Simultaneous simulations of uptake in plants and leaching to groundwater of cadmium and lead for arable land amended with compost or farmyard manure.

he water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year experimental field study, where four organic amendments were applied every second year. Predicted concentrations slightly decreased (Cd) or stagnated (Pb) in control soils, but increased in amended soils by about 10% (Cd) and 6% to 18% (Pb). Estimated plant uptake was lower in amended plots, due to an increase of Kd (dry soil to water partition coefficient). Predicted concentrations in plants were close to measured levels in plant residues (straw), but higher than measured concentrations in grains. Initially, Pb was mainly predicted to deposit from air into plants (82% in 1998); the next years, uptake from soil became dominating (30% from air in 2006), because of decreasing levels in air. For Cd, predicted uptake from air into plants was negligible (1–5%)

Conséquences de la variabilité spatiale et temporelle de l anoxie sur le devenir du sélénium dans le sol

Le sélénium est un micro-élément essentiel qui peut être toxique aux concentrations classiquement trouvées dans les sols et les sédiments. De plus, l un de ses isotopes est présent dans les déchets radioactifs de longue vie, faisant l objet de recherches sur la faisabilité d un stockage géologique profond. Les réactions du sélénium dans les sols et son impact sur les activités microbiennes ont été peu étudiés à des teneurs dites non toxiques. Les transformations du sélénium sont très sensibles à l aération, aux activités microbiennes et aux conditions d oxydoréduction qui peuvent être hétérogènes dans un sol structuré. Cette hétérogénéité, présente à différentes échelles (dans un profil vertical de sol, dans la rhizosphère, à proximité de matières organiques en décomposition et au centre des agrégats de sol), pourrait avoir de fortes conséquences sur les prédictions du devenir du sélénium faites à partir des valeurs moyennes de certains paramètres du sol. Cette étude a été réalisée en deux parties: des incubations d agrégats de sols en conditions contrôlées aérobies ou anaérobies strictes, une expérience avec des colonnes d agrégats de sol compactés où existait un gradient vertical d humidité, conduisant à des conditions d aération variables. Les activités respiratoires ont été suivies au cours du temps et des mesures ponctuelles ont permis de caractériser les changements au niveau des populations et activités microbiennes, et du fractionnement chimique du sélénium dans le sol. L ajout de sélénium a modifié les activités microbiennes, en particulier en conditions anaérobies, révélant de probables changements au sein des populations microbiennes. Les pertes nettes de sélénium par volatilisation ont été très différentes suivant les sols et pour l un des sols, elles ont augmenté avec la quantité de sélénium apportée. Ces pertes ont été plus importantes dans les colonnes de sol compactées que dans les sols incubés sans compactage. La mobilité verticale du sélénium dans les colonnes de sol a résulté de flux en solution mais aussi d autres processus mal identifiés. Le sélénium a été fortement immobilisé dans les sols anaérobies, à la fois dans la zone saturée en eau des colonnes et en conditions contrôlées anaérobies. En conditions aérées, cette tendance à devenir moins extractible a été beaucoup moins marquée pour tous les sols. Il a été difficile de relier de façon simple la valeur de la fraction volumique anoxique dans les colonnes de sol à des modifications du fractionnement chimique du séléniumSelenium is an essential micronutrient that is potentially toxic at concentrations close to the normal range found in soils and sediments. Furthermore one of its isotopes is an important component of long-lived radioactive waste for which long term geological storage is planned. Few data exist on the dynamics of selenium in soil and its impact on microbial activity at levels usually considered to be non toxic. The dynamics of selenium are strongly sensitive to aeration, microbial activity and redox conditions which may be very heterogeneous in structured soil. This heterogeneity, present at various scales (in a vertical soil profile, in the rhizosphere, near decomposing organic matter and at the centre of soil aggregates), could have important consequences on the prediction of the fate of selenium based on average measurements of soil properties. This investigation was carried out at two levels; controlled studies of aggregated moist soil incubated under aerobic or strictly anaerobic conditions and in columns packed with soil aggregates with a vertical moisture gradient, imposing varying aeration conditions. Respiratory activity was monitored and changes in microbial populations, microbial activity and selenium chemical fractionation in soil were measured. Selenium addition modified microbial activity, particularly under anaerobic conditions, reflecting probable changes in microbial populations. Net losses from soil by selenium volatilization varied considerably between soils and for one soil increased with increasing level of selenium. Volatilization losses were much larger from the compacted columns than from the looser packed soils. Solute flux but also poorly identified processes contributed to the observed vertical mobility of selenium in soil columns. Selenium was strongly immobilized in anaerobic soils, both in the water-saturated zone of the columns and in the anaerobic incubations. There was a less marked tendency for selenium to become less easily extractable in soils incubated under aerated conditions. In soil columns, there was not a simple relation between the volumic fraction of anoxic soil and changes in selenium fractionationAVIGNON-BU Centrale (840072102) / SudocSudocFranceF

Fate of 14C-acetyl sulfamethoxazole during the activated sludge process

Compared to antibiotic parent molecule, human metabolites are generally more polar and sometimes not less toxic in wastewater.However, most researches focus on the fate of parent molecule. Therefore, behaviors of human metabolites are little known.Moreover, though much has been done on the fate of antibiotics during activated sludge process, there are still some limitationsand gaps. In the present study, [Ring-14C] acetyl sulfamethoxazole (14C-Ac-SMX) was used to investigate the fate of humanmetabolite of SMX during activated sludge process at environmentally relevant concentration. At the end of 216 h, 3.1% of thespiked activity in the initial aqueous phase was mineralized, 50% was adsorbed onto the solid phase, and 36.5% still remained inthe aqueous phase, indicating that adsorption, not biodegradation, was the main dissipation pathway. In the existence of microbialactivities, accumulation into the solid phase was much higher, which was less bioavailable by chemical sequential extraction. Themultimedia kinetic model simultaneously depicted the fate of Ac-SMX in the gas, aqueous, and solid phases, and demonstratedthat microbially accelerated accumulation onto the solid phase was attributed to lower desorption rate from the solid phase to theaqueous phase, where adsorption rate was not the key factor. Therefore, Ac-SMX cannot be efficiently mineralized and remain inthe aqueous or the solid phases. The accumulation in the solid phase is less bioavailable and is hard to be desorbed in the existenceof microbial activities, and should not be easily degraded, and may lead to the development of antibiotic-resistant bacteria andgenes after discharge into the environment

The COP-SOIL model for mineralization and bioavailability of organic micropollutants during composts decomposition in soil

UMR INRA EGC et PESSAC, Véolia EnvironnementThe COP-SOIL model for mineralization and bioavailability of organic micropollutants during composts decomposition in soil. 15. International Conferences of RAMIRAN (Network on Recycling of Agricultural, Municipal and Industrial Residues in Agriculture

Effect of aeration on mobility of selenium in columns of aggregated soil as influenced by straw amendment and tomato plant growth

International audienceSelenium is an essential nutrient that is potentially toxic: one of its radio-elements is also a component of long-lived radioactive waste for which long-term deep geological storage is envisaged. The chemistry of Se in soils is complex and very sensitive to redox potential and microbial activity which largely determine its oxidation state and chemical form. The dynamics of Se have been extensively studied in soils where it is deficient, and even more so when concentrations are potentially toxic. In contrast, relatively little information is available on the fate of Se in soils at intermediate concentrations (1–5 mg kg− 1). Some chemical reactions and biological processes that influence Se dynamics may be strongly concentration dependent. We have followed microbial activity by monitoring soil gas composition and Se volatilization and measured changes in Se fractionation using chemical extractions in a column of aggregated soil. A small proportion of soil Se was accumulated in the leaves, stems and fruits of tomato plants. Net Se volatilization losses were small (0.12% in a two-month period). There was a considerable upward movement of freshly added Se, but not of native soil Se. This vertical mobility was greater than that predicted from solute movement driven by evaporation. Selenium was strongly immobilized at the water-saturated, anoxic base of the soil columns. Straw amendment and the growth of a tomato plant did not lead to stronger association with soil organic matter. It was not possible to correlate changes in fractionation of Se between treatments and along a soil profile with the calculated fraction of anoxia, except in the completely anoxic zone

Dynamics of Tc Immobilization in Soils Under Flooded Conditions and Extent of Reoxidation Following Aeration

International audienceThe dynamics and bioavailability of 99Tc, an important radioactive contaminant, depend largely on its redox state. Both biotic and abiotic reactions determine the rate, extent and reversibility of Tc immobilization. We monitored Tc solubility and chemical extractability in five contrasting soils. Tc remained water-soluble in aerated soils, but was immobilized under flooded conditions. Immobilization was only partly reversible. Immobilized Tc was associated with soil organic matter and was possibly chemically reduced in one soil. Water solubility was a sensitive probe of Tc dynamics. The extent of immobilization and reversibility were not simple functions of soil chemical or biological properties

Development of a soft extraction method for sulfamethoxazole and transformation products from agricultural soils: Effects of organic matter co-extraction on the environmental availability assessment

The recycling of biosolids and livestock manure in agriculture may lead to the introduction of antibiotic residues, i.e., parent molecule and transformation products, into amended soils. Their fate in soils can be approached through the assessment of their environmental availability. In this work, the environmental availability of sulfamethoxazole (SMX) and three transformation products (N4-acetyl-SMX, 3-amino-5-methylisoxazole, aniline) was assessed in soils amended with sludge compost or cow manure throughout a three-month incubation, using soft extractions with CaCl2, EDTA or cyclodextrin solutions. First, the freeze-storage of soil samples was shown to decrease the SMX extractability. The SMX extractability depended on the initial concentration, the amendment type and the extracting solution at day 0. From 1.9% up to 63% of the SMX total content was initially extractable. The lowest fractions were quantified in EDTA extracts in which the dissolved organic matter was the most complex and responsible for high matrix effects in mass spectrometry compared to CaCl2 extracts. The purification of cyclodextrin extracts highly reduced the matrix effects, but CaCl2 was considered as the most suitable extractant. SMX extractability strongly decreased after the first 8days of incubation to finally reach 0.4-0.8% after 84days, whatever the initial conditions. This high decrease could be related to humification observed through the increasing complexity of extracted dissolved organic matter. Very low levels of transformation products were quantified throughout the incubation period. The low environmental availability of SMX was mainly due to its sorption on soil organic matter and resulted in its low biotransformation in these amended soils

A new UHPLC-MS/MS analytical method to assess the environmental availability of sulfamethoxazole and three transformation products in soil amended with manure

A new UHPLC-MS/MS analytical method to assess the environmental availability of sulfamethoxazole and three transformation products in soil amended with manure. 1st International Conference on the Risk Assessment of PHarmaceuticals in the Environmen

Contribution of chemical inputs on the trace elements concentrations of surface soils in urban allotment gardens

International audienceAbstractPurposeUrban soil contamination by heavy metals is one of the foremost challenges for urban soil quality, especially in the urban agriculture context. Urban gardening is a common practice in many industrialized and developing countries. How sources of soil contamination relate to inputs and influence the heavy metal content in soils, however, is not established yet.Materials and methodsThis study aims to assess the potential of pesticide applications (such as Bordeaux mixture) on soil quality. A set of 104 allotment gardens was selected in three cities in France, and topsoil was sampled and analyzed.Results and discussionThe four most abundant metals in urban vegetable garden topsoils were Zn, Pb, Cu, and Cr. The past and/or present industrial and urban activities are not the only cause of the metal contamination in urban vegetable garden soils. Gardens, where pesticides such as the Bordeaux mixture are being used showed significantly higher total Cu values in soils (78 mg kg−1 compared with 49 mg kg−1 for untreated gardens).ConclusionsEven though the risk of metal contamination through vegetable consumption is usually considered low, we clearly identified indicators of anthropogenic Cd, Cu, Pb, and Zn pollution due to pesticides inputs. This link was particularly strong between the use of Bordeaux mixture and increases Cu levels

Assessing the environmental availability of sulfamethoxazole and its acetylated metabolite in agricultural soils amended with compost and manure: an experimental and modeling study

Assessing the environmental availability of sulfamethoxazole and its acetylated metabolite in agricultural soils amended with compost and manure: an experimental and modeling study. EGU 2017, European Geophysical Union General Assembly 201