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

Abstract

The contamination of agricultural soils by the toxic trace metals arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu) and zinc (Zn) was investigated in an industrial district in Vietnam. In this district, irrigation agriculture is conducted via channels; additionally, there are two industrial parks on nearby agricultural land. The purpose of the study was to clarify the magnitude and spatial distribution the trace metal concentrations, the source of the trace metals, the difference was in concentration between the two industrial park areas, and the usability of the soils for agriculture. In this study, eighteen soil samples were taken, and the trace toxic metals in soils were determined using atomic absorption spectrometer. Our results showed that 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 terms of concentration. Cr and Zn concentrations were highest near the factories in the park areas, and the other trace metals were also comparatively high in these areas, demonstrating that the trace metals originated from the factories via wastewater. The correlations observed in the concentrations between the Cd, Pb and Zn, Cr and Zn, and Cu and As suggested that there were several sources of wastewater supplying the trace metals. Concentrations of all trace metals exceeded the permissible level for agricultural soils; therefore, remediation measures are necessary to reduce contamination.