Heavy metal soil content as an indicator of pollution

ABSTRACT. Two soil sample series were collected from 7 contaminated sites situated along a transect from the pollutant source, Zlatna copper ore-processing plant, and analyzed using different analytical methods. The soils collected in 1998 were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after extraction with DTPA for trace metals and those collected in 1999 were analyzed with flame atomic absorption spectrometry (FAAS) following two acid digestion procedures. The DTPA extraction procedure produced lower results than the acid digestions. Also, the pH values for all samples was measured and the results obtained during autumn compared with those in spring after a long winter with heavy snow falls. The correlation between Cu, Pb, Zn (for samples collected in May 1999) and pH was investigated. The pattern of chemical abundance of contaminants (Cu, Pb, Zn, Fe, Cd and Ni) was determined in soil at 0-50 cm depth. This study indicates that Pb is the most polluting element up to 25 km downwind from Zlatna town