Levels and Chemodynamics of Pesticides in Soil and Sediments At Kilombero Sugarcane Plantations and Environs, Morogoro Region, Tanzania

The study reports on the levels and chemodynamics of pesticides and their metabolites in soil and sediment samples from Kilombero sugarcane plantations and environs, Morogoro Region, Tanzania. The samples were screened for 56 different pesticide residues and their metabolites using GC-ECD and GC-NPD and the results were confirmed by GC-MS. A total of 31 soil samples and 19 sediment samples were analysed in this study and a total of 16 different pesticides/metabolites were detected in soil samples; and 12 different pesticides/metabolites were detected in sediment samples. o,p’-DDT was shown to have the highest concentration of all the detected pesticides/metabolites in soil samples with a mean concentration of 21.04µg/kg d.w whereas the highest concentrations of 19.64µg/kg d.w. was recorded for p,p’-DDD in sediment samples. The other DDT metabolites detected in soil and sediment samples were p,p’-DDT, p,p’-DDE, o,p’-DDE, p,p’-DDD and o,p’-DDD with the concentration ranging from 2.00µg/kg to 18.3µg/kg d.w.  α-Endosulfan was detected in soil and sediment samples at concentrations ranging from 1.09 to 13.41µg/kg d.w. whereas endosulfan sulphate was detected with a concentration range of 2.04 – 3.48µg/kg d.w. For HCH, only the α and γ isomers were detected with concentrations ranging from 2.76 to 17.06µg/kg d.w. whereas aldrin and dieldrin were in the concentration range of 1.11µg/kg to 11.20µg/kg. γ-Chlordane and parathion were detected in the concentration range of 2.30µg/kg to 7.48µg/kg and 1.00µg/kg to 7.14µg/kg respectively. Chloroneb and metolachlor being reported for the first time in Tanzanian environmental samples were found to have the concentration ranging from 1.10µg/kg d.w. to 12.83µg/kg d.w. and 3.07 to 9.41µg/kg d.w. respectively. There was a significant difference in terms of detection frequencies and concentrations between the dry and rainy season samples. However, the detected pesticide residues were generally lower than the safety standards stipulated by TBS and WHO/FAO except for aldrin, which was found to be slightly higher than the safety standards.