| Along with the acceleration of the process of industrialization,quickly increasing amount of hazardous wastes were generated. Because of the serious harmfulness and long-term latent dangers, the weak management of the dangerous wastes disposal site, Groundwater environment may be easily polluted. Vadose zone soil layer is natural barriers to ground water system. Studies of the behavior characteristics of these pollutants are of great theoretic meaning and the practical value to the reveals of the polluting mechanism and the adoption of pollution-prevention measures.In this study arsenic is the specific pollutant. Through the static adsorption and dynamic soil column experiments, studies the characteristic of adsorption-desorption and the laws of migration and transformation of arsenic pollutants in the vadose zone. come to the following conclusion:（1） Dosage of Adsorbent affected the adsorption rate of arsenic, adsorption rate of arsenic increased obviously with increase of the amount of the dosage of Adsorbent. In order to gain better adsorption isotherms fitting effects, the quality fraction of water vs. soil（mL/g）in the adsorption experiment was let be 20.（2） Soil had adsorption and purification capacities to arsenic. In the absorption reaction, adsorption of arsenic increased and get saturated over time. adsorption processcan be classified as fast absorption stage and slow absorption stage. equilibrium adsorption concentration of arsenic is 16h.（3） The adsorption of arsenic can be fitted with Langmuir, Freundlich equations and linear isothermal Adsorption equation. The process of isothermal Adsorption is consistent with Langmuir, Freundlich equations, and the correlation coefficients were significant or extremely significant. When the initial concentration of arsenic was at a low level （less than 10mg/L）, The process of Adsorption was basically consistent with linear adsorption equation.（4） Desorption experiment indicated that part of the arsenic adsorbed in the soil will be desorbed. The adsorbed Arsenic desorbed less readily, and the amount of the desorption increased with the increase of the amount of the adsorption.（5） Along with the increase of the depth of the vadose zone soil layer, the migration and transformation of arsenic becomes slow. This reflects that vadose zone may delay the migration and transformation of heavy metal.The migrating form of As（Ⅴ） is HAsO42-, the migration rate of arsenic in the soil B is a bit larger than in the soil A. When chromic（Ⅵ） and arsenic（Ⅴ） coexist the migration rate of them are less than that arsenic（Ⅴ） exists alone, indicating that chromic（Ⅵ） affects the migration and transformation of arsenic in the vadose zone. |
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