The natural river water certified reference material SLRS‐5 (NRC‐CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made ...using ICP‐MS. Because no certified values are assigned by NRC‐CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given.
Le matériau de référence certifié d'eau de rivière naturelle SLRS‐5 (NRC‐CNRC) est analysé régulièrement comme contrôle qualité par dix laboratoires français étudiant les éléments majeurs et en trace dans les solutions naturelles. La plupart des mesures sont réalisées par ICP‐MS. Le silicium et 35 éléments en trace (terres rares, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y et Zr) ne sont pas certifiés par NRC‐CNRC. Aucun rapport isotopique n'est disponible. Nous proposons, pour ces éléments, des valeurs moyennes et leurs incertitudes associées obtenues par les différents laboratoires participants. Le rapport isotopique de Sr est aussi mesuré.
We present a 3-year time series of lead (Pb) and mercury (Hg) concentrations and isotope signatures in total suspended particulate (TSP) matter and as total gaseous Hg (TGM) in Xi’an, Northwestern ...China. Mean concentrations of TSP (299 ± 120 μg m–3), PbTSP (0.33 ± 0.15 μg m–3) and HgTSP (0.64 ± 0.54 ng m–3), and TGM (5.7 ± 2.7 ng m–3) were elevated. We find that atmospheric Pb levels in winter in Xi’an have decreased by 4.6% per year since 2003, yet remain elevated relative to air quality guidelines and therefore a major health concern. δ202HgTSP and Δ199HgTSP averaged −0.80 ± 0.30‰ (1σ) and −0.02 ± 0.10‰ (1σ) and δ202HgTGM and Δ199HgTGM averaged −0.08 ± 0.41‰ (1σ) and 0.00 ± 0.04‰ (1σ). Relative to raw coal from Shaanxi and surrounding provinces, δ202HgTSP is enriched in the light Hg isotopes, whereas δ202HgTGM is enriched in the heavy isotopes. TSP and TGM Δ199Hg signatures are indistinguishable from raw coal, indicating little photochemical mass independent fractionation of atmospheric Hg in the near-field urban-industrial environment. δ202HgTGM correlates significantly with TGM levels (r 2 = 0.3, p < 0.01) and likely reflects binary mixing of local industrial TGM emissions with global background TGM.
A procedure is described for the determination of thirty‐seven minor and trace elements (LILE, REE, HFSE, U, Th, Pb, transition elements and Ga) in ultramafic rocks. After Tm addition and acid sample ...digestion, compositions were determined both following a direct digestion/dilution method (without element separation) and after a preconcentration procedure using a double coprecipitation process. Four ultramafic reference materials were investigated to test and validate our procedure (UB‐N, MGL‐GAS GeoPT12, JP‐1 and DTS‐2B). Results obtained following the preconcentration procedure are in good agreement with previously published work on REE, HFSE, U, Th, Pb and some of the transition elements (Sc, Ti, V). This procedure has two major advantages: (a) it avoids any matrix effect resulting from the high Mg content of peridotite, and (b) it allows the preconcentration of a larger trace element set than with previous methods. Other elements (LILE, other transition elements Cr, Mn, Co, Ni, Cu, Zn, as well as Ga) were not fully coprecipitated with the preconcentration method and could only be accurately determined through the direct digestion/dilution method.
Key Points
Thirty‐seven minor and trace elements are investigated in four reference materials (UB‐N, MGL‐GAS, JP‐1 and DTS‐2B).
A double co‐precipitation method appears to be suitable for the determination of REE, HFSE, U, Th, Pb, Sc, Ti and V in ultradepleted peridtotites.
Other LILE, transition elements and Ga can be determined only following a standard digestion/dilution method.
Although CO2 is a ubiquitous volatile in geological fluids typically ranging from a few to more than 50wt%, its effect on metal vapor–liquid fractionation during fluid boiling and immiscibility ...phenomena in the Earth’s crust remains virtually unknown. Here we conducted first experiments to quantify the influence of CO2 on the partition of different metals in model water+salt+sulfur+CO2 systems at 350°C and CO2 pressures up to 100bar, which are typical conditions of formation of many hydrothermal ore deposits. In addition, we performed in situ Raman spectroscopy measurements on these two-phase systems, to determine sulfur and carbon speciation in the liquid and vapor phases. Results show that, in S-free systems and across a CO2 concentration range of 0–50wt% in the vapor phase, the absolute vapor–liquid partitioning coefficients of metals (Kvap/liq=Cvap/Cliq, where C is the mass concentration of the metal in the corresponding vapor and liquid phase) are in the range 10−6–10−5 for Mo; 10−4–10−3 for Na, K, Cu, Fe, Zn, Au; 10−3–10−2 for Si; and 10−4–10−1 for Pt. With increasing CO2 from 0 to 50wt%, Kvap/liq values decrease for Fe, Cu and Si by less than one order of magnitude, remain constant within errors (±0.2 log unit) for Na, K and Zn, and increase by 0.5 and 2 orders of magnitude, respectively for Au and Pt. The negative effect of CO2 on the partitioning of some metals is due to weakening of hydration of chloride complexes of some metals (Cu, Fe) in the vapor phase and/or salting-in effects in the liquid phase (Si), whereas both phenomena are negligible for complexes of other metals (Na, K, Zn, Mo). The only exception is Pt (and in a lesser extent Au), which partitions significantly more to the vapor of S-free systems in the presence of CO2, likely due to formation of volatile carbonyl (CO) complexes. In the S-bearing system, with H2S content of 0.1–1.0wt% in the vapor, Kvap/liq values of Cu, Fe, Mo, and Au are in the range 0.01–0.1, those of Pt 0.5–2.0, those of alkali metals are similar to the S-free system, and the partitioning of none of the studied metals is influenced by the presence of CO2 (up to 50wt% in the vapor). Our data thus confirm the large enhancement of volatility in the presence of reduced sulfur (H2S) due to formation of sulfide complexes for chalcophile metals such as Au, Pt, Mo and, to a lesser extent, Cu and Fe, as reported in previous studies of CO2-free water-salt systems. The negligible effect of CO2 on vapor–liquid partitioning of the studied metals in S-bearing systems is due to the lack of hydration of metal sulfide species making them little sensitive to changes in water activity and solvation power of CO2–H2O vapor. Our findings, combined with existing data over a wide range of temperature on vapor–liquid partitioning of metals in H2O-dominated systems, suggest that CO2 exerts mostly an indirect impact on metal fractionation, by extending vapor–liquid immiscibility to higher temperatures and pressures or depth compared to a CO2-free H2O-S-salt system. The deeper vapor–liquid separation, in particular in S-bearing systems, is expected to cause more significant partitioning of precious metals and molybdenum (Au, Pt, Mo) into the vapor phase while base metals (Fe, Zn, Cu) remain concentrated in the salt-rich (NaCl, KCl) liquid phase. In addition, irrespective of the presence of sulfur, an expansion of the immiscibility domain to higher temperature and pressure conditions in the presence of CO2 will also increase the depth of ore deposition and affect the vertical metal zonation in hydrothermal systems.
Snow cover is known to be an efficient and unique natural archive of atmospheric input and an indicator of ecosystem status. In high latitude regions, thawing of snow provides a sizable contribution ...of dissolved trace metals to the hydrological network. Towards a better understanding of natural and anthropogenic control on heavy metals and metalloid input from the atmosphere to the inland waters of Siberian arctic and subarctic regions, we measured chemical composition of dissolved (<0.22 µm) fractions of snow across a 2800 km south–north gradient in Western Siberia. Iron, Mn, Co, Ni, and Cd demonstrated sizable (by a factor of 4–7) decrease in concentration northward, which can be explained by a decrease in overall population density and the influence of dry aerosol deposition. Many elements (Mn, Ni, Cu, Cd, Pb, As, and Sb) exhibited a prominent local maximum (a factor of 2–3) in the zone of intensive oil and gas extraction (61–62° N latitudinal belt), which can be linked to gas flaring and fly ash deposition. Overall, the snow water chemical composition reflected both local and global (long-range) atmospheric transfer processes. Based on mass balance calculation, we demonstrate that the winter time atmospheric input represents sizable contribution to the riverine export fluxes of dissolved (<0.45 µm) Mn, Co, Zn, Cd, Pb, and Sb during springtime and can appreciably shape the hydrochemical composition of the Ob River main stem and tributaries.
Due to their properties, graphene-based nanomaterials (GBMs) are triggering a great interest leading to an increase of their global production and use in new applications. As a consequence, their ...release into the environment is expected to increase in the next years. When considering the current knowledge in the evaluation of GBMs ecotoxic potential, studies aiming to evaluate the hazard associated to these nanomaterials towards marine species and particularly considering potential interactions with other environmental pollutants such as metals are scarce. Here we evaluated the embryotoxic potential of GBMs, which include graphene oxide (GO) and its reduced form (rGO), both individually and in combination with copper (Cu) as a referent toxicant, towards early life stages of the Pacific oyster through the use of a standardized method (NF ISO 17244). We found that following exposure to Cu, dose-dependent decrease in the proportion of normal larvae was recorded with an Effective Concentration leading to the occurrence of 50% of abnormal larvae (EC50) of 13.85 ± 1.21 μg/L. Interestingly, the presence of GO at a non-toxic dose of 0.1 mg/L decreased the Cu EC50 to 12.04 ± 0.85 μg/L while it increased to 15.91 ± 1.57 μg/L in presence of rGO. Based on the measurement of copper adsorption, the obtained results suggest that GO enhances Cu bioavailability, potentially modifying its toxic pathways, while rGO mitigates Cu toxicity by decreasing its bioavailability. This research underscores the need to characterize the risk associated to GBMs interactions with other aquatic contaminants and supports the adoption of a safer-by-design strategy using rGO in marine environments. This would contribute to minimize the potential adverse effects on aquatic species and to reduce the risk for economic activities associated to coastal environments.
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•GO and rGO do not exert early developmental toxicity towards oyster larvae.•Cu sorption capacity of GO is higher compared to rGO.•Cu toxicity is promoted by co-exposure with non-toxic dose of GO.•Cu toxicity is mitigated by co-exposure with non-toxic dose of rGO.
The source and proportion of REY, Th, and U exported by groundwater and by the ephemeral stream along with the elemental proportions passing through vegetation have been assessed in the subhumid ...tropical forested CZO of Mule Hole, Southern India. The study relies on a pluriannual hydrogeochemical monitoring combined with a hydrological model. The significant difference between the soil input (SI) and output (SO) solute fluxes (mmol/km2/yr) of LREE (SI‐SO = 13,250‐1,500), HREE (1,930‐235), Th (64‐12), and U (63‐25) indicates a strong uptake by roots carried by canopy and forest floor processes. The contribution of atmospheric dust leaching can reach about 60% of LREE and 80% of HREE. At the watershed scale, the U solute flux exported by groundwater (180 mmol/km2/yr) mainly originates from the breakdown of primary U‐bearing accessory minerals and dominates by a factor of 25 the stream flux. The precipitation of authigenic U‐bearing phases and adsorption onto Fe‐oxides and oxyhydroxides play a significant role for limiting the U mobility. In the groundwater, the plagioclase chemical weathering is efficiently traced by the positive Eu‐anomaly. The very low (REY) to nil (Th) contents are explained by the precipitation of authigenic phases. In the stream flow, dominated by the overland flow (87% of the yearly stream flow), the solute exports (in mmol/km2/yr) of REY (1,080 for LREE and 160 for HREE) and of Th (14) dominate those by groundwater. Their mobility is enhanced by chelation with organic ligands produced by forest floor and canopy processes.
Key Points
Source of solute rare earths, thorium, and uranium in the Mule Hole tropical watershed has two main origins: heavy accessory bearing minerals and atmospheric dusts
Rare earths and thorium, mainly from atmospheric dust leaching origin, are significantly recycled by vegetation and exported by overland flow as organic complexes
Solute export by groundwater is much more significant for uranium than for rare earths and thorium, which transfer is limited by precipitation of secondary phosphates and oxides
AIMS: Varietal screening was conducted to characterize how French durum wheat lines (Triticum turgidum L. subsp. durum) differ in the concentration of cadmium (Cd) in their grains and to identify the ...main (eco) physiological processes behind these differences. METHODS: Eight French and two Canadian durum wheat lines were grown hydroponically in a nutrient solution with a low concentration of Cd (2 nM). At maturity, the partitioning of biomass and Cd among organs was analyzed and elemental profiles of the grain were obtained. RESULTS: Grain Cd concentration ranged from 0.03 to 0.08 μg gâ»Â¹ and was thus in the same range as that measured in field trials. The level of Cd in the grain was correlated with levels of P, Mn and Zn. French lines behaved like high-Cd cultivars. A 2.4-fold variation in grain Cd was observed within French lines, which was not explained either by a difference in uptake or by a difference in the root sequestration of Cd. One important finding is that the leaf biomass was the most influential variable explaining the genotypic variation in grain Cd observed within French lines. CONCLUSIONS: The partitioning of aboveground biomass may influence the concentration of Cd in grain, in addition to the sequestration of Cd in roots.
Despite the ubiquity of arsenic in hydrothermal-magmatic environments, its abundance, distribution, and chemical and structural status in natural silicate melts and glasses remain poorly known. Here ...we report the first in situ measurements of the redox state and molecular structure of As, using X-ray absorption fine structure (XAFS) spectroscopy, in a rhyolitic peraluminous glass from Macusani (SE Peru) that is representative of anatectic melts derived from metasedimentary crustal protoliths. Arsenic abundances as well as the concentrations of other trace elements were measured in the glass using a femtosecond laser ablation-inductively coupled plasma-quadrupole mass spectrometry (LA-ICP-QMS). The glass shows enrichments, by factors of 10 to 100, in comparison with the mean continental crust values, for As and other incompatible trace elements (e.g., Be, B, Rb, Sn, Sb, and Ta), and by factors of 100 to 200 for Li, Cd, and Cs. Arsenic is present in the peraluminous glass in trivalent state in the form of oxy-hydroxide complexes like AsO(OH)2- and/or As(OH)3, similar to those dominant in the aqueous fluid vapor phases at hydrothermal-magmatic conditions. The similar As chemical speciation between the fluid and the melt is consistent with As fluid/melt partitioning coefficients close to one, as observed in experiments on rhyolite-water systems. The depolymerized melt structure caused by elevated H2O, F, and P contents is likely to allow accomodation of high concentrations of metalloid hydroxide/hydrated complexes. Consequently, hydrous silicate melts may be important transporting media in shallow magmatic-hydrothermal settings for As and similar elements like B and Sb due to their high affinity to water and hydroxide ligands.
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