Trace metal contamination of water at a solid waste disposal site at Kariba, Zimbabwe

Abstract

Trace metal concentrations were determined in soil samples collected from within, and close to, a solid waste disposal site at Kariba, Zimbabwe, and in water flowing from the area during 1996 and 1997. Soil samples were collected from the surface inside the disposal site and at distances of 3m, 25m and 50m (from the surface and at a depth of 15cm) along two transects on the downward slope away from the site, as well as from a control site at a distance of 75m away, across a gully. Accumulation of Cu, Pb, Fe and Zn was found within the disposal site. Concentrations of Zn, Pb and Cu in surface soil samples declined with increasing distance down the slope away from the waste disposal site. Surface soil samples contained higher concentrations of Cu, Pb and Zn than soil samples collected at a depth of 15cm, suggesting that there may have been surface movement of trace metals away from the disposal site. Water samples showed high levels of Hg and Pb. High lead concentrations in rainwater samples suggested that at least some of the lead may originate from atmospheric deposition associated with rain.

Keywords: leachates, soil contamination, solid waste disposal, trace metals, water contamination

African Journal of Aquatic Science 2007, 32(1): 71–78