POLLUTION LEVELS AND SPATIAL DISTRIBUTION OF HEAVY METALS IN HOUSE DUST FROM AN INDUSTRIAL AREA IN XI'AN, CENTRAL CHINA

Industrial activities are thought to contribute large amounts of heavy metals to the environment, posing risks to human and ecosystem health. To investigate heavy-metal pollution in a heavy industrial area in Xi'an, house dust samples were collected from households in sixteen residential quarters, and their <63 mu m fractions were analyzed for heavy metals. The results show that Cr, Mn, Co and V in dust are basically unpolluted; whereas Ni, Cu, Zn and Pb are moderately to strongly polluted, mainly caused by industrial emissions in this area. Spatial analysis suggests a relatively high spatial variability of the four polluted metals in house dust, implying that area-source and point-source pollution may occur simultaneously. High pollution levels of heavy metals occur mainly in the southwest, presumably resulting from the influence of emissions of a coal-fired power generation plant. The pollution load index of these eight metals suggests a moderately polluted level in most house dust, implying that heavy-metal pollution related to industrial activities in this area is an important environmental problem and thus should be controlled.