Browsing by Author "Mmochi, Aviti John"

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    Levels and chemodynamics of pesticide residues and metabolites in the Zanzibar coastal marine environment
    (University of Dar es Salaam, 2005) Mmochi, Aviti John
    This thesis reports on the levels of pesticide residues in water, soil/sediment and biota in two drainage basins in Zanzibar Island, Tanzania. A total of 10 pesticides and related compounds, namely a-HCH, y- HCH and 8- HCH ; a- endosulphan and endosulphan sulphate; p,p -DDT, p,p -DDD and p,p -DDE; fenitrothion and propanil were found. Most of the samples had concentrations below the method detection limits (MDLs) with only up 35% of the samples having concentrations above the MDLs. The highest concentrations in the various matrices were as follows: water: 7.5 fag/1 of fenitrothion; soil: 171.5 of propanil; biota: 533 H-g/kg (d.w.) of p, p -DDE. The thesis also reports on development of a method of identification and quantification of 29 photosynthesis- inhibiting herbicides and 4 metabolites. The method was used in analysis of field samples. The results compared favourably with those of GC. Because of the importance of propanil as a herbicide in rice farms in Zanzibar, its presence in Mapopwe creek and reports of regular fish mortalities, it was found necessary to study its properties in soil and water. Soil sorption experiments indicated that the herbicide has a Kd of 1.85, KoC of 185 and a half-life of 14 hours. The low Kd in Cheju of 1.25 compared with 9.62 for Makoba and 5.05 for Mchanga in the Mahonda-Makoba drainage basin indicates that the herbicide may contaminate ground water and seawater in Cheju-Mapopwe drainage basin. From the study, the Zanzibar environment can be considered pristine as far as pesticide pollution is concerned.