Adhikari K, Pal S, Chakraborty B, Mukherjee S N, Gangopadhyay A
Department of Earth and Environmental Studies, National Institute of Technology, Durgapur, India,
Environ Monit Assess. 2014 Oct;186(10):6417-32. doi: 10.1007/s10661-014-3864-9. Epub 2014 Jun 15.
The movement of contaminants through soil imparts a variety of geo-environmental problem inclusive of lithospheric pollution. Near-surface aquifers are often vulnerable to contamination from surface source if overlying soil possesses poor resilience or contaminant attenuation capacity. The prediction of contaminant transport through soil is urged to protect groundwater from sources of pollutants. Using field simulation through column experiments and mathematical modeling like HYDRUS-1D, assessment of soil resilience and movement of contaminants through the subsurface to reach aquifers can be predicted. An outfall site of effluents of a coke oven plant comprising of alarming concentration of phenol (4-12.2 mg/L) have been considered for studying groundwater condition and quality, in situ soil characterization, and effluent characterization. Hydrogeological feature suggests the presence of near-surface aquifers at the effluent discharge site. Analysis of groundwater of nearby locality reveals the phenol concentration (0.11-0.75 mg/L) exceeded the prescribed limit of WHO specification (0.002 mg/L). The in situ soil, used in column experiment, possess higher saturated hydraulic conductivity (KS = 5.25 × 10(-4) cm/s). The soil containing 47 % silt, 11 % clay, and 1.54% organic carbon content was found to be a poor absorber of phenol (24 mg/kg). The linear phenol adsorption isotherm model showed the best fit (R(2) = 0.977, RMSE = 1.057) to the test results. Column experiments revealed that the phenol removal percent and the length of the mass transfer zone increased with increasing bed heights. The overall phenol adsorption efficiency was found to be 42-49%. Breakthrough curves (BTCs) predicted by HYDRUS-1D model appears to be close fitting with the BTCs derived from the column experiments. The phenol BTC predicted by the HYDRUS-1D model for 1.2 m depth subsurface soil, i.e., up to the depth of groundwater in the study area, showed that the exhaustion point was reached within 12 days of elapsed time. This clearly demonstrated poor attenuation capacity of the soil to retard migration of phenol to the groundwater from the surface outfall site. Suitable liner, based on these data, may be designed to inhibit subsurface transport of phenol and thereby to protect precious groundwater from contamination.
污染物在土壤中的运移会引发各种地质环境问题，包括岩石圈污染。如果上覆土壤的恢复能力或污染物衰减能力较差，近地表含水层往往容易受到地表源的污染。为保护地下水免受污染物源的影响，迫切需要预测污染物在土壤中的运移情况。通过柱实验进行现场模拟，并使用如HYDRUS - 1D这样的数学模型，可以预测土壤的恢复能力以及污染物通过地下层到达含水层的运移情况。为研究地下水状况和水质、原位土壤特性及废水特性，选取了一个焦炉厂废水排放口，其苯酚浓度令人担忧（4 - 12.2毫克/升）。水文地质特征表明在废水排放地点存在近地表含水层。对附近地区地下水的分析显示，苯酚浓度（0.11 - 0.75毫克/升）超过了世界卫生组织规定的限值（0.002毫克/升）。柱实验中使用的原位土壤具有较高的饱和水力传导率（KS = 5.25×10(-4)厘米/秒）。发现含有47%粉砂、11%黏土和1.54%有机碳含量的土壤对苯酚（24毫克/千克）的吸附能力较差。线性苯酚吸附等温线模型对测试结果显示出最佳拟合（R(2)=0.977，RMSE = 1.057）。柱实验表明，苯酚去除率和传质区长度随床层高度增加而增加。总体苯酚吸附效率为42 - 49%。HYDRUS - 1D模型预测的突破曲线（BTCs）似乎与柱实验得出的BTCs拟合度较高。HYDRUS - 1D模型针对1.2米深度的地下土壤（即研究区域内地下水的深度）预测的苯酚BTC显示出，在经过12天的时间内达到了耗尽点。这清楚地表明土壤阻止苯酚从地表排放口向地下水迁移的衰减能力较差。基于这些数据，可以设计合适的衬层来抑制苯酚的地下运移，从而保护珍贵的地下水免受污染。
