CHEMICAL FRACTION ANALYSIS AND ASSESSMENT OF ASERNIC IN SOILS SAMPLED IN A Pb/Zn MINING AT HICH VILLAGE IN THAI NGUYEN PROVINCE

Abstract

The pollution of heavy metals in ore mining areas is severe at present in Vietnam as well as in the world. Assessing the level and risk of contamination of arsenic (As) in the soil in the ore mining area is essential for environmental management. The total content and chemical fractions of As in the soil samples were performed according to Tessier’s extraction procedure and using the ICP-MS method. The average concentration of As in the 5 tailing samples ranged from 10.14 ÷ 44.68 mg kg^-1 and in the 7 agricultural samples was 5.66 ÷ 7.65 mg/Kg. In the investigated soil samples, As was found mainly in the fractions of residues (F5) > carbonate (F2) > Fe/Mn oxides (F3) > Organic carbon (F4) > exchangeable fraction (F1). According to Vietnamese standards, the concentration of As in agricultural soil samples was all lower than the allowable limit, while 3/5 of the tailing samples had As concentrations less than the permissible limit in agricultural soil and the other 2 samples had As concentrations higher than the allowable limit. According to the Igeo index, most soil samples had Igeo values ​​at a mildly contaminated level. According to the Risk Assessment Code (RAC), 10/12 soil samples analyzed were at medium risk.