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Spatial assessment of major and trace element concentrations from Lower Athabasca Region Trout-perch (Percopsis omiscomaycus) otoliths

Year: 2019
Products: SC-2 DX
Authors: Sinnatamby, RN;Loewen, TN;Luo, Y;Pearson, DG;Bicalho, B;Grant-Weaver, I;Cuss, CW;Poesch, M;Shotyk, W;
Journal: Sci. Total Environ.

The Lower Athabasca Region (LAR) is home to the largest bitumen deposit in Alberta, and has seen industrial development related to the extraction and processing of bituminous sands since the late 1960s. Along with industrial and economic growth related to oil sands development, environmental concerns have increased in recent decades, including those about potential effects on fish. We measured major and trace element concentrations in Trout-perch otoliths from the Athabasca and Clearwater Rivers in the LAR, to illustrate spatial variations and identify possible industrial impacts. Both laser ablation ICP-MS and solution-based ICP-MS methods were employed. Of the trace elements enriched in bitumen (V, Ni, Mo and Re), only Ni and Re were above the limits of detection using at least one of the methods. The only significant differences in element concentrations between upstream and downstream locations were found for Li, Cu, and Pb which were more abundant upstream of industry. For comparison and additional perspective, otoliths from the same fish species, but taken from the Batchawana River in northern Ontario, were also examined. The fish from Alberta yielded greater concentrations of Ba, Bi, Li, Mg, Na, Re, Sc, Th and Y, but the Ontario fish had more Cr, Rb and Tl, likely because of differences in geology.

Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin

Year: 2019
Products: SC-DX SeaFAST S2
Authors: Hermans, M;Lenstra, W;van Helmond, N;Behrends, T;Egger, M;Seguret, M;Gustafsson, E;Gustafsson, B;Slomp, C;
Journal: Geochimica et Cosmochimica Acta

The Baltic Sea is characterized by the largest area of hypoxic (oxygen (O2) < 2 mg L-1) bottom waters in the world’s ocean induced by human activities. Natural ventilation of these O2-depleted waters largely depends on episodic Major Baltic Inflows from the adjacent North Sea. In 2014 and 2015, two such inflows led to a strong rise in O2 and decline in phosphate (HPO42-) in waters below 125 m depth in the Eastern Gotland Basin. This provided the opportunity to assess the impact of such re-oxygenation events on the cycles of manganese (Mn), iron (Fe) and phosphorus (P) in the sediment for the first time. We demonstrate that the re-oxygenation induced the activity of sulphur (S)-oxidising bacteria, known as Beggiatoaceae in the surface sediment where a thin oxic and suboxic layer developed. At the two deepest sites, strong enrichments of total Mn and to a lesser extent Fe oxides and P were observed in this surface layer. A combination of sequential sediment extractions and synchrotron-based X-ray spectroscopy revealed evidence for the abundant presence of P-bearing rhodochrosite and Mn(II) phosphates. In contrast to what is typically assumed, the formation of Fe oxides in the surface sediment was limited. We attribute this lack of Fe oxide formation to the high flux of reductants, such as sulphide, from deeper sediments which allows Fe(II) in the form of FeS to be preserved and restricts the penetration of O2 into the sediment. We estimate that enhanced P sequestration in surface sediments accounts for only ∼5% of water column HPO42- removal in the Eastern Gotland Basin linked to the recent inflows. The remaining HPO42- was transported to adjacent areas in the Baltic Sea. Our results highlight that the benthic O2 demand arising from the accumulation of organic-rich sediments over several decades, the legacy of hypoxia, has major implications for the biogeochemical response of euxinic basins to re-oxygenation. In particular, P sequestration in the sediment in association with Fe oxides is limited. This implies that artificial ventilation projects that aim at removing water column HPO42- and thereby improving water quality in the Baltic Sea will likely not have the desired effect.

Terrestrial sources as the primary delivery mechanism of mercury to the oceans across the Toarcian Oceanic Anoxic Event (Early Jurassic)

Year: 2019
Products: Apex-Q desolvation unit
Authors: Them, T;Jagoe, C;Caruthers, A;Gill, B;Grasby, S;Gröcke, D;Yin, R;Owens, J;
Journal: Earth and Planetary Science Letters

This study evaluates the utility of sedimentary mercury (Hg) contents as a proxy for fingerprinting ancient massive volcanism, which is often associated with biogeochemical perturbations. Herein we present new Hg geochemical data from anoxic marine basins across the Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma) as a test of the complex Hg cycle. The T-OAE was likely initiated by the main eruptive phase of the Karoo–Ferrar large igneous province, which caused a subsequent cascade of environmental perturbations and resulting mass extinction. At present the leading interpretation of sedimentary Hg anomalies has been volcanogenic outgassing as the primary source. Our study and compilation results suggest, however, that Hg/TOC anomalies were restricted to shallow-water, and/or proximal environments, while deep-water, more distal depositional settings document no significant Hg-related anomalies. Furthermore, asynchronous stratigraphic deviations in Hg enrichments favor terrestrially sourced materials and local redox variability, rather than direct volcanogenic emissions, as a primary control mechanism. Additionally, Hg isotope signatures from our only study site documenting an Hg anomaly are also consistent with a terrestrial Hg origin during the T-OAE. Therefore, our results suggest that Hg anomalies in the geological record need to be re-evaluated as a “smoking gun” proxy that only infers volcanogenic inputs.

Size exclusion chromatography – Inductively coupled plasma – Mass spectrometry for determining metal-low molecular weight compound complexes in natural wines

Year: 2019
Products: SeaFast SC2 DX autosampler
Authors: Latorre, M;Herbello-Hermelo, P;Peña-Farfal, C;Neira, Y;Bermejo-Barrera, P;Moreda-Piñeiro, A;
Journal: Talanta

Size exclusion chromatography (SEC) hyphenated to inductively coupled plasma – mass spectrometry (ICP-MS), as a specific detector for metals, has been used for monitoring and determining metal-low molecular weight organic compound (LMWC) complexes in natural wines. SEC with UV detection (wavelength of 205 nm) was used for monitoring organic compounds eluted from the chromatographic column. SEC-UV has revealed the presence of low molecular weight compounds (commonly three fractions of molecular weights ranging from 230 to 1579 Da).’ Further experiments using ICP-MS as a detector showed that elements such as B, Cu, Li, Mn, Ni, Ti, and Zn are bound to compounds of molecular weights within the 338–1579 Da range. Total metal concentrations, as well as metal concentrations in SEC fractions were also assessed in several monovarietal red (five varieties) and monovarietal white (three varieties) wines.

Enzymatic hydrolysis as a sample pre-treatment for titanium dioxide nanoparticles assessment in surimi (crab sticks) by single particle ICP-MS

Year: 2019
Products: SeaFast SC2 DX autosampler
Authors: Taboada-López, M;Herbello-Hermelo, P;Domínguez-González, R;Bermejo-Barrera, P;Moreda-Piñeiro, A;
Journal: Talanta

A reliable sample pre-treatment based on enzymatic hydrolysis has been fully optimized and validated for TiO2 NPs isolation and determination/characterization in surimi (crab sticks). Efficient extractions have been found when using a pancreatin/lipase mixture at pH 7.4 and 37 °C for 12 h under continuous stirring. The proposed sample pre-treatment procedure has been found not to change TiO2 NPs size distribution, therefore guaranteeing TiO2 NPs integrity. TiO2 NPs determination (TiO2 NPs concentration) and TiO2 NPs characterization (size distribution) were assessed by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) working with dwell times in the microsecond range (high frequency of data acquisition). Method validation was performed for TiO2 NPs concentrations and TiO2 NPs sizes. Good repeatability (25% and 8% for TiO2 NPs concentration and TiO2 NPs most frequent size), and sensitivity (limit of detection of 5.28 × 105 NPs g−1for TiO2 NPs concentrations, and 31.3–37.1 nm for TiO2 NPs size) were obtained. Accuracy, calculated through analytical recovery was adequate. Recoveries for TiO2 NPs standards of 50 and 100 nm were 108 ± 5 and 105 ± 4%, respectively. The proposed methodology was applied to several surimi samples for assessing TiO2 NPs concentrations and size distribution. Some surimi samples were found to contain TiO2 NPs (concentrations from 1.40 × 107 to 1.19 × 109 NPs g−1). TiO2 NPs size distributions were very different among the samples, and some of them showed wide size ranges (the most frequent size varied from 53.8 to 62.1 nm; whereas, the mean size values were within the 73.4–217.5 nm range).

Metabolism and disposition of arsenic species from oral dosing with sodium arsenite in neonatal CD-1 mice. IV. Toxicokinetics following gavage administration and lactational transfer

Year: 2019
Products: PC3
Authors: Twaddle, NC;Vanlandingham, M;Beland, FA;Fisher, JW;Doerge, DR;
Journal: Food Chem. Toxicol.

Arsenic is a ubiquitous contaminant, with typical human dietary intake below 1 μg/kg bw/d and extreme drinking water exposures up to ∼50 μg/kg bw/d. The formation and binding of trivalent metabolites are central to arsenic toxicity and strong human evidence suggests special concern for early life exposures in the etiology of adult diseases, especially cancer. This study measured the metabolism and disposition of arsenite in neonatal mice to understand the role of maturation in metabolic activation and detoxification of arsenic. Many age-related differences were observed after gavage administration of arsenite, with consistent evidence in blood and tissues for higher exposures to trivalent arsenic species in neonatal mice related to the immaturity of metabolic and/or excretory functions. The evidence for greater tissue binding of arsenic species in young mice is consistent with enhanced susceptibility to toxicity based on metabolic and toxicokinetic differences alone. Lactational transfer from arsenite-dosed dams to suckling mice was minimal, based on no dosing-related changes in the levels of arsenic species in pup blood or milk collected from the dams. Animal models evaluating whole-life exposure to inorganic arsenic must use direct dosing in early neonatal life to predict accurately potential toxicity from early life exposures in children.

A common parentage-low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds

Year: 2019
Products: APEX-Q high-efficiency sample introduction system
Authors: Krebs, M;Pearson, D;Stachel, T;Laiginhas, F;Woodland, S;Chinn, I;Kong, J;
Journal: Lithos

Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. “Planed” and “ribbed” trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.

High-resolution Sr-isotopic evolution of Black Sea water during the Holocene: Implications for reconnection with the global ocean

Year: 2019
Products: ESI SC-2 autosampler
Authors: Ankindinova, O;Hiscott, R;Aksu, A;Grimes, V;
Journal: Marine Geology

The 10 m-thick Holocene succession at core site M02-45 (41°41.17′N, 28°19.08′E, −69 m water depth) has key advantages for investigation of the Sr-isotopic evolution of the Holocene Black Sea. Earlier studies have focussed on thinner successions and coquinas. At the M02-45 site (augmented by nearby core M05-03P), 87Sr/86Sr determinations on mollusc shells extracted at mostly 10–20 cm depth increments provide a temporal resolution mostly <200 years in sediment older than ~5500 cal yr BP, and ~20–25 years for the early Holocene reconnection between the Black Sea (formerly the Neoeuxine Lake) and the global ocean. Isotopic measurements are in stratigraphic order, so temporal trends are unambiguous. Measurements were made using a Neptune multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) and have 1σ uncertainties of ~ ±0.000015. There are four stages of 87Sr/86Sr increase and salination associated with the reconnection. From 12,145–9580 cal yr BP (stage A), before first Mediterranean inflow, the Sr-isotopic ratio varied from 0.708847–0.708881. Modelling suggests that the Sr concentration in the Neoeuxine Lake might have been several times higher than modern river values because of evaporative concentration. For ~100 years immediately before reconnection (9580–9490 cal yr BP, stage B), 87Sr/86Sr values dropped to their lowest levels: 0.708841–0.708843. Abruptly (in geological terms), 87Sr/86Sr then began to climb starting 9465–9490 cal yr BP and reached a quasi-steady-state ‘plateau’ with ratios ~0.708965 by ~9380 cal yr BP (stage C). The sharp 87Sr/86Sr increase marks the first significant intrusion of saline water into a previously isolated Neoeuxine Lake. The quasi-steady-state condition lasted 350–400 years. Subsequently, starting ~8985 cal yr BP and proceeding to the present day, there was a step-wise rise of 87Sr/86Sr to modern levels (stage D), during which a salinity threshold was passed that allowed widespread replacement of brackish-water faunas by Mediterranean species. Modelling suggests that the lake/sea level likely did not, and could not, rise from −120 m to −30 m between 9490 and 9380 cal yr BP unless (a) the Sr concentration in the pre-reconnection Neoeuxine Lake was 3–4 times higher than today, or (b) the water column was strongly stratified during first entry of saline water. The second alternative is very unlikely because of seasonal vertical mixing (downwelling/upwelling) in what was then a rather homogeneous temperate lake. Catastrophic flooding of a lowstand lake would require an average discharge through the Strait of Bosphorus of ~9500 m3 s−1, whereas saline entry of Mediterranean water as an underflow into an already high lake could reproduce the first stage of 87Sr/86Sr increase with an average discharge as low as ~2200 m3 s−1. Because the M02-45 site is ~50 m above the late Pleistocene lowstand shoreline and contains sub-wavebase sediments with 87Sr/86Sr values that record the first entry of saline water into the Neoeuxine Lake, the surface of the lake must have been significantly higher than −70 m at the time of the reconnection. Two prominent ‘plateaux’ which punctuate the long-term 87Sr/86Sr increase are attributed to decadal to centennial periods of increased discharge from European rivers, creating a positive hydrological balance and effectively blocking or seriously impeding saline-water advance up the Strait of Bosphorus toward the Black Sea.

Single particle mineralogy of microparticles from Himalayan ice-cores using SEM/EDX and ATR-FTIR imaging techniques for identification of volcanic ash signatures

Year: 2019
Products: Apex HF
Authors: Malek, M;Eom, H;Hwang, H;Hur, S;Hong, S;Hou, S;Ro, C;
Journal: Chemical Geology

In this study, insoluble microparticles from four discrete layers of ice-cores drilled out from the East Rongbuk glacier of the Himalayas were characterized on a single particle basis by scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) imaging. The combined application of the two single particle analytical techniques for the analysis of the same individual particles provided complementary information, i.e., their elemental compositions and morphology by SEM/EDX and their molecular species, functional groups, and crystallinity by ATR-FTIR imaging, which is crucial for the definite identification of the mineral species including their polymorphs. The results showed that the integrated signatures of volcanic ash (VA), involving their mineralogical characteristics for silica polymorphs, vitreous nature of silica and silicate particles, chemical heterogeneity within the micrometer sized particles, and unique morphology, can be used to clearly differentiate micrometer sized VA from the mineral dust of a soil origin on a single-particle basis. The different mineralogical characteristics among the volcanic samples would be due to their association with different volcanic eruptions.

Matrix separation of Sr and Pb for isotopic ratio analysis of Ca-rich samples via an automated simultaneous separation procedure

Year: 2019
Products: prepFAST-MC™
Authors: Zimmermann, T;Retzmann, A;Schober, M;Pröfrock, D;Prohaska, T;Irrgeher, J;
Journal: Spectrochimica Acta Part B: Atomic Spectroscopy

This paper presents a systematic investigation of the effects of Ca on the matrix separation of Sr and Pb and subsequent isotope-amount ratio measurements using a variety of synthetic solutions and reference materials with varying Ca content during the application of an automated analyte/matrix separation approach. The separation method based on the DGA Resin was optimized by using increased column bed volumes, comparing two different column sizes (1-mL and 3-mL-bed volume). Certified reference materials (synthetic calcium carbonate – MACS-3, basalt – BCR-2, saggital otolith – FEBS-1, bone meal – NIST SRM 1486, bone ash – NIST SRM 1400, and skim milk powder – BCR-063R) with varying Ca content, Ca/Sr and Ca/Pb mass fraction ratios were separated using the optimized method and analyzed for the Sr and Pb isotopic composition by multi collector inductively coupled plasma mass spectrometry (MC ICP-MS). The developed separation method based on the 3-mL-bed volume column provides quantitative recoveries (84% to 105% for Sr, 77% to 96% for Pb), while maintaining a quantitative separation of Sr and Pb. Procedural blank levels were < 0.04 ng g−1 for Sr and < 0.05 ng g−1 for Pb, respectively. The method allows for the automated extraction of Sr in Ca-rich matrices with Ca/Sr mass fraction ratios of up to 4051 corresponding to an absolute Ca load of 965 μg ± 86 μg (BCR-063R, milk powder). Furthermore, the method allows for the simultaneous extraction of Pb from these matrices showing Ca/Pb mass fraction ratios of up to 42,095 corresponding to an absolute Ca load of 761 μg ± 122 μg on column (NIST SRM 1400, bone tissue), respectively. This results in at least 5-times higher tolerable Ca loads compared to previous methods. Measured δ(87Sr/86Sr)NIST SRM 987 values of FEBS-1 (−1.58 ‰ ± 0.23 ‰ (U, k = 2)), MACS-3 (−4.11 ‰ ± 0.29 ‰ (U, k = 2)) and NIST SRM 1400 (3.87 ‰ ± 0.23 ‰ (U, k = 2)) were in accordance with published results. Measured δ(208Pb/206Pb)NIST SRM 981 (−29.87 ‰ ± 0.07 ‰ (U, k = 2)), δ(207Pb/206Pb)NIST SRM 981 (−66.95 ‰ ± 0.17 ‰ (U, k = 2)) and δ(208Pb/204Pb)NIST SRM 981 (51.55 ‰ ± 0.26 ‰ (U, k = 2)) values of NIST SRM 1400 were also in accordance with published results. Furthermore, we propose a n(87Sr)/n(86Sr) isotope-amount ratio of 0.70884 ± 0.00017 (U, k = 2) corresponding to a δ(87Sr/86Sr)NIST SRM 987 value of −2.11 ‰ ± 0.24 ‰ (U, k = 2) for the BCR-063R reference material. Additionally, we propose a n(208Pb)/n(206Pb) isotope-amount ratio of 2.0793 ± 0.0001 (U, k = 2) corresponding to a δ(208Pb/206Pb)NIST SRM 981 of −40.97 ‰ ± 0.05 ‰ (U, k = 2), a n(207Pb)/n(206Pb) isotope-amount ratio of 0.84995 ± 0.00008 (U, k = 2) corresponding to a δ(207Pb/206Pb)NIST SRM 981 of −70.72 ‰ ± 0.09 ‰ (U, k = 2) and a n(208Pb)/n(204Pb) isotope-amount ratio of 38.221 ± 0.008 (U, k = 2) corresponding to a δ(208Pb/204Pb)NIST SRM 981 of 40.82 ‰ ± 0.23 ‰ (U, k = 2) for the reference material MACS-3.

LA-ICP-MS/MS improves limits of detection in elemental bioimaging of gadolinium deposition originating from MRI contrast agents in skin and brain tissues

Year: 2019
Products: MicroMist concentric nebuliser
Authors: Clases, D;Fingerhut, S;Jeibmann, A;Sperling, M;Doble, P;Karst, U;
Journal: J Trace Elem Med Biol

A novel analytical method to detect the retention of gadolinium from contrast agents for magnetic resonance imaging (MRI) in tissue samples of patients is presented. It is based on laser ablation - inductively coupled plasma - triple quadrupole - mass spectrometry (LA-ICP-MS/MS). Both Gd and P were monitored with a mass shift of +16, corresponding to mono-oxygenated species, as well as Zn, Ca, and Fe on-mass. This method resulted in a significantly reduced background and improved limits of detection not only for phosphorus, but also for gadolinium. These improvements were essential to perform elemental bioimaging with improved resolution of 5 μm x 5 μm, allowing the detection of small Gd deposits in fibrotic skin and brain tumour tissue with diameters of approximately 50 μm. Detailed analyses of these regions revealed that most Gd was accompanied with P and Ca, indicating co-precipitation.

Detrital zircon ages and heavy mineral composition along the Gulf of Tonkin - Implication for sand provenance in the Yinggehai-Song Hong and Qiongdongnan basins

Year: 2019
Products: NWR213 frequency-quintupled solid state Nd:YAG laser system
Authors: Fyhn, M;Thomsen, T;Keulen, N;Knudsen, C;Rizzi, M;Bojesen-Koefoed, J;Olivarius, M;Tri, T;Phach, P;Minh, N;Abatzis, I;Nielsen, L;
Journal: Marine and Petroleum Geology

Neogene reservoir sand in the Yinggehai-Song Hong (YGH-SHB) and Qiongdongnan basins (QDNB) was derived from the Red River, Hainan Island and the Vietnamese Truong Son Belt. We investigate the sand dispersal pathways through comparisons of detrital zircon geochronology and heavy mineral analyses of modern Vietnamese river sand, Holocene to Recent near-coastal sand from Hainan Island and Vietnam and offshore Neogene sand, and we evaluate the methodologies. Eleven distinct zircon age clusters characterize the Gulf of Tonkin provenances. Red River sand contains the most complex age pattern with ∼35Ma, ∼88Ma, ∼155Ma, ∼250Ma, ∼440Ma peaks and broader pre-Cambrian clusters. The ∼88Ma peak uniquely occurs in Red River sand. Northern Truong Son Belt sand contains ∼35Ma, ∼250Ma, ∼440Ma peaks and pre-Cambrian clusters comparable to the Red River. The lack of Cretaceous zircons and a high proportion of ∼250Ma relative to ∼440Ma zircons distinguishes the northern Truong Son Belt from the Red River. The southern Truong Son Belt is characterized by low proportions of ∼250Ma relative to ∼440Ma zircons and the absence of Cretaceous and Cenozoic zircons. Hainan Island sand is identified by the presence of ∼100 Ma zircons and the absence of Cenozoic and ∼88 Ma zircons. The zircon age patterns suggest simple, although dynamic, sand dispersal pathways with mixed sand sources over much of the basins likely resulting from sediment reworking and down-stream river merging induced by Neogene sea-level fluctuations. Sand in the western YGH-SHB was mainly sourced from the Truong Son Belt, the Red River sourced the northern and central YGH-SHB and QDNB, and Hainan sand was primarily deposited along the island margin.

Association between catatonia and levels of hair and serum trace elements and minerals in autism spectrum disorder

Year: 2019
Products: ESI SC-2 DX4 autosampler
Authors: Tinkov, AA;Skalnaya, MG;Simashkova, NV;Klyushnik, TP;Skalnaya, AA;Bjørklund, G;Notova, SV;Kiyaeva, EV;Skalny, AV;
Journal: Biomed. Pharmacother.

The objective of the study was to investigate the association between catatonia in autism spectrum disorder (ASD) and the levels of hair and serum trace elements and minerals in children with ASD. The levels of hair and serum trace elements and minerals of boys suffering from ASD with (n = 30) and without (n = 30) catatonia, as well as 30 age- and sex-matched neurotypical controls were assessed using ICP-MS. Hair calcium (Ca) and selenium (Se) levels were lower in ASD patients as compared to the controls. Hair mercury (Hg) levels in ASD patients were more than 3-fold and 2-fold higher as compared to the controls and children with catatonia in ASD. Hair iodine (I) and manganese (Mn) were the lowest and the highest in ASD + Catatonia, respectively. Serum aluminium (Al) and cadmium (Cd) levels in healthy controls were significantly higher in comparison to the patients of both groups. Serum chromium (Cr), copper (Cu) levels were significantly increased in patients with ASD and catatonia, whereas vanadium (V) levels were elevated in patients both with and without catatonia. Multiple regression analysis demonstrated that hair Hg and serum Al and Cd levels were negatively associated with catatonia in ASD in crude and adjusted models. Although the etiology of catatonia in ASD is unclear, the obtained data demonstrate that catatonic symptoms in ASD may be at least partially mediated by altered trace element levels. Further studies are required to elucidate the role of trace elements in the potential signaling mechanisms of catatonia.

Speciation of zinc in fish feed by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry - using fractional factorial design for method optimisation and mild extraction conditions

Year: 2019
Products: FAST SC-4Q DX
Authors: Silva, MS;Sele, V;Sloth, JJ;Araujo, P;Amlund, H;
Journal: J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.

Zinc (Zn) is an element essential to all living organisms and it has an important role as a cofactor of several enzymes. In fish, Zn deficiency has been associated with impaired growth, cataracts, skeletal abnormalities and reduced activity of various Zn metalloenzymes. Fish meal and fish oil traditionally used in salmon feed preparation are being replaced by plant-based ingredients. Zinc additives are supplemented to salmon feed to ensure adequate Zn levels, promoting good health and welfare in Atlantic salmon (Salmo salar). The main objective of the present study was to evaluate Zn species found in an Atlantic salmon feed. This work describes a Zn extraction method that was optimized using a fractional factorial design (FFD), whereby the effect of six factors could be studied by performing only eight experiments. The effects of the type of extraction solution and its molar concentration, pH, presence of sodium dodecyl sulphate, temperature and extraction time on Zn extraction were investigated. Mild extraction conditions were chosen in order to keep the Zn species intact. Total Zn (soluble fractions and non-soluble fractions) was determined by inductively coupled plasma mass spectrometry (ICP-MS). The highest Zn recovery was obtained using 100 mM Tris-HCl, pH 8.5 at a temperature of 4 °C for 24 h where the total Zn in soluble fraction and non-soluble fraction was 9.9 ± 0.2% and 98 ± 6%, respectively. Zinc speciation analysis (on the soluble fractions) was further conducted by size exclusion inductively coupled plasma mass spectroscopy (SEC-ICP-MS). The SEC-ICP-MS method provided qualitative and semi-quantitative information regarding Zn species present in the soluble fractions of the feed. Four Zn-containing peaks were found, each with different molecular weights: Peak 1 (high molecular weight - ≥600 kDa), peak 2 and peak 3 (medium molecular weight - 32 to 17 kDa) were the least abundant (1-6%), while peak 4 (low molecular weight - 17 to 1.36 kDa) was the most abundant (84-95%).

An evaluation of Rb-Sr isotope dilution analyses with a 86Sr-enriched tracer and Multiple Collection-ICP-MS

Year: 2019
Products: Apex IR
Authors: Beranoaguirre, A;Pin, C;Sanchez-Lorda, M;García de Madinabeitia, S;Gil Ibarguchi, J;
Journal: International Journal of Mass Spectrometry

A straightforward method is described allowing to determine on a routine basis Rb and Sr concentrations and 87Rb/86Sr isotope by using the isotope dilution method with isotopic tracers enriched in 87Rb and in 86Sr, respectively, and MC-ICP-MS for mass spectrometric measurements. The 87Sr/86Sr isotope ratios are measured separately on unspiked sample aliquots, thereby alleviating the need for correcting the contribution that would arise in case of total spiking with an 84Sr enriched tracer. The sample preparation involves sample dissolution with hydrofluoric acid, and the separation of Rb and Sr from matrix elements and from each other by combining extraction chromatography and cation exchange in nitric acid medium. The concentration and 87Rb/86Sr data measured on replicate dissolutions of several international geostandards display the very good reproducibility typical of the isotope dilution method, even at low analyte concentration. The within-run precisions of 87Sr/86Sr isotope ratios (2 S.E. from 1 10−5 to 3 10-5) are not as good as those typically achieved by TIMS, but the data show a good reproducibility (0.002% RSD) and are accurate, based on their fair agreement with recommended values. However, these figures are significantly worse at low Sr concentration, indicating that 87Sr/86Sr ratios should preferably be measured by TIMS when Sr-poor samples are processed.

Mesoscale variability related to iron speciation in a coastal Ross Sea area (Antarctica) during summer 2014

Year: 2019
Products: PFA-ST microne- bulizer
Authors: Rivaro, P;Ardini, F;Grotti, M;Aulicino, G;Cotroneo, Y;Fusco, G;Mangoni, O;Bolinesi, F;Saggiomo, M;Celussi, M;
Journal: Chemistry and Ecology

Dissolved iron (Fe) distribution and speciation was determined in water samples (0–200 m) collected in a coastal area near Terra Nova Bay during the austral summer of 2014. Nutrients, dissolved oxygen, chlorophyll-a, phytoplankton composition and prokaryotic biomass distribution were investigated in combination with measurements of the physical properties of the water columns and its dynamics. The dFe value was above the limiting growth concentration, ranging from 0.52 to 4.51 nM, and it showed a spatial variability with a horizontal length scale of about 10 km, according to the variability of the water column physical properties and to iron sources. The organic ligands (L) maintained the concentrations of dFe at levels much higher than the inorganic solubility of Fe, keeping it available for phytoplankton and the log K’FeL values found (from 22.1 to 23.6) highlighted the presence of complexes of differing stabilities.

Reproducible automated renewable column generation

Year: 2019
Products: prepFAST MC
Authors: Shalina C. Metzger,Brian W. Ticknor,Kayron N. Tevepaugh,Debra A. Bostick,Eddy H. McBay,M. Paul Field,Hwan Kim & Cole R. Hexel
Journal: Separation Science and Technology

Preparation of chromatographic columns requires considerable time during chemical separation procedures. Automated systems capable of repeatedly generating renewable, uniformly packed columns would find widespread use in analytical laboratories. Here, a fully automated commercial-off-the-shelf (COTS) system was utilized to pack and unpack 1 mL TEVA and UTEVA columns. To accurately determine the reproducibility of the resin load per column, studies were conducted over several weeks. Method optimization yielded an improvement in loading from 15–19% to 3–5% relative standard deviation. Availability of automated COTS equipment capable of reproducibly generating separation columns has the potential to reduce time and costs associated with column separation.

Evaluation and Specifications for In-Line Uranium Separations Using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) Detection for Trace Elemental Analysis

Year: 2019
Products: prepFAST IC
Authors: Benjamin T. Manard, Shalina C. Metzger , C. Derrick Quarles Jr., Kayron T. Rogers, Brian W. Ticknor, Debra A. Bostick, Eddy H. McBay, and Cole R. Hexel
Journal: Applied Spectroscopy

Automated introduction platforms integrated with inductively coupled plasma optical emission spectroscopy (ICP-OES) systems are continuously being improved. Expanding on the introduction systems, a newly developed automated ion chromatography system was explored for performing rapid in-line separations coupled to ICP-OES for the detection of trace elements in uranium. Trace elements are separated from a uranium material and the analytes are directed into the ICP-OES for subsequent detection. Detection parameters such as exposure time frequency, wavelength selection, and settling times were explored to gain insight on optimal detection schemes for in-line trace elemental analysis. The methodology was applied in the analysis of a uranium oxide (U3O8) certified reference material, CRM-124. It was found here that the sensitivity and uncertainty of the technique are greatly affected by how the ICP-OES is employed to collect data. Overall it was determined that faster exposure replicates can provide greater peak resolution with higher fidelity measurements but are limited with respect to the total analysis time (i.e., limited in detection timely separations). Zeta scores, which combine accuracy and uncertainty of certified values and experimental values, were used to validate the ICP-OES modes of operation.

Fully oxygenated water columns over continental shelves before the Great Oxidation Event

Year: 2019
Products: Apex inlet system
Authors: Ostrander, CM;Nielsen, SG;Owens, JD;Kendall, B;Gordon, GW;Romaniello, SJ;Anbar, AD;
Journal: Nat Geosci

Late Archaean sedimentary rocks contain compelling geochemical evidence for episodic accumulation of dissolved oxygen in the oceans along continental margins before the Great Oxidation Event. However, the extent of this oxygenation remains poorly constrained. Here we present thallium and molybdenum isotope compositions for anoxic organic-rich shales of the 2.5 billion-year-old Mount McRae Shale from Western Australia, which previously yielded geochemical evidence of a transient oxygenation event. During this event, we observe an anti-correlation between thalium and molybdenum isotope data, including two shifts to higher molybdenum and lower thalium isotope compositions. Our data indicate pronounced burial of manganese oxides in sediments elsewhere in the ocean at these times, which requires that water columns above portions of the ocean floor were fully oxygenated: all the way from the air-sea interface to well below the sediment-water interface. Well-oxygenated continental shelves were likely the most important sites of manganese oxide burial and mass-balance modeling results suggest that fully oxygenated water columns were at least a regional-scale feature of early-Earth's oceans 2.5 billion years ago.

Revisiting the distribution of oceanic N2 fixation and estimating diazotrophic contribution to marine production

Year: 2019
Products: SeaFASTpico introduction system
Authors: Tang, W;Wang, S;Fonseca-Batista, D;Dehairs, F;Gifford, S;Gonzalez, AG;Gallinari, M;Planquette, H;Sarthou, G;Cassar, N;
Journal: Nat Commun

Marine N2 fixation supports a significant portion of oceanic primary production by making N2 bioavailable to planktonic communities, in the process influencing atmosphere-ocean carbon fluxes and our global climate. However, the geographical distribution and controlling factors of marine N2 fixation remain elusive largely due to sparse observations. Here we present unprecedented high-resolution underway N2 fixation estimates across over 6000 kilometers of the western North Atlantic. Unexpectedly, we find increasing N2 fixation rates from the oligotrophic Sargasso Sea to North America coastal waters, driven primarily by cyanobacterial diazotrophs. N2 fixation is best correlated to phosphorus availability and chlorophyll-a concentration. Globally, intense N2 fixation activity in the coastal oceans is validated by a meta-analysis of published observations and we estimate the annual coastal N2 fixation flux to be 16.7 Tg N. This study broadens the biogeography of N2 fixation, highlights the interplay of regulating factors, and reveals thriving diazotrophic communities in coastal waters with potential significance to the global nitrogen and carbon cycles.

Reconstruction of Atlantic herring (Clupea harengus) recruitment in the North Sea for the past 455 years based on the δ13C from annual shell increments of the ocean quahog (Arctica islandica)

Year: 2019
Products: Elemental Scientific micromill system
Authors: Estrella-Martínez, J;Schöne, B;Thurstan, R;Capuzzo, E;Scourse, J;Butler, P;
Journal: Fish and Fisheries

Understanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ13C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution for δ13C analysis. Our results indicate that the anthropogenically driven relative depletion of 13C, the oceanic Suess effect (oSE), became evident in the northern North Sea in the 1850s. We calculated a regression line between the oSE‐detrended δ13C results (δ13CṠ) and diatom abundance in the North Sea, the regression being mediated by the effect of phytoplankton on the δ13C of the ambient dissolved inorganic carbon. We used this regression to build an equation mediated by a nutritional link to reconstruct herring recruitment using δ13CṠ. The reconstruction suggests that there were five extended episodes of low‐recruitment levels before the 20th century. These results are supported by measured recruitment estimates and historical fish catch and export documentation. This work demonstrates that molluscan sclerochronological records can contribute to the investigation of ecological baselines and ecosystem functioning impacted by anthropogenic activity with implications for conservation and stock management.

An Acinetobacter baumannii, Zinc-Regulated Peptidase Maintains Cell Wall Integrity during Immune-Mediated Nutrient Sequestration

Year: 2019
Products: ESI auto sampler
Authors: Lonergan, ZR;Nairn, BL;Wang, J;Hsu, YP;Hesse, LE;Beavers, WN;Chazin, WJ;Trinidad, JC;VanNieuwenhze, MS;Giedroc, DP;Skaar, EP;
Journal: Cell Rep

Acinetobacter baumannii is an important nosocomial pathogen capable of causing wound infections, pneumonia, and bacteremia. During infection, A. baumannii must acquire Zn to survive and colonize the host. Vertebrates have evolved mechanisms to sequester Zn from invading pathogens by a process termed nutritional immunity. One of the most upregulated genes during Zn starvation encodes a putative cell wall-modifying enzyme which we named ZrlA. We found that inactivation of zrlA diminished growth of A. baumannii during Zn starvation. Additionally, this mutant strain displays increased cell envelope permeability, decreased membrane barrier function, and aberrant peptidoglycan muropeptide abundances. This altered envelope increases antibiotic efficacy both in vitro and in an animal model of A. baumannii pneumonia. These results establish ZrlA as a crucial link between nutrient metal uptake and cell envelope homeostasis during A. baumannii pathogenesis, which could be targeted for therapeutic development.

High-Precision Measurements of the Isotopic Composition of Common Lead Using MC-ICPMS: Comparison of Calibration Strategies Based on Full Gravimetric Isotope Mixture and Regression Models

Year: 2019
Products: PFA self-aspirating nebulizer MCN50
Authors: Tong, S;Meija, J;Zhou, L;Methven, B;Mester, Z;Yang, L;
Journal: Anal. Chem.

The determination of isotope ratios of lead finds many important applications in earth and planetary sciences. In this study, we report the first independent and fully calibrated absolute isotope ratio measurements of a common lead since the seminal work by the NIST in the 1960s, which has provided the widely used standards SRM 981 and SRM 982. This work employs MC-ICPMS for the absolute isotope ratio measurements, which were calibrated using two independent methods: the full gravimetric isotope mixture method based on the use of all four near-pure lead isotopes (the first application of this primary method to lead) and the regression method with NIST SRM 997 thallium isotopic standard as the primary calibrator. Both calibration methods provide results consistent to a few parts in 104, which were used to characterize isotope ratios of lead in an NRC candidate reference material, high-purity common lead HIPB-1.

Low-temperature fusion using NH4HSO4 and NH4HF2 for rapid determination of Pu in soil and sediment samples

Year: 2019
Products: APEX-Q
Authors: Wang, H;Ni, Y;Zheng, J;Huang, Z;Xiao, D;Aono, T;
Journal: Anal. Chim. Acta

Two fusion methods were established for rapid determination of Pu in soil and sediment samples. The methods consisted of NH4HSO4 or NH4HF2 fusion procedures incorporated with procedures for CaF2/LaF3 co-precipitation, extraction chromatography and SF-ICP-MS measurement. The fusion procedures were done on a portable hot plate instead of in a cumbersome muffle furnace and took only 15 min heating-up time from room temperature to 250 °C and 15 min fusion time at 250 °C. Chemical recoveries of Pu after completing the NH4HSO4 and NH4HF2 fusion methods for 0.5-1 g sample were approximately 70% and more than 90%, respectively, and decreased with the increase of sample weight from 0.5 g to 5 g. Sediment samples were pre-ignited at different temperatures ranging from 450 °C to 1000 °C to form refractory fractions of Pu, with which the dissolution rates of Pu by the NH4HSO4 and NH4HF2 fusion were investigated. With the increase of pre-ignition temperature of the sediment samples, the dissolution rates of Pu from the samples prepared by NH4HSO4 fusion declined dramatically from near 100% for 450 °C to 8% for 1000 °C. In contrast, the NH4HF2 fusion was capable of completely releasing Pu from samples that were pre-ignited at temperatures over 450 °C to 1000 °C, which was comparable to releases obtained by the hazardous and time-consuming HNO3-HF digestion, and was superior to the conventional HNO3 digestion. Additionally, because HF is not used in any procedure of the NH4HF2 fusion, a safer and greener alternative to NH4HSO4 fusion and HNO3-HF digestion is realized for rapid Pu determination in environmental samples for nuclear emergency response and application in environmental studies.

First assessment on trace elements in sediment cores from Namibian coast and pollution sources evaluation

Year: 2019
Products: Peltier cooling system
Authors: Orani, AM;Vassileva, E;Renac, C;Schmidt, S;Angelidis, MO;Rozmaric, M;Louw, D;
Journal: Sci. Total Environ.

Trace elements (TEs), Rare Earth Elements (REEs) and Pb isotope ratios were determined in six small cores sampled along the Namibian coast and different indices, such as Enrichment Factor, Geo-accumulation Index and Pollution load index, were calculated to evaluate possible metal contamination in the area. Concentrations of Pb, Cu, As and Cd were strongly enhanced at the upper 7 cm of core C5, which is located at Walvis Bay, at the major harbor and urban/industrial center of Namibia, indicating the impact from the recent anthropogenic activities. Principal Component Analysis was applied to the data set indicating possible common sources of the contaminants. Pb stable isotope ratios, combined with the dating of core C5 at Walvis Bay, further confirmed the anthropogenic provenance of Pb sources in the recent sediment deposits, which occurred after 1945, when the anthropogenic activities in the area began to increase. REEs profiles were also determined, showing enrichment in REEs for some of the samples, typical for the minerals present in the area. Ce anomaly was detected in one of the cores but the REEs profile did not reveal anomalies ascribable to anthropogenic influence.

Extreme spatial variation of Sr, Nd and Pb isotopic signatures and 48 element mass fractions in surface sediment of the Elbe River Estuary - Suitable tracers for processes in dynamic environments?

Year: 2019
Products: automated sample preparation system prepFAST-MC®
Authors: Reese, A;Zimmermann, T;Pröfrock, D;Irrgeher, J;
Journal: Sci. Total Environ.

The Elbe River has been long considered as one of the most anthropogenically impacted rivers in Europe. Its estuary is characterized by strong tidal effects, continuous dredging and dumping of sediment, and intense ship traffic between the North Sea and the Port of Hamburg. The aim of this study was to elucidate if a combined multi-element fingerprinting and isotopic tracer approach represented a suitable tool to investigate transport and mixing processes of inorganic contaminants within a complex and highly dynamic estuarine environment. A total of 37 surface sediment samples from the tidal Elbe were characterized in a comprehensive survey by determining the mass fractions of 48 elements and the isotopic signatures of stable Sr, Nd and Pb. Statistical data analysis resolved four discrete clusters of sampling locations in the estuary: One cluster upstream of the city of Hamburg, two clusters within the mixing zone between Hamburg and the mouth of the Elbe Estuary and one cluster in the mouth of the Estuary. River sediment entering the estuary carry significantly higher loads of metals (e.g. Cu, Zn, Sb, Cd and Pb), which are rapidly "diluted" by lower elemental mass fractions in marine sediment on a remarkably small regional scale. The cluster within the mouth of the estuary is mainly characterized by extreme isotopic variations of n(208Pb)/n(204Pb) ranging from 38.67 ± 0.15 to 73.86 ± 0.29, beside high mass fractions of U, Th, and some rare-earth elements. Determined Pb isotope ratios are among the highest reported values for terrestrial materials. This study indicates the general potential of combined element fingerprinting and isotope tracer approaches to elucidate processes in complex river systems. Furthermore, it represents an initial characterization of the catchment area of the Elbe River as basis for future studies on river and harbor management.

Evaluation of multi-biomarker response in fish intestine as an initial indication of anthropogenic impact in the aquatic karst environment

Year: 2019
Products: autosampler SC-2 DX FAST
Authors: Mijošek, T;Filipović Marijić, V;Dragun, Z;Krasnići, N;Ivanković, D;Erk, M;
Journal: Sci. Total Environ.

In order to assess the extent of existing anthropogenic influence on biota of the vulnerable karst ecosystem of the Krka River, multi-biomarker approach was applied in the intestinal tissue of brown trout Salmo trutta Linnaeus, 1758. Biomarkers of the general stress (total cytosolic proteins), oxidative stress (malondialdehyde), antioxidant capacity (catalase activity, total glutathione) and of an exposure and effect of contaminants, especially metals (metallothionein) and organophosphorous pesticides and metals (acetylcholine esterase activity) were compared in the intestine of fish from the reference site (river source) and downstream of the technological and municipal wastewater impacted site (town of Knin) in two seasons, October 2015 and May 2016. Biological response was additionally evaluated by metal/metalloid concentrations in intestinal cytosol. Site-specific differences were observed as significantly higher As, Ca, Co, Cu, Se and Sr concentrations in intestinal cytosol of fish from the contaminated compared to the reference site. Significant seasonal differences existed for Ni, Cd, Mo, Cs and Na, with higher levels in autumn, following the trend of most of the dissolved metal levels in the river water. Impact of improperly treated wastewaters was also confirmed by significantly increased levels of glutathione, total proteins and Foulton condition indices, with 1.5, 1.13 and 1.12 times higher average values in fish from that site compared to the river source, respectively. The other biomarkers showed similar trend and pointed to specific biological changes regarding oxidative stress or metal exposure in fish from the anthropogenically impacted site, especially in autumn, but without significant differences. Thus, the anthropogenic impact still seems to be only moderate, although cytosolic metals and most of the biomarkers in fish intestine were confirmed as initial indicators of pollution impact, which pointed to the need of continuous monitoring of the Krka River in order to protect this natural karst world phenomenon.

High-resolution elemental mapping of the root-rhizosphere-soil continuum using laser-induced breakdown spectroscopy (LIBS)

Year: 2019
Products: Optima 8300 dual-view ICP-OES system
Authors: Ilhardt, P;Nuñez, J;Denis, E;Rosnow, J;Krogstad, E;Renslow, R;Moran, J;
Journal: Soil Biology and Biochemistry

Understanding the complex chemical nature of root-soil interactions is essential for building the next generation of sustainable agricultural systems and facilitating long-term environmental remediation strategies. Techniques currently suited to investigate spatial controls on nutrient exchange in plant rhizospheres, however, are hindered by limitations in throughput, cost, analytical scope, and sample preparation needs. We describe here a method for rapid, high-resolution (∼100 μm), multi-element imaging of both organic content and inorganic constituents in root-rhizosphere-soil systems using laser-induced breakdown spectroscopy (LIBS). A switchgrass assemblage (Panicum virgatum) was grown in compact rhizotrons containing a sandy loam Alfisol from the Kellogg Biological Station (KBS), Michigan, USA. Root-soil samples were extracted using custom plastic coring devices for live root sampling and a modified drill press for sectioning frozen stabilized soil. A 266 nm, Nd:YAG laser was rastered over ∼10 mm2 sample surfaces and broadband spectra from single-pulse ablations were collected and mapped to discrete XY spatial coordinates for simultaneous imaging of 17 macronutrients, micronutrients and matrix elements. In order to rapidly process LIBS raster data and investigate chemical trends in the rhizosphere, an open-source Python module was developed, in which we used a novel calibration-free masking algorithm (based on principal components analysis (PCA) of normalized spectral intensities) to discriminate soil mineral grains, root fragments, and associated rhizosphere regions. We observed fine-scale chemical gradients within only a millimeter of switchgrass roots, consistent with rhizodeposition of organic compounds and proximal uptake of inorganic nutrients. Detection of trace element and carbon accumulations with diagnostic spectral signatures in the rhizosphere suggested the presence of residues (detritusphere) that could serve as sites of preferential microbial accumulation. These results highlight potential applications of LIBS within the growing field of spatially-resolved plant-soil analysis and extend its versatile imaging capabilities to the complex root-rhizosphere-soil network.

Biogeochemical Cycling of Dissolved Zinc in the Western Arctic (Arctic GEOTRACES GN01)

Year: 2019
Products: SeaFAST-pico system
Authors: Jensen, L;Wyatt, N;Twining, B;Rauschenberg, S;Landing, W;Sherrell, R;Fitzsimmons, J;
Journal: Global Biogeochem. Cycles

The biogeochemical cycling of dissolved zinc (dZn) was investigated in the Western Arctic along the U.S. GEOTRACES GN01 section. Vertical profiles of dZn in the Arctic are strikingly different than the classic “nutrient‐type” profile commonly seen in the Atlantic and Pacific Oceans, instead exhibiting higher surface concentrations (~1.1 nmol/kg), a shallow subsurface absolute maximum (~4–6 nmol/kg) at 200 m coincident with a macronutrient maximum, and low deep water concentrations (~1.3 nmol/kg) that are homogeneous (sp.) with depth. In contrast to other ocean basins, typical inputs such as rivers, atmospheric inputs, and especially deep remineralization are insignificant in the Arctic. Instead, we demonstrate that dZn distributions in the Arctic are controlled primarily by (1) shelf fluxes following the sediment remineralization of high Zn:C and Zn:Si cells and the seaward advection of those fluxes and (2) mixing of dZn from source waters such as the Atlantic and Pacific Oceans rather than vertical biological regeneration of dZn. This results in both the unique profile shapes and the largely decoupled relationship between dZn and Si found in the Arctic. We found a weak dZn:Si regression in the full water column (0.077 nmol/μmol, r2 = 0.58) that is higher than the global slope (0.059 nmol/μmol, r2 = 0.94) because of the shelf‐derived halocline dZn enrichments. We hypothesize that the decoupling of Zn:Si in Western Arctic deep waters results primarily from a past ventilation event with unique preformed Zn:Si stoichiometries.

Calcium isotopic signatures of carbonatite and silicate metasomatism, melt percolation and crustal recycling in the lithospheric mantle

Year: 2019
Products: prepFAST MC
Authors: Ionov, D;Qi, Y;Kang, J;Golovin, A;Oleinikov, O;Zheng, W;Anbar, A;Zhang, Z;Huang, F;
Journal: Geochimica et Cosmochimica Acta

Ca isotopes can be strongly fractionated at the Earth’s surface and thus may be tracers of subducted carbonates and other Ca-rich surface materials in mantle rocks, magmas and fluids. However, the δ44/40Ca range in the mantle and the scope of intra-mantle isotope fractionation are poorly constrained. We report Ca isotope analyses for 22 mantle xenoliths: four basalt-hosted refractory peridotites from Tariat in Mongolia and 18 samples from the Obnazhennaya (Obn) kimberlite on the NE Siberian craton. Obn peridotites are Paleoproterozoic to Archean melting residues metasomatised by carbonate-rich and/or silicate melts including unique xenoliths that contain texturally equilibrated carbonates. δ44/40Ca in 15 Obn xenoliths shows limited variation (0.74–0.97‰) that overlaps the value (0.94 ± 0.05‰) inferred for the bulk silicate Earth from data on fertile lherzolites, but is lower than δ44/40Ca for non-metasomatised refractory peridotites from Mongolia (1.10 ± 0.03‰). Bulk δ44/40Ca in four Obn peridotites containing metasomatic carbonates ranges from 0.81 ± 0.08‰ to 0.83 ± 0.06‰, with similar values in acid-leachates and leaching residues, indicating isotopic equilibration of the carbonates with host rocks.


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