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International audience; Irrigated maize-based Cropping Systems (CS) are questioned because of the high risk of herbicide transfer to water. An 8-year systemic experiment was conducted to i) compute a multi-performance comparison between a Conventional Maize Monoculture (MMConv) and four CS that aimed to reduce irrigation and herbicide leaching: MMLI, a low-input MM using cover crop and Integrated Weed Management (IWM) techniques; MMStill, a Strip-tillage MM using cover crop; MMCT, a Conservation Tillage MM with cover crop; Maize-MSW, an IWM Maize rotated with Soybean and Wheat and ii) determine the main drivers and evaluate the influence of CS on herbicide leaching in maize. Drainage water was collected through 1-m depth lysimeter plates and analysed for 6 herbicide molecules and 1 degradation metabolite.MMLI yielded 10.7 t ha(-1) close to MMConv (11.5 t ha(-1)) despite a lower herbicide use (-57%) and irrigation (-21%). MMLI and Maize-MSW had less drainage events compared to MMConv. MMCT and MMStill both yielded less (respectively 7.6 t ha(-1) and 6.2 t ha(-1)) while their herbicide use increased (both +24%). Mean annual herbicide losses were 0.5 +/- 1.0 g ha(-1) for MMLI, 0.7 +/- 1.2 g ha(-1) for Maize-MSW, 1.3 +/- 2.1 g ha(-1) for MMStill, 2.0 +/- 4.8 g ha(-1) MMConv and 3.0 +/- 9.6 g ha(-1) for MMCT. Herbicide leaching remained variable but was consistently and mostly influenced by drainage volume. According to the CS, only 1.5 to 6.0 drainage events were responsible for 90% of the herbicide losses. High leaching peaks were identified for mesotrione and glyphosate and may indicate that preferential flows occurred, especially under MMCT. Quantity applied had limited influence on herbicide leaching. To reduce the herbicide leaching risk, CS must concomitantly manage water quality and quantity through a combination of agroecological practices, as in MMLI, a CS able to reach other technical objectives. Present study recommends assessing CS through a diversity of performance indicators.

International audience; The very rapid development of vertical flow constructed wetlands (VFCW) in Europe and throughout the world has induced a growing concern on the conditions of management of their surface sludge deposits (SD). The leaching of organic components from SD was explored in this study with respect to their potential impact on biochemical oxygen demand (BOD) and their role as complexing agents in the release of trace contaminants. The aromaticity and molecular size of leached organic compounds was investigated over a large range of pHs. Experimental results showed that the pH of the leaching aqueous solution influenced the concentration and characteristics of leached OC. Around the natural pH of SD aqueous suspensions (6 to 8), truly dissolved organics (8), large organic colloids (>30 kDa) were found predominant, exhibiting a low aromaticity growing with pH. Under acidic conditions (pH

Understanding the conditions of dissolved organic matter (DOM) release from thawing peat in the Arctic regions and identifying the pathways of processing DOM by soil and aquatic heterotrophic bacteria are critical in the context of rapid climate change. Until now, experimental approaches did not allow quantitative predictions of temperature and biota effects on carbon release from peat in permafrost-affected aquatic environments. In this study, we incubated frozen peat and its aqueous leachate at various temperatures (4, 25 or 45 degrees C), with and without culturable heterotrophic bacteria Iodobacter sp., extracted from thermokarst lakes, to quantify the release and the removal rate of organic carbon (OC) with time. The metabolic diversity of the native microbial community associated with the substrates involved in OC processing was also characterized. Transmission electron microscopy revealed that, after degradation, the associated bacteria are mostly located in the inner parts of plant cells, and that the degradation of organic matter around bacteria is more pronounced at 4 and 25 degrees C compared to 45 degrees C. The metabolic diversity of heterotrophic bacteria was equally high at 4 and 25 degrees C, but lower at 45 degrees C. Regardless of the microbial consortium (native community alone or with added culturable heterotrophs), both the OC release from peat and the OC removal from peat leachate by bacteria were similar at 4 and 25 degrees C. Very low apparent activation energies of DOM biodegradation between 4 and 25 degrees C (- 4.23 +/- 12.3 kJ mol(-1)) suggest that the short-period of surface water warming in summer would have an insignificant effect on DOM microbial processing. Such duration (1-3 weeks) is comparable with the water residence time in peat depressions and permafrost subsidences, where peat degradation and DOM microbial processing occur. This questions the current paradigm of a drastic effect of temperature rise on organic carbon release from frozen peatlands, and should be considered for modelling short-term climate impacts in these regions.

Made available in DSpace on 2020-12-12T01:10:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Innovative composites based on an amorphous-carbon matrix containing a second phase ZnO oxide and/or highly dispersed Zn metallic were synthesized via a modified Pechini route, in which a partial pyrolysis method was reached. Studies of adsorption in the dark and the photocatalytic activity for the cationic azo-dye, basic blue 41, and degradation were carried out. X-ray diffraction patterns for the carbon matrix and its composite with Zn show characteristics of the amorphous carbon. The infrared in the mid region of the composite prepared with ZnO and Zn exhibit vibrational bands related to bonds zinc oxide. The surface pH of the material is the main factor responsible for the adsorption of the azo-dye, but the contribution of mesopores favored the diffusion of molecules from the bulk of solution to the pore framework. Esters-like functional groups on the surface of carbons hinder the adsorption of the azo-dye. When Zn is embedded within amorphous carbon the photocatalytic activity of the composites showed up to 2.4 higher than neat ZnO. The enhancement in the photocatalytic activity and stability of C/ZnO/Zn and C/Zn composites is discussed in terms of a protector effect by the carbon layers inserted in composites. Carbon layers are responsible to inhibit the lixiviation of ZnO particles along irradiation. Department of Chemistry and Biochemistry São Paulo State University (Unesp) School of Technology and Sciences Laboratory of Composites and Ceramics Functional Department of Physics São Paulo State University (Unesp) School of Technology and Sciences Technological Development Unit (UDT) University of Concepcion Millennium Nuclei on Catalytic Processes Towards Sustainable Chemistry (CSC) Department of Chemistry and Biochemistry São Paulo State University (Unesp) School of Technology and Sciences Laboratory of Composites and Ceramics Functional Department of Physics São Paulo State University (Unesp) School of Technology and Sciences FAPESP: 02/05997-9 FAPESP: 07/03510-9 FAPESP: 14/11189-0 FAPESP: 19/06623-6

Alkylphenol (AP) and bisphenol A (BPA) contamination of urban runoff has already been established. Potential sources of these contaminants in runoff are endogenous to the urban watershed and are mainly related to traffic and leaching from construction materials. This article summarizes the results of experimental work carried out on a selection of building materials, automotive materials, and consumables, which can be in contact with rain, to assess their potential emission of alkylphenols, alkylphenol ethoxylates, and bisphenol A into runoff. 36 samples of materials, new and used, across 7 major families of building materials (PVC, concrete, polycarbonate, SBS-modified bitumen, drainage materials) and automotive materials (body, tires) were subjected to leaching tests with methanol and then, for a selection of them, with water. Automotive fluids were also directly analyzed. The results demonstrate the ubiquitous presence of APs and BPA in urban materials and their extractable character with water. The compounds with the strongest emission rates were bisphenol A and nonylphenol. The most important BPA emissions into water (10 to 300 ng/g) were measured for polycarbonate, tires, some car bodies, and PVC. Nonylphenol was leached in large quantities (1 to 10 ng/g) from PVC, some concretes, SBS-modified bitumen, and body samples. The tires were the only materials having a strong emission in octylphenol (1 to 10 ng/g). The analysis of automotive fluids confirmed the presence of BPA (0.3 to 5.5 g/L) and nonylphenol (2.3 to 2.9 mg/L) in brake fluids, while APs and BPA were found at trace levels in coolants and windscreen washer. Graphical abstract ᅟ.

Long-term bare fallow (LTBF) experiments with historical sample archives offer unique opportunities to study long-term impacts of anthropogenic activities on mineral soil fractions. In natural agro- and ecosystems, such impacts are often masked by organic matter due to its buffering action and rapid turnover. The 42-plot LTBF trial of INRA (Institut National de la Recherche Agronomique) started in Versailles (France) in 1928 to assess the impacts of prolonged application of fertilizers and amendments on the composition and properties of loamy soils. Here, we established geochemical budgets of major and trace elements on surface samples from 1929 and 2014 for four groups of treatments relevant for developed soil processes. We considered accompanying effects of soil compaction or decompaction due to changing physicochemical conditions over 85 years. Element losses from the surface horizon were quantified via fertilization-induced or -amplified soil processes: clay leaching favored by Na- or K-based fertilization, and lixiviation of major and trace elements in acidic or alkaline soil conditions. Enhanced mineral weathering was shown for acidified and nonamended plots. Conclusions on trace metal migration were confirmed by selected analyses on subsurface horizons. Additional information was provided on specific element inputs via fertilizers and/or diffuse inputs via atmospheric deposition Financial support came from INRA and from the Agence de l’Environnement et de la Maîtrise de l’Energie ADEME SI

El maíz (Zea mays L.) es el segundo cereal de mayor cultivo a nivel mundial el cual es empleado como materia prima en diferentes industrias. Hasta el momento no se han encontrado reportes de la obtención del ácido giberélico (GA3) en esta planta. En el presente trabajo se compararon los métodos de extracción sólido-líquido por lixiviación y la extracción dinámica con disolvente asistida por sonicación (DSASE) para la obtención del GA3 a partir de semillas germinadas de maíz. Los factores trabajados en la extracción por lixiviación fueron el método físico, el solvente y el tiempo, mientras que los parámetros por DSASE fueron el flujo, el solvente y el tiempo. La mayor concentración del GA3 se obtuvo con el método DSASE (30,012 mg/kg), empleando como solvente acetonitrilo-ácido fórmico 5% (80:20, v:v) a un flujo de 0,4 mL/min y un tiempo de extracción de 25,0 min. La identificación y la cuantificación del GA3 se realizó mediante cromatografía líquida de alta eficiencia (HPLC) con detector de arreglo de diodos (DAD). Estos resultados evidenciaron que la DSASE es una alternativa novedosa para la obtención del GA3, dada su alta eficiencia, el bajo consumo de solvente y su simplicidad en la obtención del extracto. Corn (Zea mays L.) is the second most cultivated cereal in the world and is use as raw material for different kind of industries. To date no reports about obtaining giberellic acid (GA3) from corn have been found. In the present study two methods for extracting solid samples were evaluated: lixiviation and dynamic sonication-assisted solvent extraction (DSASE), for obtaining giberellic acid from corn germinated seeds. In lixiviation, the physical method (agitation and sonication), solvent, and time were the parameters analyzed; while in DSASE the variables were: solvent, flow, and time. The most efficient technique was DSASE employing acetonitrile-formic acid 5% (80:20, v:v) as solvent at a flow of 0.4 mL/min for 25,0 min, obtaining a concentration 30.012 mg/kg giberellic acid. The identification and quantification were performed by high performance liquid chromatography (HPLC) with diode array detector (DAD). These results showed that dynamic sonication-assisted solvent extraction (DSASE) is a novel and powerful alternative technique for obtaining giberellic acid, because of its high efficiency; low solvent consumption and simplicity in obtaining the extract.

Two different precursors of zinc oxide were prepared via the ammoniacal ammonium carbonate leaching of the black mass obtained during the recycling of alkaline batteries. For a concentration of 0.1 mol/L of ammonium in the leaching solution, zinc basic carbonate, was obtained, while for higher ammonium concentrations (0.5 and 1 mol/L), zinc ammonium carbonate was the final product. These precursors were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA/DTG) and Scanning electron microscopy (SEM), and calcined to obtain ZnO. Raman spectroscopy, X-ray diffraction and Transmission electron microscopy (TEM) analysis of the resulting zinc oxide samples indicated a wurtzite hexagonal lattice with a parameter values ranging from 3.23 Å to 3.30 Å, and c parameter values from 5.18 Å to 5.21 Å (values close to typical). The room temperature photoluminescence spectra of the zinc oxide samples showed two main bands: a high energy UV-blue band centred at either 412 or 382 nm (depending on the NH concentration of the leaching solution used), and a green band centred at 527 nm. These emission bands are comparable to those reported for pure zinc oxide., This work has supported by the Envirobat España S.L. and by the Spanish Ministerio de Economía y Competitividad MINECO (Projects MAT 2012-31959 and CSD2009-00013) and MINECO/FEDER (MAT2015-65274-R; 2016-2019), Ministry of Economy and Competitiveness for their Postdoctoral Junior Grants (Ref. FPDI-2013-16391) contracts co-financed by the European Social Fund. PhD. Ana López Fernández expresses her gratitude to the Comunidad de Madrid for their Technical Junior Grants (Ref. PEJ15/AMB/Al-0049) contracts co-financed by the European Social Fund.

Negative-feedback scanning electrochemical microscopy (SECM) is successfully applied to visualize spatially resolved differences in the topography of coated metal samples upon exposure to aqueous electrolyte solutions of different composition. This method allows the investigation of the uptake of reactants from the electrolyte phase through the polymeric matrix to the metal/polymer interface to be performed even at early exposures. Yet, the method must be carefully checked to discard transport processes from the organic matrix into the solution phase, such as those related to lixiviation. In this later case, the topography of the polymer layer may evolve with time accordingly, not longer exclusively responding to the uptake by the polymer matrix of components from the electrolyte phase. Furthermore, lixiviated species may also react with the SECM tip, eventually leading to the continuous modification of the active surface area of the electrode during the measurements. In this work, the effect of lixiviation from a nickel foil coated with plasticized PVC (PVC Plastisol) on its topographic characterization by SECM was investigated.

In this work we studied the Indirect Carbonation of concrete waste and steel slag in order to find the best conditions of each of then aims the CO 2 storage and find a useful destination of the waste. A complete study was developed with steel slag and the best results were adopted to concrete waste owing the expansion of construction industry in Brazil. The lixiviation with HCl acid, time, rate Liquid/Solid, temperature and concentration of acid was deep studied with a goal to use milder conditions avoiding energy penalty in the industrial process. Therefore a Calcium Carbonate was obtained and the feedstock could be re-used in the industries. The experiments were performed in a glass reactor at atmospheric pressure. The solutions and solid phases were characterized by Flame Atomic Absorption Spectroscopy (FAAS), Scanning Electron Microscopy (SEM) and Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES).

This study focused the ecotoxicological evaluation of four different pesticides (chlorpyrifos, glyphosate, vinclozolin, endosulfan), sprayed into an agricultural soil, using a standard battery of aquatic bioassays for testing of soil elutriates: Vibrio fischeri -Microtox ® ; Pseudokirchneriella subcapitata growth inhibition; Daphnia magna acute and chronic toxicity. Despite relevant pesticide residues were recovered from the soil matrix (concentrations higher than 1000 μg kg −1 ), much lower concentrations could be retrieved from elutriates (highest records for endosulfan of ca. 250 ng L −1 and 1400 ng L −1 ; dissolved and particulate concentration, respectively) and little effects were generally found in the bioassays. Lethal effects ( D. magna 48 h-EC50 of 36.8%) could be noticed following exposure to the endosulfan elutriate. Elutriates induced no toxicity on V. fischeri ; algal growth was generally inhibited at high elutriate dilutions and stimulated at the lower elutriate dilutions; and no overall impairment of D. magna life-history was noticed. Results revealed that cross-contamination during field application, input of organic matter and nutrients by elutriates in test solutions, and choice of test species and endpoints may constrain the ecotoxicological assessment. Suitability of established aquatic bioassay test batteries for these purposes, and questioning on whether direct assays with soil organisms could be more protective tools is discussed.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:50:16Z No. of bitstreams: 1 S0100-69162010000200017.pdf: 156850 bytes, checksum: c86d483d0367b37c1149f8d43f50bfaf (MD5) Made available in DSpace on 2013-08-22T18:50:16Z (GMT). No. of bitstreams: 1 S0100-69162010000200017.pdf: 156850 bytes, checksum: c86d483d0367b37c1149f8d43f50bfaf (MD5) Previous issue date: 2010-04-01 Made available in DSpace on 2013-09-30T17:43:45Z (GMT). No. of bitstreams: 2 S0100-69162010000200017.pdf: 156850 bytes, checksum: c86d483d0367b37c1149f8d43f50bfaf (MD5) S0100-69162010000200017.pdf.txt: 44912 bytes, checksum: 0c1a09464a6307307219d10fb896a65d (MD5) Previous issue date: 2010-04-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:19:30Z No. of bitstreams: 2 S0100-69162010000200017.pdf: 156850 bytes, checksum: c86d483d0367b37c1149f8d43f50bfaf (MD5) S0100-69162010000200017.pdf.txt: 44912 bytes, checksum: 0c1a09464a6307307219d10fb896a65d (MD5) Made available in DSpace on 2014-05-20T13:19:30Z (GMT). No. of bitstreams: 2 S0100-69162010000200017.pdf: 156850 bytes, checksum: c86d483d0367b37c1149f8d43f50bfaf (MD5) S0100-69162010000200017.pdf.txt: 44912 bytes, checksum: 0c1a09464a6307307219d10fb896a65d (MD5) Previous issue date: 2010-04-01 O objetivo deste trabalho foi avaliar possíveis efeitos da aplicação de taxas de água residuária de suinocultura (ARS), quanto às concentrações de cobre e zinco, tanto no solo quanto na água percolada de lisímetros de drenagem, durante o ciclo da cultura da soja. O experimento foi conduzido em ambiente protegido, onde havia 24 lisímetros de drenagem. Semeou-se soja cultivar CD 202, e foram aplicadas ARS nas seguintes dosagens: 0; 100; 200 e 300 m³ ha-1 no ciclo, combinadas com duas adubações na semeadura (com e sem adição da adubação recomendada na semeadura), em três repetições por tratamento. Foram feitas seis coletas do material percolado durante o ciclo da cultura e realizadas determinações de cobre e zinco. No solo, foram feitas três coletas em cada parcela experimental, para a determinação do pH, da matéria orgânica, da capacidade de troca catiônica, do cobre e do zinco. O delineamento foi em blocos casualizados, num esquema fatorial de 4 x 2. Observou-se que o cobre no solo não apresentou diferenças significativas com a aplicação de ARS e adubação, enquanto as concentrações de zinco no solo foram influenciadas pelas taxas aplicadas de ARS. As transferências de cobre e de zinco por percolação foram pouco expressivas. The objective of this paper is to evaluate the possible effects of applying different rates of swine wastewater (ARS), when it comes to the concentration of copper and zinc and in the percolated water of drainage lysimeters on the soil cultivated with soybeans. The experiment was conducted in a protected environment containing 24 drainage lysimeters. Cultivar CD 202 was sowed and swine wastewater was applied in the following dosages: 0, 100, 200, and 300 m³ ha-1 during the cycle, combined with two fertilizing at sewing (with and without added fertilizing recommended at sewing), in three repetitions per treatment. It was accomplished six collections of percolated material during the crop cycle and it was determinate both copper and zinc. In soil, three collections were accomplished in each experimental plot to determine the pH, organic matter, cationic exchange capacity, copper and zinc. The experiment delimitation was carried out in random blocks in a 4 x 2 factorial scheme. It was observed that copper did not present differences in the application of ARS and fertilizer, while the concentration of zinc on the soil was influenced by rates of ARS Copper and zinc transfer per lixiviation was not meaningful. PUC Centro de Ciências, Tecnologia e Produção UNESP FCA Departamento de Engenharia Rural UNIOESTE Centro de Ciências Exatas e Tecnológicas UNIOESTE Centro de Ciências Agrárias UNESP FCA Departamento de Engenharia Rural

This work estimated the leaching behavior of metolachlor from montmorillonite-based and commercial emulsifiable concentrate (EC) formulations in soil columns and field plots by using bioassay and chemical techniques. A montmorillonite-based formulation of metolachlor was prepared by adsorbing metolachlor to montmorillonite–benzyltrimethylammonium (BTMA) complex from aqueous solution. Bioassay and gas chromatography (GC) techniques detected high metolachlor concentrations in the top soil layers (0–9 cm) in soil columns and field plots sprayed with montmorillonite–BTMA–metolachlor complex. These results were also evident by severe growth inhibition restricted to the top soil layers (0–9 cm) and normal growth at deeper layers in soil columns and field plots. A wider range of metolachlor concentrations were detected in soil layers in columns treated with EC formulation in both soil columns and field plots. Relatively higher metolachlor concentrations were detected in the soil layers in field plots than in soil columns. A bioassay technique was a more sensitive tool than chemical technique and detected diluted concentration of metolachlor at deeper layers. The different leaching behavior of metolachlor applied as montmorillonite–BTMA complex is due to the adsorption capacity of montmorillonite–BTMA complex. Key words: metolachlor, montmorillonite–BTMA, leaching, soil columns, field plots.

On the South Pacific islands, the change from traditional to more intensive agricultural practices is leading to more fertilizer use, both extensively and intensively. Nutrient leaching should be minimized to avoid plant deficiencies and ground water pollution. The fate of nitrate and potassium under corn (Zea mays L.) and perennial grass (Rhodes grass, Chloris gayana Kunth.) was monitored during three wet seasons on a Ferralsol soil from Mare in the Loyalty Islands. In 1995, 130 and 41% of the applied NO 3 - and K + , respectively, leached beyond the root zone. Split application of the fertilizers in 1996 decreased the amounts leached to 48 and 11%, respectively. This reduction occurred even though the rainfall nearly doubled from 1995 to 1996. Nitrate and potassium transport, however, can be decreased due to their retention by this Ferralsol. Nitrate can be adsorbed on the positively charged surface of aluminum and ferric oxides. Due to the rapid drainage under tropical rainfall, however, this phenomenon is not very effective. Potassium is usually tightly fixed on 2:1 clay minerals, but these are nonexistent in our soil. Potassium also is bound to humic substances and the organic matter reaches 15% in the subsoil of this Ferralsol. Leaching of K + was retarded compared with NO 3 - , but was still quite high compared with others studies on tropical soils.

Constructed wetlands (CW) provide good removal of organic matter and nitrogen (Hammer, 1989; Kadlec et al, 2000. Molle et al, 2005), but their performance for phosphorus removal are the subject of debate (Vymazal et al, 1998. Brix et al, 2001.). However, phosphorus is a factor in eutrophication of surface waters, and it is therefore necessary to limit discharges into the natural environment. In order to improve denitrification and phosphorus removal as compared to classical vertical flow constructed wetlands (VFCWs), the French company SCIRPE has developed a process called Azoé® patented in 2007 (Michel, 2007). The process includes a pre-treatment on a biological trickling filter to partly degrade the organic load, followed by two vertical stages of partially saturated constructed wetlands for the removal of nitrogen by nitrification and denitrification. The reduction of phosphorus in the Azoé® system is achieved through the addition of FeCl3 as a coagulant, followed by filtration through the VFCWs. Phosphorus thus precipitated is thereby accumulated in the form of a sludge layer mostly at the surface of the 1st filter. Over time, the sludge layer progressively grows and may eventually release part of the accumulated phosphorus depending on the biophysicochemical conditions (Kim et al., 2013). The objective of this study was to determine the influence of pH on the solubilization of phosphorus from sludge material sampled from a plant in operation. Results showed that the buffering capacity of the sludge allowed to stabilize pH when in contact with moderately acidic (pH 4) or alkaline (pH 10) solutions. Under more drastic conditions, changes of pH were observed, but the release of phosphorus remained fairly low. Even after several successive leaching stages with very acidic (pH 2) or alkaline (pH 12) solutions, only 9% and 12% respectively of phosphorus initially present in the sludge was leached., Les Filtres Plantés de Roseaux (FPR) permettent une bonne élimination des matières organiques et de l’azote (Hammer, 1989 ; Kadlec et al., 2000 ; Molle et al., 2005), mais leurs performances pour l’élimination du phosphore font l’objet de débat (Vymazal et al., 1998 ; Brix et al., 2001). Or, le phosphore est un facteur d’eutrophisation des eaux superficielles, et il est donc nécessaire d’en limiter les rejets dans le milieu naturel. Afin d’améliorer la dénitrification et la déphosphatation des FPRs à écoulement vertical, la société française SCIRPE a développé un procédé de FPR appelé Azoé® breveté en 2007 (Michel, 2007). Le procédé comprend un prétraitement biologique sur lit bactérien qui élimine une partie de la pollution carbonée, puis deux étages de FPR à écoulement vertical partiellement saturés complétant l’épuration de la charge organique et assurant l’élimination de l’azote par nitrification-dénitrification. L’abattement du phosphore est réalisé par addition en sortie de lit bactérien de FeCl3 qui agit comme coagulant, puis par filtration via les FPR. Le phosphore ainsi précipité s’accumule principalement en surface du 1er filtre sous forme d’une couche de boues. Après plusieurs années de fonctionnement, cette couche de surface représente un stock de phosphore potentiellement mobilisable en fonction des conditions biophysicochimiques du milieu (Kim et al., 2013). Dans ce contexte, l’objectif de l’étude était d’estimer les risques de libération du phosphore en fonction de différents facteurs d’influence. Plus spécifiquement, il s’agissait d’estimer l’influence du pH sur la solubilisation du phosphore. Les résultats ont montré que le pouvoir tampon des boues est suffisant pour maintenir un pH relativement stable au contact d’eaux acides (pH 4) ou alcalines (pH 10). En présence de conditions acides ou alcalines plus extrêmes, le pH du milieu est modifié, mais le phosphore est très faiblement solubilisé. Ainsi même après plusieurs lixiviations successives en conditions extrêmes (pH 2 et 12), seuls 9 % et 12 % respectivement du phosphore initialement présent dans les boues a été solubilisé.

International audience; Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can be used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.

O objetivo do experimento foi avaliar a eficiência da adubação nitrogenada na forma de uréia, em pastagem de triticale mais azevém, submetida a pastejo com lotação contínua. Foram usados quatro níveis de nitrogênio em cobertura: 0, 150, 300 e 450 kg N/ha, divididos em cinco aplicações. A massa de forragem disponível foi de 1404, 1437, 1619 e 1599 kg MS/ha, respectivamente. A produção total de forragem foi de 6039, 6914, 7877 e 7662 kg MS/ha e a produção de nitrogênio, de 191,6; 247,7; 303,2 e 307,2 kg/ha, para os níveis 0, 150, 300 e 450 kg N/ha, respectivamente. A eficiência da adubação nitrogenada foi de 5,83; 6,13; e 3,61 kg MS/kg de nitrogênio aplicado e a recuperação de nitrogênio, de 37,39; 37,21 e 25,69%, para os níveis 150, 300 e 450 kg N/ha, respectivamente. Na avaliação da concentração de nitrogênio nas camadas do perfil do solo (0-5, 5-10, 10-20 e 20-40 cm de profundidade), em duas datas (20/07 e 20/09), constatou-se aumento no teor de nitrogênio mineral, da primeira para a segunda avaliação, principalmente nas maiores profundidades e nos maiores níveis de nitrogênio, indicando que houve perdas por lixiviação, diminuindo a recuperação e eficiência no uso deste nutriente. The objective of this experiment was to evaluate the nitrogen fertilization efficiency using urea, on triticale plus Italian ryegrass pasture, submitted to continuous stocking. Four nitrogen levels were used: 0, 150, 300 and 450 kg of N/ha, divided in five applications. The herbage mass was 1404, 1437, 1619 and 1599 kg of DM/ha. The total herbage production was 6039, 6914, 7877 and 7662 kg of DM/ha and the nitrogen production was 191.6, 247.7, 303.2 and 307.2 kg of N/ha for the 0, 150, 300 and 450 kg of N/ha levels, respectively. The nitrogen fertilization efficiency was 5.83, 6.13 and 3.61 kg of DM produced/kg of nitrogen applied and the nitrogen recovery was 37.39, 37.21 and 25.69% for the levels of 150, 300 and 450 kg of N/ha, respectively. The nitrogen concentration in different depth of the soil profile (0-5, 5-10, 10-20 and 20-40 cm of depth) in two dates (07/20 and 09/20) was evaluated. An increase of the mineral nitrogen content, from the first to the second evaluation, mainly for the deepest layers and for the highest nitrogen levels was observed, indicating that lixiviation losses of nitrogen occured, reducing the nitrogen recovery and his efficiency

International audience; Laboratory incubations and a field experiment were carried out to determine the factors controlling N mineralization and nitrification, and to estimate the N losses (leaching and volatilization) in a sewage-sludge-amended Oxisol. Aerobically digested sludge was applied at a rate equivalent to 625 kg N/ha. The incubations were conducted as a factorial experiment of temperature (20 degreesC, 30 degreesC, and 40 degreesC) x soil water (-30 kPa and -1500 kPa) x sludge type [fresh (FS) water content 6230 g/kg; dry (DS) water content 50 g/kg]. The amount of nitrifiers was determined at the beginning and at the end of the experiment. The incubation lasted 24 weeks. The field study was conducted using bare microplots (4 m(2)) and consisted of a factorial experiment of sludge type (FS and DS) x sludge placement (subsurface, I+; surface, I-). Ammonia volatilization and the profile (0-0.90 m) of mineral N concentration were measured during 6 and 29 weeks after sludge application, respectively. After 24 weeks of incubation at 40 degreesC and -30 kPa, net N mineralization represented 52% (FS) and 71% (DS) of the applied N. The difference between sludges was due to an initial period of N immobilization in FS. Nitrification was more sensitive than N mineralization to changes in water potential and it was fully inhibited at -1500 kPa. The introduction of a large amount of nitrifiers with FS did not modify the rate of nitrification, which was principally limited by soil acidity (pH 4.9). Although N mineralization was greatest at 30 degreesC, nitrification increased continuously with temperature. Nitrogen mineralization from DS was well described by the double-exponential equation. For FS, the equation was modified to take into account an immobilization-remineralization period. Sludge placement significantly affected the soil NO3-/NH4+ ratio in the field: 16 for I+ and 1.5 for I-, after 11 weeks. In the I- treatment, nitrification of the released NH4+ was limited by soil moisture because of the dry soil mulch formed a few hours after rain. At the end of the field experiment, the estimated losses of N by leaching were 432 kg N/ha for I+ and 356 kg N/ha for I-. Volatilization was not detectable in the I+ microplots and it represented only 0.5% of the applied N in the I- microplots. The results showed that placement of sludge may be a valuable tool to decrease NO3- leaching by placing the sludge under unfavourable conditions for nitrification.

Parmi les differentes possibilites pour resorber les excedents de production de pommes, l'epandage in situ est une solution flexible et bon marche. Six colonnes de sol ayant recu 0, 200 ou 500 Mg.ha -1 de pommes ont ete suivies en laboratoire dans des conditions d'irrigation variant par les doses et le calendrier d'apport d'eau, et en imposant une alternance entre des periodes d'irrigation et des periodes seches. Les solutions drainees a la base des colonnes ont ete recuperees a differentes dates et analysees. L'apport de matiere organique fraiche a stimule l'activite microbienne, induisant une consommation de O 2 et une production de CO 2 . En consequence, le sol est devenu reducteur. Des cations mis en jeu par dissolution minerale et echanges cationiques tels Ca 2+ , Mg 2+ et K + sont lixivies. L'immobilisation d'azote, et probablement la denitrification, expliquent la disparition rapide du nitrate. Du carbone organique est lixivie, et l'intensite des conditions reductrices induit la mise en solution de Mn et la sulfato-reduction. La reoxydation du sol suite aux phases de dessechement restaure des conditions oxydantes potentiellement moins polluantes. Des quantites de matiere organique fraiches inferieures a 200 Mg.ha -1 sont recommandees pour minimiser les risques de pollution environnementale par lixiviation.

For the uplifted coral atolls of the Loyalty Islands (New Caledonia), the prime source of potable water is the freshwater lenses that underlie the islands. The recent adoption of more-intensive agricultural practices, particularly the use of nitrogeneous fertilizers, may, however, represent a threat for these fragile Pacific ecosystems. To assess the risk posed by nitrate leaching, experiments have been conducted on the permeable oxisols of the island of Mare, using both cropped and bare soil sites. Drainage below the root zone was found to be very important, about 50% of the rainfall, even on the cropped site. The soils are thin and permeable, and the frequent tropical storms have high rainfall intensities. Nitrate fertilizers thus have potential to be leached, in large amounts, even up to 100% of the nitrate supply, especially if fertilizers are not supplied according to weather conditions and in concert with the plant's ability to extract them.

Dissolution kinetics of a pure sphalerite have been studied in concentrated non-oxidising chloride acid medium by the rotating disk method. The reaction rate, uncontrolled by difftision, is slow and constant. The reaction is influenced by the following factors : temperature, concentrations of H+, CI-, H2S, ZnT (total dissolved zinc). The specific rate of solubilisation, expressed in mole.cm-2.s-1, can be described by the equation : r = 8.2 . 10-3 . aH+ . aCl- . (ZnT)-1/2 . p H2S-1 . exp [-7500/T] This heterogeneous surface reaction being a chemical equilibrium, the reaction mechanism proposed for the interpretation of experimental data assumes, on the one hand, a competitive adsorption between active species at solid surface and, on the other hand, a chemical equilibrium between solid and adsorbed phase as rate controlling step., La cinétique de dissolution d'une blende mielleuse, sphalérite pratiquement exempte d'impuretés, a été étudiée en milieu acide chloruré non oxydant concentré, par la méthode du disque tournant. La vitesse de la réaction, qui n'est pas contrôlée par la diffusion, est faible et constante. Les paramètres réactionnels sont les suivants : température, concentrations en H+, Cl-, H2S et zinc total ZnT. La vitesse spécifique de solubilisation, exprimée en mole. cm-2. s-1 se formalise selon l'équation : r = 8,2. 10-3 . aH+ . aCl- . (ZnT)-1/2 . p H2S-1 . exp [-7500/T] Cette réaction étant équilibrée, le mécanisme réactionnel retenu pour interpréter les résultats expérimentaux suppose que, d'une part, il y a compétition d'adsorption des espèces actives à l'interface et, d'autre part, l'étape limitante est constituée par un équilibre chimique entre le solide et la phase adsorbée., Ammou-Chokroum Michel. Réaction de la sphalérite en milieu acide chloruré non oxydant. I. - Influence des paramètres physico-chimiques liés à la solution. In: Bulletin de Minéralogie, volume 108, 6, 1985. pp. 779-800.

Nitrogen fluxes in intensive grassland have been studied in lysimeters (3 m2, 0.80 m deep) with15N labelled fertilizers (360 kg N/ha). The harvested fertilizer uptake efficiency was around 52% of which 45% was exported and 7% “stored”. Leaching losses were very low, despite considerable drainage. The immobilization of mineral N during the first year was very important (40–50%) and the remineralization was slight. The N recovered in soil after two years was 40% of N-fertilizer applied of which 19% is contained in free organic matter and 21% in organo-mineral fraction (< 50µ). The immobilization of N is greater in the surface top of soil: 68% in the first 5cm. Beneath a growing crop the in-depth migration of the N takes place exclusively through root growth. The global N balance and cycle in soil were discussed.

Although current bio-oxidation processes with mesophilic bacteria result from the occurrence of mixed populations, the mutual effect of the various species has not been studied very extensively to date. Mixed cultures made up of pure Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans strains of the DSM collection were batch tested for their ability to oxidize a cobaltiferous pyrite ore. The most efficient population for pyrite oxidation was composed of the three bacterial species. The influence of the relative abundance of the different strains in the inoculum was studied. The cobalt solubilization rate obtained with T. ferrooxidans increased when L. ferrooxidans was present but was not affected by the initial concentration of L. ferrooxidans . The bioleaching with T. ferrooxidans was only improved by adding T. thiooxidans when the initial concentration of T. thiooxidans was higher than the initial concentration of T. ferrooxidans . During continuous bioleaching of the cobaltiferous pyrite at 20% solids with a natural mesophilic mixed population, rod-shaped and Leptospirillum -like bacteria were enumerated in the liquid phase. The 100 l bioleaching unit is made up of 3 or 4 reactors arranged in cascade. The concentration of Leptospirillum -like organisms rose exponentially versus dissolved ferric iron, whereas the concentration of rod-shaped bacteria did not change from the value obtained in the first reactor, providing the solution contained less than 60 g.l −1 ferric iron. At higher Fe 3+ concentrations, the rod-shaped population in the liquid phase decreased. These results suggest that the rod-shaped bacteria performed the earlier steps of pyrite oxidation, whereas Leptospirillum -like organisms participated in the later phase of bioleaching. The effluent from the last reactor was treated with CaCO 3 in order to precipitate iron. Recycling of partially neutralized bioleach solution to the feed seemed to increase the concentration of Leptospirillum -like bacteria in all reactors. Two hypotheses are proposed to explain this phenomenon: some bacteria may have been brought into the first tank with the recycled liquid, or the cobalt concentration may have affected the distribution of Leptospirillum -like bacteria between liquid and solid phases.

Average annual precipitation (AAP) is one of the principal environmental factors that regulates processes in terrestrial ecosystems. The effect of AAP on the availability of edaphic nutrients is poorly understood, especially in tropical zones with high rainfall. In order to evaluate the effects of high AAP on the availability of soil N, P, and K, physicochemical parameters were measured in soils of three tropical rainforests in the Chocó biogeographical region with different AAPs (7,500, 8,000, and 10,000 mm yr-1). Furthermore, a bibliographical review was carried out that including studies for distinct tropical Ultisols and AAP ranging from 1,800 to 10,000 mm yr-1. The evaluated soils presented extreme acidity with high contents of Al, organic matter (OM) and total N, and low quantities of P, Mg, and Ca. The K concentrations were intermediate and the effective cation exchange capacity (ECEC) was low. On the other hand, in the evaluation of the influence of the AAP on the availability of N, P, and K in the soil, contrasting tendencies were observed. On one side, a positive curvilinear relationship was found between the availability of N and the increase in the AAP. On the other side, the available P content significantly decreased with increasing AAP. In conclusion, the excessive AAP resulted in increases in total N and low availability of P, thereby altering the dynamics of the nutrients and the carbon balance of the tropical forest