Combination of nitrate (N, O) and boron isotopic ratios with microbiological indicators for the determination of nitrate sources in karstic groundwater

International audienceA new approach based on measurements of nitrate and boron isotopic composition associated with microbiological indicators for the determination of nitrate origin in karstic groundwater (SW, France) is presented. Nitrate and boron isotopic data indicate an animal source of nitrate (delta N-15-NO3- > 5 parts per thousand, delta O-18-NO3- < 10 parts per thousand and delta B-11 similar to 25 parts per thousand). Microorganism detection (bacteriophages) confirmed contamination from animal sources and proved fast water transfer (2-3 days) from surface to groundwater

Fractionnement isotopique du cuivre et du zinc lors de processus biogéochimiques dans les sols

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Boron behavior in the rivers of Réunion island, inferred from boron isotope ratios and concentrations of major and trace elements

International audienceA combined study of boron concentrations and isotopic ratios and of major and trace elements measured in Réunion waters, sampled up to four times between 1995 and 2012, illustrates boron behavior during water-rock interactions in tropical basaltic catchments. Boron isotope ratios measured in Réunion rivers and springs show a large range of variation between 1 and 48‰, that reflect mixed B sources and water-rock interaction processes: rain (δ 11 B≈40‰), hydrothermalism (δ 11 B≈0‰), low temperature basalt weathering in steep sided basins (δ 11 B≈30‰), and cycling within soil and vegetation (δ 11 B>40‰). Réunion rivers have schematically two types of δ 11 B signatures for low-temperature water-rock interactions: ≈30‰ for rivers with high weathering rates, and ≈45‰ for small forested catchments with relatively smoother slopes and lower weathering rates. High temperature water-rock interaction produces B enriched waters with a B isotopic signature close to that of the rocks. B behavior in the soil and vegetation cycle is more difficult to characterize but seems to result in soil solutions enriched in 11 B, with δ 11 B≥45‰

Zn isotope measurements in freshwater and its use as a probe of anthropogenic contamination in the Seine River

International audienc

Rivers from Volcanic Island Arcs: The subduction weathering factory

International audienc

Detection of nanoparticles by single-particle ICP-MS with complete transport efficiency through direct nebulization at few-microlitres-per-minute uptake rates

International audienceMeasurement of nanoparticle (NP) concentration and size by single-particle inductively coupled plasma mass spectrometry(spICP-MS) usually requires the use of a NP reference material to determine the loss of NPs and/or ions during their transportfrom the sample solution to the detection system. The determination of this loss, qualified as nebulization efficiency (ηNebulization)and/or transport efficiency (ηTransport), is time-consuming, costly and lacks reliability. Nebulization of the NPs directly into theplasma (without a spray chamber) results in ηNebulization = 100% and is thus a promising strategy to avoid these calibration steps.In this work, we used the μ-dDIHEN introduction system: a demountable direct injection high-efficiency nebulizer (dDIHEN)hyphenated to a flow-injection valve and a gas displacement pump. For the first time with a continuous flow nebulizer, completetransport efficiency was reached (i.e. ηTransport = 100%). Operated at a very low uptake rate (as low as 8 μL min−1), the μ-dDIHEN accurately and reproducibly determined average diameters of Au-, Ag- and Pt-NPs, in full agreement with theirreference values. It was also successfully tested for Au-NPs in complex matrices, such as surface waters. spICP-MS analyses with the μ-dDIHEN sample introduction system only require a dissolved standard calibration to determine NP average diameter(dNPs in nm) and number concentration (NNPs) from a simplified set of equations

MC-ICP-MS Isotope Measurements with Direct Injection Nebulisation (d-DIHEN): Optimisation and Application to Boron in Seawater and Carbonate Samples

International audienc

Boron isotope ratios of surface waters in Guadeloupe, Lesser Antilles

International audienceLarge variations are reported in the B concentrations and isotopic ratios of river and thermal springwaters in Guadeloupe, Lesser Antilles. Rivers have d11 B values around 40‰ and B concentrations lowerthan 30 lg/L, while thermal springs have d11B of 8–15‰ and B concentrations of 250–1000 lg/L. Riversamples strongly impacted by hydrothermal inputs have intermediate d11B and B contents. None of thesesurface water samples have d11 B comparable to the local unweathered volcanic rocks (around 0‰),implying that a huge isotopic fractionation of 40‰ takes place during rock weathering, which could beexplained by preferential incorporation of 10 B during secondary mineral formation and adsorption onclays, during rock weathering or in the soils. The soil-vegetation B cycle could also be a cause for sucha fractionation. Atmospheric B with d11B of 45‰ represents 25–95% of the river B content. The varietyof the thermal spring chemical composition renders the understanding of B behavior in Guadeloupehydrothermal system quite difficult. Complementary geochemical tracers would be helpful

Behaviors of major and trace elements during single flood event in the Seine River, France

International audienceThis study examines for the first time the characteristics of suspended particulate matter (SPM) and geochemical behaviors of major and trace elements during one single flood event of the Seine River, France. Source contribution, dilution by silicates and carbonates are the main scenarios consecutively occurring during the flood event, as can be inferred from the geochemical behaviors for major and trace elements. This study confirms the importance of flood events for the flux of materials transported by rivers to the ocean and emphasizes the need of systematic studies on the chemical variability of elements transported during flood events