Atmospheric Concentrations of Organochlorine Pesticides in the Northern Lake Victoria Watershed

Abstract

Organochlorine pesticides may still be in use in the Eastern African region for agricultural purposes and for the control of mosquitoes. Atmospheric concentrations of organochlorine pesticides are expected to be higher in the tropics compared to temperate regions due to prevailing high temperatures. However, no study has been conducted to investigate atmospheric transport and deposition of pesticides in East Africa. In this study atmospheric concentration of organochloride pesticides in the air were determined at Kakira near Jinja from November 1999 to March 2000. Total DDT was in the range 64.8-610.9 pg/m³, dieldrin 23.6-90.8 (average 45.7) pg/m³ , a-endosulfan 32.5-206.1 (average 92.4) pg/m³ , lindane (y-HCH) 20.3-183.6 (average 70.5) pg/m³ , chlordane and heptachlor and hexachlorobenzene (HCB) ranged from <0.1- 10.1 pg/m³. The insecticide p,p'-DDT metabolite, p,p'-DDE was the predominant DDT isomer ranging from 22.6-390.1 pg/m³. However, o,p'-DDT isomer was frequently detected (11.2-62.8 pg/m³ ) and its metabolite p,p' DOE was relatively high ranging from 29.9-109.9 pg/m³ . The most predominant organochloride pesticides in decreasing average concentration levels DDT (total), a-endosulfan and lindane, p,p-DDT, p,p' -DDT, p,p' -DOE, dieldrin and o,p' -DDT. Average levels of p,p' -DDT and p,p' -DOE at Kakira were lower than those reported for Brazzaville but higher than those reported for Lake Baikal and Southern Ontario while a-HCH, y-HCH, total chlordane, and hexachlorobenzene (HCB) concentrations for Kakira were lower than those reported for Brazzaville, Lake Baikal in Russia, Southern Ontario. ln comparison with data from Senga Bay, Lake Malawi in Malawi, average DDT (total), p,p'-DDE, p,p'-DDT, o,p'-DDT, lindane (y-HCH) and LHCH levels were higher and average dieldrin, a-HCH, chlordane and HCB levels were lower. The presence of these chemicals in air at Kakira was most likely due to both local and regional inputs .

Keywords: Concentration levels, organochloride pesticides, air, Lake Victoria