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 traditional wells, boreholes, and a lake in Burkina Faso. A multiresidue analysis was developed for 25 pesticides identified 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 monitoring period allowed for identifying potential interactions between resources, seasonal patterns, and origins of contaminants. Atrazine, azadirachtin, carbofuran, chlorpyrifos, cypermethrin, dieldrin, imidacloprid, and profenofos exceeded 0.1 μg L-1, indicating a potential risk for the consumers. Ecological risk assessment was performed using the Pesticide Tool Index for fish, cladocerans, and benthic invertebrates. Peak concentrations of cypermethrin and chlorpyrifos were systematically associated with hazard to the studied taxa.
Keywords: GC-MS; Market gardening; Multiresidue analysis; POCIS; PRC; Pesticide residues; Risk assessment; UPLC-MS/MS.