Browsing by Author "Mihale, Matobola Joel"

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    Chemodynamics of obsolete pesticides at Vikuge farm, Kibaha district, Tanzania
    (University of Dar es Salaam, 2002) Mihale, Matobola Joel
    This thesis reports on the chemodynamics of obsolete pesticides in soil, sediment and water samples at Vikuge farm, Kibaha District, Tanzania. Samples were collected from within and around the old storage site and in the neighboring areas. Samples were screened for 80 pesticide residues and metabolites using GC-ECD and GC-NPD and the results were confirmed with two GCs with different polarities and with TLC. Pesticide levels in soil samples were up to 2.82 xlO^ mg/kg dry weight (28.2% by mass) for EDDT and up to 6.34 xlO4 mg/kg dry weight (6.3% by mass) for EHCH. Pendimethalin and y-chlordane levels were up to 4.09 xlO4 mg/kg dry weight (4.1% by mass) and 9.22 xlO2 mg/kg dry weight, respectively. The pesticide levels decreased with increasing distance from the old storage site and with increasing depth from the surface. Pesticide levels in sediments varied from 2.8 xlO2 mg/kg to 7.4 xlO3 mg/kg dry weight for XHCH and from 3.49 xlO3 mg/kg to 9.96 xlO4 mg/kg dry weight for 2DDT. Pesticide levels in sediments were increasing with increasing distance from the site. In the water samples, the levels were up to 6.15 (J.g/1 for EHCH and up to 32.71 jxg/1 for ZDDT. Among the water samples, groundwater from the lowland areas had the highest concentrations of all the residues. The relative high levels of pesticides in groundwater can be attributed to surface runoff. In tapwater, the relatively high levels can be due to runoff and back siphoning due to low pressure in the pipe when water was not flowing. Runoff, together with volatilization contributed to the detected levels in surface water samples. These results show that Vikuge Farm is a classic case of environmental contamination by obsolete pesticides - with consequent direct implications to people, livestock and wildlife in and around the area. Immediate measures should be taken to de-contaminate the area.