的定量统计关系.结果表明,对污染羽特征因子具有广泛影响的主控因子为降解系数、弥散度、渗流速度和源浓度,特征因子与主控因子之间具有良好的统计关系,根据实际情况可选用不同主控因子数量表征的统计模型对特征因子进行预测,这将为基于自然衰减修复的场地或区域地下水污染优化控制与高效修复提供重要依据.

Whether the groundwater pollution plume of a contaminated site or a regional area can be stabilized and the stability characteristics of the plume would directly determine the feasibility of the natural attenuation restoration.In this study,a typical aquifer structure with a phreatic aquifer,an impermeable aquifer,and a confined aquifer from top to bottom was constructed to simulate the migration and diffusion of the constant source pollution plume of phreatic water.The stable area,stable concentration and starting stable time of the groundwater pollution plume were taken as characteristic variables.Firstly,the sensitive factors were identified from numerous influence factors through sensitivity analysis method.Secondly,orthogonal experiments were used to identify the main controlling factors.Finally,the multiple regression model was used to construct the quantitative statistical relationship for characteristic variables.The results show that the common primary controlling factors are the degradation coefficient,dispersivity,seepage velocity and the source concentration.Moreover,there are adequate statistical relationships between the characteristic variables and the primary controlling factors.The statistical models characterized by different numbers of factors can be used to predict the characteristic variables.This study would provide an important basis for optimization of the site pollution control and effective remediation which are based on natural attenuation remediation.