陕北风沙滩地区包气带抗污能力试验研究

In situ experiment of the pollution resistance of vadose zone in the blown-sand region in northern Shaanxi of China

为了研究陕北风沙滩地区包气带风积沙的抗污能力,在榆林煤化工厂厂区及其周边地区选择4个试验点,采用双环入渗法,选择渣场炉渣浸出液(Cd、Cr、Cu、Mn、Ni和Pb重金属污染物溶液)进行渣场污水入渗试验,采用人工配置污染物溶液(COD、氨氮、F、石油类和挥发酚)进行了配污试点试验。渣场污水入渗试验过程中,由于水流的冲刷作用,剖面上大部分污染物的含量都小于入渗前的含量;而渗后样的测定结果则表明包气带风积沙对污水中Cr、Cu、Mn、Ni和Pb的净化能力较强。配污试点试验表明包气带对无机污染物的阻滞作用会延缓其对地下水的污染,石油类在包气带中的运移速度缓慢,难以在水流的作用下到达含水层,而COD容易造成地下水污染,挥发酚对含水层的污染能力要小于COD。应考虑采取适当方式降低地下水位,增大包气带厚度,以加强包气带对地下水的保护能力。

A series of in situ experiments were carried out in the blown-sand region of northern Shaanxi to investigate the pollution resistance of the vadose zone.The field experiments were performed with the bicyclical infiltration method at four selected sites of the Yulin Coal Chemical plant and its surrounding areas.The leaching solution（Cd,Cr,Cu,Mn,Ni and Pb solutions） of slag and some manual configuration solutions（COD,ammonia nitrogen,F,petroleum,and volatile phenol） were selected for the field experiments.For the selected heavy metals,most of the contaminants in the profile are less than before infiltration.The soil analysis after infiltration shows that the Aeolian sands composing the vadose zone are of high purification ability for Cr,Cu,Mn,Ni,and Pb.The vadose zone will block and delay the inorganic pollutants from polluting the groundwater.The oil cannot easily transport through the vadose zone and reach the aquifers,while the COD is easy to transport through the vadose zone and leads to groundwater pollution.The abilities of volatile phenol of polluting groundwater are weaker than that of COD.The manager of the plant should consider to lower groundwater levels artificially to increase the thickness of the vadose zone for groundwater protection.