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Study of the uptake and bioaccumulation of palladium nanoparticles by Sinapis alba using single particle ICP-MS

Year: 2018
Products: ICP;ICP-MS;Nebulizer;
Authors: Kińska, K;Jiménez-Lamana, J;Kowalska, J;Krasnodębska-Ostręga, B;Szpunar, J;
Journal: Science of The Total Environment

In recent years, increased palladium content has been found in the environment, due to its wide use in various fields, especially as catalytic converters. Palladium can be emitted as a range of soluble and insoluble compounds and in the form of palladium nanoparticles (PdNPs). The level of toxicity is equally dependent on concentration and form of palladium and hence, it is important to determine not only the total content of this element, but also its forms of occurrence. This study for the first time investigates the uptake degree and distribution of PdNPs by model plant Sinapis alba, in comparison with a platinum salt (Pd(NO3)2). An enzymatic digestion method which allows the extraction of PdNPs from the different plant tissues without altering their properties was applied. After extraction, samples were analysed by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) to provide information about the presences of palladium in nanoparticulated or dissolved form, the nanoparticle size and the nanoparticle number concentration. Significant amounts of PdNPs were found even in aboveground organs, but no significant changes in plant morphology were observed. Size distributions of PdNPs found in all tissues presented lower diameters than size distribution of the PdNPs stock suspension, suggesting that bigger nanoparticles are not taken up by the plant. The average size found is in good agreement between the different organs. Moreover, dissolved palladium was found in all samples, with the biggest contribution, in relative terms, observed in leaves followed by stems and roots.

Propagation of sub-atmospheric methyl formate flames

Year: 2018
Products: Nebulizer;TR-50-A3;
Authors: Lee, DJ;Burrell, RR;Egolfopoulos, FN;
Journal: Combustion and Flame

Laminar flame speeds of methyl formate/air mixtures were measured at sub-atmospheric pressures for which limited data exist. The experiments were carried out in the counterflow configuration at an unburned mixture temperature of 333 K. The flow velocities were measured using particle image velocimetry. Particle phase slip correction was applied to low-pressure data sets for which the density disparity between the flow tracers and the gaseous phase is notable. The data were modeled using two recently developed kinetic models of methyl formate oxidation, and significant disagreements were realized at all pressures especially under fuel-rich conditions. Additionally, the computed species profiles of CO and CO2 in the burner-stabilized flame configuration using the two models were found to differ significantly. Reaction path analysis revealed that the kinetics of CH2OCHO that is produced directly from the fuel affects the overall reactivity, and the attendant rate constants differ between the two models. The variation of laminar flame speed with pressure revealed also a different behavior between experiments and simulations. Further insight into the sources causing the observed discrepancies were investigated and it was determined that reactions involving formyl radical, methanol, and formaldehyde could also be responsible for the reduction in reactivity specifically under fuel-rich conditions.

Growth, structure and characterization of physico-chemical and magnetic properties of CdCr2Se4: Mn single crystals

Year: 2018
Products: Concentric;
Authors: Jendrzejewska, I;Gron, T;Kusz, J;Goraus, J;Kita, A;Barsova, Z;Slebarski, A;Fijałkowski, M;Pietrasik, E;Zajdel, P;Duda, H;
Journal: Journal of Alloys and Compounds

Crystal structure, magnetic and specific heat measurements, electrical conductivity, as well as DSC/TG measurements for single-crystalline CdxMnyCrzSe4
(where x + y + z ≈ 3) spinels are presented. The electrical conductivity and dc magnetic susceptibility measurements exhibit thermally activated semiconducting properties and ferromagnetic (FM) order for all compositions below the Curie temperature TC = 130 K, respectively. The long-range FM interactions, defined by the Curie temperature, do not substantially depend on the manganese content, and the nearest neighbour FM interactions, represented by the positive value of the Curie-Weiss temperature, decrease from 183 K to 156 K. Hysteresis loops of all crystals have a very small coercive field (~18 Oe) and remanence (~0.09 µB/f.u.) with full saturation above 10 kOe. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including spin defects.

Ion-pairing reversed-phase chromatography coupled to inductively coupled plasma mass spectrometry as a tool to determine mercurial species in freshwater fish

Year: 2018
Products: Concentric;Concentric nebulizer;ICP;ICP-MS;TR-30-A1;
Authors: Cheng, H;Chen, X;Shen, L;Wang, Y;Xu, Z;Liu, J;
Journal: J Chromatogr A

Most of analytical community is focused on reversed phase high performance liquid chromatography (RP-HPLC) for mercury speciation by employing mobile phases comprising of high salts and moderate amounts of organic solvents. This study aims at rapid mercury speciation analysis by ion-pairing RP-HPLC with inductively coupled plasma mass spectrometry (ICP-MS) detection only using low salts for the sake of green analytical chemistry. Two ion-pairing HPLC methods were developed on individual usage of positively and negatively charged ion-pairing reagents (tetrabutylammonium hydroxide -TBAH and sodium dodecylbenzene sulfonate -SDBS), where sodium 3-mercapto-1-propysulfonate (MPS) and L-cysteine (Cys) were individually added in mobile phases to transform mercury species into negative and positive Hg-complexes for good resolution. Addition of phenylalanine was also utilized for rapid baseline separation in combination of short C18 guard columns. Optimum mobile phases of 2.0 mM SDBS+2.0 mM Cys+1.0 mM Phe (pH 3.0) and 4.0 mM TBAH+2.0 mM MPS+2.0 mM Phe (pH 6.0) both achieved baseline separation of inorganic mercury (Hg2+), methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) on two consecutive 12.5-mm C18 columns. The former mobile phase was selected for mercury speciation in freshwater fish because of short separation time (3.0min). Detection limits of 0.015 for Hg2+, 0.014 for MeHg, 0.028 for EtHg and 0.042 µg L-1 for PhHg were obtained along with satisfactory precisions of peak height and area (1.0-2.8% for 5.0 µg L-1 Hg-mixture standard). Good accordance of determined values of MeHg and total mercury in certified reference materials of fish tissue (GBW 10029) and tuna fish (BCR-463) with certified values as well as good recoveries (91-106%) proved good accuracy of the proposed method. An example application to freshwater fish indicated its potential in routine analysis, where MeHg was presented at 3.7-20.3 µg kg-1 as the dominate species.

Rapid determination of ultra-trace plutonium isotopes (239Pu, 240Pu and 241Pu) in small-volume human urine bioassay using sector-field inductively coupled plasma mass spectrometry

Year: 2018
Products: APEX-Q
Authors: Ni, Y;Zheng, J;Guo, Q;Men, W;Tagami, K;Uchida, S;
Journal: Anal. Chim. Acta

A rapid method with enhanced 238U decontamination was developed for ultra-trace Pu analysis in small-volume urine bioassays. This method consists of acid digestion, co-precipitation, extraction chromatography and sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) measurement. Parameters that may influence the analytical performance were studied systematically. This method achieved a high 238U decontamination factor (3.8 x 106) and the 242Pu recovery was stable for 20 mL and 100 mL urine bioassays with an average value of 72.7 ± 5.5%. The limits of detection for 239Pu, 240Pu and 241Pu by the method were 0.016 fg mL-1, 0.016 fg mL-1 and 0.019 fg mL-1 for 20 mL urine samples and 0.003 fg mL-1, 0.002 fg mL-1 and 0.003 fg mL-1 for 100 mL urine samples, respectively. Considering the small volume of urine employed in this study, the absolute detection limits of the method were comparable or even better than those measured with thermal ionization mass spectrometry and accelerator mass spectrometry. All procedures for 20 mL and 100 mL urine bioassays were completed in 9.5 h and 11 h, respectively, and analysis of 10 samples could be finished within one day. With the considerably low detection limits of Pu isotopes and high sample throughput, this method would be a promising tool for the quick response to radiological emergencies and for rapid screening of unexpected occupational exposures of workers involved in the future FDNPP reactor decommissioning operations.

Kinetic stable Cr isotopic fractionation between aqueous Cr(III)-Cl-H2O complexes at 25°C: Implications for Cr(III) mobility and isotopic variations in modern and ancient natural systems

Year: 2018
Products: Elemental Scientific (ESI) SC-2 DX autosampler
Authors: Babechuk, MG;Kleinhanns, IC;Reitter, E;
Journal: Geochimica et Cosmochimica Acta

The stable Cr isotope fractionation preserved in natural substances has been attributed predominantly to Cr(III)-Cr(VI) redox transformations. However, non-redox reaction pathways (e.g., ligand-promoted dissolution, ligand exchange, adsorption of Cr(III)) are liable to contribute to isotopic fractionation in natural systems given that soluble Cr(III)-ligands have been directly documented or modeled in several marine, continental, and hydrothermal environments. This study isolates the stable Cr isotope fractionation accompanying Cl-H2O ligand exchange during the transformation of three aqueous species in the Cr(III)-Cl-H2O system, [CrCl2(H2O)4]+aq (abr. CrCl2+ or S1), [CrCl(H2O)5]2+aq (abr. CrCl2+ or S2), and [Cr(H2O)6]3+aq (abr. Cr3+ or S3), at low pH (≤2). In dilute HCl (0.01 to 1 M), Cr3+ is the kinetically favoured species and transformation of CrCl2+ to CrCl2+ to Cr3+ via 2 steps of dechlorination/hydrolyzation begins immediately upon dissolution of a Cr(III)-Cl solid. Individual species are separated with cation exchange chromatography at different stages of transformation and inter- and intra-species (across an elution peak of one species) isotopic fractionation of up to 1 and 2‰ (δ53/52Cr), respectively, is documented. Comparison of peak elution characteristics with Cr-Cl-H-O isotopologue mass abundances suggests mass-dependent sorting of isotopologues alone cannot explain intra-species fractionation, supporting a previously published proposal that preferential adsorption of light Cr isotopes on the resin is driven by vibrational energy effects. The transformation of CrCl2+ to CrCl2+ is faster than CrCl2+ to Cr3+ and the rates of both transformations increase with solution pH. Preferential reaction of light Cr(III) isotopes into product species occurs during each transformation, consistent with closed-system, kinetic fractionation during Cl-H2O ligand exchange. Inter-species fractionation is assessed using time-series experiments beginning from the dissolution of two Cr(III)-Cl solids (dried NIST SRM979 standard and commercial CrCl3·6H2O salt) in 0.01 M HCl (pH≈2). The ε53/52Cr(CrCl2+/CrCl2+) for the CrCl2+ to CrCl2+ reaction is -0.19‰ (SRM979) and -0.38‰ (salt) and the ε53/52Cr(Cr3+/CrCl2+) for the CrCl2+ to Cr3+ reaction is consistent for both experiments at -0.49‰ (SRM979) and -0.51‰ (salt). Experiments where SRM979 is dissolved in 0.1 and 1 M HCl for a longer aging period provide preliminary evidence that the Cr3+/CrCl2+ Cr(III) isotopic fractionation scales with HCl concentration (transformation rate). Chromium(III) dissolved in 6 M HCl and aged 5 months still yields an inter-species Cr isotope distribution that is apparently inherited from kinetic effects (light Cr isotopes in Cr3+), attesting to the slow development of inter-species isotopic equilibrium, which instead predicts progressively heavier Cr isotopes from CrCl2+ to CrCl2+ to Cr3+. The kinetic Cr(III) isotopic fractionation documented herein is proposed to be relevant to understanding systems where aqueous Cr(III)-Cl species may be temporarily stable (e.g., metamorphic and hydrothermal systems or lateritic weathering). Further, the complexation of Cr(III) with other ligands (e.g., CO32-, organics), combined with additional kinetic effects of Cr(III) potentially occurring in soils or sediment, must be explored prior to establishing the significance of empirical stable Cr isotope signatures in marine and continental environments. Further understanding of non-redox effects may lead to stable Cr isotopes developing as a proxy for system pH or ligand chemistry.

Sources and processes affecting the distribution of dissolved Nd isotopes and concentrations in the West Pacific

Year: 2018
Products: automated seaFAST-pico system
Authors: Behrens, MK;Pahnke, K;Schnetger, B;
Journal: Geochimica et Cosmochimica Acta

In the Atlantic, where deep circulation is vigorous, the dissolved neodymium (Nd) isotopic composition (expressed as εNd) is largely controlled by water mass mixing. In contrast, the factors influencing the εNd distribution in the Pacific, marked by sluggish circulation, is not clear yet. Indication for regional overprints in the Pacific is given based on its bordering volcanic islands. Our study aims to clarify the impact and relative importance of different Nd sources (rivers, volcanic islands), vertical (bio)geochemical processes and lateral water mass transport in controlling dissolved εNd and Nd concentration ([Nd]) distributions in the West Pacific between South Korea and Fiji. We find indication for unradiogenic continental input from South Korean and Chinese rivers to the East China Sea. In the tropical West Pacific, volcanic islands supply Nd to surface and subsurface waters and modify their εNd to radiogenic values of up to +0.7. These radiogenic signatures allow detailed tracing of currents flowing to the east and differentiation from westward currents with open ocean Pacific εNd composition in the complex tropical Pacific zonal current system. Modified radiogenic εNd of West Pacific intermediate to bottom waters upstream or within our section also indicates non-conservative behavior of εNd due to boundary exchange at volcanic island margins, submarine ridges, and with hydrothermal particles. Only subsurface to deep waters (3000 m) in the open Northwest Pacific show conservative behavior of εNd. In contrast, we find a striking correlation of extremely low (down to 2.77 pmol/kg Nd) and laterally constant [Nd] with the high-salinity North and South Pacific Tropical Water, indicating lateral transport of preformed [Nd] from the North and South Pacific subtropical gyres into the study area. This observation also explains the previously observed low subsurface [Nd] in the tropical West Pacific. Similarly, Western South Pacific Central Water, Antarctic Intermediate Water, and Lower Circumpolar Deep Water in the southern and equatorial West Pacific are marked by vertically and laterally almost invariant [Nd] indicating a dominance of conservative behavior of [Nd]. In contrast, Central and Intermediate Water in the North West Pacific are characterized by increasing [Nd] with depth reflecting Nd release from particles. Overall, our data demonstrate a dominant lateral transport control on [Nd] distributions and clear non-conservative modification of εNd in the West Pacific. The latter affords tracing of surface and subsurface zonal transport in the tropical Pacific, but prevents the use of εNd as strictly conservative tracer of the major meridionally circulating water masses in the West Pacific between 15°S and 28°N.

Lithium, magnesium and sulfur purification from seawater using an ion chromatograph with a fraction collector system for stable isotope measurements

Year: 2018
Products: PFA MicroFlow
Authors: Yoshimura, T;Araoka, D;Tamenori, Y;Kuroda, J;Kawahata, H;Ohkouchi, N;
Journal: J Chromatogr A

We describe the mass descrimination and validation of an offline method for purification of Li, Mg and S with an ion chromatograph coupled to an automated fraction collector for use prior to stable isotope measurements. Significant sub-fraction mass fractionation was observed for both the Li and the Mg stable isotope ratios. The lighter Li and heavier Mg isotopes were preferentially retained by the column, resulting in 7Li/6Li and 26Mg/24Mg biases up to 85.8‰ and 0.95‰, respectively. The isotopic compositions of Li, Mg, and S separated from seawater were δ7LiL-SVEC = +30.9‰, δ26MgDSM3 = -0.83 ± 0.10‰, and δ34SVCDT = +19.4 ± 0.6‰; each chromatographic peak was completely recovered, and the results were in good agreement with the published values regardless of whether or not chemical suppressor was used. The purification method enables multi-isotope analysis of a sample using various mass spectrometry techniques, such as multiple-collector inductively coupled plasma and thermal ionization mass spectrometry.

Excess Lead-210 and Plutonium-239+240: Two suitable radiogenic soil erosion tracers for mountain grassland sites

Year: 2018
Products: APEX HF
Authors: Meusburger, K;Porto, P;Mabit, L;La Spada, C;Arata, L;Alewell, C;
Journal: Environ. Res.

The expected growing population and challenges associated with globalisation will increase local food and feed demands and enhance the pressure on local and regional upland soil resources. In light of these potential future developments it is necessary to define sustainable land use and tolerable soil loss rates with methods applicable and adapted to mountainous areas. Fallout-radionuclides (FRNs) are proven techniques to increase our knowledge about the status and resilience of agro-ecosystems. However, the use of the Caesium-137 (137Cs) method is complicated in the European Alps due to its heterogeneous input and the timing of the Chernobyl fallout, which occurred during a few single rain events on partly snow covered ground. Other radioisotopic techniques have been proposed to overcome these limitations. The objective of this study is to evaluate the suitability of excess Lead-210 (210Pbex) and Plutonium-239+240 (239+240Pu) as soil erosion tracers for three different grassland management types at the steep slopes (slope angles between 35 and 38°) located in the Central Swiss Alps. All three FRNs identified pastures as having the highest mean (± standard deviation) net soil loss of -6.7 ± 1.1, -9.8 ± 6.8 and -7.0 ± 5.2 Mg ha-1 yr-1 for 137Cs, 210Pbex and 239+240Pu, respectively. A mean soil loss of -5.7 ± 1.5, -5.2 ± 1.5 and -5.6 ± 2.1 was assessed for hayfields and the lowest rates were established for pastures with dwarf-shrubs (-5.2 ± 2.5, -4.5 ± 2.5 and -3.3 ± 2.4 Mg ha-1 yr-1 for 137Cs, 210Pbex and 239+240Pu, respectively). These rates, evaluated at sites with an elevated soil erosion risk exceed the respective soil production rates. Among the three FRN methods used, 239+240Pu appears as the most promising tracer in terms of measurement uncertainty and reduced small scale variability (CV of 13%). Despite a higher level of uncertainty, 210Pbex produced comparable results, with a wide range of erosion rates sensitive to changes in grassland management. 210Pbex can then be as well considered as a suitable soil tracer to investigate alpine agroecosystems.

Arsenolipid biosynthesis by the unicellular alga Dunaliella tertiolecta is influenced by As/P ratio in culture experiments

Year: 2018
Products: ESI PC3 Peltier-cooled cyclonic spray chamber
Authors: Glabonjat, RA;Ehgartner, J;Duncan, EG;Raber, G;Jensen, KB;Krikowa, F;Maher, WA;Francesconi, KA;
Journal: Metallomics

The influence of arsenate and phosphate levels in water on the formation of arsenic-containing lipids (arsenolipids) and water-soluble arsenicals by a unicellular marine alga was investigated by exposing Dunaliella tertiolecta to five regimes of arsenic and phosphate, and determining the biosynthesized organoarsenicals with HPLC/mass spectrometry. Under all conditions, the major arsenolipid produced by D. tertiolecta was the novel phytyl 5-dimethylarsinoyl-2-O-methyl-ribofuranoside (AsSugPhytol546) representing ca. 35-65% of total arsenolipids. The new compound contains a phytol aglycone and a methoxy group replacing a sugar hydroxyl - two structural features not previously observed for arsenolipids. Minor arsenolipids were several previously reported arsenosugar phospholipids (AsSugPLs, in particular AsSugPL958 and the previously unknown AsSugPL978), the relative quantities of which increased with increasing phosphate exposure, and an arsenic-containing hydrocarbon (AsHC360), which remained unaffected by the different treatments. The relative amount of total arsenolipids produced by D. tertiolecta remained remarkably constant (ca. 45% of total As) and independent of the culture conditions. In contrast, with rising As-concentrations we observed an increase of hydrophilic arsenicals, which were dominated by arsenate and arsenosugars. The results highlight a possible major difference in arsenic biochemistry between macroalgae and unicellular algae with potential implications for how various algae handle their natural arsenic exposure in the world's oceans.

Vertical distributions and source identification of the radionuclides 239Pu and 240Pu in the sediments of the Liao River estuary, China.

Year: 2018
Products: APEX-Q high efficiency sample introduction system
Authors: Zhang, K;Pan, S;Liu, Z;Li, G;Xu, Y;Hao, Y;
Journal: J Environ Radioact

Activity concentration of plutonium (Pu) and its isotopic compositions are extensively used for measuring transport processes of Pu and identifying its source. We investigated the spatial distribution characteristics of 239+240Pu activity concentrations and 240Pu/239Pu atom ratio in several sediment cores collected from the Liao River coastal zone. Additionally, we calculated the 239+240Pu inventories and based on the 240Pu/239Pu atom ratio to trace Pu source. The activity concentrations of 239+240Pu in surface sediments of the Liao River estuary ranged between 0.103±0.008 and 0.978±0.035 mBq/g, with an average of 0.294±0.024 mBq/g. The 240Pu/239Pu atom ratios, ranging from 0.173±0.047 to 0.215±0.061 (mean: 0.188±0.049 (1σ)), were consistent with global fallout value, which indicates the global atmospheric fallout is the main source of Pu in sediment cores from the both sides of Liao River estuary. As for the tidal flat core LT-2, the mean 240Pu/239Pu atom ratio, slightly higher than that of the global fallout value, was 0.217±0.050. Such pattern of Pu isotopic compositions indicated that Pu on the tidal flat in the Liao River estuary is sourced from a combination of global fallout and close-in fallout from the PPG by ocean currents transporting. And by using a two end-member mixing model, the results indicate the relative contribution of the PPG close-in fallout to core LT-2 is round 27% and 73% can be attributed to global fallout and river input. Therefore, these results clearly indicate that the direct global fallout is the main source of Pu in the Liao River estuary.

A new procedure for high precision isotope ratio determinations of U, Cu and Zn at nanogram levels in cultured human cells: What are the limiting factors?

Year: 2018
Products: PC3-SSI Peltier-cooled double-pass spray chamber
Authors: Paredes, E;Avazeri, E;Malard, V;Vidaud, C;Ortega, R;Nonell, A;Isnard, H;Chartier, F;Bresson, C;
Journal: Talanta

The monitoring of isotopic fractionations in in vitro cultured human cell samples is a very promising and under-exploited tool to help identify the metabolic processes leading to disease-induced isotopic fractionations or decipher metabolic pathways of toxic metals in these samples. One of the limitations is that the analytes are often present at small amounts, ranging from tens to hundreds of ng, thus making challenging low-uncertainty isotope ratio determinations. Here we present a new procedure for U, Cu and Zn purification and isotope ratio determinations in cultured human neuron-like cells exposed to natural U. A thorough study of the influence of the limiting factors impacting the uncertainty of δ239U, δ66Zn and δ65Cu is also carried out. These factors include the signal intensity, which determines the within-day measurement reproducibility, the procedural blank correction and the matrix effects, which determine the accuracy of the mass bias correction models. Given the small Cu and U amounts in the cell samples, 15-30 and 20 ng respectively, a highly efficient sample introduction system was employed in order to improve the analyte transport to the plasma and, hence, the signal intensity. With this device, the procedural blanks became the main uncertainty source of δ239U and δ65Cu values, accounting over 65% of the overall uncertainty. The matrix effects gave rise to inaccuracies in the mass bias correction models for samples finally dissolved in the minimal volumes required for the analysis, 100-150 µL, leading to biases for U and Cu. We will show how these biases can be cancelled out by dissolving the samples in volumes of at least 300 µL for Cu and 450 µL for U. Using our procedure, expanded uncertainties (k = 2) of around 0.35‰ for δ239U and 0.15‰ for δ66Zn and δ65Cu could be obtained. The analytical approach presented in this work is also applicable to other biological microsamples and can be extended to other elements and applications.

Tree bark as a bioindicator of the presence of scandium, yttrium and lanthanum in urban environments

Year: 2018
Products: APEX-E
Authors: Minganti, V;Drava, G;
Journal: Chemosphere

Although rare earth elements (REEs) are important in modern industry, few processes use them, so the possibility of these elements being dispersed in the environment is small. For this reason, there are few studies on their presence in urban environments. REEs exhibit similar chemical properties, and Group 3 elements may be used as indicators of the presence of other REEs in the environment. Tree bark is a suitable collector of airborne trace elements and has been successfully used as a bioindicator. In this study, samples of holm oak bark were collected from three sampling sites subjected to different anthropic pressures (one area is far from human influence, while the other two sites are urban areas characterized by different types of human impact). The reference area is significantly different from urban areas where the concentrations measured are up to 5 times higher (Y) than the reference area. The differences between the two urban areas are also significant. The presence of industrial activities causes a 50% higher exposition of the population with respect to an urban area where only residential activities are present. In the case of La, there is no significant difference between the reference and the residential areas, while the industries are responsible for higher La concentrations (0.9 µg g-1 vs. 0.4-0.6 µg g-1). The availability of samples, due to the wide distribution of trees in urban environments, makes possible the production of maps indicating the sources of these elements and highlighting areas which are critical for certain atmospheric pollutants.

High-precision determination of lithium and magnesium isotopes utilising single column separation and multi-collector inductively coupled plasma mass spectrometry

Year: 2018
Products: APEX-IR
Authors: Bohlin, MS;Misra, S;Lloyd, N;Elderfield, H;Bickle, MJ;
Journal: Rapid Commun. Mass Spectrom.

Rationale: Li and Mg isotopes are increasingly used as a combined tool within the geosciences. However, established methods require separate sample purification protocols utilising several column separation procedures. This study presents a single-step cation-exchange method for quantitative separation of trace levels of Li and Mg from multiple sample matrices. Methods: The column method utilises the macro-porous AGMP-50 resin and a high-aspect ratio column, allowing quantitative separation of Li and Mg from natural waters, sediments, rocks and carbonate matrices following the same elution protocol. High-precision isotope determination was conducted by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) on the Thermo ScientificTM NEPTUNE PlusTM fitted with 1013 Ω amplifiers which allow accurate and precise measurements at ion beams ≤0.51 V. Results: Sub-nanogram Li samples (0.3-0.5 ng) were regularly separated (yielding Mg masses of 1-70 µg) using the presented column method. The total sample consumption during isotopic analysis is <0.5 ng Li and <115 ng Mg with long-term external 2σ precisions of ±0.39‰ for σ7 Li and ±0.07‰ for σ26 Mg. The results for geological reference standards and seawater analysed by our method are in excellent agreement with published values despite the order of magnitude lower sample consumption. Conclusions: The possibility of eluting small sample masses and the low analytical sample consumption make this method ideal for samples of limited mass or low Li concentration, such as foraminifera, mineral separates or dilute river waters.

Spatially resolved quantification of gadolinium deposited in the brain of a patient treated with gadolinium-based contrast agents

Year: 2018
Products: PFA flow nebulizer
Authors: Fingerhut, S;Niehoff, AC;Sperling, M;Jeibmann, A;Paulus, W;Niederstadt, T;Allkemper, T;Heindel, W;Holling, M;Karst, U;
Journal: J Trace Elem Med Biol

Due to its paramagnetic properties resulting from seven unpaired f-electrons, Gd is frequently applied in magnetic resonance imaging examinations. Due to the acute toxicity of free Gd3+, ligand ions based on polyaminocarboxylic acids are used to create thermodynamically stable linear or macrocyclic complexes. The highly water soluble Gd-based contrast agents (GBCAs) are known to be excreted fast and unmetabolized, mostly via the kidneys. Nevertheless, recent studies showed that Gd traces persists not only in animal but also in human brain. Aim of this study was the development and application of an analytical method for the spatially resolved quantification of gadolinium traces in human brain thin sections of a patient treated with GBCAs. For this retrospective study different human brain regions were selected to analyze the distribution of gadolinium. An additional patient served as control sample, as no GBCA was administered. Deep-frozen brain thin sections were analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and matrix-matched gelatin standards were prepared to quantify the gadolinium deposits via an external calibration. LA-ICP-MS analyses with high spatial resolution showed gadolinium deposits in different brain regions with highest concentrations above 800 ng g-1 more than two years after the last application of a GBCA. An excellent limit of quantification of 7 ng g-1, which is far below the limits of detection of MRI methods, could be achieved. The found concentrations confirm recent reports on gadolinium depositions in human brain, which were obtained without high spatial resolution. LA-ICP-MS provides limits of quantification, which are well suited to detect ultratrace amounts of gadolinium in human brain. Therefore, it provides valuable information on the distribution of gadolinium traces in the human brain even after single administration of GBCAs.

Molybdenum isotope fractionation in plants measured by MC-ICPMS

Year: 2018
Products: Apex-Q high sensitivity sample inlet system
Authors: Malinovsky, D;Kashulin, NA;
Journal: Analytical Methods

A new method was developed for precise and accurate Mo isotope ratio measurements in plant materials by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). It is based on the use of anion-exchange chromatography to isolate Mo from concomitant matrix elements in sample digests, a desolvating Apex-Q sample inlet system as a means of Mo signal enhancement and on-line normalisation to an admixed internal standard (Pd) to correct for instrumental mass bias. Mo isotope ratios were determined in sample solutions with Mo concentrations as low as 10 ng g-1. The developed method was successfully applied to the determination of natural variations in the isotopic composition of Mo in different anatomical parts of plants. We show for the first time that Mo isotope fractionation can occur during long-distance transport of Mo in plants. Our data also show that the magnitude of Mo isotope fractionation during translocation of Mo is different for different plant species. Mo isotope ratio data obtained by MC-ICPMS can therefore be used as a sensitive probe of processes controlling transport and distribution of molybdenum in plants.

Chemical Analysis of Dumped Chemical Warfare Agents During the MODUM Project

Year: 2018
Products: chromatographic column CF-Kit-As35
Authors: Söderström, M;Östin, A;Qvarnström, J;Magnusson, R;Rattfelt-Nyholm, J;Vaher, M;Jöul, P;Lees, H;Kaljurand, M;Szubska, M;Vanninen, P;Beldowski, J;
Journal: Towards the Monitoring of Dumped Munitions Threat (MODUM)

MODUM project continued the work on monitoring of the chemical weapons (CW) dumped in the Baltic Sea started in previous projects. As a new aspect, on board analysis methods - headspace gas chromatography-mass spectrometry (GC-MS) and capillary electrophoresis (CE) - were developed and tested in laboratory conditions and during cruises. The GC-MS method could be successfully applied on board to verify that collected sediment samples contained degradation products for sulfur mustard, one of the major chemical warfare agents dumped in Baltic Sea. This method could in future project be used during cruises to redirect sample collection in order to make most of the available ship time. Other part of the analysis task during MODUM project was the work done at the reach back laboratories. These analyses were done to both verify the results obtain on board and to fully identify the chemicals related to the sea-dumped CW agents. Reach back analysis of CW-related chemicals were done on sediment samples collected around a wreck in Bornholm Deep (same samples as analyzed on board) and on monitoring samples collected in Bornholm, Gotland and Gdańsk Deeps. The samples from Bornholm and Gotland Deeps are in line with previous findings. Samples from Gdańsk Deep are in line with previous findings that this area has been used as a dump site. Additionally, α-chloroacetophenone (CN) was found in the area for the first time. In addition to the analysis of CW-related chemicals, a new method was developed for measurement for arsenic concentrations in sediment samples. A method was also developed for arsenic speciation, which could help in estimation of the source of arsenic in the sediments.

New understandings of ethanol oxidation reaction mechanism on Pd/C and Pd2Ru/C catalysts in alkaline direct ethanol fuel cells

Year: 2018
Products: ESI MP2 micro peristaltic pump
Authors: Guo, J;Chen, R;Zhu, F;Sun, S;Villullas, HM;
Journal: Applied Catalysis B: Environmental

Ethanol oxidation reaction (EOR) on Pd2Ru/C and Pd/C catalysts in alkaline media is studied comprehensively by cyclic voltammetry, chronoamperometry, in situ FTIR, single fuel cell test and electrochemical impedance spectroscopy measurements. The results show that, as compared to Pd/C, Pd2Ru/C favors acetaldehyde formation and hinders its oxidation. Based on X-ray absorption data, which evidence that Ru promotes a larger electronic vacancy of the Pd 4d band, it is expected that the formation of adsorbed ethoxy is favored on Pd2Ru/C and followed by its oxidation to acetaldehyde facilitated by oxygenated species provided by Ru. In contrast, acetaldehyde oxidation is more difficult on Pd2Ru/C than on Pd/C likely because the adsorption energy of the reactive species is increased. We also show that the performance of Pd2Ru/C anode in alkaline direct ethanol fuel cell (ADEFC) is initially better but degrades much more rapidly than that with Pd/C anode under the same test conditions. The degradation is demonstrated to result from the accumulation of large amounts of acetaldehyde, which in alkaline media forms dimers by the aldol condensation reaction. The dimers tend to be responsible for blocking the active sites for further ethanol oxidation. This comprehensive study provides new understandings of the roles of Ru in Pd2Ru/C for EOR in alkaline media, unveils the causes of the performance degradation of fuel cells with Pd2Ru/C and demonstrates that initial good performances are not necessarily a valid criterion for selecting appropriate anode catalysts for ADEFC applications.

Copper Ion Assisted Photochemical Vapor Generation of Chlorine for Its Sensitive Determination by Sector Field Inductively Coupled Plasma Mass Spectrometry

Year: 2018
Products: perfluoroalkoxy alkane (PFA) self-aspirating nebulizer
Authors: Hu, J;Sturgeon, RE;Nadeau, K;Hou, X;Zheng, C;Yang, L;
Journal: Anal. Chem.

A novel, reliable, and sensitive approach for the determination of chlorine by sector field inductively coupled plasma mass spectrometry (SF-ICPMS) using photochemical vapor generation for sample introduction is presented. Methyl chloride is generated from different chlorine species in a flow-through photochemical reactor using a 1% solution of acetic acid containing 7.5 µg g-1of Cu2+. The volatile product is directed by an argon carrier gas to a gas-liquid separator and introduced into the instrument. A sample flow rate at 1.7 mL min-1and a 45 s irradiation time provided a 74-fold enhancement in sensitivity compared to conventional nebulization. A blank-limited detection limit of 0.5 ng g-1for chloride, suitable for quantitation at trace levels, was achieved. The proposed method was validated by analysis of two certified reference materials, NIST SRM 1568b rice flour and SRM 1571 orchard leaves, with satisfactory results, as well as three varieties of bottled water, achieving spike recoveries between 101% and 105%.

Ultrasound assisted enzymatic hydrolysis for isolating titanium dioxide nanoparticles from bivalve mollusk before sp-ICP-MS

Year: 2018
Products: seaFast SC2 DX autosampler
Authors: Taboada-López, MV;Iglesias-López, S;Herbello-Hermelo, P;Bermejo-Barrera, P;Moreda-Piñeiro, A;
Journal: Anal. Chim. Acta

Applicability of single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) using dwell times equal to or shorter than 100 µs has been tested for assessing titanium dioxide nanoparticles (TiO2NPs) in bivalve mollusks. TiO2NPs isolation from fresh mollusk tissues was achieved by ultrasound assisted enzymatic hydrolysis procedure using a pancreatin/lipase mixture. Optimum extraction conditions imply ultrasonication (60% amplitude) for 10 min, and 7.5 mL of a solution containing 3.0 g L-1 of pancreatin and lipase (pH 7.4). The developed method was found to be repeatable (repeatability of 17% for the over-all procedure, TiO2NPs concentration of 5.33 x 10(7) x 8.89 x 10(6), n = 11), showing a limit of detection of 5.28 x 10(6)NPs g-1, and a limit of detection in size of 24.4-30.4 nm, based on the 3σ criteria, and on the 3σ/5 σ criteria, respectively. The analytical recovery within the 90-99% range (use of TiO2NPs standards of 50 nm at 7 and 14 µg L-1 as Ti). Several bivalve mollusks (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analyzed for total titanium (ICP-MS after microwave assisted acid digestion), and for TiO2NPs by the proposed method. TiO2NPs concentrations were within the 2.36 x 10(7)-1.25 x 10(8)NPs g-1range, and the most frequent sizes were from 50 to 70 nm.

Improved approach for routine monitoring of129I activity and129I/127I atom ratio in environmental samples using TMAH extraction and ICP-MS/MS

Year: 2018
Products: APEX-Q
Authors: Yang, G;Tazoe, H;Yamada, M;
Journal: Anal. Chim. Acta

To reconstruct (131)I deposition and identify the source of radioiodine due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident,129I activity and129I/127I atom ratio should be obtained by preparing and analyzing large numbers of samples economically. In this study, great efforts were made to realize mild TMAH (tetramethyl ammonium hydroxide) extraction of environmental samples at 90 °C to obtain solutions suitable for the following triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-QQQ) MS/MS mode analysis. After releasing iodine from organic matter in the TMAH extraction solution via K2S2O8 oxidation, organic matter was removed effectively by solvent extraction and back-extraction to avoid a serious matrix effect during ICP-QQQ analysis. At the same time, interfering elements, especially, Mo, Cd, and In were also removed effectively, to avoid their undesirable interferences during mass spectrometric analysis. In addition, 0.01% (NH4)2SO3was selected to introduce I-into ICP-QQQ to ensure there was no memory effect and a stable signal was gotten. Subsequently, ICP-QQQ MS/MS mode was applied to further eliminate polyatomic interferences (127I(H2and D)+,97MoO2+,113InO+, and113CdO+) and isobaric interference from (129)Xe(+). Finally, the developed method was successfully applied to measure 129I/127I atom ratios ((2.61-27.0) x 10(-7) and129I activities (3.51-11.4 mBq kg-1) in soil samples. The developed method allows a greater number of ordinary laboratories to participate in the field of radioiodine analysis.

Exposure and risk assessment to arsenic species in Spanish children using biomonitoring

Year: 2018
Products: PFA standard nebulizer
Authors: Yusá, V;Pérez, R;Sánchez, A;Pardo, O;Roca, M;
Journal: Sci. Total Environ.

We present a new approach to arsenic (As) risk assessment using biomonitoring. In this pilot study we determined the levels of total and speciated urinary arsenicin 109 Spanish school children aged between 6 and 11 years, and interpreted these concentrations in a risk assessment context. The geometric mean (GM) for total As (TAs) was 33.82 µ/L. The order of occurrence and average concentrations of the different species was arsenobetaine (AsB) (100%, 15 µg/L), dimethylarsinic (DMA) (97%, 8.32 µg/L), monomethylarsonic (MMA) (26%, 0.27 µg/L) and inorganic As (iAs) (4%, 0.14 µg/L). 18% of children presented exposures to inorganic arsenic (7.52 µg/g creatinine) higher than guidance value for non-cancer risk (8.3 µg/g creatinine). For cancer risk the exposure to inorganic arsenic was much higher than the guidance value. Urinary DMA was positively associated with urinary AsB, suggesting exposure directly to this specie or metabolism of organic arsenicals to this specie, mainly through seafood consumption. Consequently, the exposure to inorganic As needs to be carefully interpreted because it may be overestimated. Our study supports the hypothesis that urinary iAs + MMA is the most reliable biomarker of exposure to inorganic As.

An assessment of the Ca weathering sources to surface waters on the Precambrian Shield in central Ontario

Year: 2018
Products: APEXQ
Authors: Watmough, S;
Journal: Sci. Total Environ.

There is increasing concern over the negative ecological impacts caused by falling calcium (Ca) concentrations in lakes, particularly in central Ontario, Canada. Forecasting regional changes in lake Ca concentrations relies on accurate estimates of mineral weathering rates that are not widely available. In this study, bulk atmospheric deposition, surface water and soil chemistry along with87Sr/86Sr isotope measurements were used to provide regional insight into weathering controls on Ca concentrations in lakes. Regionally, Ca concentrations in 90% of 129 lakes sampled in central Ontario were <0.1 mmol L-1and the Ca/Sr ratio in lakes increased and the K/Sr ratio decreased with increasing Sr concentration, which is indicative of greater Ca sources from calcite or apatite in the higher Ca lakes. Significant relationships between87Sr/86Sr ratios and Ca/Sr rations in dilute acid (0.1 M HCl) soil extracts are also indicative of the presence of trace amounts of calcite or apatite in surficial soils. Within the low (<0.7 mmol L-1) Ca lakes, defined in this study that are considered most at risk from falling Ca concentrations,87Sr/86Sr ratios fell within the range observed in weak acid soil extracts and were also significantly related to Ca/Na and K/Sr ratios in surface waters. There were large inconsistencies however, between Ca/Na ratios and Ca/Sr in surface waters and soil acid extracts that suggest differences in87Sr/86Sr ratios in surface waters of the low Ca lakes do not simply reflect differences in Ca derived from non-silicate minerals in surficial soils and that that Ca sources from deeper soil or bedrock are also important contributors to surface water Ca in these low Ca lakes.

In vivo fractionation of mercury isotopes in tissues of a mammalian carnivore ( Neovison vison )

Year: 2018
Products: Apex Q desolvation system
Authors: Ma, L;Evans, R;Wang, W;Georg, R;
Journal: Science of The Total Environment

The use of isotope ratios to trace Hg contamination sources in environmental compartments is now generally accepted. However, for biota and especially for mammals, it is still unknown if and/or how Hg isotopes fractionate in vivo and which tissue is most representative of the source(s) of contamination. We measured fractionation of Hg in mink (Neovison vison) tissues (fur, brain, blood, liver, kidney) collected during a controlled feeding experiment where captive mink were fed differing amounts of methylmercury. There was no significant effect of dietary MeHg concentrations on Hg fractionation in most tissues. Net fractionation of Hg, i.e., fractionation corrected for diet (δ202Hg(tissue) - δ202Hg(diet) was observed in all tissues with the greatest net fractionation occurring in the mink liver (-1.39‰) and kidney (-0.95‰). Less net fractionation, occurred in the brain (-0.12‰), blood (0.38‰) and fur (0.30‰). In the absence of brain tissue, fur is a suitable proxy which is readily obtainable and can be non-lethally collected. In these mink, it appears that biochemical processes such as demethylation, contribute to significant fractionation of Hg in the liver and kidney, but not as much in the brain and fur, where transport of Hg via thiol-containing complexes may be more important.

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

Year: 2018
Products: PFA-ST
Authors: Boiteau, R;Shaw, J;Pasa-Tolic, L;Koppenaal, D;Jansson, J;
Journal: Soil Biology and Biochemistry

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallophores within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrices. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) of soils from native tallgrass prairies in Kansas and Iowa. Both plant and fungal metallophores were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant Fe acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamines, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-90 pmol/g soil). In contrast, the fungal siderophore ferricrocin was specific for trivalent Fe (7-32 pmol/g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Small structural modifications result in significant differences in metal ligand selectivity, and likely impact metal uptake within the rhizosphere of grassland soils.

Dissipation of transmembrane potassium gradient is the main cause of cerebral ischemia-induced depolarization in astrocytes and neurons

Year: 2018
Products: PFA-100 micronebulizer
Authors: Du, Y;Wang, W;Lutton, AD;Kiyoshi, CM;Ma, B;Taylor, AT;Olesik, JW;McTigue, DM;Askwith, CC;Zhou, M;
Journal: Exp. Neurol.

Membrane potential (VM) depolarization occurs immediately following cerebral ischemia and is devastating for the astrocyte homeostasis and neuronal signaling. Previously, an excessive release of extracellular K+and glutamate has been shown to underlie an ischemia-induced VMdepolarization. Ischemic insults should impair membrane ion channels and disrupt the physiological ion gradients. However, their respective contribution to ischemia-induced neuronal and glial depolarization and loss of neuronal excitability are unanswered questions. A short-term oxygen-glucose deprivation (OGD) was used for the purpose of examining the acute effect of ischemic conditions on ion channel activity and physiological K+gradient in neurons and glial cells. We show that a 30 min OGD treatment exerted no measurable damage to the function of membrane ion channels in neurons, astrocytes, and NG2 glia. As a result of the resilience of membrane ion channels, neuronal spikes last twice as long as our previously reported 15 min time window. In the electrophysiological analysis, a 30 min OGD-induced dissipation of transmembrane K+gradient contributed differently in brain cell depolarization: severe in astrocytes and neurons, and undetectable in NG2 glia. The discrete cellular responses to OGD corresponded to a total loss of 69% of the intracellular K+contents in hippocampal slices as measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). A major brain cell depolarization mechanism identified here is important for our understanding of cerebral ischemia pathology. Additionally, further understanding of the resilient response of NG2 glia to ischemia-induced intracellular K+loss and depolarization should facilitate the development of future stroke therapy.

Rare earth element distributions in the West Pacific: Trace element sources and conservative vs. non-conservative behavior

Year: 2018
Products: automated seaFAST-pico system in offline mode
Authors: Behrens, M;Pahnke, K;Paffrath, R;Schnetger, B;Brumsack, H;
Journal: Earth and Planetary Science Letters

Recent studies suggest that transport and water mass mixing may play a dominant role in controlling the distribution of dissolved rare earth element concentrations ([REE]) at least in parts of the North and South Atlantic and the Pacific Southern Ocean. Here we report vertically and spatially high-resolution profiles of dissolved REE concentrations ([REE]) along a NW-SE transect in the West Pacific and examine the processes affecting the [REE] distributions in this area. Surface water REE patterns reveal sources of trace element (TE) input near South Korea and in the tropical equatorial West Pacific. Positive europium anomalies and middle REE enrichments in surface and subsurface waters are indicative of TE input from volcanic islands and fingerprint in detail small-scale equatorial zonal eastward transport of TEs to the iron-limited tropical East Pacific. The low [REE] of North and South Pacific Tropical Waters and Antarctic Intermediate Water are a long-range (i.e., preformed) laterally advected signal, whereas increasing [REE] with depth within North Pacific Intermediate Water result from release from particles. Optimum multiparameter analysis of deep to bottom waters indicates a dominant control of lateral transport and mixing on [REE] at the depth of Lower Circumpolar Deep Water (≥3000 m water depth; ~75-100% explained by water mass mixing), allowing the northward tracing of LCDW to ~28°N in the Northwest Pacific. In contrast, scavenging in the hydrothermal plumes of the Lau Basin and Tonga-Fiji area at 1500-2000 m water depth leads to [REE] deficits (~40-60% removal) and marked REE fractionation in the tropical West Pacific. Overall, our data provide evidence for active trace element input both near South Korea and Papua New Guinea, and for a strong lateral transport component in the distribution of dissolved REEs in large parts of the West Pacific.

AtHMA4 Drives Natural Variation in Leaf Zn Concentration ofArabidopsis thaliana

Year: 2018
Products: SC-4 DX autosampler and Apex-HF system
Authors: Chen, ZR;Kuang, L;Gao, YQ;Wang, YL;Salt, DE;Chao, DY;
Journal: Front Plant Sci

Zinc (Zn) is an essential element for plant growth and development, and Zn derived from crop plants in the diet is also important for human health. Here, we report that genetic variation in Heavy Metal-ATPase 4 (HMA4) controls natural variation in leaf Zn content. Investigation of the natural variation in leaf Zn content in a world-wide collection of 349Arabidopsis thaliana wild collected accessions identified two accessions, Van-0 and Fab-2, which accumulate significantly lower Zn when compared with Col-0. Both quantitative trait loci (QTL) analysis and bulked segregant analysis (BSA) identified HMA4 as a strong candidate accounting for this variation in leaf Zn concentration. Genetic complementation experiments confirmed this hypothesis. Sequence analysis revealed that a 1-bp deletion in the third exon of HMA4 from Fab-2 is responsible for the lose of function of HMA4 driving the low Zn observed in Fab-2. Unlike in Fab-2 polymorphisms in the promoter region were found to be responsible for the weak function of HMA4 in Van-0. This is supported by both an expression analysis of HMA4 in Van-0 and through a series of T-DNA insertion mutants which generate truncated HMA4 promoters in the Col-0 background. In addition, we also observed that Fab-2, Van-0 and the hma4-2 null mutant in the Col-0 background show enhanced resistance to a combination of high Zn and high Cd in the growth medium, raising the possibility that variation at HMA4 may play a role in environmental adaptation.

Mineralogical and microstructural characterization of biomass ash binder

Year: 2018
Products: Ca, Al, Si, Na, and K elements
Authors: Chaunsali, P;Uvegi, H;Osmundsen, R;Laracy, M;Poinot, T;Ochsendorf, J;Olivetti, E;
Journal: Cement and Concrete Composites

While the incineration of biomass residues is gaining traction as a globally available source of renewable energy, the resulting ash is often landfilled, resulting in the disposal of what could otherwise be used in value-added products. This research focuses on the beneficial use of predominantly rice husk and sugarcane bagasse-based mixed biomass ashes, obtained from two paper mills in northern India. A cementitious binder was formulated from biomass ash, clay, and hydrated lime (70:20:10 by mass, respectively) using 2M NaOH solution at a liquid-to-solid mass ratio of 0.40. Compressive strength of the biomass ash binder increased linearly with compaction pressure, indicating the role of packing density. Between the two mixed biomass ashes used in this study, the one with higher amorphous content resulted in a binder with higher strength and denser reaction product. Multi-faceted characterization of the biomass ash binder indicated the presence of aluminum-substituted calcium silicate hydrate, mainly derived from the pozzolanic reaction.

Strontium isotope ratios of human hair record intra-city variations in tap water source

Year: 2018
Products: FAST2 valve block
Authors: Tipple, BJ;Valenzuela, LO;Ehleringer, JR;
Journal: Sci Rep

The oxygen (18O/16O) isotope analysis of hair is commonly applied to reconstruct an individual's residence history. However, region-of-origin as determined from oxygen isotope values (δ18O) alone is often spatially indistinct. Adding additional geochemical recorders can refine region-of-origin estimates. In this capacity, strontium (87Sr/86Sr) isotope analysis has attracted increased interest. While 87Sr/86Sr reflects the influences of local geology,87Sr/86Sr of hair includes both external environmental signals as well as the internal dietary indicators. To better understand the impact of these contributions to the spatial signal encoded within87Sr/86Sr of hair, human hair was collected from three locations within Salt Lake City, Utah along with the donor's sex. The 87Sr/86Sr and δ18O of hair and local tap water were measured. There were no significant relationships between sex and either δ18O or 87Sr/86Sr of hair, nor between collection location and the δ18O of hair. However, we found significant associations between collection location and 87Sr/86Sr of hair. These findings suggest that interactions with local water may be an important source of Sr to human hair and that the 87Sr/86Sr of hair may have the capacity to record differences in 87Sr/86Sr of tap waters on small spatial scales.


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