Evaluation du rôle des phases dissoutes et particulaires dans la contamination en Chlordécone en rivière

International audienc

Monitoring agricultural pollutions from the catchment area to coastal areas

International audienceCoastal marine environments are particularly exposed to pollutants emanating from human activities such as agriculture. Phytosanitary products follow the path of the water cycle, reaching rivers and aquifers, then coastal waters through run-off, infiltrations and resurgences. « OPALE » is an observatory dedicated to the monitoring of agricultural pollutions at the scale of the rivers Pérou-Père catchment area, located in Guadeloupe (Lesser Antilles). The main objectives of OPALE are to monitor and make available data on contamination levels and study the transfer of pollutants between the different aquatic compartments (surface waters, groundwaters and coastal waters)

Monitoring agricultural pollutions from the catchment area to coastal areas

International audienceCoastal marine environments are particularly exposed to pollutants emanating from human activities such as agriculture. Phytosanitary products follow the path of the water cycle, reaching rivers and aquifers, then coastal waters through run-off, infiltrations and resurgences. « OPALE » is an observatory dedicated to the monitoring of agricultural pollutions at the scale of the rivers Pérou-Père catchment area, located in Guadeloupe (Lesser Antilles). The main objectives of OPALE are to monitor and make available data on contamination levels and study the transfer of pollutants between the different aquatic compartments (surface waters, groundwaters and coastal waters)

Co-Design and Experimentation of a Prototype of Agroecological Micro-Farm Meeting the Objectives Set by Climate-Smart Agriculture

Developing climate-smart agriculture is an urgent necessity to ensure the food security of a growing global population, to improve the adaptation of agricultural systems to climatic hazards, and to reach a negative carbon balance. Different approaches are being explored to achieve those objectives, including the development of new technologies for efficiency improvements to current systems and substitution of chemical inputs by bio-inputs, but the urgency of the climatic, social, and environmental context calls for more disruptive actions to be taken. We propose an approach to the design of climate-smart production systems structured in four steps: (1) diagnosis of the study region on the basis of the three pillars of climate-smart agriculture, (2) co-design of a disruptive system only based on agroecological and bioeconomic principles, (3) long-term experimentation of this system, and (4) in itinere adjustment of the system based on collected data and on-field evaluations with agricultural stakeholders. The outcome of this approach is the agroecological microfarm named KARUSMART, settled in 2018 on one hectare in the North Basse-Terre region of Guadeloupe (F.W.I.). This study presents its co-design and experimentation stages as well as the first performance results. At the end of the first two years, this microfarm showed a clear improvement in 15 of the 19 indicators used to evaluate the performance of the actual farming systems in the study region. Among the most striking results are a clear superiority in nutritional performance from 3 pers.ha−1 to 8 pers.ha−1 and a reduction in GHG balance from +2.4 tCO2eq.ha−1 to −1.1 tCO2eq.ha−1 for the study area and the microfarm, respectively. These results are promising for developing climate-smart agricultural systems and need to be consolidated further through longer-term monitoring data, the implementation of more similar systems in the study area, and the implementation of the design principles in other contexts

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

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