Diplom- und Master-Arbeiten (eigene und betreute):
J. Oduor Onyango:
"Pesticides Application and their Residues Contamination in Lake Naivasha Catchment";
Betreuer/in(nen): K. Irvine, N. Kreuzinger;
Institut für Wassergüte, Ressourcenmanagement und Abfallwirtschaft,
Intensifying agricultural practices, lead to high input of pesticides and spread of their residue contamination over catchments raising concern over the health hazard posed by the presence of pesticide residues in the environment. This study aim at providing a basis for monitoring pesticides residue contamination of the water bodies in Lake Naivasha catchment through; identifying the pesticides applied in the catchment, the status of selected pesticides and their potential effect to human health and life of aquatic organisms.
The study found that 59%of the pesticides applied within the L. Naivasha catchment are moderately to extremely hazardous, while more than 40% of the pesticides are moderately to highly persistence in the environment. 22% of the applied pesticides were of international concern because of their toxicity (moderately to extremely hazardous) and persistence (highly persistence). The L. Naivasha catchment was found to be contaminated by 4,4-DDT, 2,4-DDE, 4,4-DDD, γ-HCH, α-HCH and Aldrin, with higher concentrations in the sediment than the water phase. The most common pesticide residue contaminant was 4,4-DDT and 4,4-DDD. The contamination by the pesticides was found to be different among sites and between seasons (wet/dry; with all the pesticides in the study detected at Hippo point and Kingfisher flower farm site and more pesticides being detected at higher concentrations during the dry period than the wet period. During the wet period the contamination within the river sites was higher in the sediments phase and lower in the water phase, while in the dry period the contamination in the lake was higher in the water and lower in the sediments. The L. Naivasha and R. Malewa sub-catchments were found to be most impacted by pesticides contamination, while the R. Karati sub-catchment was found to be the least impacted. The water quality within the catchment was found to meet the criteria standard for drinking water with respect to pesticides residue contamination; however with respect to chronic effect to aquatic organisms as well as human health effect from consumption of water and aquatic organisms, the water was not within the criteria standard and only 4,4-DDD did not meet the standards with respect to acute effect to aquatic organisms. The quality of sediment was not within the criteria standards to affect benthic organisms.
This study recommends a shift to a locally produced less persistent pyrethrum based pesticide, a pesticides residue budget of the catchment and an understanding of the potential toxicological effects posed by the contamination.
pesticides, L. Naivasha, toxicological effects
Erstellt aus der Publikationsdatenbank der Technischen Universitšt Wien.