Study of exchangeable metal on colloidal humic acids and particulate matter by coupling ultrafiltration and isotopic tracers: Application to natural waters

A new method is proposed to characterize the complexation properties of colloids and metal-colloid interactions in natural waters. Based on the association of ultrafiltration with isotopic tracing, this method could quantify the pool of elements in an exchangeable position and also address the kinetic aspects of these exchanges. Basically, it consists of the comparison of isotopic compositions between the bulk sample and a succession of filtrates through time. Exchanges between colloidal humic acids (HA) and metals were first characterized, before applying such manipulations on natural waters. A few elements, representative of a wide range of complexation properties, were chosen: Cu, Zn, Cd, Pb, Sr, Nd, Ni, Th and U. In the case of humic acids, very small (less than 10% of isotopes), but significant isotopic shifts were observed compared to the isotopic equilibrium. It means that more than 90% of the isotopes were exchanged just after addition of isotopic tracers. Experiments on natural organic-rich waters (Mengong and Nyong streams) indicate isotopic composition variations close to those of humic acids. On the contrary, ultrafiltration performed on the total Sanaga River water (including suspended matter "SM") shows an important isotopic shift between the filtered and unfiltered solutions. It means that in the case of the Sanaga River, a significant part of the chemical elements did not exchange

uFREASI: user-FRiendly Elemental dAta procesSIng. A free and easy-to-use tool for elemental data treatment

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) allows the quantification of trace and ultra-trace elements (mg/kg to fg/kg) by separating elements as a function of their massto-charge ratios (m/z) after ionisation into an argon plasma. In spite of being rigorous and accurate, the "Results" modules provided by many manufacturers are often uneasy to use and operators have little control on the calculation. Moreover, the large amount of raw data generated makes the manual treatment very long and not reliable using a "home-made" spreadsheet. The user-FRiendly Elemental dAta procesSIng (uFREASI) software presented in this paper follows a configurable step-by-step procedure allowing a quick and reliable data treatment plus an automatic uncertainty propagation. The concentration calculation is performed using the ordinary least square method after an external calibration. The software proposes many options to correct and to monitor the signal, to warrant both quality and understanding of data treatment. uFREASI is supported by Windows, Mac OS X and Linux 2 operating system, is open and extensible, and is freely downloadable at http://www.ipgp.fr/~tharaud/uFREASI

Study of labile Cd pool in contaminated soil using stable isotope analysis, radioactive isotope dilution and sequential extraction

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Zn Isotopes as Tracers of Atmospheric Emissions from a Pb-Zn Smelter

Issue 12, Supplement 1 F.I. 3,6650info:eu-repo/semantics/publishe

Mobility and transformation of CdSe/ZnS quantum dots in soil: Role of the capping ligands and ageing effect

International audienc

An Isotopic Exchange Kinetic Model to Assess the Speciation of Metal Available Pool in Soil: The Case of Nickel

International audienc

Utility of Chromobacterium violaceum SUK1a, an indigenous bacterial isolate for the bioremediation of Cr(VI)

The potential of an indigenous bacterial strain, Chromobacterium violaceum SUK1a, isolated from surface water samples collected from Sukinda Valley in Odisha, India, has been evaluated for the first time for the bioremediation of toxic hexavalent chromium (Cr(VI)) ions. The isolate was assessed for its Cr(VI) biosorption efficiency and the various parameters affecting the biosorption process were evaluated. A maximum Cr(VI) biosorption of about 50% was obtained, and the residual chromium was in the form of less toxic Cr(III). The Gibbs free energy of biosorption was determined to be -26.3 kJ/mol, suggestive of a chemisorption process. Additionally, the Cr(VI) biosorption by the isolate followed pseudo second order kinetics. FTIR spectral studies indicated that the surface functional groups present on the bacterial isolate such as, carboxyl, hydroxyl, amino, and phosphate groups were involved in the complexation of chromium ions with the bacterial cells. X-ray photoelectron spectroscopic studies on Cr(VI) interacted bacterial cells revealed an additional peak corresponding to Cr(III) in the Cr(2p) spectra. The surface charge of the bacterial cells subsequent to interaction with Cr(VI) were less negative compared to the pristine cells, which further substantiated the bioreduction of Cr(VI) to Cr(III). The bioremediation mechanism of Cr(VI) by the bacterial isolate is delineated to be governed by both biosorption and bioreduction processes under metabolism independent conditions. The results obtained indicate that the isolate can be a promising candidate for Cr(VI) bioremediation applications

Isotopically Labeled Nanoparticles at Relevant Concentrations: How Low Can We Go? The Case of CdSe/ZnS QDs in Surface Waters

International audienceAnalytical barriers impose work at nanoparticles (NPs) concentrations orders of magnitude higher than the expected NPs concentrations in the environment. To overcome these limitations, the use of nontraditional stable isotope tracers incorporated in NPs (spiked-NPs) coupled with HR-ICP-MS has been proposed. The performance and efficiency of this analytical method was assessed in the case of quantum dots (QDs). Multi-isotopically labeled 111Cd77Se/68ZnS QDs were synthesized and their dissemination in natural aquatic matrices (river, estuarine and sea waters) was modeled at very low concentrations (from 0.1 to 5000 ppt). The QD limits of quantification (QD-LOQ) in each matrix were calculated according to the isotopic tracer. In ultrapure and simple medium (HNO3 2%), Zn, Cd, and Se originated from the QDs were quantifiable at concentrations of 10, 0.3, and 6 ppt, respectively, which are lower than the conventional HR-ICP-MS LOQs. In aquatic matrices, the QD-LOQs increase 10-, 130-, and 250-fold for Zn, Cd, and Se, respectively, but remain relevant of environmental concentrations (3.4 ppt ≤ QD-LOQs ≤ 2.5 ppb). These results validate the use of isotopically labeled ENPs at relevant concentrations in experimental studies related to either their fate, behavior, or toxicity in most aquatic matrices

Use of Cd and Zn isotopic variations in a sedimentary core to trace anthropogenic contamination

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