The fate of chloroacetanilide herbicides and their degradation products in the Nzoia Basin, Kenya.
Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2,6-diethylaniline and 2-ethyl-6-methylaniline were analyzed in water and sediment samples from 9 sites along River Nzoia, Kenya using gas chromatography. The degradation products were detected in > 90% of the sediment and water samples, while the parent compounds occurred in < 14% of the water samples. Much higher concentrations of the pesticides and their degradation products occurred in the sediment than in the water (1.4 up to 10 800-fold), indicating an accumulation of the compounds in the sediment. The constant occurrence of the degradation products in the sediment during the study period infers a persistence of these compounds. It is hypothesized that the prevailing tropical climatic conditions favor a quick breakdown of the pesticides to their environmentally stable degradation products, thereby making the latter more important pollutants than their parent products in the study area.
Osano
Odipo
O
Moi University, Eldoret, Kenya. odipo@africaonline.co.ke
Nzyuko
Daniel
D
Tole
Mwakio
M
Admiraal
Wim
W
D000081:Acetamides / Q000032:analysis / Q000378:metabolism*; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D006540:Herbicides / Q000032:analysis / Q000378:metabolism*; D007630:Kenya; D014329:Tropical Climate; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
D000081:Acetamides; D006540:Herbicides; D014874:Water Pollutants, Chemical; C000188:alachlor; C051786:metolachlor