Levels of pesticide residues in irrigation effluent from tomato fields in Owiro Estate, Tanzania

Abstract

Pesticide residues lindane, chlorpyrifos and endosulfan sulphate were detected in water from the spring source, within field and return channel of vegetable farms in Ngarenanyuki, Tanzania. Extraction of the pesticide residues were conducted by liquid-liquid extraction (LLE) method. The detection and concentrations of pesticide residues were determined by gas chromatography equipped with electron capture detector (GCECD). The percentage detections in return channel and within field were observed to be 67 and 33 respectively whereas no pesticides were detected in the spring source. The average concentrations for lindane, chlorpyrifos and endosulfan sulphate within field and return channel were 3.0, 0.27 and 3.35, and 2.8, 0.06 and 3.13 mg/L, respectively. Absence of residues detection in spring source indicates that the source of pesticides in water from the field and return channel were the applications of pesticides in vegetable farms. This work, thus, seeks to provide information on levels of pesticide residues in water that will assist in a scientific assessment of the impact of pesticides application on public health and ecosystem in Tanzania.

Keywords: Organochlorines, Organophosphorous, Water contamination, Ngarenanyuki.