Browsing by Author "Mwevura, Haji Mwevura Haji"

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    A study on the levels of organochlorine pesticide residues from selected aquatic bodies of Tanzania.
    (University of Dar es Salaam, 2000) Mwevura, Haji Mwevura Haji
    Water, sediments and biota from Msimbazi and Kizinga rivers, and Dar es Salaam coastal marine environment were analyzed for various organochlorine pesticide residues using GC-ECD. Dieldrin, p,p'-DDT, p,p'-DDE, p,p'-DDD; o,p'-DDT and yHCH were detected at significantly greater concentrations above the Method Detection Limits (MDL). Recoveries of pesticide residues ranged 65 - 85 % in water, 86.5 - 120 % in sediments and 62 - 102 % in biota. Water samples showed a marked difference in the frequency of pesticide residue detection between dry and wet seasons (p,p'-DDT 25 to 81%; p,p'-DDE 37.5 to 100%; dieldrin 0 to 100% and y-HCH 0 to 6%) and the variation in detection was not significant in sediments. However biota samples showed significant difference in levels of residues depending on mode of feeding and age of analyzed biota. Higher concentrations of residues were observed in old meat-eater type of biota. The levels of residues in some sediment and biota samples were found to be relatively higher than those reported from other parts of Tanzania; however, most of the previously reported studies lacked some of the basic information for an adequate comparison. Overall analysis indicated recent use of DDT at Jangwani and Msimbazi River is the most pesticide-polluted water body followed by Kizinga River. Levels of detected residues in the water samples suggest no acute (short-term) effects to aquatic biota but most likely to cause chronic (long-term) effects particularly during wet seasons. Although the residue levels in sediments indicated possible adverse effect to human consuming the biota that are directly exposed to the sediments, edible biota from the examined water bodies are safe for human consumption.