陕北风沙滩地区包气带抗COD污染的量化研究

Quantitative study on COD pollution of vadose zones in blown-sand regions of North Shanxi

为了研究包气带对COD的净化能力,在榆林煤化工厂厂区及其周边地区选择了4个试验点,采用双环入渗法,人工配置COD溶液进行了垂直入渗试验。分析了试验前中后包气带埋深150 cm以内的土壤中COD的变化情况,并采用回归分析和积分的方法定量研究了包气带对COD的净化能力。研究结果表明:COD极易随水流进入到包气带中,在包气带的吸附作用和微生物的降解作用下,一小部分被吸附在包气带土壤表面或被微生物分解,而大部分则在试验结束20天后通过包气带埋深150 cm的地方,进入到更深层的包气带或是含水层中。4个试验点对COD的截留作用各不相同,以试点4的截留作用最弱。随着COD源源不断的下渗,当包气带达到COD的吸附平衡时,包气带便失去了对COD的截留和保护地下水的作用。

Four sites are selected in Yulin coal chemical plant and its surrounding areas in order to study the purification of COD in vadose zones.The bicyclical infiltration method and the COD are used to perform the field tests.The variations of COD in vadose zones less than the depth 150 cm are quantitatively analyzed by using the regression analysis and the integral method.The results show that the COD can easily flow into the vadose zones with water infiltration.Because of the adsorption of the vadose zone soils and the microbiological degradation,a small portion is adsorbed to the vadose zone soil surface or degraded,but the most transport through the vadose zones with the depth 150 cm and enter into the deeper vadose zones or aquifers after 20 days.The interception of the vadose zone soils in the four sites against the COD vary and the interception in the site four is the strongest.As the steady infiltration with the COD,when the vadose zone soils reach the adsorption equilibrium,the vadose zones will lose its interception of the COD to protect the groundwater.