三氯乙烯在壤土和砂土中迁移规律的模拟研究

Simulation study on transport characteristics of trichloroethy-lene in loam and sandy soil

通过室内土柱模拟试验研究了三氯乙烯(TCE)在壤土和砂土中的迁移行为。结果表明:TCE初始含量为500 mg/L时,TCE在两种土柱中挥发达到气相平衡的时间均为96 h,在壤土和砂土中达到气相平衡的浓度分别为3.2、3.6 mg/L。砂土柱10 cm处在第7 d时达到浓度峰值,最高浓度为139.5 mg/kg,20、30 cm处均在第17 d时达到浓度峰值;壤土柱10 cm处在第17 d时达到浓度峰值,最高浓度为105.9 mg/kg,其余各点的峰值均高于10 cm处。与壤土相比,砂土中的TCE较易挥发、且往下迁移的速度较快。TCE初始含量为125 mg/L时,砂土柱中TCE挥发达到平衡的时间和浓度为120 h和1.3 mg/L,土柱中各取样点浓度变化规律相似,10 cm处在第7 d时达到浓度峰值,最高浓度为72.91 mg/kg。可见,砂土柱中TCE的加入量越大,挥发达到平衡的时间越短,浓度越高。

The transport characteristics of trichloroethylene （TCE） in loam and sandy soil were simulated in indoor soil columns. The results showed that the concentration of TCE reached gas-liquid phase equilibrium in loam and sandy soil columns were 3.2 mg/L and 3.6 mg/L respectively after 96 h of treatment with addition of 500 mg TCE. The TCE concentration at 10 cm spot in sandy soil column reached the highest （139.5 mg/kg） at 7 d, while at 20 cm and 30 cm spots, the concentration peaks were appeared at 17 d. The TCE concentration at 10 em spot in loam column reached the highest （105.9 mg/kg） at 17 d, and the TCE concentration of other spots were all higher than that of 10 cm spot. Compared to loam, the volatilization of TCE in sandy soil was easier, and vertical transport velocity was faster. When the TCE was 125 rag, the concentration of TCE reached gas-liquid phase equilibrium in sandy soil column was 1.3 mg/L after 120 h of treatment, the concentration changes of each sampling points were similar, and the highest concentration was 72.91 mg/kg at 10 cm spot. The results of this experiment illustrated that TCE volatization and downward transportation in sandy soil was easier than that in loamy soil.