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δ88/86Sr values of standards and a variety of natural samples were measured by MC-ICP-MS using the double-spike (DS) method and compared to results obtained by the standard-sample-bracketing (SSB) method and to DS-TIMS measurements. The external reproducibility of the SRM987 measurements carried out by DS-MC-ICP-MS was 0.021‰ (1SD), slightly better than previously published DS-TIMS and SSB-MC-ICP-MS results. The value of the IAPSO seawater standard (0.388 ± 0.018; 2SEM) agrees with the results of the current SSB and DS-TIMS measurements and with previously published values. Using these values a variance-weighted mean for seawater was calculated (0.387 ± 0.002, 2SEM). Compared to measurements carried out by the SSB method, natural sample measurements by the DS method are more accurate and more precise. An excellent agreement between DS-MC-ICP-MS and DS-TIMS methods was demonstrated for δ88/86Sr determination in natural samples over a range of ∼0.5‰. The DS-TIMS δ88/86Sr results had a smaller standard error than the DS-MC-ICP-MS measurements but required a much longer acquisition time. [ABSTRACT FROM AUTHOR]

In the present study we propose a new analytical method for 37 Cl/ 35 Cl analysis in perchlorate by Ion Chromatography(IC) coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). The accuracy of the analytical method was validated by analysis of international perchlorate standard materials USGS-37 and USGS -38; analytical precision better than ±0.4‰ was achieved. 37 Cl/ 35 Cl isotope ratio analysis in perchlorate during laboratory biodegradation experiment with microbial cultures enriched from the contaminated soil in Israel resulted in isotope enrichment factor ε 37 Cl = −13.3 ± 1‰, which falls in the range reported previously for perchlorate biodegradation by pure microbial cultures. The proposed analytical method may significantly simplify the procedure for isotope analysis of perchlorate which is currently applied in environmental studies. [ABSTRACT FROM AUTHOR]

Abstract: A sensitive analytical method for determining the artificial radionuclides 90Sr, 239Pu and 240Pu at the ultratrace level in groundwater samples from the Semipalatinsk Test Site area in Kazakhstan by double-focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS) was developed. In order to avoid possible isobaric interferences at m/z 90 for 90Sr determination (e.g. 90Zr+, 40Ar50Cr+, 36Ar54Fe+, 58Ni16O2 +, 180Hf2+, etc.), the measurements were performed at medium mass resolution under cold plasma conditions. Pu was separated from uranium by means of extraction chromatography using Eichrom TEVA resin with a recovery of 83%. The limits of detection for 90Sr, 239Pu and 240Pu in water samples were determined as 11, 0.12 and 0.1fgml−1, respectively. Concentrations of 90Sr and 239Pu in contaminated groundwater samples ranged from 18 to 32 and from 28 to 856fgml−1, respectively. The 240Pu/239Pu isotopic ratio in groundwater samples was measured as 0.17. This isotope ratio indicates that the most probable source of contamination of the investigated groundwater samples was the nuclear weapons tests at the Semipalatinsk Test Site conducted by the USSR in the 1960s. [Copyright &y& Elsevier]

Abstract Extreme evaporation experiments of modern seawater, up to a degree of evaporation (DE) of 870 on Li scale and brine density of 1.40 g·ml−1 were conducted under controlled semi-natural conditions. This DE is well within the bischofite facies and, to the best of our knowledge, is the highest experimental DE ever reported. During the experiments, brine temperature varied between ∼20 °C and ∼40 °C with few excursions to higher temperatures, thereby demonstrating the effect of temperature on the precipitating mineral assemblages. Results were compared to a thermodynamic simulation of the evaporation experiment at 25 °C, based on the Harvie-Møller-Weare activity coefficients correction. The relative amounts of the precipitated minerals were evaluated from the bulk chemical composition of the collected precipitates, applying a Li-based methodology for subtracting the contribution of the brine adsorbed on the precipitated salts. The following minerals were identified during the evaporation experiments: halite (NaCl), epsomite (MgSO 4 ∙7H 2 O), kainite (KMgClSO 4 ∙3H 2 O), carnallite (MgKCl 3 ∙6H 2 O), kieserite (MgSO 4 ∙H 2 O) and bischofite (MgCl 2 ∙6H 2 O). The precipitation of the Mg-salts was accompanied by continuous halite precipitation up to DE of ∼170. The experimental results are in good agreement with literature experimental data, available up to DE = 98, and generally follow the thermodynamic calculations, thereby supporting both the established methodology of the experiments and the simulation parameters and assumptions. Minor differences between the experiments and the thermodynamic calculation are mainly due to temperature variations. The experiments suggest that, at warmer temperatures (∼50 °C), kainite and bischofite precipitate instead of kieserite, which precipitates to a greater extent at lower temperatures (25–30 °C). The presence of organic matter (OM) in the brine was found to reduce the evaporation rate and the final DE at which evaporation ceased, but not to significantly affect the chemical evolution of the brine. The detailed systematic data-set presented here is useful for both geochemical and applied purposes. For example, it can be used as a reference for reconstructing the evolution of ancient marine-derived brines, using evaporitic sequences far beyond the halite facies. Hence, this study provides new insights on the formation of such evaporitic minerals and opens the way for further studies on these highly soluble evaporitic sequences as clues to the chemical composition of the ancient oceans. [ABSTRACT FROM AUTHOR]

Standard sulfur isotope analysis of aqueous samples is aimed at sulfide and sulfate, while often disregarding intermediate species, mainly due to analytical limitations. However, sulfur can form numerous intermediate species in the environment, including thiometal(loid)s such as thioarsenates ([HAs V S − II n O 4 − n ] 2 − , n = 1–4), which can play a key role in isotope fractionation. The standard precipitation procedure for separation of sulfide and sulfate was applied to monothioarsenate solutions. Monothioarsenate was found to co-precipitate together with sulfide, thus potentially impeding correct sulfide isotope analysis. To overcome the limitations associated with this standard precipitation procedure, a new method was developed based on separating sulfur species by ion chromatography followed by online isotope detection on multi-collector ICP-MS (IC-MC-ICP-MS). Applying this new method, fractionation between monothioarsenate and sulfate of up to − 6.1‰ was found during monothioarsenate oxidation. In contrast, oxidation of tetrathioarsenate via tri- and di- to monothioarsenate did not result in fractionation. However, the released sulfide became increasingly enriched in 34 S due to oxidation to sulfate. This process was found to introduce additional enrichment of up to 9.1‰ to monothioarsenate through intermolecular isotope exchange between arsenic-bound sulfur and sulfide in solution. These results help elucidate pathways of thioarsenate transformation, and thus provide valuable information for the interpretation of isotope fractionation patterns in sulfidic environments. [ABSTRACT FROM AUTHOR]

The potential of compound-specific stable isotope analysis (CSIA) to characterize biotransformation of brominated organic compounds (BOCs) was assessed and compared to chlorinated analogues. Sulfurospirillum multivorans and Desulfitobacterium hafniense PCE-S catalyzed the dehalogenation of tribromoethene (TBE) to either vinyl bromide (VB) or ethene, respectively. Significantly lower isotope fractionation was observed for TBE dehalogenation by S. multivorans (ε C = −1.3 ± 0.2‰) compared to D. hafniense (ε C = −7.7 ± 1.5‰). However, higher fractionation was observed for dibromoethene (DBE) dehalogenation by S. multivorans (ε C = −16.8 ± 1.8‰ and −21.2 ± 1.6‰ for trans - and cis -1,2- (DBE) respectively), compared to D. hafniense PCE-S (ε C = −9.5 ± 1.2‰ and −14.5 ± 0.7‰ for trans -1,2-DBE and cis- 1,2-DBE, respectively). Significant, but similar, bromine fractionation was observed for for S. multivorans (ε Br = −0.53 ± 0.15‰, −1.03 ± 0.26‰, and −1.18 ± 0.13‰ for trans -1,2-DBE, cis- 1,2-DBE and TBE, respectively) and D. hafniense PCE-S (ε Br = −0.97 ± 0.28‰, −1.16 ± 0.36‰, and −1.34 ± 0.32‰ for cis -1,2-DBE, TBE and trans- 1,2 - DBE, respectively). Variable C Br dual-element slopes were estimated at Λ (ε C /ε Br ) = 1.03 ± 0.2, 17.9 ± 5.8, and 29.9 ± 11.0 for S. multivorans debrominating TBE, cis- 1,2-DBE and trans- 1,2-DBE, respectively, and at 7.14 ± 1.6, 8.27 ± 3.7, and 8.92 ± 2.4 for D. hafniense PCE-S debrominating trans- 1,2-DBE, TBE and cis- 1,2-DBE, respectively. A high variability in isotope fractionation, which was substrate property related, was observed for S. multivorans but not D. hafniense , similar as observed for chlorinated ethenes, and may be due to rate-limiting steps preceding the bond-cleavage or differences in the reaction mechanism. Overall, significant isotope fractionation was observed and, therefore, CSIA can be applied to monitor the fate of brominated ethenes in the environment. Isotope effects differences, however, are not systematically comparable to chlorinated ethenes. [ABSTRACT FROM AUTHOR]

In this work the applicability of Ion Chromatography (IC) coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) for on-line magnesium isotope ratio analysis was explored. Various instrumental setups were employed to enable continuous magnesium separation from the sample matrix by IC followed by MC-ICPMS. The performance of two separation columns IonPac CS16 (ID 5 mm or ID 3 mm) connected with appropriate CERS 500 suppressors (4 mm or 2 mm) using dry and wet plasma conditions was compared. With the use of ID 3 mm column and 2 mm suppressor it was possible to apply dry plasma mode with Aridus II desolvation system. Mass discrimination and instrument drift were corrected by sample-standard bracketing method using the 26 Mg/ 24 Mg isotope ratio of DSM-3 as standard. Good accuracy and high precision of the magnesium isotope ratio (generally 0.15‰ (2 SD)) were achieved for wet and dry plasma modes; both were comparable to off-line Mg separation and continuous measurement. The sensitivity of MC-ICPMS measurements with dry plasma was 25 times higher in comparison to wet plasma conditions. Robustness and applicability of the method was demonstrated for matrix-rich natural water and rock samples magnesium isotope analysis. [ABSTRACT FROM AUTHOR]

Variations in the 238 U/ 235 U ratio are mostly observed in association with changes in the uranium oxidation state and therefore controlled by changes in the redox conditions, although evidence for this process has so far been indirect. Here, the δ 238 U and δ 234 U isotope composition of different redox species is studied for the first time within the same geological samples: the bulk, reduced (U(IV)) and oxidized (U(VI)) uranium species in seafloor phosphorites. In all cases, δ 238 U(IV) is higher (− 0.27 to − 0.81) than corresponding δ 238 U(VI) (− 0.64 to − 1.07), with δ 234 U(VI) displaying extremely high values (~ 500–2000) relative to δ 234 U(IV) (− 240 to − 100). By comparison, the bulk δ 238 U, δ 234 U and U concentrations are − 0.42 to − 0.85, − 10 to + 20, and 63–328 ppm, respectively. These values are mostly in the range of natural variations in previously reported samples, with the bulk δ 238 U and δ 234 U values corresponding with seawater values except for a tail in δ 238 U toward lower values. The main exception is displayed by the composition of the U(VI) fraction, which ranges toward relatively low δ 238 U values but has a very strong positive δ 234 U excursion relative to comparable samples elsewhere. Given that the studied phosphorites formed in high productivity environments, where oxygen consumption was high and hence anoxic conditions could have been favored, it is assumed that most of the initial uranium in the samples was in reduced form. Indeed, even if some of the U oxidized over time, the studied samples still consist of approximately 60–80% U(IV). The process of 238 U radioactive decay resulted in the oxidation of the decay product, 234 U, and consequently, the δ 234 U(VI) within the samples has very high values. The evolution of δ 238 U is related to the effect of the ‘nuclear field shift’, which predicts that nuclides with higher atomic masses will be reduced preferentially over those with lower atomic masses. Accordingly, it is easier to reduce 238 U than 235 U in the same environment, which would result in higher δ 238 U of U(IV). This is indeed the case observed here, although in addition, the evidence here shows that the δ 238 U fractionation occurred during U oxidation and that the final differences of δ 238 U between both oxidation states reflect the combined effect of the depositional nuclear field shift and the in-situ recoil-related oxidation . A set of quantitative models are used to evaluate the role and rate of the different processes and suggest that because of the independent evolution of U(IV) and U(VI) over time, their relative fraction and isotopic compositions can be used to evaluate the formation ages of seafloor phosphorites, which has so far not been possible using U-decay series. [ABSTRACT FROM AUTHOR]

Abstract: A new methodology has been developed for precise and accurate determination of 228Ra and the radium isotope ratio (228Ra/226Ra) by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) in natural water. The method was tested on waters from Lake Kinneret (The Sea of Galilee) and saline springs that flow into it. The radium is pre-concentrated from 60L of Lake Kinneret water (or 2L of the saline springs water) by co-precipitation with MnO2. The separation of radium from the matrix elements was conducted by BioRad® AG50W-X8 and Sr Spec® resins. The instrumental limit of detection for 226Ra and 228Ra was 5fgmL−1 (0.05ppq) or 0.1 and 30dpmL−1, respectively, and the absolute limit of detection 0.005fg. Internal precision of the radium isotope ratio (228Ra/226Ra) in Lake Kinneret for 228Ra concentration as low as 0.10fgL−1 (0.06dpmL−1) was 2.8% (2σ) and external precision was 10% (2σ, n =9). [Copyright &y& Elsevier]

Measurements of 44Ca/42Ca and 143Nd/144Nd isotope ratios in carbonate fluorapatite (CFA) through the Aptian-Eocene section of the Negev (Israel), together with quantified rates of P and Ca accumulation and bulk sedimentation, permit an examination of the relationships of these five factors to Tethyan phosphogenesis. The data provide an Aptian-Eocene (ca. 70 Ma) record of the Ca isotope composition of 35 CFA samples (24 of which were also analyzed for Nd isotopes), representing 11 time-stratigraphic phosphate horizons within the sequence. The δ44Ca values are significantly lower in the Aptian-Albian samples (δ44Ca = -0.11% to -0.06%) than in the Campanian-Eocene samples (δ44Ca = +0.22%c to +0.42%), whereas the εNd(T) values increase from continental crust like in the Aptian-Albian [εNd(T) = -10.9] to more radiogenic, Pacific-like [εNd(T) = - 6.6 to -6.1] in the Campanian. Both peaks of δ44Ca and εNd(T) in the Campanian coincide with the peak of Tethyan phosphogenesis in the Negev, which is marked by a sharp increase of P accumulation rates (from <:200 μmol.cm-2.k.y.-1 in pre-Campanian time to ∼1700 μmol.cm-2.k.y.-1 in the Campanian) and a decrease in rates of Ca accumulation and bulk sedimentation. The coincident increases of δ44Ca and εNd(T) values and P accumulation rates in the Negev area during the Campanian suggest that they are related in this time interval and were induced by the global Late Cretaceous sea level rise and increasing circumequatorial Tethyan flow. Keywords: δ44

• Foraminifera incorporate Zn and Pb in their calcite shells proportionate to seawater. • No species-specific or temperature effect on metal incorporation is observed. • Heavy metal concentrations can be measured by laser-ablation of individual chambers. • Such single-chamber analyses could record short-term pollution events. The establishment of sustainable coastal industries requires better temporal and spatial monitoring of heavy metal (HM) pollutants, even at low concentrations and during pulse-release events, before their accumulation becomes hazardous for local ecosystems or for the use of seawater in desalination (for drinking water). Foraminifera, unicellular marine organism, build their shells by sequential addition of chambers made of calcite, which contains impurities reflecting the composition of the growth medium. Therefore, the chemical composition of each chamber reflects HM in the ambient water at the time of calcification. To test the applicability of single-chamber analyses of foraminifera shells as a tool for HM monitoring in seawater, we conducted culturing experiments to calibrate the relationship of zinc and lead in foraminiferal shells and the ambient seawater. Two species of the cosmopolitan genus Amphistegina were cultured under a range of concentrations of both metals and two temperatures. We show that concentrations of zinc and lead in shells increase linearly with metal concentration in seawater with no difference between species and no effect of temperature. Our experiments further show that the concentrations in seawater can be directly inferred from concentrations in the shells at least up to the levels representing chronic pollution for both metals (68 ug/L for Zn and 8 ug/L for Pb). Combined with their high abundances in all marine environments and good preservation of their shells in sediments, our results demonstrate that foraminifera represent a powerful natural recording system offering high spatial and temporal resolution, allowing the establishment of historical baselines and detection of confined or short-term events of HM release, which could escape traditional monitoring methods. [ABSTRACT FROM AUTHOR]

In this paper, we present C export data from the southeastern Levantine Basin, 50 km west of Haifa, at water depth of 1500 m. Particulate organic carbon (POC) fluxes were measured for 18 months by automated and single bottle sediment traps at the recently-deployed DeepLev observatory and compared with water column profiles of 234Th. Calculations, based on POC/234Th ratios, result in water column-integrated export of 18 mmolC m−2 d−1 at the end of summer (Dec 2017) and remineralization during spring (e.g. 14.4 mmolC m−2 d−1, Apr, 2018). Based on the sediment traps POC export in the basin was generally low (0.05–1 mmolC m−2 d−1 at the base of the photic zone during Dec 2017–May 2018). Fluxes were quite variable, and the export pattern was mainly controlled by coastal discharge or shelf-resuspension (winter peaks) rather than by marine primary production. This was demonstrated by: i) larger POC fluxes measured by deep water (1300 m) and twilight zone (280 m) traps compared to fluxes measured at the base of euphotic zone, ii) tight correlation of POC with total mass flux, iii) decrease of the POC percentage during winter peak events and iv) imbalance (large integrated deficit or excess) of water column 234Th. Both deficit and excess are evidence of lateral flux, where the first probably results from wave-induced shelf resuspension of organic-poor material, which underwent minimal remineralization and induced scavenging, while the latter derives from the conveyance of large amount of land-derived organic matter, which undergoes remineralization, therefore input of 234Th to the water column. [ABSTRACT FROM AUTHOR]

This study introduces a simplified purification method for analyzing 82 Se/ 78 Se isotope ratios in diverse natural samples using hydride generation MC-ICP-MS. Unlike the thiol resin method, which is time-consuming and sensitive to the concentrations of reagents used at individual stages, our proposed alternative is quicker, simpler, and robust. The procedure involves coprecipitation of selenium with iron hydroxide and dissolution in hydrochloric acid. Combining hydride generation and a second cleanup stage achieves sufficient purification for Se isotope ratio measurements. The method is efficient, taking 3-4 h after sample decomposition, utilizing common reagents [HCl, Fe(NO 3 ) 3 , NH 4 Cl] without evaporation or clean lab conditions. Results on 82 Se/ 78 Se isotope ratios in various matrices are presented, comparing them with literature data. All isotopic results have been subjected to a newly proposed state-of-the-art approach to uncertainty estimation dedicated to isotope ratio measurements. The approach is based on applying Monte Carlo simulations with consideration of different samples' results normalized by the expected value. By doing that, we obtained estimated uncertainty for any Se sample with the influence of particular measurements on the final estimation included. We employ a Monte Carlo simulation-based uncertainty estimation approach for isotope ratio measurements, providing estimated uncertainty for each selenium sample.

Isotope fractionation of metals/metalloids in biological systems is an emerging research area that demands the application of state-of-the-art analytical chemistry tools and provides data of relevance to life sciences. In this work, Se uptake and Se isotope fractionation were measured during the biofortification of baker's yeast (Saccharomyces cerevisiae)-a product widely used in dietary Se supplementation and in cancer prevention. On the other hand, metabolic labeling with 15 N is a valuable tool in mass spectrometry-based comparative proteomics. For Se-yeast, such labeling would facilitate the assessment of Se impact on yeast proteome; however, the question arises whether the presence of 15 N in the microorganisms affects Se uptake and its isotope fractionation. To address the above-mentioned aspects, extracellularly reduced and cell-incorporated Se fractions were analyzed by hydride generation-multi-collector inductively coupled plasma-mass spectrometry (HG MC ICP-MS). It was found that extracellularly reduced Se was enriched in light isotopes; for cell-incorporated Se, the change was even more pronounced, which provides new evidence of mass fractionation during biological selenite reduction. In the presence of 15 N, a weaker preference for light isotopes was observed in both, extracellular and cell-incorporated Se. Furthermore, a significant increase in Se uptake for 15 N compared to 14 N biomass was found, with good agreement between hydride generation microwave plasma-atomic emission spectrometry (HG MP-AES) and quadrupole ICP-MS results. Biological effects observed for heavy nitrogen suggest 15 N-driven alteration at the proteome level, which facilitated Se access to cells with decreased preference for light isotopes., (© 2023. The Author(s), under exclusive licence to Society for Biological Inorganic Chemistry (SBIC).)

The source for Lead (Pb) pollution in soils from the heavily industrialized area located along the coast of the Eastern Mediterranean, Haifa Bay, Northern Israel, is studied using the lead isotopic composition. The uniqueness of the studied data set is that it includes samples of soils, road-wash, and storm-dust sampled for nearly three decades (1988-2017). Road-wash sediments are similar in both elemental and Pb isotopic composition to soils sampled in the same year (2010), indicating re-suspension of local soil, as its origin. Soils sampled during and before 1993 show no evidence for Pb contamination (bulk soil values), although Pb as an additive was already in use. Furthermore, soil overturns hinder the possibility to trace changes in the Pb isotopic composition with time in soils of the same location. Soils sampled from 1995-8 to 2013 were significantly dominated by Post-1992 Pb additive, pointing to Pb's peak as an additive. Soils Pb and Zn Enrichment factors for most samples are below 5, and their anthropogenic source is likely common. Forest fire enriched Pb and Zn in the soil, and their Pb isotope compositions reflect this enrichment. Lead from the Hod Assaf recycling plant detected up to some 2.5 km away, and although not analyzed in the current study, dioxin-like compounds possibly accompanied Pb., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

High-precision on-line procedure for measurement of calcium isotopic ratio by coupling ion chromatography to multicollector inductively coupled plasma mass spectrometry was developed. Calcium separation from the sample matrix was achieved on an ion chromatography column-IonPac CS16-ID 3 mm connected with CERS 500 2 mm suppressor and followed by multicollector inductively coupled plasma mass spectrometry calcium isotopic ratio determination. Dry plasma mode was used with Aridus II desolvation system. To sustained samples with high level of total dissolved salts as well as account capacity of applied analytical column, the method has been optimized regarding calcium isotope ratio measurements with low-resolution mass spectrometry. Mass discrimination and instrument drift were corrected by sample-standard bracketing method using the 44 Ca/ 42 Ca isotope ratio of SRM 915a as a standard. Good accuracy and reasonable precision of calcium isotope ratio (generally 0.20‰ [2SD]) were achieved, which are comparable to off-line Ca separation and continuous measurement. The reproducibility of the proposed analytical procedure was verified by measuring the SRM 915a standard as a sample randomly over 3 months (n = 56). Applicability of the protocol was demonstrated for matrix-rich natural water samples, coral samples, and bone standard reference materials., (Copyright © 2017 John Wiley & Sons, Ltd.)

In the present study we propose a new analytical method for 37 Cl/ 35 Cl analysis in perchlorate by Ion Chromatography(IC) coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). The accuracy of the analytical method was validated by analysis of international perchlorate standard materials USGS-37 and USGS -38; analytical precision better than ±0.4‰ was achieved. 37 Cl/ 35 Cl isotope ratio analysis in perchlorate during laboratory biodegradation experiment with microbial cultures enriched from the contaminated soil in Israel resulted in isotope enrichment factor ε 37 Cl = -13.3 ± 1‰, which falls in the range reported previously for perchlorate biodegradation by pure microbial cultures. The proposed analytical method may significantly simplify the procedure for isotope analysis of perchlorate which is currently applied in environmental studies., (Copyright © 2017. Published by Elsevier Ltd.)