地学前缘 ›› 2008, Vol. 15 ›› Issue (6): 185-191.

• 论文 • 上一篇    下一篇

1, 2-二氯乙烷和1, 2-二氯丙烷在某污染场地包气带的吸附-解吸特性

  

  1. 中国地质大学(北京) 水资源与环境工程北京市重点实验室, 北京 100083

  • 出版日期:2008-06-20 发布日期:2008-06-20
  • 作者简介:刘玉龙(1971—),男,博士研究生,主要研究地下水污染评价与控制。E-mail: liuyulong98@yahoo.com.cn
  • 基金资助:

    国家自然科学基金项目(40572146)

Adsorption and desorption of 1, 2-dichloroethane and 1, 2-dichloropropane by soils in an unsaturated zone.

  1. Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China

  • Online:2008-06-20 Published:2008-06-20

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摘要：

1, 2-二氯乙烷(1, 2-DCA)和1, 2-二氯丙烷(1, 2-DCP)是某污染场地地下水中检出最高的挥发性有机污染物。文中采用批试验方法,研究污染场地包气带中三种不同深度土壤样品对1, 2-DCA和1, 2-DCP的吸附解吸特性。结果表明:土壤中有机质决定其吸附行为,三种土壤对1, 2-DCA和1, 2-DCP的吸附符合Henry线性等温方程,分配系数在2049～22.43 L·kg-1,1, 2-DCA和1, 2-DCP在三种土壤中分别具有相似的吸附能力;同一土壤中两种目标污染物的吸附能力为Kd(1, 2-DCA)>Kd(1, 2-DCP),但差别不大。1, 2-DCA和1, 2-DCP在三种土壤中的解吸可用Freundlich等温方程拟合,解吸的难易程度与土壤中黏粒含量相关,黏粒含量越高,目标污染物的解吸越困难,第三层(地下4.9～5.1 m)土壤的防污能力较强;两种污染物在三种土壤中的解吸都存在明显的滞后效应,1, 2-DCP的滞后指数比1, 2-DCA的大。

关键词: 包气带;1, 2-二氯乙烷(1，2-DCA);1, 2二氯丙烷(1,2-DCP);吸附;解吸;滞后效应

Abstract:

1, 2Dichloroethane (1, 2DCA) and 1, 2dichloropropane (1, 2DCP) are two kinds of volatile organic compounds (VOCs) which are among the most frequently detected pollutants in groundwater at one contaminated site. In this paper the adsorption and desorption of 1, 2DCA and 1, 2DCP on three soil samples collected from the vadose zone are studied by batch experiments. The results showed that the adsorption isotherms of 1, 2DCA and 1, 2-DCP fit linear Henry isotherm equations well, and the partition coefficient (Kd) ranges  from 2049 to 2243 L·kg-1. The adsorption capacity of 1, 2-DCA and 1, 2-DCP on the three soils are very similar, suggesting that the contents of natural organic matter are responsible for adsorption. For the same soil, the adsorption capacity of 1, 2-DCA is slightly higher than that of 1, 2DCP. Meanwhile, the desorption isotherms of the two pollutants can be described with nonlinear Freundlich isotherm equations. Differences in desorption capacities among the soils are related to the clay contents; the higher clay contents, the lower desorption capacity. The soil within the deepest layer, which is about 4951 m below surface, has the lowest vulnerability to 1, 2-DCA and 1, 2-DCP. Desorption of both chemicals has significantly retarded and the hysteresis indices of 1, 2DCP are higher than those of 1, 2-DCA.

Key words:

unsaturated zone; 1, 2dichloroethane (1, 2DCA); 1, 2dichloropropane (1, 2DCP); adsorption; desorption; hysteresis

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