Spatial distribution of sediment pesticides concentrations in the Maritime Region of Canada

This study measured pesticide concentrations at 51 distinct sampling sites in freshwater streams in three maritime provinces of Canada (New Brunswick, Nova Scotia and Prince Edward Island) in 2020–2021. There were 50 different pesticides analysed in each sediment samples. The majority of those pesticides had concentrations below the detection limit of the laboratory. However, nine pesticides had detections that ranged from one to nine sites. Terbufos and parathion were the two most detected pesticides of this study. Surprisingly, terbufos has not been registered for use in Canada since 2012 which showcases the prevalence of some legacy contamination in sediments. The results align with other recent Canadian research, suggesting that pesticide occurrence in sediment is complex and not explained by a single factor like organic matter or chemical properties alone. Instead, it is a result of multiple interacting factors, including land use, the pesticide's solubility, its concentration in the surrounding water, and the persistence of legacy products.