The rivers that comprise the Atibaia and Jaguari medium size subbasins and their interconnected reservoirs (Cantareira Water System) provide drinking water for about one-third of São Paulo's State ...population. Native vegetation covers nearly 30% of the catchments' territory, and the remaining comprises small-scale farming, reforestation, industries, and urban agglomerations. The study aimed to find at which extent the silicate rock lithologies, land uses, and the water transference between reservoirs influence the rivers' water composition. Forty-seven river water samples, collected before and after the dams during a rainy and a dry period, presented circumneutral pH values, while electric conductivity, major ions and dissolved organic carbon concentrations increased in the downstream direction, controlled by silicate weathering, noticeable anthropogenic inputs, and negligible seasonal influence. The water type is Na–Ca–HCO3, the overall total dissolved solids (TDS) presented one order of magnitude difference between higher and lower reaches, and evidences of solute transference between the two subbasins. River water turbidity was higher during the rainy season and positively correlated with the ∑REE measured in the <0.22 μm pore filtered samples because of the dispersion of sediments (eroded soil) in the water bodies. We show that rock weathered material dispersed in water can increase the ∑REE and originate positive Ce anomalies in its filtrate, similar to features observed in normalized patterns in the river water samples. Most samples exhibited flat shale-normalized REE distributions, with less fractionation between light and heavy REE than the regional lithotypes. Most samples also presented positive Eu anomalies, which source are the rocks of the area. The more urbanized stretches of the rivers exhibited discrete anthropogenic Gd anomalies. The results of this study demonstrate increasing signatures from human activities in the water bodies.
•Total dissolved solids in riverine water evidenced the transference of solutes between drainage basins.•Major dissolved species presented discrete seasonal changes.•Strong correlation between dissolved rare earth elements and water turbidity.•Sediments dispersed in river water could produce positive Ce anomalies as obtained by dispersing soil in tap water.
We present new reference values for nineteen USGS, GSJ and GIT‐IWG rock reference materials that belong to the most accessed samples of the GeoReM database. The determination of the reference values ...and their uncertainties at the 95% confidence level follows as closely as possible ISO guidelines and the Certification Protocol of the International Association of Geoanalysts. We used analytical data obtained by the state‐of‐the‐art techniques published mainly in the last 20 years and available in GeoReM. The data are grouped into four categories of different levels of metrological confidence, starting with isotope dilution mass spectrometry as a primary method. Data quality was checked by careful investigation of analytical procedures and by the application of the Horwitz function. As a result, we assign a new and more reliable set of reference values and respective uncertainties for major, minor and a large group of trace elements of the nineteen investigated rock reference materials.
Nous présentons de nouvelles valeurs de référence pour dix‐neuf matériaux de référence de roche de l'USGS, GSJ et GIT‐IWG qui appartiennent aux échantillons les plus recherchésacc de la base de données “GeoReM”. La détermination des valeurs de référence et leur incertitude au niveau de confiance de 95% suit d'aussi près que possibles les directives de l'ISO et le protocole de certification de l'Association Internationale des Géoanalystes. Nous avons utilisé des données d'analyse obtenues par les techniques de l'état de l'art publiées principalement dans les 20 dernières années et disponibles dans GeoReM. Les données sont regroupées en quatre catégories de différents niveaux de confiance métrologiques, en commençant par la dilution isotopique par spectrométrie de masse comme méthode principale. La qualité des données a été vérifiée par unexamen attentif des procédures d'analyse et par l'application de la fonction de Horwitz. En conséquence, nous attribuons un nouveau et plus fiable ensemble de valeurs de référence et des incertitudes respectives pour les éléments majeurs, mineurs et un grand groupe d'oligo‐éléments des dix‐neuf matériaux de référence de rocheétudiés.
Key Points
A new, more reliable set of reference values and 95% CL uncertainties is presented for nineteen USGS, GSJ and GIT‐IWG rock reference materials
Derivation by closely following ISO guidelines and the certification protocol of the IAG
Data quality checked by careful investigation of analytical procedures and application of the Horwitz function
Anthropogenic gadolinium (Gd
anth
) is a frequent contaminant in surface water that receives wastewater treatment (WWT) effluents due to the high stability of Gd-based contrast agents (Gd-CAs) used ...in magnetic resonance imaging (MRI) exams and excreted by patients. This study describes the presence of Gd
anth
in surface water of a small drainage area (circa 4 km
2
), which does not receive WWT effluents. The unexpected Gd
anth
anomalies were attributed to raw sewage leaking from underground effluent removal pipes. The study area is within a university campus with a hospital that regularly runs MRI exams employing Gd-CAs. Besides Gd, the whole lanthanide (Ln) series was measured and except for Gd, all remaining Ln data were correlated, implicating that besides the natural Gd, a distinct Gd species contributes up to 95% to its whole content in the water samples. Besides surface water, samples of the local sewage and pluvial water networks were collected and analyzed. The ratio between measured and expected Gd values (Gd/Gd*) in surface water samples ranged between 1 and 46, the first corresponding to pristine locations and absence of Gd anomaly and the second nearby the sewage and pluvial water networks. The Gd
anth
anomalies presented transient values, probably associated with the application of the Gd-CAs to patients and their permanence in the hospital. Other proxies commonly associated to sewage discharge also presented transient values, not necessarily correlated Gd
anth
, because of the input of distinct anthropogenic sources in the study area.
We present new reference values for the NIST SRM 610–617 glasses following ISO guidelines and the International Association of Geoanalysts’ protocol. Uncertainties at the 95% confidence level (CL) ...have been determined for bulk‐ and micro‐analytical purposes. In contrast to former compilation procedures, this approach delivers data that consider present‐day requirements of data quality. New analytical data and the nearly complete data set of the GeoReM database were used for this study. Data quality was checked by the application of the Horwitz function and by a careful investigation of analytical procedures. We have determined quantitatively possible element inhomogeneities using different test portion masses of 1, 0.1 and 0.02 μg. Although avoiding the rim region of the glass wafers, we found moderate inhomogeneities of several chalcophile/siderophile elements and gross inhomogeneities of Ni, Se, Pd and Pt at small test portion masses. The extent of inhomogeneity was included in the determination of uncertainties. While the new reference values agree with the NIST certified values with the one exception of Mn in SRM 610, they typically differ by as much as 10% from the Pearce et al. (1997) values in current use. In a few cases (P, S, Cl, Ta, Re) the discrepancies are even higher.
Nous présentons des nouvelles valeurs de référence pour les verres NIST SRM 610–617 en suivant les recommandations de l’ISO et le protocole de l’IAG. Les incertitudes au niveau de confiance de 95% ont été déterminées à des fins d’analyse totale et de micro‐analyse. Contrairement aux procédures de compilation précédentes, cette approche fournit des données qui tiennent compte des exigences actuelles dans la qualité des données. De nouvelles données analytiques et le jeu de données presque complet de la base de données GeoReM ont été utilisés pour cette étude. La qualité des données a été vérifiée par l’application de la fonction de Horwitz et par un examen minutieux des procédures analytiques. Nous avons déterminé quantitativement les possibles inhomogénéités d’élément en utilisant des prises d’essai de masses différentes correspondant à 1, 0.1 et 0.02 μg. Bien que nous ayons évité les zones de bordure des disques de verre, nous avons trouvé des inhomogénéités modérées pour plusieurs éléments chalcophiles/sidérophiles et des inhomogénéités flagrantes de Ni, Se, Pd et Pt pour les prises d’essai de petites masses. La mesure d’inhomogénéité a été incluse dans la détermination des incertitudes. Alors que les nouvelles valeurs de référence sont en accord avec les valeurs NIST certifiées à la seule exception du Mn dans SRM 610, elles sont généralement différentes, avec des écarts de près de 10%, des valeurs de Pearce et al. (1997) qui sont d’un usage courant. Dans quelques cas (P, S, Cl, Ta, Re), les écarts sont encore plus élevés.
The concentrations of rare earth elements (REE), measured in water samples from Atibaia River and its tributary Anhumas Creek, Brazil, present excess of dissolved gadolinium. Such anthropogenic ...anomalies of Gd in water, already described in other parts of the world, result from the use of stable and soluble Gd chelates as contrast agents in magnetic resonance imaging. Atibaia River constitutes the main water supply of Campinas Metropolitan area, and its basin receives wastewater effluents. The REE concentrations in water samples were determined in 0.22-μm pore size filtered samples, without and after preconcentration by solid-phase extraction with bis-(2-ethyl-hexyl)-phosphate. This preconcentration method was unable to retain the anthropogenic Gd quantitatively. The probable reason is that the Gd chelates dissociate slowly in acidic media to produce the free ion that is retained by the phosphate ester. Strong correlations between Gd and constituents or parameters associated with effluents confirmed the source of most Gd in water samples as anthropogenic. The shale-normalized REE patterns of Atibaia River and Anhumas Creek water samples showed light and heavy REE enrichment trends, respectively. Also, positive Ce anomalies in many Atibaia River samples, as well as the strong correlations of the REE (except Gd) with terrigenous elements, imply that inorganic colloidal particles contributed to the REE measured values.
Sample digestion is a critical stage in the process of chemical analysis of geological materials by ICP‐MS. We present a new HF/HNO3 procedure to dissolve silicate rock samples using a high pressure ...asher system. The formation of insoluble AlF3 was the major obstacle in achieving full recoveries. This was overcome by setting an appropriate digestion temperature and adding Mg to the samples before digestion. Sodium peroxide sintering was also investigated and the inclusion of a heating step to the alkaline sinter solution improved the recoveries of thirteen elements other than the lanthanides. The results of these procedures were compared with data sets generated by common acid decomposition techniques. Forty‐one trace elements were determined using an ICP‐QMS equipped with a collision cell. Under optimum conditions of gas flow and kinetic energy discrimination, polyatomic interferences were eliminated or attenuated. The measurement bias obtained for eight reference materials (BCR‐2, BHVO‐2, BIR‐1, BRP‐1, OU‐6, GSP‐2, GSR‐1 and RGM‐1) and intermediate precision (RSD) were generally better than ± 5%. The expanded measurement uncertainties estimated for two certified reference materials were mostly between 7 and 15%. New data sets for the reference materials are provided, including constituents with previously unavailable values and also for the USGS candidate reference material G‐3.
La digestion d’un échantillon est une étape cruciale dans le processus d’analyse chimique des matériaux géologiques par ICP‐MS. Nous présentons une nouvelle procédure HF/HNO3 de dissolution des échantillons de roches silicatées à l’aide d’un système asher de haute pression. La formation d’AlF3 insoluble a été le principal obstacle à l’obtention de recouvrements intégraux. Ce problème a été résolu par la fixation d’une température de digestion appropriée et l’ajout de Mg dans les échantillons avant la digestion. Le frittage au peroxyde de sodium a été aussi étudié et l’inclusion d’une étape de chauffage à la solution alcaline de frittage a permis d’améliorer les recouvrements de treize éléments autres que les lanthanides. Les résultats de ces procédures ont été comparés à des bases de données générées par les techniques conventionnelles de décomposition à l’aide d’acides. Quarante et un éléments traces ont été déterminés en utilisant une ICP‐QMS équipée d’une cellule de collision. Dans des conditions optimales de débit de gaz et de discrimination de l’énergie cinétique, les interférences polyatomiques ont étééliminées ou atténuées. Les biais de mesure obtenus pour huit matériaux de référence (BCR‐2, BHVO‐2, BIR‐1, BRP‐1, OU‐6, GSP‐2, GSR‐1 et RGM‐1) et les précisions intermédiaires (RSD) sont généralement meilleures que ± 5%. Les incertitudes de mesure étendues estimées pour deux matériaux de référence certifiés sont pour la plupart comprises entre 7 et 15%. Les nouvelles bases de données pour les matériaux de référence ainsi que pour le matériau candidat à la référence G‐3 de l’USGS sont fournies, y compris celles concernant des constituants dont les valeurs étaient précédemment indisponibles.
The use of environmental tracers brings comprehensive benefits to the management of water resources since it helps to prevent their pollution, minimize public health risks, and thus reduce the impact ...of urbanization. In Brazil, the Guarani Aquifer System (GAS) has strategic and environmental importance, making its preservation and sustainable exploitation mandatory. The present study aimed at evaluating sources of contamination in the GAS using the combination of geochemical data and two environmental tracers: nitrate isotopes (
15
N
NO3
and
18
O
NO3
) and one rare earth element (Gadolinium—Gd). For that, five wells—four exploiting the GAS and one the Bauru Aquifer System (BAS)—were selected to discuss the human inputs in groundwater used for public supply in an urban area. Traditional physicochemical analyses were conducted for six campaign samplings and nitrate monitoring for this period was evaluated on a time scale, also considering the accumulated rainfall. Besides that, the double isotopic method (DIM), e.g., δ
18
O
NO3
e δ
15
N
NO3
, was applied to identify the fractionation and enable the distinction of the nitrate contamination source. In addition, the determination of anomalies of Gd, a wastewater-derived contaminant, was also performed to verify recent human inputs in groundwater. The results show that the local existence of nitrate in the GAS and BAS—even at low concentrations (values from 0.26 to 6.68 mg L
−1
)—originated from anthropogenic inputs (septic waste), as indicates the typical isotopic signals ratio in the isotopic approach. Associated with that, the evaluation of Gd permitted the separation of groundwater samples into older or more recent leakages. The use of environmental tracers to assess anthropogenic inputs in groundwater reiterates the importance of adopting more effective protection strategies for water resources management systems, in order to prevent contamination.
Graphical Abstract
This work aimed at analyzing quartz lumps rejected from a major metallurgical grade silicon producer and at studying the effect of several processing techniques over its purification. The final ...objective was to enable the use of these lumps as a raw material for silica glass production. Chemical analyses using ICP-MS technique were conducted to understand the nature of the chemical impurities in the rejected lumps, aiming to identify rather if the impurity was inside or outside the quartz lattice. The processing procedures were divided in two steps, the first consisting of only a physical treatment and the second one consisting of a chemical treatment. The physical treatment consisted of washing, milling (and separating the material by its particle size) and magnetic separation. This treatment reduced most of the impurities present in quartz, purifying over 90% of the Fe contamination and over 60% of the Al contaminations, but it was incapable of producing a powder with similar chemistry to commercial raw materials. The chemical treatment was conducted using two different acid mixtures (dilute HCl and dilute HCl+HF). Interesting results were obtained using the HF containing mixtures. These mixtures were able to produce a powder with commercial purity (with Al impurities lower than 50ppm). This treatment was also able to reduce lattice impurities.
•We processed quartz lump rejects into powder capable of manufacturing silica glass.•We noticed that the presence of HF in acid leaching is highly relevant.•We noticed that the larger amount of impurities is removed on physical treatment.•Both treatments are necessary to produce a commercial grade raw material.
Inductively coupled plasma mass spectrometry (ICP-MS) is the best fitted analytical technique for multi-element analysis of waters, because of its low detection limits. One limitation is the ...polyatomic interferences produced in the plasma and in the interface (e.g., 35Cl16O+ on 51V+, 40Ar16O+ on 56Fe+, 40Ar35Cl+ on 75As+ and 40Ar38Ar+ on 78Se+). These polyatomic ions can be significantly reduced by ion molecule interactions in a collision cell (CC). Several experiments done in a ICP-MS equipped with a CC pressurized by premixed H2 7% in He, under optimized gas flow rates, demonstrate the beneficial effect of KED to suppress Ar and Cl-based interferences. These results are opposed to reports where the role of KED was denied. Under such conditions the background equivalent concentration of 51V, 52Cr, 56Fe, 63Cu, 75As and 78Se were improved by two orders of magnitude, allowing the quantification of these elements at low ng L-1 level, without the need for mathematical corrections. Moreover, we present results obtained with a multi-mode method of analysis for twenty eight elements in two water certified reference materials (CRM). In this method isotopes free from polyatomic interferences are measured in standard mode and interfered ones using CC mode. The certified and reference values were used to evaluate the analytical trueness, which was better than 5%, with all z-scores within the recommended limit. Intermediate precision was mostly better than 6% and method detection limits are fit for hydrogeochemical studies and to monitor regulated toxic trace elements in waters.
In this paper we describe a flux‐free fusion technique for the highly precise LA‐ICP‐MS bulk analysis of geological samples. For this purpose we have developed an automated iridium‐strip heater with ...temperature and melt time control. To optimise the homogeneity of the fused glasses and to reduce possible depletion of volatile elements during melting, we undertook experiments with basaltic rock and glass powders using different melting temperatures (1300–1700 °C) and melting times (5‐80 s). Major and trace element microanalysis was performed using EPMA and LA‐ICP‐MS. Homogeneous glasses were obtained for temperatures ≥ 1500 °C and melting times ≥ 10 s. High loss (20‐90%) of highly volatile elements (e.g., Cs, Ge, Sn, Pb) was observed for high melting temperatures (≥ 1600 °C) and long melting times (80 s). Standard melting conditions (1600 °C, 10 s) represent a compromise, as the glasses were homogeneous with respect to major and trace elements and, at the same time, were not depleted in elements with condensation temperatures (at a pressure of 10−4 bar) higher than about 900 K (e.g., Zr, Hf, Ba, Sr, REE, U, Mo, Ni, Rb, Ga). Several international geological reference materials with SiO2 ranging between 47% m/m and 59% m/m were prepared using our standard melting conditions (1600 °C, 10 s) and subsequently analysed by LA‐ICP‐MS. These samples also include the new Brazilian basaltic reference material BRP‐1. Matrix‐matched calibration of the LA‐ICP‐MS data was performed using the basaltic reference glasses KL2‐G, ML3B‐G, BCR‐2G and BHVO‐2G. Most analytical data agreed within uncertainty at the 95% confidence level with the GeoReM preferred values published in the GeoReM database for reference materials of geological and environmental interest. To demonstrate routine bulk LA‐ICP‐MS analyses of geochemical and cosmochemical samples using the whole rock fusion technique, we also present trace element data for ocean island basalts from Lanai (Hawaii) and of Martian meteorites.
Dans cet article, nous présentons une technique de fusion sans fondant en vue de mesures globales de grande précision par LA‐ICP‐MS d'échantillons géologiques. Nous avons développé dans ce but un four automatique à chauffage par filament d'iridium, avec contrôles de la température et du temps de fusion. Pour optimiser l'homogénéité des verres fondus et pour réduire les pertes potentielles d'éléments volatiles durant la fusion, nous avons effectué des expériences avec des poudres de roches de basaltes et de verres avec différentes températures de fusion (de 1300 à 1700 °C) et différents temps de fusion (de 5 à 80 s). La micro‐analyse des éléments majeurs et en trace a été effectuée par EMPA et LA‐ICP‐MS. Des verres homogènes ont été obtenus pour des températures supérieures à 1500 °C et des temps de fusion ≥ 10 s. Des pertes importantes (de 20 à 90%) des éléments très volatiles tels que Cs, Ge, Sn, Pb ont été observées aux températures de fusion élevées (≥ 1600 °C) et aux longs temps de fusion (80 s). Les conditions standards retenues (1600 °C, 10 s) représentent un compromis garantissant l'obtention de verres homogènes par rapport aux éléments majeurs et traces et, en même temps, la conservation des éléments ayant des températures de condensation (à une pression de 10−4 bar) supérieures à 900 K (Zr, Hf, Ba, Sr, REE, U, Mo, Ni, Rb, Ga). Plusieurs matériaux de référence certifiés internationaux ayant des teneurs en SiO2 entre 47% m/m et 59% m/m ont été préparés en appliquant ces conditions de fusion standards (1600 °C, 10 s) et analysés ensuite par LA‐ICP‐MS. Ces échantillons comprennent le nouveau matériau basaltique de référence brésilien BRP‐1. La calibration avec des étalons de même matrice a été effectuée en utilisant les verres de référence basaltiques KL2‐G, ML3B‐G, BCR‐2G et BHVO‐2G. La plupart des données est en accord, aux incertitudes de 95% près, avec les valeurs recommandées publiées dans la base de données GeoReM pour les matériaux de référence géologiques et environnementaux. Pour prouver la qualité des analyses de routine par LA‐ICP‐MS d'échantillons géologiques et cosmologiques par la technique de fusion de roche totale, nous présentons aussi des données d'éléments en trace sur des basaltes d'îles océaniques de Lanai (Hawaii) et de météorites martiennes.
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