Because of their ubiquitous presence in aquatic environment, pesticides impact aquatic organisms, without being systematically accumulated. Although quantification methods for accumulated metals, and their uptake mechanisms, in biofilms are nowadays well known, they are poorly developed for organic compounds. This is why new approaches dedicated to the determination of pesticides in biofilm matrix are necessary to implement, for a better understanding of their toxicokinetic mechanisms (bioaccumulation, transfer, distribution), linked to their effects (photosynthetic activity inhibition). In this study we carried out specific method developments. They allowed us to determine both kinetic and partition constants, and propose a first mechanisms model, according to biologic impacts observed.