On-line and off-line quantification of trace elements associated to colloids by As-Fl-FFF and ICP-MS

cited By 27International audienceA quantification procedure of trace elements during colloid size fractionation was developed and validated. This procedure is based on the hyphenation between Asymmetrical Flow Field-Flow Fractionation (As-Fl-FFF) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The optimisation of the procedure was performed on a soil leachate spiked with six trace elements selected for their environmental and health impact (As, Cd, Sb, Se, Sn and Pb). The elements in the spiked sample were on-line monitored during the fractionation. The validation was carried out by comparison with a second off-line quantification procedure based on fraction collection and total element analysis by ICP-MS. This off-line one was previously validated using reference materials. Finally, the analytical performances of the two procedures were compared. © 2008 Elsevier B.V. All rights reserved

Retention capacity of natural sands for the treatment of waters containing arsenic trace levels

The aim of this work is to study the As retention capacity of two natural sand, a quartz sand and a volcanic red sand. Sorption experiments were performed in batch reactors at a constant ionic strength (0.010 M Na0$_3$). pH was controlled by acid or base microadditions. As, Fe, Al and Si were analysed in the aqueous phase to control their fate. Kinetic experiments of arsenic sorption showed that a fast step followed by a slow one could be observed depending on the sand. In the most rapid step, the formation of monodentate complexes could be the main phenomenon while in the slowest one bidendate and binuclear complexes could predominate. During As (V) sorption, the analyses of Al, Fe and Si showed that the dissolution of the different minerals present in the sands as Al, Si and Fe (hydr) oxides was not affected by As (V) sorption. From the point of view of the surface reactivity, the quartz sand bas more available sites for arsenic sorption than the volcanic sand However, the red soil shows a better retelltion capacity as expressed in amount of As per solid mass unit : 666 nmol g$^{-1}$ and 9.4 nmol g$^{-1}$ for the red soil and the quartz sand, respectively, for a contact time of 288 h

Assessment of trace metals in natural gas, biogas and biomethane

AFFInternational audienc

Study of metal trace element transfers in a natural gas aquifer storage

AFFInternational audienc

Selenium speciation analysis at trace level in soils

cited By 28International audienceThis paper describes the development of an analytical methodology to determine speciation of selenium present in soils at trace level (μgkg-1). The methodology was based on parallel single extractions and high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICPMS). Two complementary chromatographic separations were used to confirm Se species identity. Different extractants, selected on the basis of sequential extraction schemes, were compared. Ultrapure water, 0.1molL-1 phosphate buffer (KH2PO4/K2HPO4) at pH 7 and 0.1molL-1 sodium hydroxide extractants were finally chosen owing to their efficiency in extracting Se and compatibility with Se species stability. These extractants allow also assessing respectively water-soluble Se (i.e. the most mobile Se fraction), exchangeable Se (i.e. sorbed onto soil component surface) and Se bound to soil organic matter. This methodology gives thus information on Se mobility related to its distribution in soil with preservation of original Se speciation. Detection limits range from 3 to 29ng(Se)L-1 and from 0.1 to 10μg(Se)kg-1, allowing determination of Se species concentrations in extracts from soils containing native Se at trace level. The methodology was applied to three soils with total Se concentrations between 210 and 1560μg(Se)kg-1. © 2010 Elsevier B.V

Optimisation of asymmetrical flow field flow fractionation for environmental nanoparticles separation

cited By 61International audienceThe fractionation of natural nanoparticles by Asymmetrical Flow Field Flow Fractionation (As-Fl-FFF) was optimised by considering the following operating conditions: ionic strength, surfactant concentration and crossflow rate. The method performances such as fractionation recovery and fractionation efficiency were evaluated on a stable solution of colloidal-size natural inorganic particles. The online multi-detection by ultraviolet/visible spectrophotometer (UV) and multi-angle laser light scattering (MALLS) provided the monitoring of the sample during the separation and the evaluation of the fractionation efficiency. The lowest ionic strength and surfactant concentrations (i.e. 10-3 mol L-1 NH4NO3 and 3 × 10-4 mol L-1 SDS) allowed to obtain the highest sample recovery and lowest loss of the largest particles. The crossflow rate was investigated in order to avoid significant membrane-sample interaction. The applicability of the fractionation in optimised conditions was evaluated on a natural soil leachate, which was filtrated with different filter cut-offs. Filtration efficiency was stressed by the decrease of the large unfractionated particle influence in the void volume. For the first time, robust operating conditions were proposed to well size-fractionate and characterize soil nanoparticles within a single multi-detection analysis. © 2008 Elsevier B.V. All rights reserved

Trace elements analysis in natural gas with a High Pressure Bubbling Sampler

AFFInternational audienc

Sampling and analysis of trace metal elements in natural gas by high pressure bubbling sampler and ICP-MS analysis

COMInternational audienc

Iodine distribution and cycling in a beech (Fagus sylvatica) temperate forest

International audienceRadioiodine is of health concerns in case of nuclear events. Possible pathways and rates of flow are essential information for risk assessment. Forest ecosystems could influence the global cycle of long-lived radioiodine isotope (129I) with transfer processes similar to stable isotope (127I). Understanding iodine cycling in forest involves study of the ecosystem as a whole. In this context, we determined the 127I contents and distribution in soil, tree compartments and atmospheric inputs during a three years in situ monitoring of a temperate beech forest stand. The iodine cycle was first characterized in terms of stocks by measuring its concentrations in: tree, litterfall, humus, soil, rainfall, throughfall, stemflow and soil solutions. Main annual fluxes (requirement, uptake and internal transfers) and forest input-output budget were also estimated using conceptual model calculations. Our findings show that: (i) soil is the main I reservoir accounting for about 99.9% of ecosystem total stock; (ii) iodine uptake by tree represents a minor fraction of the available pool in soil (<0.2%); (iii) iodine allocation between tree compartments involves low immobilization in wood and restricted location in the roots; (iv) translocation of excess iodine towards senescing foliage appears as an elimination process for trees, and (v) litterfall is a major pathway in the I biological cycling. In our soil conditions, the input - output budget shows that the ecosystem behaves as a potential source of I for groundwater

Impact of forest canopy on iodine, selenium and cesium atmospheric inputs on forest ecosystems

International audienceRadioisotopes 131I, 129I, 79Se, 134Cs and 137Cs are of health concerns in case of nuclear events. Due to their largeinteracting surface area by canopy, forests could impact the quantity and speciation of elements incoming from atmospheric inputs to the ground. This study investigated the atmospheric inputs of stable iodine, selenium and cesium,during one year in rainfall (twenty-seven monitored sites) as well as their canopy output in throughfall (fourteen sites)throughout France. Results showed that annual rainfall I concentrations were much higher than those of Se and Cs(mean = 1.57, 0.045 and 0.006 µg L‒1, respectively). Annual concentrations of I, Se and Na in rainfall were positivelycorrelated, suggesting common atmospheric scavenging mechanisms by rains and/or common source(s) for theseelements. Annual rainfall fluxes of elements varied greatly from one site to another (6.9-47.8, 0.20-1.86 and 0.02-0.11 gha‒1 yr.‒1 for I, Se and Cs respectively), mostly influenced by rainfall amounts. For most sites, concentrations and fluxes of elements in throughfall were higher than corresponding rainfall ones. Throughfall enrichments were shown to be mostly due to dry depositions for I and Se, and to leaching after canopy recretion for Cs. Iodine and selenium speciation (i.e., I‒, IO3‒, SeO32‒ and SeO42‒) was also determined.Results evidenced significant modifications of I and Se speciation from rainfall to throughfall, with a substantial increase of unidentified iodine and selenium compoundsproportions and a drastic decrease of inorganic I and Se species. Data issued from this work clarified spatial variationof iodine, selenium and cesium inputs and improved our understanding for cycle modelling in forest ecosystems