ANALYSIS OF CHEMICAL FRACTIONS AND EVALUATION OF COPPER (Cu) CONTAMINATED LEVELS IN SOIL SAMPLES OBTAINED FROM A Pb/Zn MINING SITE LOCATED IN HICH VILLAGE, THAI NGUYEN PROVINCE

Abstract

Currently, the contamination of heavy metals within ore mining regions is pronounced both domestically in Vietnam and globally. The primary objective of this study is to elucidate the chemical speciation of copper (Cu) and conduct an assessment of the magnitude and probability of contamination of Cu in soil samples procured from the Pb/Zn mining, at the Hich village, Dong Hy district, Thai Nguyen province, in order to furnish critical data pertinent to the environmental stewardship of soil resources within this geographical domain. The determination of Cu’s chemical fractions in soil specimens was conducted following Tessier's extraction procedure, utilizing the ICP-MS technique. Results revealed that the mean Cu concentrations across the five tailing samples ranged from 15.524 to 35.192 mg kg^-1, while in the seven agricultural samples, concentrations ranged between 15.359 to 21.198 mg kg^-1. Predominantly, Cu was identified within the soil fractions in the order of residues (F5) > carbonate (F2) > Fe/Mn oxides (F3) > exchangeable fraction (F1) > organic carbon (F4). Compliant with Vietnamese standards, Cu concentrations in agricultural soil samples remained below permissible limits. Based on the Igeo index, the majority of soil samples exhibited mildly contaminated levels. Furthermore, according to the Risk Assessment Code (RAC), 11 out of the 12 analyzed soil samples were classified as having a medium risk level.