Lead and zinc adsorption by agricultural soils from trade villages in Bac Ninh Province, northern Viet Nam

Abstract

The objective of the current paper is to assess the heavy metal status and adsorption behavior of heavy metals in agricultural soils from Vanmon Commune, Yenphong District and Chaukhe Commune, Tuson District of Bacninh Province, located in the Red River Delta region, northern Vietnam. Total and available concentrations of Cd, Cu, Pb and Zn were determined for the soils collected in Vanmon and Chaukhe Communes which are engaged in recycling of steel as a trade village. Total concentrations of twenty-one soils ranged between 0.18 and 0.62 mg/kg for Cd, 17.9 and 39.6 mg/kg for Cu, 19.5 and 45.2 mg/kg for Pb, and 25.6 and 236.8 mg/kg for Zn. Based on the comparison with the Vietnamese standard for heavy metal concentrations in agricultural soils, total concentrations of those heavy metals were regarded to be in a normal range, except Zn at two sites in a village of Chaukhe Commune, Tuson District. In the correlation between total and available concentrations of heavy metals, the total Pb concentration showed a significant correlation with the total concentrations of Zn and Cd (1% level), and Cu (5% level). The concentration of available Zn extracted by 0.1 M HNO3 was found to be higher for the examined soils than for the other agricultural soils in the Red River Delta. The adsorption of Pb and Zn by the agricultural soils, carried out in the concentrations ranging from 100 to 7,500 mg/L for Pb and from 1 to 2,500 mg/L for Zn, indicated that adsorption isotherms of both heavy metals were well fitted to the Freundlich equation. The adsorption capacity of the agricultural soils was larger for Pb than for Zn.