A comparison of organochlorine pesticide residues in upper Ncema and lower Umguza dams, Zimbabwe

Journal article from page 26 to 30.,This study examined the levels of chlorinated hydrocarbons (organochloride pesticides) in the ecosystem of Ncema and Umguza dams. Samples of water, water weeds, mud and fish were collected from each dam. The fish species collected from the two dams were river sardine (Mesobo/a brevianus), branded bream (Tilapia sparmanii), African catfish (e/arias gariepinus) and red-breasted bream (Tilapia rendelli). The samples were analysed for hexachlorocyclohexane, DDT, and its metabolites, DOE and DOD, aldrin and dieldrin. DDT was detected in all the samples, its concentration ranging from 1,12 J.l9 per kg in water weeds to 265 J.l9 per kg in mud from Upper Ncema dam. Aldrin was also detected in all the samples (except for branded bream from Upper Ncema dam), the highest level __being 223 ~g per kg in_ ~atdln~$'-rom Lower Umguza dam. Traces.of hexachlorocyclohexane were detected in some of the samples, the highest level of 20,1 ~g per kg in African catfish from Upper Ncema dam. Dieldrin was detected only in mud samples from Lower Umguza dam at a concentration of 80,5 ~g per kg. Overall, this study indicates that Upper Ncema dam has a higher pesticide load compared to Lower Umguza dam.