Pesticide application in gardening : assessment of resulting impact on water resources quality using grab samples and pocis, case study of Loumbila lake, Burkina Faso

This study proposes a comprehensive assessment of water resources contamination by pesticides in a gardening area. Multiresidue extraction procedure was developed to quantify 48 pesticides identified during field surveys. Drinking water samples were collected from traditional wells, boreholes and the lake. Levels of azadirachtin, chlorpyrifos, imidacloprid and profenofos in traditional wells exceed the threshold limit of 0.1 μg/l indicating a potential risk for the consumers. Residues of acetamiprid, atrazine, emamectin benzoate and imidacloprid were found in boreholes but in low concentrations. Levels in lake appeared to depend on seasons. Increase during the rainy season, in absence of gardening activity, suggests the contamination by other activities located upstream. In parallel, we conducted an in-situ calibration of Polar Organic Chemical Integrative Samplers (POCIS). Comparison with results from water samples shows that POCIS are suitable for measuring time weighted average concentration for atrazine and its metabolites, in environmental conditions of the study area.