Investigation of heavy metals in agricultural soils and vegetables irrigated with river water exposed to industrial effluent in Mojo, Ethiopia

Abstract

The objective of this study was to examine the level of heavy metals and alkali metals in soil, cabbage and water samples collected from Qoka Negewo, where Mojo River is used for irrigation. Mixture of nitric acid, perchloric acid, and hydrogen peroxide was used for optimizing the wet digestion method for soil and cabbage samples. One way anova test result revealed that there were significant difference (p < 0.05) at 95 percent confidence level in concentration of metals among soil, cabbage and water in all samples. The heavy metal concentration of soil samples was found to be relatively a little higher than the corresponding concentration in cabbage samples. The concentration of the metals was compared with internationally recommended permissible limits, and most of them were found below the permissible limits, indicating insignificant health risk by consuming the cabbage, and using the water for irrigation purpose. The hazard risk index calculated for cabbage was found to be <1, which also indicates the predicted exposure is unlikely to pose potential health risks.