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

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.