Spatial distribution and mobility factor of heavy metals in agricultural soil in the vicinity of abandoned lead ore dressing plant, Klity village, Thailand

Abstract

© 2015, Thai Society of Higher Eduation Institutes on Environment. All rights reserved. The concentration and mobility spatial distribution of heavy metals (lead, zinc, cadmium and chromium) including potential ecological risk have been evaluated for the polluted surface soil from mining activities in Upper Klity village, Thailand. Soil samples were collected from the residential and agricultural areas and the area of ore dressing plant. Heavy metals content presented higher in the ore dressing plant area than those found in residential and agricultural areas. Lead was the predominant polluted metal with two hot spots surrounding the ore dressing plant and open pit mine. Mobility distribution of these metals was followed closely with their concentration. Vertical soil profiles proved that mobility factors were only high at the top soil layer and became lower at deeper soil layers for all metals, and the quantities of lead, zinc, cadmium and chromium in both soil profiles can be ordered from large to small as: Reducible, Residual, Oxidizable, Acid extraction and Exchangeable fractions. These results indicated that the contamination was caused by anthropogenic mining activities. Potential Ecological Risk (PER) exhibited a low potential ecological risk with the averages of 3.79 and 81.3 in agricultural and ore dressing plant areas, respectively. However, most individual potential ecological risk values were small and classified as low for all heavy metals. This study recommends that heavy metals were unlikely to cause additional adverse health risk effects in residential and agricultural area. On the other hand, the risk of heavy metals pollution in the ore dressing plant area should be of primary concern.