Heavy Metal Soil Content as an Indicator of Pollution

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. INTRODUCTION Atmospheric deposits and the disposal of a variety of wastes on land have recently been found to increase a range of biologically important metals in soils, sometimes to harmful levels [1]. Soil acts as a buffer by controlling the bioavailability and transport of toxic substances in the environment. Many contaminants are thus immobilised by soil, and the risk to ecosystem health is therefore reduced. The concentration of heavy metals is associated with biological and geological cycles [2]. The main environmental damages in the area of Zlatna (Romania) town are caused by mining and mineral processing. Metal contamination from minerals processing of Zlatna town has lead to environmental degradation over a wide area around smelter emissions. Gaseous emissions (SO2, NOx) and fall-out of particles enriched in Pb, Zn, Cu and Cd from the 1 Department of Chemistry, Babes-Bolyai University, Cluj-Napoca, Romania 2 Department of Mineralogy, The Natural History Museum, London, UK 3 Department of Geology, Babes-Bolyai University, Cluj-Napoca, Romania 4 Department of Biology, Babes-Bolyai University, Cluj-Napoca, Romania 5 Department of Botany, The Natural History Museum, London, UK