Determination of selected acaricide residues in soils and water resources around cattle dip tanks in Mbarara district, western Uganda

Abstract

This study determined the levels of selected acaricide residues in soils and water samples around cattle dips in Mbarara District western Uganda. Samples were collected, prepared and analysed for amitraz, chlorpyrifos and cypermethrin residues by gas chromatography equipped with a Flame Ionization Detector (GC/FID). The obtained data revealed evidence of amitraz, chlorpyrifos and cypermetherine contributing to the presence of acaricide residues in the area. The observed quantities were higher than United States permissible maximum residue limits (MRL) for agricultural soils. The amitraz, chlorpyrifos and cypermethrin residue concentrations at the sampled sites are high near the dip and reduce with all investigated distance of 25 m, 50 m and 75 m away from the cattle dip tank. This could be as a result of the cattle carrying some acaricide as they move away from the cattle dip tank and not all the acaricides flow back into the cattle dip tank. The data obtained from obtained from analysis of samples indicated presence of amitraz, chlorpyrifos and cypermetherin present in the area for all the studied farms. There was a significant difference in amitraz residue concentration in water samples from farms A compared to farms B and C this is due to different dosing in farm A compared to B and C. However, farms D and E were at zero because amitraz was not used as acaricide in these particular farms At farms D and E, only chlorpyrifos and cypermethrin residues were detected and no amitraz residues was detected at any of the studied distances away from the cattle dip tanks. The data obtained from water resources showed that only amitraz residues were detected from water samples collected from farms A, B, and C at all studied distances away from the cattle dip tanks with no Chlorpyrifos and cypermethrin being detected at the three farms A, B and C xii At farms D and E, only Chlorpyrifos and Cypermethrin residues were reported from water samples collected at farms E and D and no amitraz residues was detected at any of the studied distances away from the cattle dip tanks. The study from cattle dip samples showed that amitraz was found in the three dip tanks from farms A, B, and C while Chlorpyrifos and cypermethrine were detected from farms D and E. Farm A had the highest amitraz concentration, followed by farm B and then farm C. All the concentrations exceeded the allowable maximum standard values / Normal range of 250 ± 5 ppm of amitraz inside the cattle dip tank an indication of overdosing of the cattle dip tanks by farmers. At farms D and E, both Chlorpyrifos and cypermethrin were reported with farm E having the highest concentration of Chlorpyrifos and cypermethrine followed by farm D with concentration of Chlorpyrifos and cypermethrine. All the concentrations exceeded the allowable maximum standard values / Normal range of 500 ± 5 ppm Chlorpyrifos and 50 ± 5 ppm for cypermethrin inside the cattle dip tank an indication of overdosing of the cattle dip tanks.