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Poster De Conférence Année : 2022

Toxicokinetic of a pesticides cocktail pulse on stream biofilms with different hydrological histories

Résumé

Session: Microbial roles in contaminant fate and bioremediation The potential adverse effects of pesticides on stream ecosystems subjected to extreme hydrological events has been poorly explored. Therefore, there is an urgent need to increase our knowledge to propose suitable pesticide mitigation strategies in the context of global change scenarios affecting stream ecosystems. In this study, a microcosm experiment was performed to assess the dissipation kinetics of a pulse of pesticide mixture (glyphosate, aminomethylphosphonic acid (AMPA), tebuconazole, terbuthylazine and imidacloprid) by stream biofilms with a different hydrological history. The effects of two types of drought events caused by hydropeaking (short and more frequent droughts) and agricultural practices (long and less frequent droughts) on aquatic biofilm structure-function were evaluated and compared with an immersed control, before and after the pesticide cocktail pulse. Different biomass and functional parameters were analyzed in biofilms to determine the combined impact of droughts and pesticides, whereas the dissipation kinetics of each pesticide molecule of the cocktail was evaluated in the water as well as in the biofilm. Algal biomass measured as chlorophylla concentration was significantly lower under drought conditions compared to the control and these differences were more remarkable after the application of the pesticides cocktail. Microbial respiration per unit of microbial (algal and bacterial) carbon was higher in biofilms subjected to droughts, which tended to accumulate lower extracellular polymeric substances (EPS) comparing to the immersed control. Droughts also modified the organic matter decomposition fingerprint of stream biofilms, independently from pesticides cocktail exposure. The diffusion of glyphosate and AMPA into biofilms was lower than that of tebuconazole, terbuthylazine and imidacloprid and this was explained by the differences in molecules’ hydrophobicity. However, long droughts tended to further decrease the diffusion of pesticides per unit of biofilm EPS in comparison the short droughts and control treatments.
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Dates et versions

hal-03990045 , version 1 (15-02-2023)

Identifiants

  • HAL Id : hal-03990045 , version 1

Citer

Lluís Bertrans-Tubau, Meritxell Abril, Isabelle Batisson, Nicolas Creusot, Nicolas Mazzella, et al.. Toxicokinetic of a pesticides cocktail pulse on stream biofilms with different hydrological histories. EcotoxicoMic 2022 - Third International Conference on Microbial Ecotoxicology, Nov 2022, Montpellier, France. ⟨hal-03990045⟩
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