Assessment of water resource contamination by pesticides in vegetable-producing areas in Burkina Faso

This study proposes a comprehensive approach to investigate water resource contamination by pesticides under the specific climatic and hydrological conditions of the Sudano-Sahelian climate. Samples were collected from tradi- tional wells, boreholes, and a lake in Burkina Faso. A multiresidue analysis was developed for 25 pesticides identi- fied during field surveys. Polar organic chemical integrative samplers (POCIS) were used to confirm trends observed with grab samples. Uptake kinetics of POCIS were assessed by in situ calibration. The proposed use of nonlinear least squares regression proved to be a robust approach for estimating time- weighted average concentration in cases of nonlinear uptake. High sampling rates for triazines in a quasi-stagnant lake were attributed to warm water temperatures (30.8 ± 1.3 °C). The combination of sampling techniques during a 3-year monitor- ing period allowed for identifying potential interactions be- tween resources, seasonal patterns, and origins of contami- nants. Atrazine, azadirachtin, carbofuran, chlorpyrifos, cypermethrin, dieldrin, imidacloprid, and profenofos exceeded 0.1 μg L−1, indicating a potential risk for the con- sumers. Ecological risk assessment was performed using the Pesticide Tool Index for fish, cladocerans, and benthic inver- tebrates. Peak concentrations of cypermethrin and chlorpyri- fos were systematically associated with hazard to the studied taxa.