CHEMICAL SPECIATION ANALYSIS AND ASSESSMENT OF POLLUTION RISK BY Zn IN TAILING SOIL OF THE Pb/Zn MINING ORE ZONE IN HICH VILLAGE, DONG HY DISTRICT, THAI NGUYEN PROVINCE

Abstract

Soil samples in the waste dump of ​​the lead-zinc mine in Hich village, Dong Hy district, Thai Nguyen province were collected and analyzed. The total Zn content in the soil samples was determined by plasma mass spectrometry (ICP-MS). Tessier's sequential extraction procedure was applied to extract and analyze the chemical fractions of Zn in soil samples. The obtained results showed that the total content of Zn in the soil samples ranged from 2305.4 ÷ 7479.1 mg/Kg, which was 7.7 ÷ 24.9 times higher than the permissible standards of the Vietnamese Ministry of environmental resources for industrial land. The results of chemical analysis showed that zinc exists mainly in the form of residues (F5) or bound to Fe/Mn oxides (F3) and minimally in the bonding organic fraction (F4). The geo-accumulation index (Igeo) has evaluated the content of Zn in the soil samples in the waste dump area of ​​the lead/zinc mine with high and very high pollution levels. According to the Risk Assessment Index (RAC), the content of Zn in tailing soil samples is at medium and high environmental risk.