Fate of organotin compounds in the soil – plant system: soil persistence, plant accumulation and toxicity

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Optimisation using experimental designs of the sample pretreatment: application to the control of the organotins in sewage sludge by GC-FPD

International audienceThe optimisation of the simultaneous extraction of the butyl- and phenyltins from sewage sludge and their derivatization using sodium tetraethylborate (NaBEt4) are reported. The methodology of experimental designs was used which allowed the evaluation of the influence of eight analytical parameters on the peak areas (S) and decomposition (D) of triphenyltin (according to its poor stability). The stirring times during extraction and derivatization as well as the NaBEt4 amount were found the most important factors. The optimal operating conditions were determined by modelling S and D. Several samples of urban sewage sludge were analysed and results compared with those obtained by other analytical methods, in order to verify the convenience of the optimised method

Spatial Variation in the Molecular Composition of Dissolved Organic Matter from the Podzol Soils of a Temperate Pine Forest

International audienceSpatial Variation in the Molecular Composition of Dissolved OrganicMatter from the Podzol Soils of a Temperate Pine ForestEmmanuelle Maria,†Pierre Crançon,‡Gaëtane Lespes,†and Maxime C. Bridoux*,‡†Universitéde Pau et des Pays de l’Adour (UPPA)/CNRS, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement,UMR IPREM 5254, Technopôle Hélioparc, Av. du Président Angot, 64000 PAU, France‡CEA, DAM, DIF, F-91297 Arpajon, France*SSupporting InformationABSTRACT:In podzols, the production and mobilization ofdissolved organic matter (DOM) account for a considerableloss of carbon from the forestfloor. The dynamics of DOM inthe podzol soils of a pine forest result from complexinteractions between water infiltrations, weathering, biologicaltransformation, and retention-mobilization mechanisms. How-ever, little is known about how the molecular composition ofDOM changes spatially in the podzol soil as it moves from theupper horizons (organic (O) and eluvial (E)) to the illuvialhorizon (B(h/s)) to the groundwater. In this study, DOMsamples were collected in the upper (A1) and accumulation(Bh) horizons of a sandy permeable podzol with a hydrologyoccurring exclusively through drainage of shallow water (no surface runoff), as well as from the groundwater. Samples wereconcentrated on a Strata-X-AW solid-phase extraction cartridge and directly infused using electrospray ionization in the negativemode coupled with an LTQ-Orbitrap mass spectrometer. Over 2300 monoisotopic molecular formulas of CHO and CHONwith molecular weights up to 600 Da, assigned mainly to lignin-like compounds (53%), tannins (22%), condensed aromatics(14%), protein-like compounds, lipids (3%), aminosugars/carbohydrates (1%), and unsaturated hydrocarbons, were identifiedin DOM from the upper podzol horizon (A1), indicating that leaching of plant debris dominates the DOM pool released in thesoil seepage waters. Among all molecular formulas detected, 31% were unique to A1, while only 6.9% were only detected in Bhand 12.9% in Gw. Van Krevelen diagrams of these unique formulas clearly highlighted an evolution of the OM molecularcomposition along the podzol soil profile, from the upper horizon, through the accumulation horizon, to the groundwater with ashift from the high-oxygen, plant-derived compounds (tannins-like and lignin-like) to the low-oxygen classes (unsaturated andcondensed hydrocarbon), suggesting a reduction process either microbially mediated or via preferential adsorption of oxygen-functionalized DOM compounds to mineral surface

Characterization of volcanic ash nanoparticles and study of their fate in aqueous medium by asymmetric flow field-flow fractionation–multi-detection

International audienceDimensional and elemental characterization of environmental nanoparticles is a challenging task that requires the use of a set of complementary analytical methods. Asymmetric flow field-flow fractionation coupled with UV-Vis, multi-angle laser light scattering and ICP-MS detection was applied to study the nanoparticle fraction of a volcanic ash sample, in a Milli-Q water suspension at pH 6.8. It has been shown that the separated by sedimentation nanoparticle fraction of the Klyuchevskoy volcano ash suspension contains 3 polydisperse populations for which size ranges (expressed in gyration radius, rG), hydrodynamic behaviours (evaluated via shape index) and elemental compositions are different. These 3 populations did not dissolve over the 72-h study but aggregated and settled out differently. Thus, the population of particles with gyration radii <140 nm (P1), which contained 6% Al2O3 and represented approximately 20% by mass of the nanoparticle fraction, remained in suspension without observable aggregation. The populations P2 and P3, which represented 67% and 13% by mass in the initial suspension, covered the rG range 25-250 nm and contained 17% and 15% Al2O3, respectively. Over time, populations P2 and P3 aggregated and their concentration in suspension at 72 h decreased by approximately 40% compared with the initial suspension. The decrease of these nanoparticle populations occurred either from the beginning of the temporal monitoring (P2) or after 30 h (P3). Aggregation generated a new population (P4) in suspension with rG up to 300 nm and mostly consisting of P2. This population represented only up to 6 to 7% of the nanoparticle fraction and decreased beyond 50 h. As a result, the trace elements present in the nanoparticle fraction and monitored (Cu and La) were also no longer found in the suspension. The results obtained can offer additional insights into the fate of volcanic ash nanoparticles in the environment

Organotin plant uptake from a contaminated soil: phytoaccumulation and biotransformation into cultivated plant

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Behaviour of colloidal trace metals (Cu, Pb and Cd) in estuarine waters: An approach using frontal ultrafiltration (UF) and stripping chronopotentiometric methods (SCP)

International audienceThe frontal cascade ultrafiltration (UF) technique in conjunction with stripping chronopotentiometry (SCP) has been evaluated for determining the colloidal distribution of Cu, Pb and Cd in estuarine waters. Metallic concentrations in seven size fractions (0.45 μm–0.22 μm; 0.22 μm–300 kDa; 300–50 kDa; 50–30 kDa; 30–10 kDa; 10–5 kDa; <5 kDa) were determined with the aim to investigate their changes along the salinity gradient of the Penzé system (NW France). These data, completed by analysis of the total dissolved metals at 10 stations over the whole freshwater–seawater mixing zone, provided some insights in the removal and addition processes that affect Cu, Pb and Cd in estuaries

Assessment of metal–extracellular polymeric substances interactions by asymmetrical flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

Extracellular polymeric substances (EPSs) excreted by the bacterium Sinorhizobium meliloti and associated Ca, Cd and Pb were characterised by asymmetrical flow field-flow fractionation coupled with UV spectrophotometry and inductively coupled plasma mass spectrometry in terms of molar-mass distributions, number- and weight-average molar masses and polydispersity index. Two major populations with weight-average molar masses of 74 × 10^3 and 1.35 × 10^6 g mol^–1 were obtained for the EPS. Characterisation of the whole EPS–metal interactions evidenced the preferential binding of Ca and Cd to the low molar mass fraction, whereas Pb associated mainly with the high molar mass (HMM) fraction. Comparison with the EPS produced by exoY-mutant, deficient in HMM-EPS excretion, confirmed the preferential binding of Pb to the high molar mass fraction. Enrichment of the EPS with increasing metal concentrations induced the formation of aggregates, which was most pronounced in the presence of 10^–4 mol L^–1 Pb

Solid phase microextraction (SPME): a new procedure for the control of butyl- and phenyltin pollution in the environment by GC-FPD

International audienceA new alternative to liquid-liquid extraction for the speciation of organotin compounds is proposed using NaBEt4 ethylation-simultaneous solid phase microextraction (SPME)-GC-FPD. SPME is carried out using a polydimethylsiloxane (PDMS) fibre immersed in 100 ml of solution for an adsorption time of 60 min. The optimisation step confirms the importance of stirring the solution. The higher efficiency of mechanical stirring is also clearly demonstrated. Under these conditions, SPME was applied for the first time to the simultaneous extraction of butyl- and phenyltins and the analytical performances were evaluated. Very low detection limits were reached, in the range 0.006-0.031 ng Sn 1-1 for butyltins and 0.2-0.6 ng Sn 1-1 for phenyltins. The repeatability is also improved compared with classical liquid-liquid extraction thanks to the small volume of the fibre and the on-line procedure (between 3 and 9% except for triphenyltin). The new method was applied to various environmental samples such as natural aqueous samples, sediment and sewage sludge. The competitive extractions between some organotins and organic matter present in complex matrices are discussed

The fate of iron nanoparticles in environmental waters treated with nanoscale zero-valent iron, FeONPs and Fe3O4NPs

International audienceAmong the different nanoparticles (NPs) that are used in the remediation of contaminated environmental waters, iron nanoparticles (FeNPs) are the most frequently applied. However, if these FeNPs remain in the waters after the treatment, they can cause a hazard to the environment. In this work the time dependent size distribution of iron particles was investigated in Milli-Q water, forest spring water and landfill leachate after a variety of FeNP treatments. The efficiency of the metal removal by the FeNPs was also examined. The concentrations of the metals in the aqueous samples were determined before and after the nano-remediation by inductively coupled plasma mass spectrometry (ICP-MS). The data revealed that the settling and removal of the FeNPs after the treatment of the waters was related to the sample characteristics and the ways of dispersing the NPs. When mixing was used for the dispersion, the nano zero-valent iron (nZVI), FeONPs and Fe3O4NPs settled quickly in the Milli-Q water, the forest spring water and the landfill leachate. Dispersion with tertramethylammonium hydroxide (TMAH) resulted in a slower settling of the iron aggregates. In the Milli-Q and forest spring waters treated with FeONPs and dispersed by TMAH, the nanosized iron remained in solution as long as 24 h after the treatment and could represent a potential threat in environmental waters with a low ionic strength. The removal of the metals strongly depended on the type of FeNPs, the chemical speciation of the elements and the sample matrix. If the FeNPs are contaminated by a particular metal, this contaminant could be, during the NPs treatment, released into the water that is being remediated. © 2016 Elsevier Ltd