Flow patterns and pathways of legacy and contemporary pesticides in surface waters in tropical volcanic catchments

Voltz Marc, Andrieux Patrick, Samouelian Anatja, Ponchant Lise, Grünberger Olivier, Bajazet Thierry, Comte Irina, Nanette Jean-Baptiste, Onapin Germain, Bussière François, Richard Antoine. 2023. Flow patterns and pathways of legacy and contemporary pesticides in surface waters in tropical volcanic catchments. Science of the Total Environment, 893:164815, 15 p.

http://doi.org/10.1016/j.scitotenv.2023.164815

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Résumé : Severe water pollution issues due to legacy and contemporary pesticides exist in tropical regions and are linked to cash crops requiring intensive plant protection practices. This study aims to improve knowledge about contamination routes and patterns in tropical volcanic settings to identify mitigation measures and analyse risk. To this aim, this paper analyses four years of monitoring data from 2016 to 2019 of flow discharge and weekly pesticide concentrations in the rivers of two catchments grown predominantly with banana and sugar cane in the French West Indies. The banned insecticide chlordecone, applied in banana fields from 1972 to 1993, was still the major source of river contamination, while the currently used herbicide glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and postharvest fungicides also exhibited high contamination levels. A value of 0.5 of the Gustafson Ubiquity Score (GUS) was shown to separate contaminant and noncontaminant pesticides, indicating a high vulnerability to pollution by pesticides in this tropical volcanic context. The patterns and routes of river exposure to pesticides differed markedly between the pesticides in accordance with the hydrological behaviour of volcanic islands and the history and nature of pesticide uses. Concerning chlordecone and its metabolites, observations confirmed previous findings of a main subsurface origin of river contamination by this compound but also showed large erratic short-term variations, suggesting the influence of fast surface transport processes such as erosion for legacy pesticides with large sorption capacity. Concerning herbicides and postharvest fungicides, observations have suggested that surface runoff and fast lateral flow in the vadose zone control river contamination. Accordingly, mitigation options need to be considered differently for each type of pesticide. Finally, this study points out the need for developing specific exposure scenarios for tropical agricultural contexts in the European regulation procedures for pesticide risk assessment.

Mots-clés Agrovoc : pesticide, pollution de l'eau, chlordécone, pollution par l'agriculture, Musa, zone tropicale, lutte après récolte

Mots-clés géographiques Agrovoc : France, Guadeloupe, Antilles françaises, rivière Cane

Mots-clés libres : Chlordecone, Glyphosate, Fungicides, River contamination, Banana, Sugar cane

Classification Agris : H02 - Pesticides
P02 - Pollution

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Agences de financement européennes : European Commission, European Regional Development Fund

Agences de financement hors UE : Conseil Regional de la Guadeloupe

Projets sur financement : (EU) RIVAGE

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