The general objective of this thesis is to contribute to the improvement of knowledge on the fate of plant protection products in soils and their transfer to aquatic environments, by developing innovative analytical strategies based on the detection of these compounds and their transformation products using high-resolution mass spectrometry.

Pesticides are compounds used to prevent, mitigate, or destroy pests. Once in agricultural watersheds, pesticides transform according to variable kinetics, which depend on the intrinsic properties of the compounds as well as the environmental conditions. These transformations, orchestrated by biotic or abiotic processes, lead to the generation of numerous transformation products (TPs), the vast majority of which are unknown. In contrast to the extensive knowledge that exists on pesticides, knowledge on transformation products in terms of analysis, occurrence, and properties is still insufficient. This combined lack of knowledge and plurality of possible molecules makes it practically impossible to use targeted analytical techniques, which work by identifying compounds using analytical standards.

The development of high-resolution mass spectrometry over the last decade has allowed the emergence of powerful analytical strategies, such as so-called non-targeted and suspect analyses. By overcoming the need for standards, they allow the qualitative search for a wider range of contaminants, by detecting and assigning chemical signals in environmental samples. In this context, this thesis work aims to identify transformation products of selected pesticides, through the implementation of innovative analytical strategies based on suspected and non-targeted analytical approaches. A workflow was developed, using and confronting in-silico prediction tools with literature data, leading to the creation of improved databases, needed for the suspected analysis of pesticide transformation products. This workflow was applied to tebuconazole to identify its transformation products in the water and soil matrices in a controlled 120-day laboratory experiment. In addition to this methodology, the application of a non-targeted analysis identified TPs not detected by the suspect analysis. Based on data from the literature and national and European regulations, this workflow was extended to all pesticides applied or having been applied in viticulture in France. Created databases allowed the identification of pesticides and associated TPs through the suspect analysis of environmental samples of various matrices taken from an agricultural parcel in a vineyard watershed (Site Atelier Ardières Morcille).

References

• Anagnostopoulou, K., Nannou, C., Evgenidou, E. and Lambropoulou, D. (2022) Overarching issues on relevant pesticide transformation products in the aquatic environment: A review. Science of The Total Environment 815, 152863.
• Escher, B.I., Stapleton, H.M. and Schymanski, E.L. (2020) Tracking complex mixtures of chemicals in our changing environment. Science 367(6476), 388.
• Fenner, K., Canonica, S., Wackett, L.P. and Elsner, M. (2013) Evaluating Pesticide Degradation in the Environment: Blind Spots and Emerging Opportunities. Science 341(6147), 752-758.
• Merel, S., Margoum, C., Rocco, K., Coquery, M. and Miège, C. (2021) Focus - Intérêt pour la directive cadre européenne sur l’eau de l'analyse chimique non-ciblée de micropolluants organiques dans les milieux aquatiques. Science Eaux & Territoires 37 (Directive cadre européenne sur l’eau – Bilan de vingt années de recherche pour la reconquête de la qualité des masses d’eau), p. 110-113.
• Moschet, C., Piazzoli, A., Singer, H. and Hollender, J. (2013) Alleviating the Reference Standard Dilemma Using a Systematic Exact Mass Suspect Screening Approach with Liquid Chromatography- High Resolution Mass Spectrometry. Analytical Chemistry 85(21), 10312-10320.
• Pérez-Lucas, G., Vela, N., El Aatik, A. and Navarro, S. (2019) Environmental risk of groundwater pollution by pesticide leaching through the soil profile. Pesticides-use and misuse and their impact in the environment, Chapter 3 (IntechOpen, ISBN: I978-1-83880-047-5), 1-28.
• Rocco, K., Coquery, M., Margoum, C. (2021) Identification de produits de transformation de pesticides dans les milieux aquatiques : enjeux et verrous de l’analyse suspectée par LC-HRMS. Présentation Orale, SEP 2021 (http://www.sep2021.fr/programme-sep21)

Cite the thesis

Kevin Rocco. Stratégies analytiques innovantes pour étudier le devenir des pesticides dans les hydrosystèmes. Ecologie, Environnement. Université Claude Bernard - Lyon I, 2023. Français. ⟨NNT : 2023LYO10093⟩. ⟨tel-04515491⟩

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