Zhang Renduo, Wood A Lynn, Enfield Carl G, Jeong Seung-Woo
Dep. of Renewable Resources, Univ. of Wyoming, Laramie, WY 82071-3354, USA.
J Environ Qual. 2003 May-Jun;32(3):957-65. doi: 10.2134/jeq2003.9570.
Stochastical analysis was performed to assess the effect of soil spatial variability and heterogeneity on the recovery of denser-than-water nonaqueous phase liquids (DNAPL) during the process of surfactant-enhanced remediation. UTCHEM, a three-dimensional, multicomponent, multiphase, compositional model, was used to simulate water flow and chemical transport processes in heterogeneous soils. Soil spatial variability and heterogeneity were accounted for by considering the soil permeability as a spatial random variable and a geostatistical method was used to generate random distributions of the permeability. The randomly generated permeability fields were incorporated into UTCHEM to simulate DNAPL transport in heterogeneous media and stochastical analysis was conducted based on the simulated results. From the analysis, an exponential relationship between average DNAPL recovery and soil heterogeneity (defined as the standard deviation of log of permeability) was established with a coefficient of determination (r2) of 0.991, which indicated that DNAPL recovery decreased exponentially with increasing soil heterogeneity. Temporal and spatial distributions of relative saturations in the water phase, DNAPL, and microemulsion in heterogeneous soils were compared with those in homogeneous soils and related to soil heterogeneity. Cleanup time and uncertainty to determine DNAPL distributions in heterogeneous soils were also quantified. The study would provide useful information to design strategies for the characterization and remediation of nonaqueous phase liquid-contaminated soils with spatial variability and heterogeneity.
进行了随机分析，以评估土壤空间变异性和非均质性对表面活性剂强化修复过程中比水密度大的非水相液体（DNAPL）回收的影响。使用三维、多组分、多相、组成模型UTCHEM来模拟非均质土壤中的水流和化学物质传输过程。通过将土壤渗透率视为空间随机变量来考虑土壤空间变异性和非均质性，并使用地质统计学方法生成渗透率的随机分布。将随机生成的渗透率场纳入UTCHEM中，以模拟非均质介质中DNAPL的传输，并基于模拟结果进行随机分析。通过分析，建立了平均DNAPL回收率与土壤非均质性（定义为渗透率对数的标准差）之间的指数关系，决定系数（r2）为0.991，这表明DNAPL回收率随土壤非均质性的增加呈指数下降。比较了非均质土壤中水相、DNAPL和微乳液相对饱和度的时空分布与均质土壤中的情况，并与土壤非均质性相关。还对确定非均质土壤中DNAPL分布的清理时间和不确定性进行了量化。该研究将为设计具有空间变异性和非均质性的非水相液体污染土壤的表征和修复策略提供有用信息。
