Abstract
This study measured pesticide concentrations at 51 sites in streams in three maritime provinces of Canada in 2020–2021. There were 50 pesticides analysed in each sediment samples. Most 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. Furthermore, the concentrations of terbufos, chlorpyrifos and clothianidin exceeded the calculated sediment threshold which indicates the potential for ecological harm. The results align with other recent 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.