Volatile organochlorine behavior and remendiation in subsurface environment

修复地下环境的成本很高，因此修复的成功完全取决于根据污染物在地下环境中的存在形式，选择合适的修复技术来修复地下污染。在此背景下，发展了土壤气体测量作为远程化探的一种选择，以确定污染源以确定打孔地点。迄今为止，日本污染地点采用的修复技术包括土壤排气、地下水开采和土壤挖掘，以物理去除污染物。并将其应用于研究现场，对污染规模的有效性和应用范围进行了评价。结果表明，土壤排气对包气带中挥发性有机氯的去除是非常独特和有效的。在研究现场，还利用了地下水开采。三氯乙烯的两种脱除速率的比较显示…此外，土壤排气的去除速率比地下水开采的去除速率高一个数量级，而且两者的去除速率都随着运行时间的延长而下降。土壤排气的去除速率比地下水开采的去除速率下降得更快，因此，两者的去除速率将趋于一致。穿越时间过后，地下水的开采将克服土壤的排气。在另一个污染现场，挖掘了建筑物下多达1000米^3的污染土壤。作业结束后，地下水开采继续修复含水层，吸收了约20吨三氯乙烯，使地下水浓度降至接近饮用极限。有机氯基本上不溶于水，地下水开采修复受污染的含水层需要相当长的时间。然而，与土壤排气和土壤开挖相比，地下水开采具有去除更多污染物的可能性。研究结果表明，地下水开采是清理受污染含水层的必然技术。较少

The remediation operation for subsurface environment is so costly, therefore, the success of the remediation totally depends on picking up the suitable techniques to repair the subsurface pollution, corresponding to contaminant existing form in subsurface environment. In this context, soil-gas survey as an option of remote geochemical exploration to identify the pollutant source to determine the sites for making boreholes was developed.The remediation technologies employed in the pollution sites in Japan so far are the soil venting, groundwater extraction and soil excavation to physically remove the contaminants. All of them were applied to the study sites to evaluate the effectiveness and the application limit to the pollution scale. The result shows that the soil venting is so unique and useful to remove the volatile organochlorine from vadose zone. In the study sites, the groundwater extraction was also utilized. The comparison of both removal rates for trichloroethylene revealed th … More at the removal rate by soil venting is one order as high as the groundwater extraction, and both removal rates are going down with operation time. The removal rates by soil venting is reducing more quickly than groundwater extraction, therefore, both removal rates are going to meet each other. After the crossing time, groundwater extraction will overcome the soil venting. In another pollution site, the polluted soil of up to 1,000m^3 under the building was excavated. After the operation, the groundwater extraction has continued to repair th aquifer and leads to uptake about twenty tons of trichloroethylene, reducing the groundwater concentration to near the drinkable limit. The organochlorines are basically little soluble in water so that the groundwater extraction needs fairly long time to repair the polluted aquifer. However, the groundwater extraction holds a possibility to remove much more contaminants, compared to the soil venting and soil excavation. The results obtained in this research mention that the groundwater extraction is inevitable technology for cleaning up the polluted aquifer. Less