Status of heavy metals in agricultural soils of Vietnam

Status of Cd, Cr, Cu, Ni, Pb, and Zn in agricultural soils of Vietnam was examined. The six heavy metals were selected from tide viewpoint of public concern in the country. The concentration of Cd was low and independent of that of the parent rocks from which the soils were derived. The concentrations of Cr, Cu, Ni, Pb, and Zn more or less varied with the parent rocks. Among them, the concentration was, in general, In the sequence of sandstone < alluvium < limestone < basalt for Cr and Ni and of sandstone < alluvium < basalt <less than> limestone for Cu and Zn. The Pb concentration, however, tended to be the lowest for basalt followed by sandstone. The concentrations of the six heavy metals in the soils derived from alluvium, sandstone, and basalt were generally within and around the concentration ranges reported for! the respective parent rocks, except for the possible Zn pollution in the rice-vegetable field in Hanoi. In contrast, the heavy metal concentrations in the soils derived from limestone were much higher than those reported for limestone except for Cd.