邻苯二甲酸二甲酯在紫色土中的淋溶释放特征及其影响因素研究

采用土柱淋溶试验方法,研究了模拟江水淋溶下,三峡库区典型土壤-紫色土中的有机污染物邻苯二甲酸二甲酯(DMP)的淋溶释放机制及其影响因素。结果表明,随着淋溶时间的延长,不同DMP含量水平的紫色土中DMP的累积释放量均增加,双常数方程是描述紫色土中DMP淋溶释放动力学的最佳方程;随着紫色土中DMP含量增加,紫色土向模拟江水淋溶释放DMP的累积量越多,但是累积释放率却减小,累积释放率仅0.58%~1.35%,表明紫色土中的DMP不易淋溶释放。离子强度对DMP的释放量影响显著,在试验离子强度范围内,累积释放率总体上较低,介于0.43%~0.74%;试验p H范围内,紫色土中DMP累积释放量、累积释放率与淋滤液p H呈极显著负相关;紫色土中外源有机质的添加显著增加了紫色土对DMP的吸持量,减小了紫色土中DMP的淋溶释放量;当紫色土中表面活性剂十二烷基苯磺酸钠(SDBS)添加量为50 mg/kg时,降低了紫色土中DMP的累积释放量和累积释放率,而当SDBS添加量大于200 mg/kg时,紫色土中DMP的累积释放量和累积释放率反而随着SDBS投加量的增加而增加,并且均高于对照。

Release Leaching Characteristics of Dimethyl Phthalate in Purple Soil and its Influencing Factors

Release leaching characteristics of the organic contaminant Dimethyl Phthalate(DMP) in typical soil-purple soil from the Three Gorges Reservoir and its influencing factors was studied with simulated river water soil column leaching experiment. All of the cumulative release amounts of DMP in the different levels of DMP purple increase with increasing leaching time, and the double constant equation best describe the release kinetics of DMP in the soil. The higher the DMP content in the purple, the higher the cumulative release amount of DMP releases into the leaching solution, but the cumulative release rate decreases. The cumulative release rates of DMP were only in the range of 1.35%-0.58%, indicating that DMP in the contaminated purple is not easy to be released. The ionic strength in leaching solution had significant effects on release of DMP. Within the range of ionic strength of the test range, the cumulative release rates of DMP were low on the while, only in the range of 0.43%-0.74%.Within the range of pH, both of cumulative release amount and cumulative release rate of DMP in the soil have negative correlation with initial leaching solution pH. The addition of exogenous organic matter(OM) in purple soil increases the adsorption amount of DMP by purple soil,and decreases the release amount of DMP in the contaminated purple. The addition of surfactant sodium dodecyl benzene sulfonic acid(SDBS) in purple soil also has significant effects on the release of DMP. It decreases the release amount and release rate of DMP in the purple, when addition amount of SDBS is 50 mg/kg.However, the release amounts and release rates of DMP increase with increasing addition amounts of SDBS, when the addition amounts of SDBS are higher than 200 mg/kg.Moreover, both of the release amounts and release rates of DMP are higher than that of control group.