International audience | Introduction: The degradation and mineralization of two triketone (TRK) herbicides, including sulcotrione and mesotrione, by the electro-Fenton process (electro-Fenton using Pt anode (EF-Pt), electro-Fenton with BDD anode (EF-BDD) and anodic oxidation with BDD anode) were investigated in acidic aqueous medium. Methods: The reactivity of both herbicides toward hydroxyl radicals was found to depend on the electron-withdrawing effect of the aromatic chlorine or nitro substituents. The degradation of sulcotrione and mesotrione obeyed apparent first-order reaction kinetics, and their absolute rate constants with hydroxyl radicals at pH 3. 0 were determined by the competitive kinetics method. Results and discussion: The hydroxylation absolute rate constant (kabs) values of both TRK herbicides ranged from 8. 20 × 108 (sulcotrione) to 1. 01 × 109 (mesotrione) L mol-1 s-1, whereas those of the TRK main cyclic or aromatic by-products, namely cyclohexane 1,3-dione, (2-chloro-4-methylsulphonyl) benzoic acid and 4-(methylsulphonyl)-2-nitrobenzoic acid, comprised between 5. 90 × 108 and 3. 29 × 109 L mol-1 s-1. The efficiency of mineralization of aqueous solutions of both TRK herbicides was evaluated in terms of total organic carbon removal. Mineralization yields of about 97-98% were reached in optimal conditions for a 6-h electro-Fenton treatment time. Conclusions: The mineralization process steps involved the oxidative opening of the aromatic or cyclic TRK by-products, leading to the formation of short-chain carboxylic acids, and, then, of carbon dioxide and inorganic ions.

International audience

International audience | Alkylphenols and alkylphenol ethoxylates (APE) are toxics classified as endocrine-disrupting compounds; they are used in detergents, paints, herbicides, pesticides, emulsifiers, wetting and dispersing agents, antistatic agents, demulsifiers, and solubilizers. Many studies have reported the occurrence of alkylphenols in different environmental matrices, though none of these studies have yet to establish a comprehensive overview of such compounds in the water cycle within an urban environment. This review summarizes APE concentrations for all environmental media throughout the water cycle, from the atmosphere to receiving waters. Once the occurrence of compounds has been assessed for each environmental compartment (urban wastewater, wastewater treatment plants [WWTP], atmosphere, and the natural environment), data are examined in order to understand the fate of APE in the environment and establish their geographical and historical trends. From this database, it is clear that the environment in Europe is much more contaminated by APE compared to North America and developing countries, although these APE levels have been decreasing in the last decade. APE concentrations in the WWTP effluent of developed countries have decreased by a factor of 100 over the past 30 years. This study is aimed at identifying both the correlations existing between environmental compartments and the processes that influence the fate and transport of these contaminants in the environment. In industrial countries, the concentrations observed in waterways now represent the background level of contamination, which provides evidence of a past diffuse pollution in these countries, whereas sediment analyses conducted in developing countries show an increase in APE content over the last several years. Finally, similar trends have been observed in samples drawn from Europe and North America.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699 | International audience | P-spiked Linz-Donawitz (LD) slag was used as a soil additive to improve physico-chemical soil properties and in situ stabilize Cu and other trace metals in a sandy Cu-contaminated soil (630 mg kg-1 soil) from a former wood preservation site. The LD slag was incorporated into the contaminated soil to consist four treatments: 0 % (T1), 1 % (T2), 2 % (T3), and 4 % (T4) per air-dried soil weight. A similar uncontaminated soil was used as a control (CTRL). After a one-month reaction period, potted soils (1kg) were used for a 2-week growth experiment with dwarf beans (Phaseolus vulgaris L.). Soil pH increased with the incorporation rate of LD slag from 5.7 in the T1 soil up to 7.9 in the T4 soil. Similarly the soil electrical conductivity (EC, in mS cm- 1) rose from 0.15 (T1 soil) up to 1.17 (T4 soil). Bean plants grown on the T1 soil showed a high phytotoxicity. All incorporation rates of LD slag increased the root and shoot dry weight yields compared to the untreated soil (T1). The foliar Ca concentration of beans was enhanced for all LD slag-amended soils, while the foliar Mg, K, and P concentrations were not increased. Foliar Cu, Zn, and Cr concentrations of beans decreased with the LD slag incorporation rate. The 2% incorporation rate was sufficient to obtain the highest bean growth and foliar Ca concentration, to reduce foliar Cu concentration below its upper critical value, and to avoid an excessive soil EC and Zn deficiency.

Book chapter | IFPRI4; 2020 | Non-PR | DGO

This study is a first attempt to investigate the impact of urban contamination on metal tolerance of heterotrophic river biofilms using a short-term test based on beta-glucosidase activity. Tolerance levels to Cu, Cd, Zn, Ni and Pb were evaluated for biofilms collected at three sites along an urban gradient in the Seine river (France). Metallic pollution increased along the river, but concentrations remained low compared to environmental quality standards. Biofilm metal tolerance increased downstream from the urban area. Multivariate analysis confirmed the correlation between tolerance and contamination and between multi-metallic and physico-chemical gradients. Therefore, tolerance levels have to be interpreted in relation to the whole chemical and physical characteristics and not solely metal exposure. We conclude that community tolerance is a sensitive biological response to urban pressure and that mixtures of contaminants at levels lower than quality standards might have a significant impact on periphytic communities. (C) 2011 Elsevier Ltd. All rights reserved.

Non-PR | IFPRI4; 2020 | DGO

Although recent research has shown that marine litter has made it even to the remotest parts of our planet, little information is available about temporal trends on the deep ocean floor. To quantify litter on the deep seafloor over time, we analysed images from the HAUSGARTEN observatory (79°N) taken in 2002, 2004, 2007, 2008 and 2011 (2500m depth). Our results indicate that litter increased from 3,635 to 7,710 items km-2 between 2002 and 2011 and reached densities similar to those reported from a canyon near the Portuguese capital Lisboa. Plastic constituted the majority of litter (59%) followed by a black fabric (11%) and cardboard/paper (7%). 67% of the litter was entangled or colonised by invertebrates such as sponges (41%) or sea anemones (15%). The changes in litter could be an indirect consequence of the receding sea ice, which opens the Arctic Ocean to the impacts of man’s activities.

International audience | This study examined the distribution of virioplankton and bacterioplankton in two coral reef systems (Ahe and Takaroa atolls) in the Tuamotu Archipelago, in comparison with the surrounding oligotrophic ocean. Mean concentrations of 4.8 x 10^5 and 6.2 x 10^5 cells ml-1 for bacteria and 8.1 x 10^6 and 4.3 x 10^6 VLP (virus-like particle) ml-1 were recorded in Ahe and Takaroa lagoons, respectively. Chlorophyll a concentrations and dissolved organic matter were higher in Ahe whereas 3H thymidine incorporation rates were higher in Takaroa. First data on lytic and lysogenic strategies of phages in coral reef environments were discussed in this paper. The fraction of visibly infected cells by viruses was negligible regardless of the lagoon station (mean = 0.15%). However, the fraction of lysogenic cells ranged between 2.5% and 88.9%. Our results suggest that the distribution patterns of virioplankton are apparently not coupled to the spatial dynamics of the bacterioplankton communities.

International audience | This study examined the distribution of virioplankton and bacterioplankton in two coral reef systems (Ahe and Takaroa atolls) in the Tuamotu Archipelago, in comparison with the surrounding oligotrophic ocean. Mean concentrations of 4.8 x 10^5 and 6.2 x 10^5 cells ml-1 for bacteria and 8.1 x 10^6 and 4.3 x 10^6 VLP (virus-like particle) ml-1 were recorded in Ahe and Takaroa lagoons, respectively. Chlorophyll a concentrations and dissolved organic matter were higher in Ahe whereas 3H thymidine incorporation rates were higher in Takaroa. First data on lytic and lysogenic strategies of phages in coral reef environments were discussed in this paper. The fraction of visibly infected cells by viruses was negligible regardless of the lagoon station (mean = 0.15%). However, the fraction of lysogenic cells ranged between 2.5% and 88.9%. Our results suggest that the distribution patterns of virioplankton are apparently not coupled to the spatial dynamics of the bacterioplankton communities.