International audience | The herbicide diuron is frequently applied to vineyard soils in Burgundy, along with repeated treatments with Bordeaux mixture (a blend of copper sulfate and calcium hydroxide) that result in elevated copper concentrations. Cu could in principle affect the fate and transport of diuron or its metabolites in the soil either directly by complexation or indirectly by altering the populations or activity of microbes involved in their degradation. To assess the effect of high Cu concentrations on diuron transport, an experiment was designed with ten undisturbed columns of calcareous and acidic soils contaminated with 17–509 mg kg−1 total Cu (field-applied). Grass was planted on three columns. Diuron was applied to the soils in early May and in-ground lysimeters were exposed to outdoor conditions until November. Less than 1.2% of the diuron applied was found in the leachates as diuron or its metabolites. Higher concentrations were found in the effluents from the grass-covered columns (0.1–0.45%) than from the bare-soil columns (0.02–0.14%), and they were correlated with increases in dissolved organic carbon. The highest amounts of herbicide were measured in acidic-soil column leachates (0.98–1.14%) due to the low clay and organic matter contents of these soils. Cu also leached more readily through the acidic soils (32.8–1042 μg) than in the calcareous soils (9.5–63.4 μg). Unlike in the leachates, the amount of diuron remaining in the soils at the end of the experiment was weakly related to the Cu concentrations in the soils. Cu accumulation, from Bordeaux mixture, in vineyard soils may be affecting microbial activity and thus slightly increasing the persistence of diuron in the soils. Cu accumulation, from Bordeaux mixture, in vineyard soils may be affecting microbial activity and thus slightly increasing the persistence of diuron in the soils.

National audience

International audience | Periurban areas, zone of transition between urban and rural areas, are submitted to several sources of pollution, both gaseous and particulate. These pollutions originate from local sources such as residential sector, traffic road and agricultural activities, but also from regional ones from adjacent urban and (pseudo-)natural areas. This paper presents a synthesis of the different sources affecting air quality in periurban areas. It is clear that pollutions from anthropogenic activities cannot be fully dissociated to those from (pseudo-)natural ecosystem functioning in these areas. Finally, the atmospheric pollution issues are discussed in emphasis with periurban agriculture, already present and under development in these areas due to the development of short food supply chains and local food consumptions. | Les territoires périurbains, zones de transition entre les zones urbaines et rurales, sont soumis à de nombreuses pollutions à la fois gazeuses et particulaires. Ces pollutions proviennent de sources locales comme les activités résidentielles, le trafic routier et les activités agricoles, mais également de sources régionales issues des activités urbaines et des émissions des zones (pseudo-)naturelles adjacentes. Cet article présente une synthèse des différentes sources de pollution affectant la qualité de l’air en milieu périurbain. Il est évident que les pollutions purement anthropiques ne peuvent être dissociées de celles issues du fonctionnement des écosystèmes (pseudo-)naturels dans ces espaces. Enfin, les enjeux vis-à-vis de l’agriculture périurbaine, fortement présente et en développement du fait d’une volonté de consommer des productions locales, sont discutés.

International audience | Aquatic wildlife is exposed through trophic transfer of hazardous substances to several threats inducing physiological impairments. We aimed at assessing the impact of contamination in one of the hot spots of pollution along Mediterranean coasts, the gulf of Gabes in Tunisia, on Common tern Sterna hirundo, a piscivorous top predator bird. Firstly, we compared the reproductive effort of breeding adults through clutch size distribution in three sites with different levels of pollution. Then, a battery of genotoxicity and oxidative stress biomarkers was carried out to assess physiological impairments in chicks. While defense mechanisms showed a depletion, lipid peroxidation and genotoxicity increased significantly according to pollution level. The multi-biomarker approach used here, discriminated chicks according to contamination degree of their nesting sites. Increases in genotoxicity and oxidative stress were correlated to a decrease in chick body mass known to lead to long-term impacts on juvenile survival and recruitment in birds.

International audience | The level and the ecological risk assessment of heavy metals (Zn, Cu, Mn, Fe, Ni, Cr, V, As, Pb, Cd and Co) were evaluated in surface sediments from fifty-one stations along the Algerian coast. The main objective was to evaluate the risk that such metals may cause to the ecosystem, and thus the stations were choose in relation with the fishing trawlable areas of Algeria. The usual chemical indexes Geoaccumulation index (Igeo), Enrichment factor (EF) and Pollution Load Index (PLI) as well as potential ecological risk index reveal that the metal pollution along this coast is low, and is only related to As contents. Nevertheless, the concentrations of Ni, Cr and As exceed their respective ERL values (Effect range low) usually applied for Sediment Quality Guideline. However, Cr and Ni are mainly natural and cannot be related to anthropogenic inputs and their ecotoxicological levels as to be questioned.

Polycyclic aromatic hydrocarbons (PAHs) are hardly biodegradable carcinogenic organic compounds. Bioremediation is a commonly used method for treating PAH contaminated environments such as soils, sediment, water bodies and wastewater. However, bioremediation has various drawbacks including the low abundance, diversity and activity of indigenous hydrocarbon degrading bacteria, their slow growth rates and especially a limited bioavailability of PAHs in the aqueous phase. Addition of nutrients, electron acceptors or co-substrates to enhance indigenous microbial activity is costly and added chemicals often diffuse away from the target compound, thus pointing out an impasse for the bioremediation of PAHs. A promising solution is the adoption of bioelectrochemical systems. They guarantee a permanent electron supply and withdrawal for microorganisms, thereby circumventing the traditional shortcomings of bioremediation. These systems combine biological treatment with electrochemical oxidation/reduction by supplying an anode and a cathode that serve as an electron exchange facility for the biocatalyst. Here, recent achievements in polycyclic aromatic hydrocarbon removal using bioelectrochemical systems have been reviewed. This also concerns PAH precursors: total petroleum hydrocarbons and diesel. Removal performances of PAH biodegradation in bioelectrochemical systems are discussed, focussing on configurational parameters such as anode and cathode designs as well as environmental parameters like porosity, salinity, adsorption and conductivity of soil and sediment that affect PAH biodegradation in BESs. The still scarcely available information on microbiological aspects of bioelectrochemical PAH removal is summarised here. This comprehensive review offers a better understanding of the parameters that affect the removal of PAHs within bioelectrochemical systems. In addition, future experimental setups are proposed in order to study syntrophic relationships between PAH degraders and exoelectrogens. This synopsis can help as guide for researchers in their choices for future experimental designs aiming at increasing the power densities and PAH biodegradation rates using microbial bioelectrochemistry.

International audience | Abstract Nanomaterials are increasingly being used to improve the properties and functions of common building materials. A new type of self-cleaning cement incorporating TiO2 nanomaterials (TiO2-NMs) with photocatalytic properties is now marketed. This promising cement might provide air pollution-reducing properties but its environmental impact must be validated. During cement use and aging, an altered surface layer is formed that exhibits increased porosity. The surface layer thickness alteration and porosity increase with the cement degradation rate. The hardened cement paste leaching behavior has been fully documented, but the fate of incorporated TiO2-NMs and their state during/after potential release is currently unknown. In this study, photocatalytic cement pastes with increasing initial porosity were leached at a lab-scale to produce a range of degradation rates concerning the altered layer porosity and thickness. No dissolved Ti was released during leaching, only particulate TiO2-NM release was detected. The extent of release from this batch test simulating accelerated worst-case scenario was limited and ranged from 18.7 ± 2.1 to 33.5 ± 5.1 mg of Ti/m2 of cement after 168 h of leaching. TiO2-NMs released into neutral aquatic media (simulate pH of surface water) were not associated or coated by cement minerals. The TiO2-NM release mechanism is suspected to start from freeing of TiO2-NMs in the altered layer pore network due to partial cement paste dissolution followed by diffusion into the bulk pore solution to the surface. The extent of TiO2-NM release was not solely related to the cement degradation rate.