After reviewing the literature on factors influencing zinc availability in soils, it was decided to investigate further aspects of the well documented zinc/phosphate interaction for the soil/maize system and to study the migration and transformations of inorganic and organic (sludge) fertilizer zinc in soils. A conventional pot experiment with maize to look at zinc/phosphate interaction, with thorough mixing of added fertilizer, indicated that phosphate could alleviate zinc toxicity effects, but did not show whether this was a soil or plant effect. A subsequent experiment in which soils treated with zinc and phosphate fertilizers were spatially separated by nylon net provided evidence that the interaction occurred, at least in part, in plant roots. This suggests limited benefit in the field for separate placement. Under field conditions, it is unrealistic to expect the same degree of soil mixing as used in typical pot experiments. Therefore an experiment with <SUP>65</SUP>Zn was used to study the vertical movement of surface-applied inorganic zinc fertilizer. The same experiment was also used to study the changes in distribution of added zinc between a range of soil fractions (exchangeable, organic, manganese oxide, iron oxide and residual) at three soil pH values. Uptake was higher at lower pH, corresponding to greater amounts of zinc being retained on exchange sites. However, much of the added zinc was found in the manganese oxide fraction especially at higher pH. Zinc mobility during the experiment was almost negligible. Subsequently the soils left at the end of this experiment were incubated for 6 months and then used for a further pot experiment, to gain insight into residual zinc fertilizer effects. This showed a reduction in exchangeable zinc and plant uptake, with increases in zinc associated with organic matter and iron oxides.

New economically viable methods for the detection and removal of organic pollutants from water samples are needed to meet modern safety requirements. Development of techniques to produce antibody fragments in Escherichia coli (E. coli) have provided the opportunity to exploit antibodies as specialised chemicals for affinity detection and removal technologies. The variable heavy and light antibody domains of the anti-paraquat monoclonal antibody PQXB1/2 have been cloned into the single-chain antibody (scAb) expression vector, pBG1. Anti-paraquat scAb (0.1-0.4 mg/L bacterial culture) was expressed in E. coli. Characterisation of scAb by antigen binding profile and competition ELISA showed it to have a sensitivity one order of magnitude below that of the parent monoclonal. ScAb was purified as a monomer or dimer and analysed by HPLC size exclusion chromatography. When immobilised on polystyrene beads the scAb could remove 85% of paraquat-bovine serum albumin conjugate from solution in a single step.

Les charrées de chrome, résidus d’extraction du minerai de chrome (ou COPR), sont des matériaux de pH très basique (>10) composés de phases minérales cimentaires peu stables incorporant le chrome d’état d’oxydation +VI. La solution porale du matériau est chargée en Cr(VI) à des concentrations souvent supérieures à 100 mg/L. Les teneurs du matériau s’élèvent à 4-7 g Cr(VI)/kg. Le chrome VI est toxique. Par le passé, les charrées de chrome ont été utilisées en remblai d’infrastructures. C’est le cas d'une infrastructure dans le nord de la France. Notre étude a visé à développer une méthode de dépollution. Nous avons élaboré un couplage de la technique électrocinétique et d’une réduction chimique du Cr(VI). Nous apportons un réducteur qui migre à travers le matériau grâce à un champ électrique. Nous montrons que la réduction du chrome VI en chrome III précipité et moins toxique est possible avec une efficacité de 97 % et que les phases minérales ciment résistent à ce traitement. Nos travaux montrent que 60 à 70 % de la matière dans les charrées de chrome étudiées sont constitués de phases minérales amorphes. Elles sont sensibles aux variations de pH dans le milieu lors du traitement et réagissent en partie par dissolution, re-précipitation et transport. L’hydroxyde de Cr(III) formé lors du traitement est colloïdal et en partie mobiles. Des ajustements de la méthode sont possibles, en particulier le contrôle des variations de pH et la suppression de la mobilité indésirable du Cr(III). Les perspectives industrielles de cette méthode également adaptable à d’autres polluants rédox-sensibles, sont prometteuses. / Chromite Ore Processing Residues (COPR) are materials with strongly alcaline pH (>10) containing fairly soluble cement phases bearing hexavalent chromium as a substituted anion. The pore water contains high concentrations of mobile Cr(VI) often above 100 mg/L. The bulk concentration of Cr(VI) is 4 - 7 g /kg COPR. Hexavalent chromium is a toxic compound. Historically, COPR was used for embankments and backfills in construction works. This was the case for an infrastructure in the north of France. In this study we aimed to develop a remediation method suitable for treatment of this backfills in-situ. We coupled the electrokinetics technique with in situ chemical reduction of Cr(VI). In this method, the added reductive compound migrates through the material under the effect of an electric field. We show that Cr(VI) reduction to the less toxic Cr(III) is possible with as high as 97% efficiency. Results show that the crystallized mineral phases are not impacted by the treatment. However, 60 to 70% of the mineral phases are amorphous as quantification studies show. The pH change during treatment fragilizes them, resulting in some dissolution, reprecipitation, electromigration and electrophoretic transport phenomena. Cr(III)-hydroxide, produced during the treatment, also appear to be in a mobile colloidal form. Optimisations of the technique are possible, in particular the control of pH changes and the suppression of colloidal Cr(III) mobility. Industrial perspectives are promising. This method can be adapted to other materials and redox sensitive pollutants.

Les friches industrielles en milieu urbain représentent un grand potentiel de redéveloppement urbain mais l’aménagement sur les sites et sols polluées complexifie la prise de décision. Ces décisions sont basées sur des informations fournies par un grand nombre d’acteurs. Une méthode d’étude par la systémique communicationnelle a été retenue. Afin de modéliser ce système pour le réaménagement des friches industrielles, une méthodologie basée sur le retour d’expérience a été mise au point. Une grille a été construite dans le but de recueillir, pour chacune des sept phases des projets de réaménagement, les typologies d’acteurs, les typologies de données qu’ils acquièrent en urbanisme et en environnement et les problèmes que rencontrent ces acteurs. Enfin, un ensemble de règles permettant de modéliser l’évolution des données dans la dimension informationnelle a été défini. Les grilles de recueil ont été appliquées à trois terrains d’études. Une validation croisée des données par la méthode de triangulation en sciences humaines a été réalisée. Ces données a ensuite été utilisées pour modéliser le système communicationnel. Les résultats de la validation croisée ont montré que, les typologies d’acteurs et de données étaient fiables de par leur répétabilité. Cependant, des faiblesses ont été détectées en fin de projet : il a été difficile d’identifier les données utilisées. La structure du modèle a été étudiée et a montré que la structure des échanges était simple. Ensuite, les problèmes rencontrés par les différents acteurs ont été analysés. Ces problèmes sont principalement concentrés sur deux phases du projet : la première et la cinquième. Il a été démontré que les problèmes rencontrés sont liés à l’acquisition des données. Ce manque de données engendre des incertitudes pouvant remettre en cause le projet. En termes de perspectives, il faudrait réaliser des interviews complémentaires pour identifier les typologies manquantes en fin de projet. / Brownfields in urban areas have great potential for redevelopment of cities, but urbanization on contaminated sites complicates decision making. The decisions are based on information provided by a lot of stakeholders. A method based on the systemic of communication was chosen. A methodology based on the feedback was developed to model this system of brownfield redevelopment. A grid was built in order to analyze in each stages of redevelopment projects: the types of involved stakeholders; the types of data they collect in urban planning and environment; and problems faced by these actors. Finally, a set of rules to model the evolution of the data in the informational dimension was defined. The collection grids were applied for three fields of study. Cross-validation of the data by the method of triangulation was achieved. All types of data was used to set up the communicational system. The model was established and its structure has been analyzed. This study showed that the pattern of trade between stakeholders was simple. Then, the problems found by stakeholders were studied. Problems were highlighted mainly into two stages: the first and fifth stages corresponding respectively to the beginning of conception of projects and the beginning of preparation works. The problems encountered are mostly related to the collection of data. This lack of data generate big uncertainty that could affect the project limiting the alternative scenarios. The results of cross-validation shown that the types of stakeholders and data are valid because of their repeatability. However, weaknesses were detected at the end of the project: it was difficult to identify the data which was used. Perspectives would require to make further interviews to identify missing typologies of data at the end of project.

No description available.

Hydrocarbon contamination of soil from accidental spills and negligence represents a major cause of sub-surface contamination. There are numerous physical, chemical and biological techniques available for contaminant remediation. However, many of these methods can be difficult to implement at sites where access to soils, or delivery of treatments, requires substantial excavation works and disruption (for example where contamination is located beneath or adjacent to building structures and underground services). An innovative technology that may provide a solution for the remediation of subsurface contamination without causing interim damage is that of electrokinetic remediation. Electrokinetic remediation is the application of a low voltage, direct current (of the order of mA/cm²) between electrodes placed in a contaminated soil system. The production of an electric field causes a number of electrically-induced processes to occur that can promote soil remediation, principally: electromigration, electroosmosis, electrophoresis, and electrolysis. This study examined the use of electrokinetics coupled with biodegradation to remediate kerosene and transformer oil from sub-surface soils. The principal investigations carried out within this study included: the use of electroosmosis as an in situ flushing technique; use of electrokinetics to deliver surfactants into the soil to promote mobilisation of contaminants within the sub-surface; and the use of electrokinetics to create optimum conditions for biodegradation by the delivery of nutrients and electron acceptors, the removal of toxic metabolites, and by controlling the pH and moisture content of the soil. As an integral part of the research, a field trial was designed and set up to determine whether electrokinetics could be used to promote the biodegradation of transformer oil from the subsurface. This was one of the first field trials in the UK for the electrokinetic remediation of hydrocarbon contaminants. The results of the study support the use of electrokinetics as a field tool for the enhancement of remediation in the sub-surface. Laboratory-scale studies showed the potential to mobilise the more soluble hydrocarbons (such as toluene and xylene) in the soil, to deliver enhancing agents (e.g. surfactants and nutrients) and to remove toxic metabolites. The field-scale experiment demonstrated the concept of a relatively low cost treatment cell on-site and provided some evidence that biodegradation of the transformer oil was promoted. Consequently, it is suggested that electrokinetics, with the correct engineering controls in place, provides a valuable method of optimising the biodegradation of hydrocarbons in the sub-surface.

No description available.

No description available.

No description available.

Phosphorothioate insecticides such as parathion (0,0, diethyl O-pnitrophenyl phosphorothioate) must undergo metabolic activation to form oxygen analogs in order to exert their toxicity. The specific isoforms of cytochrome P450 involved in this oxidative desulphuration reaction were examined in rat liver microsomes and a panel of sixteen human liver microsomes. In the rat, parathion (20μM and 200μM) was activated to paraoxon with an apparent Km of 10.4±0.25μM (n=3), the metabolic rates were 241±17 and 256±18 pmol/min/mg protein, respectively. p-Nitrophenol was also formed, at 235±15 and 220±23 pmol/min/mg protein. Human liver microsomes activated parathion (20μM and 200μM) with an apparent Km of 9μM-16μM (n=3), the metabolic rates were 23.3-199.3 and 18.7-310.3 pmol/min/mg protein (n=16). p-Nitrophenol was also formed, at 321.1- 769.2 and 406.2-778.3 pmol/min/mg protein. The activation of parathion (200μM) by human liver microsomes was positively correlated with nifedipine oxidation, indicating the involvement of CYP3A. Correlations were not significant with ethoxyresorufin-0-dealkylation, pentoxyresorufin-0-dealkylation, pnitrophenol hydroxylation, paraoxon hydrolysis or phenylvalerate hydrolysis. Paraoxon formation from parathion by human liver microsomes was markedly inhibited by the CYP3A inhibitors ketoconazole, quercetin and naringenin (apparent Ki=21μM). Metyrapone and a-naphthflavone had some inhibitory effect. The inhibitors were generally less effective towards parathion metabolism by rat liver microsomes. Experiments with EDTA indicated that A-esterase was not functionally important at low levels of paraoxon. Human P450s 3A4 and 3A5 expressed microsomes were the most efficient at biotransforming parathion to paraoxon, although P450s 1A1,2B6 and 2C8 also catalysed the reaction. The present study has shown marked interindividual variation in the metabolism of parathion, which may influence toxicity following exposure to this or other phosphorothioates. Co-administration of inhibitors or inducers of the enzymes involved may affect the fate of parathion and thus enhance or reduce its toxicity.