SPECIATION OF METALS AND CONTAMINATION ASSESSMENT OF Sb, Bi IN SURFACE SEDIMENTS OF THE CAU RIVER - THAI NGUYEN CITY

Abstract

Antimony (Sb) and Bismuth (Bi) are two heavy metals that have many practical applications, but both are toxic, especially Sb is as toxic as As. Therefore, this study focuses on analyzing the concentration of the bonded forms and the total metal concentration of both Sb and Bi, which have never been studied in surface sediments of the Cau river - Thai Nguyen city. The bound form of the metal in the sediment was separated based on a modified sequential extraction procedure of BCR and Tessier. Contamination levels of Sb and Bi were assessed according to Igeo, %RAC and ICF. The analysis results showed that the bonding form of Sb follows the order F5 > F3 > F4 > F1,2 and that of Bi follows F3 > F5 > F4 > F1,2. Bi concentration is about 3.54 mg/kg – 5.55 mg/kg and Sb concentration is from 0.32 mg/kg to 1.69 mg/kg. The level of contamination and ecological risk of Sb is low (Igeo < 1, %RAC < 10 and ICF < 1) except for 3 locations S2, S5, S6. For Bi, the pollution level was heavily to extremely contaminated according to Igeo (3 < Igeo < 5) and moderately according to ICF (1 < ICF <3) but has a low risk to the ecosystem (%RAC < 10), this is because the F1,2 form of Bi was very small, only about 0.27% - 2.9%. These results will provide reference data for studies on heavy metal pollution in Cau river sediments.