石油类污染物自然衰减能力现场试验验证研究

在北京地区某加油站开展的前期石油类污染物自然衰减现场试验的基础上,进一步开展了验证试验,结果表明本次试验得到的挥发性有机物(VOCs)变化趋势及O2、CO2含量沿土壤深度分布和前期试验结果呈现相同的规律,说明基于自然衰减法设计实施的加油站现场试验检测分析结果可靠,试验方法具有合理性、可操作性及可重复性.进一步的理论分析对前期试验结果进行了验证,得出以下结论:(1)通过氧平衡和碳平衡计算对加油站土壤内的自然衰减方式进行评价,验证了该加油站地下土壤中实际发生的微生物降解既有需氧降解也有厌氧降解；(2)利用有机物的一级衰减模型对该污染现场土壤中石油类污染物的降解速率和半衰期进行计算表明,2次试验计算得到的石油类污染物的半衰期基本一致,该污染现场石油类污染物的半衰期为50 d左右；(3)在此基础上,对该加油站包气带土壤的自然衰减能力和环境质量进行评价,2次试验结果均表明该污染现场在自然衰减的作用下已经不存在环境风险.

Confirmatory research on the natural attenuation capacity of oil pollutants based on in-situ experiment

A confirmatory in-situ experiment of oil pollutant natural attenuation capacity was carried out to prove the reliability of the field experiments in a representative gas station in Beijing.Both of the concentration of VOCs and profiles of O2,CO2 in the soil presented the same rule as the preliminary experiment.The results show that the primary analysis are reliable and test methods are reasonable,feasible and reproducible for the experiment designed and implemented based on natural attenuation method.Early experimental results were verified by further theoretical analysis,drawing conclusions as followed:(1) the ways of natural attenuation were proved as both aerobic and anaerobic biodegradation via oxygen and carbon equilibrium calculation.(2) The rates of the natural attenuation and half-life of the oil pollutants calculated by the first-order decay model were consistent with previous results.The half-life of petroleum contaminants in contaminated site are about 50 days.(3) Based on the analysis,the capability evaluation of monitored natural attenuation and the environmental assessment of all experiments demonstrated that the environmental risk in this gas station had been eliminated under the influence of the natural attenuation.