International audience | The influence of earthworm activity on soil-to-plant metal transfer was studied by carrying out six weeks mesocosms experiments with or without lettuce and/or earthworms in soil with a gradient of metal concentrations due to particles fallouts. Soil characteristics, metal concentrations in lettuce and earthworms were measured and soil porosity in the mesocosms was determined. Earthworms increased the soil pH, macroporosity and soil organic matter content due to the burying of wheat straw provided as food. Earthworm activities increased the metals concentrations in lettuce leaves. Pb and Cd concentrations in lettuce leaves can increase up to 46% with earthworm activities ... These results and the low correlation between estimated by CaCl2 and EDTA and measured pollutant phytoavailability suggest that earthworm bioturbation was the main cause of the increase. Bioturbation could affect the proximity of pollutants to the roots and soil organic matter.

International audience | The influence of earthworm activity on soil-to-plant metal transfer was studied by carrying out six weeks mesocosms experiments with or without lettuce and/or earthworms in soil with a gradient of metal concentrations due to particles fallouts. Soil characteristics, metal concentrations in lettuce and earthworms were measured and soil porosity in the mesocosms was determined. Earthworms increased the soil pH, macroporosity and soil organic matter content due to the burying of wheat straw provided as food. Earthworm activities increased the metals concentrations in lettuce leaves. Pb and Cd concentrations in lettuce leaves can increase up to 46% with earthworm activities ... These results and the low correlation between estimated by CaCl2 and EDTA and measured pollutant phytoavailability suggest that earthworm bioturbation was the main cause of the increase. Bioturbation could affect the proximity of pollutants to the roots and soil organic matter.

publishedVersion | On-site small-scale sanitation is common in rural areas and areas without infrastructure, but the treatment of the collected fecal matter can be inefficient and is seldom directed to resource recovery. The aim of this study was to compare low-technology solutions such as composting and lactic acid fermentation (LAF) followed by vermicomposting in terms of treatment efficiency, potential human and environmental risks, and stabilization of the material for reuse in agriculture. A specific and novel focus of the study was the fate of native pharmaceutical compounds in the fecal matter. Composting, with and without the addition of biochar, was monitored by temperature and CO2 production and compared with LAF. All treatments were run at three different ambient temperatures (7, 20, and 38°C) and followed by vermicomposting at room temperature. Materials resulting from composting and LAF were analyzed for fecal indicators, physicochemical characteristics, and residues of ten commonly used pharmaceuticals and compared to the initial substrate. Vermicomposting was used as secondary treatment and assessed by enumeration of Escherichia coli, worm density, and physicochemical characteristics. Composting at 38°C induced the highest microbial activity and resulted in better stability of the treated material, higher N content, lower numbers of fecal indicators, and less pharmaceutical compounds as compared to LAF. Even though analysis of pH after LAF suggested incomplete fermentation, E. coli cell numbers were significantly lower in all LAF treatments compared to composting at 7°C, and some of the anionic pharmaceutical compounds were detected in lower concentrations. The addition of approximately 5 vol % biochar to the composting did not yield significant differences in measured parameters. Vermicomposting further stabilized the material, and the treatments previously composted at 7°C and 20°C had the highest worm density. These results suggest that in small-scale decentralized sanitary facilities, the ambient temperatures can significantly influence the treatment and the options for safe reuse of the material.

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. | 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.

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Conséquences des pollutions atmosphériques sur l'agriculture et la forêt. Séminaire Agriculture et pollution de l’air

This paper aims at gaining an insight into the PM10 daily threshold (50 micro g/m3) exceedances measured by French regional air quality monitoring networks for the last four years. As almost three quarter of these exceedances happens to occur between November and April, we focus here on such winter (broadly speaking) pollution episodes. The deployment of monitoring devices allowing for a proper account of semi-volatile material within PM10 was achieved concomitantly to the development particulate pollution episodes largely influenced by ammonium nitrate (which is semi-volatile) in March-April 2007. Since then, such pollution events are frequently observed at this period of the year, notably due to stable meteorological conditions favoring the condensation of semi-volatile material into the particulate phase along with the resumption of manure spreading, which constitutes a major source of ammonium nitrate gaseous precursors (at least at some points of the year). Such pollution events, which are also related to combustion emissions (among which mobile sources) are typically preceded, from November to February, by frequent daily threshold exceedances with potentially significant influences of biomass burning (e.g. residential wood burning). The winter period is also impacted by long range transport episodes, corresponding notably to increases of ammonium sulfate relative abundances within PM10. Moreover, as traffic sites are generally the first ones showing PM10 exceedances due the increment of direct emissions and resuspension processes, mobile sources are also considered as a major target for action plans. Finally, it is underlined that the occurrence of daily threshold exceedances is highly influenced by meteorological conditions, so that the yearly number of these exceedances shows well-marked inter-annual variations, with 2009 and 2011 (and 2012, but not shown here) being significantly more polluted than 2008 and 2010. The on-going development of efficient forecasting systems still suffer lacks of detailed emission inventories and strong knowledge on the physical and chemical transformation processes of particles and their gaseous precursors within the boundary layer. | Cette synthèse dresse une analyse non exhaustive des dépassements du seuil réglementaire journalier de 50 micro g/m3 pour les PM10 mesurés au niveau national par les Associations Agréées de Surveillance de la Qualité de l'Air (AASQA) au cours des quatre dernières années. Près des trois quarts de ces dépassements étant observés entre fin novembre et début avril, nous nous intéressons plus particulièrement ici à ces épisodes hivernaux (au sens large). La mise en oeuvre de techniques analytiques permettant une prise en compte correcte des espèces semi-volatiles dans la composition des PM10 a coïncidé en mars-avril 2007 à la survenue de nombreux dépassements de seuil journalier s'accompagnant d'importants niveaux de nitrate d'ammonium (composé semi-volatil). Ce type d'épisode est régulièrement observé à cette période. Il s'explique notamment par la conjonction de conditions atmosphériques stables et propices à la condensation en phase particulaire des espèces labiles, et de la reprise des épandages agricoles, constituant une source majeure, au moins ponctuellement, de précurseurs gazeux azotés du nitrate d'ammonium. Ce type d'épisode, mettant également en cause les émissions anthropiques de combustion (dont les transports), est typiquement précédé entre novembre et février de fréquents dépassements pour lesquels le rôle des combustions de biomasse (incluant notamment le chauffage au bois individuel) peut être important. La période hivernale est également marquée par l'occurrence de phénomènes de transport longue distance se caractérisant par une augmentation des contributions du sulfate d'ammonium. Les sites de proximité automobile étant généralement les premiers concernés par les dépassements du seuil journalier en raison du surplus de concentrations provenant des émissions à l'échappement et des phénomènes de remise en suspension, le transport routier est également considéré comme un levier incontournable pour le respect des valeurs limites. Enfin, il est souligné que l'occurrence des différents types d'épisodes de dépassements dépend fortement des conditions météorologiques, de sorte qu'on observe une forte variabilité interannuelle du nombre de dépassements hivernaux ? : 2009 et 2011 (et 2012) étant significativement plus impactées que 2008 et 2010. Une bonne prévision de ces épisodes passe encore par l'affinage des cadastres d'émission et une meilleure compréhension du devenir dans l'atmosphère des émissions primaires (gazeuses et particulaires).