引用本文:龙雨,杨兵,秦普丰,刘寒冰,薛南冬,等.土壤包气带含水率对氯代烃垂向迁移影响的模拟研究[J].环境科学研究,2017,30(8):1255-1261.
LONG Yu,YANG Bing,QIN Pufeng,LIU Hanbing,XUE Nandong,et al.Effects of Moisture Content on Vertical Migration of Chlorinated Hydrocarbons in Soil Unsaturated Zone[J].Reserrch of Environmental Science,2017,30(8):1255-1261.]
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土壤包气带含水率对氯代烃垂向迁移影响的模拟研究
龙 雨1,2, 杨 兵2, 秦普丰1, 刘寒冰2, 薛南冬2
1.湖南农业大学资源环境学院, 湖南 长沙 4101282 ;2.中国环境科学研究院, 北京 100012
摘要:
氯代烃类挥发性有机物在土壤包气带中的垂向迁移是该类污染物呼吸暴露风险的重要途径. 为探究氯代烃在土壤包气带中的垂向迁移规律,通过室内土柱模拟试验,研究土壤包气带含水率对不同氯代烃〔TCE(三氯乙烯)、PCE(四氯乙烯)〕气相扩散速率的影响,并通过线性拟合筛选出更准确的气相有效扩散系数预测模型. 结果表明,土壤含水率与氯代烃气相有效扩散系数呈显著负相关〔R=-0.89,P<0.01,n=7(TCE);R=-0.86,P<0.01,n=7(PCE)〕. 随着土壤含水率由0.5%增至40.0%,TCE气相有效扩散系数(DT)由0.035 9 cm2/s降至0.002 5 cm2/s,平衡时间由13 h增至91 h,平衡时气体浓度由4.22 g/m3降至0.31 g/m3;PCE气相有效扩散系数(DP)由0.033 9 cm2/s降至0.001 1 cm2/s,平衡时间由15 h增至103 h,平衡时气体浓度由3.01 g/m3降至0.12 g/m3. 与Penman模型、Marshall模型模拟值相比,Millington-Quirk模型模拟值与氯代烃气相有效扩散系数实测值的拟合程度更好(R>0.95,P<0.01,n=7). 研究显示,土壤包气带含水率的增加对氯代烃气相扩散有明显的抑制作用.
关键词:  含水率  三氯乙烯  四氯乙烯  垂向迁移  气相有效扩散系数  Millington-Quirk模型
DOI:
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基金项目:国家环境保护公益性行业科研专项(20150934);国家重大科研专项(2016YFD0800202)
Effects of Moisture Content on Vertical Migration of Chlorinated Hydrocarbons in Soil Unsaturated Zone
LONG Yu1,2, YANG Bing2, QIN Pufeng1, LIU Hanbing2, XUE Nandong2
1.College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China ;2.Chinese Research Academy of Environmental Sciences, Beijing 100012, China
Abstract:
Abstract: The vertical migration of chlorinated hydrocarbons in soil is an important source of risk of inhalation exposure to volatile organic compounds. Serial soil column experiments were developed to investigate the vertical migration of chlorinated hydrocarbons. The effects of moisture content in the soil unsaturated zone on the diffusion rate of chlorinated hydrocarbons (e.g., trichloroethylene, TCE and tetrachloroethylen, PCE) were studied, and a prediction model of effective vapor diffusion coefficient was optimized by linear fitting. The results showed that moisture content in soil was significantly negatively correlated with the effective vapor diffusion coefficient of chlorinated hydrocarbons (R=-0.89, P<0.01, n=7(TCE); R=-0.86, P<0.01, n=7(PCE)). When the moisture content increased from 0.5% to 40.0%, the effective vapor diffusion coefficient of TCE(DT) decreased from 0.0359 cm2/s to 0.0025 cm2/s, equilibrium time increased from 13 h to 91 h and the equilibrium vapor concentration decreased from 4.22 g/m3 to 0.31 g/m3. When the effective vapor diffusion coefficient of PCE(DP) decreased from 0.0339 cm2/s to 0.0011 cm2/s, equilibrium time increased from 15 h to 103 h and the equilibrium vapor concentration decreased from 3.01 g/m3 to 0.12 g/m3. The effective vapor diffusion coefficient values of chlorinated hydrocarbons were well fitted with the values from the Millington-Quirk model (R>0.95, P<0.01, n=7) compared with the Penman and Marshall Models. The increase of moisture content of the soil unsaturated zone could obviously inhibit the vapor diffusion of chlorinated hydrocarbons.
Key words:  moisture content  TCE  PCE  vertical migration  effective vapor diffusion coefficient  Millington-Quirk model