土壤因子对三氯乙烯土-气分配系数的影响

Impact of soil factors on soil-gas partition coefficient of trichloroethylene

土壤-空气(简称土-气)分配是影响挥发性有机污染物环境归宿的重要环节,是形成呼吸暴露风险的重要过程。以黄土、红土、黑土和砂土4种典型土壤为研究对象,识别了影响三氯乙烯土-气分配的土壤因子,并通过单因素控制批实验定量探究了三氯乙烯在土-气界面的分配行为,构建了三氯乙烯土-气分配系数与土壤因子的定量关系。结果表明,4种典型土壤原样的三氯乙烯土-气分配系数存在显著差异(黑土>红土>砂土>黄土),黑土分配系数的影响因子主要是土壤粒径、含水率、有机质含量,其他3种土壤分配系数的影响因子主要是土壤粒径、含水率。黑土中三氯乙烯的土-气分配系数(K_(SA))与土壤影响因子的关系可定量表示为:K_(SA)=-0.744X_(1)-0.224X_(2)+0.704X_(3);而在砂土中为:K_(SA)=-0.724X_(1)-0.222X_(2);在黄土中为:K_(SA)=-0.291X_(1)-0.268X_(2);在红土中为:K_(SA)=-0.589X_(1)-0.338X_(2)(X_(1)为土壤含水率;X_(2)为粒径;X_(3)为有机质含量)。研究成果有利于深入认识三氯乙烯在我国典型土壤中土-气界面上的分配行为及土壤因子对其产生影响的规律,为土-气分配过程中多因素耦合影响量化和健康风险评估提供理论依据。

[Objective]Soil-air partitioning is a critical process influencing the environmental fate of volatile organic pollutants and a significant contributor to the risk of respiratory exposure.[Methods]Four typical soils-loess,red soil,black soil and sand were used to identify the soil factors affecting the partitioning of trichloroethylene.The partitioning behaviour of trichloroethylene at the soil-atmosphere interface was quantitatively investigated by single-factor controlled batch experiments,and the quantitative relationship between the trichloroethylene soil gas partition coefficient and soil factors was determined.[Results]The results showed significant differences in the soil-gas partition coefficients of the four typical soils(black soil>red soil>sandy soil>loess soil).The main influencing factors for the partition coefficient of black soil were primarily particle size,water content,and organic matter content.Whereas,for the other three soils,the main factors were particle size and water content.[Conclusion]The relationships between the soil gas partition coefficient of TCE and soil factors in black soil can be quantitatively expressed as follows:K SA=-0.744X_(1)-0.224X_(2)+0.704X_(3);sand:K_(SA)=-0.724 X_(1)-0.222X_(2);loess:K SA=-0.291 X_(1)-0.268X_(2);and red soil:K SA=-0.589 X_(1)-0.338X_(2)(X_(1):water content;X_(2):particle size;X_(3):organic matter content).These research aids in a deeper understanding of the distribution behaviour of trichloroethylene at the soil-atmosphere interface in typical soils in China and the influence of soil factors and provide a theoretical basis for the quantification of multifactor coupling effects and health risk assessment in the process of soil gas partitioning.