Levels of Cd, Hg and Zn in some surface waters from the Eastern Cape Province, South Africa

Total trace metals levels – Cd, Hg and Zn, which may affect human health and the “health” of the aquatic ecosystem, were determined in the Umtata, Buffalo, Keiskamma and Tyume Rivers and in the Sandile and Umtata Dams. These elements were also determined in sediment samples from some of these surface waters. Normal levels of the metals were detected in water samples from the Umtata River and the Umtata Dam but samples from Buffalo, Keiskamma and Tyume Rivers contained elevated levels of Cd. Generally the levels of Hg and Zn were normal in samples from all the surface waters. The probable sources of the metals in the rivers are diffuse, originating from rural and urban runoff and from agricultural runoff in the catchments although there could be contribution from natural and point sources.