Contamination of Agricultural Soils by Toxic Trace Metals in an Industrial District in Vietnam

Contamination of agricultural soils by toxic trace metals of arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu) and zinc (Zn) was investigated in an industrial district in Vietnam. In the district, irrigation agriculture is performed through channels, in addition, there are two industrial parks are nearby agricultural land. The purpose of the study is to clarify the magnitude and spatial distribution of the trace metal concentrations, the source of the trace metals, the difference in the concentrations between the two industrial park areas, and usability of soils for agriculture. As a result, the trace metal concentrations were in the order of Cr>Zn>Pb>Cu>As>Cd for the district. No significant differences were observed between the two park areas in concentrations. Cr and Zn concentrations were high near factories in the park areas, and the other concentrations were comparatively high in the areas, showing that the trace metals were supplied from the factories with wastewaters. The correlations observed between Cd, Pb and Zn, between Cr and Zn, and between Cu and as in the concentrations suggested that there were several groups of wastewaters supplying the trace metals. Concentrations of all kinds trace metals exceeded the permissible level for agricultural soils, and the remediation measures to reduce contamination are necessary.