土壤类型对苯并[a]芘污染土壤氧化修复的影响研究

Effects of soil types on oxidative restoration of benzopyrene contaminated soil

针对不同土壤类型对化学氧化修复效果的影响问题,选用我国3种典型土壤模拟制备苯并[a]芘污染土壤,采用活化过硫酸钠在反应条件为水土比2∶1、活化剂加量10%、反应温度25℃下对其开展化学氧化实验。探究了3种土壤类型及其各项性质对苯并[a]芘负载和氧化效果的影响。研究表明:①3种土壤类型对苯并[a]芘的负载能力中黄砂土最差、紫色土次之、黑土最优,经活化过硫酸钠氧化后土壤中苯并[a]芘降解率黑土最低、紫色土次之、黄砂土最高;②土壤中阳离子交换量、有机质含量和比表面积与苯并[a]芘负载率成正相关,pH值与苯并[a]芘负载率成负相关,相关系数的平方均大于0.92,其中有机质含量及其比表面积对苯并[a]芘负载能力影响较大;③土壤中有机质含量对其氧化效果影响最大,有机质含量越高,其苯并[a]芘降解率越低。研究结果对于不同地区苯并[a]芘污染土壤修复技术方案的设计具有指导意义。

In view of the effect of different soil types on chemical oxidation remediation,three typical soils in China were used to simulate the benzopyrene-contaminated soil in this study.Activated sodium persulfate was dosed to carry out the chemical oxidation experiments under the reaction conditions of soil/water ratio at 2∶1,activator addition at 10%and reaction temperature at 25℃.The effects of three soil types and their properties on the loading and oxidation of benzopyrene were investigated.The results showed that:(1)the loading capacity of the three soil types could be ranked as yellow sandy soil<purple soil<black soil and the order of the degradation rate were just the opposite;(2)cation exchange capacity,organic matter content and specific surface area in soil were positively correlated with benzopyrene loading rate while pH value was negatively correlated(the value of the coefficient of determination was greater than 0.92).Among the above parameteres,the contents of organic matter and its specific surface area have a great influence on the loading capacity of benzopyrene;(3)the contents of organic matter in soil were closely related with the degradation rate,showing that higher contents of organic matter would lead to lower degradation rate of benzopyrene.This study would provide a guidance for the design of remidiation process for benzopyrene-contaminated soil in different regions.