Measurements Of Major Elements Research Articles

Semi-Quantitative Analysis of Major Elements and Minerals: Clues from a Late Pleistocene Core from Campos Basin

Element and mineral associations are fundamental parameters for palaeoceanographical reconstructions but laboratory methodologies are expensive, time-consuming and need a lot of material. Here, we investigate the quality and reliability of XRF measurements of major elements (Fe, Ti and Ca) using BTX II Benchtop, by comparing them with previous ICP-OES elemental analysis for a set of Late Pleistocene marine sediments from Campos Basin. Although the numerical values of the logarithmic form of the elementary ratios were different, the lnTi/Ca and lnFe/Ca ratios measured by both techniques (XRF and ICP-OES) presented similar downcore results. To correct the XRF intensity data, a linear regression model was calculated and, based on the linear equation generated, the logarithmic values of the elementary XRF ratios were corrected. After the correction, One-Sample t-test and Bland–Altman plot show that both techniques obtained similar results. In addition, a brief paleoceanographic interpretation, during the MIS 5 and MIS 4 periods, was conducted by comparing mineralogical and elementary analysis aiming to reconstruct the variations of the terrigenous input to the studied area. As a conclusion, the results from XRF measurements (BTX II) presented to confirm the viability of such a technique, showing that analysis using BTX II is a reliable, cheap, rapid and non-destructive option for obtaining elementary ratios and mineralogical downcore results at high resolution, allowing stratigraphic and paleoceanographic interpretations.

Hydrochemical and environmental isotope characteristics of groundwater in the Hongjiannao Lake Basin, Northwestern China

Understanding the hydrochemical and isotopic characteristics of groundwater and hydrogeochemical processes is crucial for groundwater resource development and environmental protection, especially in semiarid regions. To address this question, we collected and tested groundwater and river water samples form the Hongjiannao Lake Basin. The groundwater samples were took from a porous medium aquifer and a pore-fissure aquifer. We studied hydrochemical characteristics of groundwater from both aquifers using major element measurements, statistical calculations, and the use of Piper diagrams. The hydrogeochemical processes taking place in groundwater were identified using the Gibbs diagram, Gaillardet diagram, saturation index calculations, ratios of major ions, and chloro-alkaline indices. We also investigated the origin of groundwater using stable isotopes (D and 18O) and evaluated groundwater age on the basis of piston model of tritium isotope (3H) measurements. Groundwater–river water interactions are also identified using chemical and stable isotope characteristics. The results show that groundwater in both aquifers has a chemical composition dominated by are HCO3 anions that groundwater has a low total dissolved solids (TDS) content. An assessment of the analyzed groundwater chemical data suggests that feldspar dissolution, the dissolution/precipitation of carbonate minerals (dolomite and calcite), and cation exchange play an important role in the hydrochemical evolution of groundwater in the study area. The compositions of stable isotopes and tritium imply that groundwater in the porous medium and pore-fissure aquifers originate from modern and ancient precipitation sources, respectively. The groundwater recharge is influenced by evaporation as water infiltrates through the vadose zone. In addition, river, lake, and groundwater form an organic whole. This study provides effective guidance for groundwater resource development and environmental protection in a similar area.

The fates of CO2 generated by H2SO4 and/or HNO3 during the dissolution of carbonate and their influences on the karst-related carbon cycle

To distinguish the two fates of CO2 generated by H2SO4 and/or HNO3 during the dissolution of carbonate rock and to reveal the effect of this CO2 on the karst-related carbon cycle at short timescales, Baishuwan Spring (BSW; overlying secondary forest) and Lanhuagou Spring (LHG; overlying farmland) were monitored monthly by measurement of major elements and the stable carbon isotope of dissolved inorganic carbon (δ13CDIC) in spring water. The average net CO2 consumption, CO2 consumption by H2CO3, and CO2 emission by H2SO4 and/or HNO3 were 2.43, 2.65, and 0.23 mmol/L at BSW, whereas they were 1.07, 2.27, and 1.2 mmol/L at LHG, respectively. The low CO2 consumption by H2CO3 and the high CO2 emission by H2SO4 and/or HNO3 collectively led to a lower net CO2 consumption at LHG than at BSW; the effect of CO2 emissions was greater than the effect of CO2 consumption. The fates of the CO2 generated by H2SO4 and/or HNO3 were quantified. On average, 35.26% of this CO2 escaped from the water at BSW, whereas 82.82% escaped from the water at LHG, presumably due to different water-rock reaction times. Changes in the fate of CO2 may influence emissions and the karst-related carbon cycle.

An Orbitrap-based laser desorption/ablation mass spectrometer designed for spaceflight.

The investigation of cryogenic planetary environments as potential harbors for extant life and/or contemporary sites of organic synthesis represents an emerging focal point in planetary exploration. Next generation instruments need to be capable of unambiguously determining elemental and/or molecular stoichiometry via highly accurate mass measurements and the separation of isobaric interferences. An Orbitrap™ analyzer adapted for spaceflight (referred to as the CosmOrbitrap), coupled with a commercial pulsed UV laser source (266 nm), was used to successfully characterize a variety of planetary analog samples via ultrahigh resolution laser desorption/ablation mass spectrometry. The materials analyzed in this study include: jarosite (a hydrous sulfate detected on Mars); magnesium sulfate (a potential component of the subsurface ocean on Europa); uracil (a nucleobase of RNA); and a variety of amino acids. The instrument configuration tested here enables: measurement of major elements and organic molecules with ultrahigh mass resolution (m/Δm ≥ 120,000, FWHM); quantification of isotopic abundances with <1.0% (2σ) precision; and identification of highly accurate masses within 3.2 ppm of absolute values. The analysis of a residue of a dilute solution of amino acids demonstrates the capacity to detect twelve amino acids in positive ion mode at concentrations as low as ≤1 pmol/mm2 while maintaining mass resolution and accuracy requirements. The CosmOrbitrap mass analyzer is highly sensitive and delivers mass resolution/accuracy unmatched by any instrument sent into orbit or launched into deep space. This prototype instrument, which maps to a spaceflight implementation, represents a mission-enabling technology capable of advancing planetary exploration for decades to come.

Update on element content profiles in eleven wild edible mushrooms from family Boletaceae

The aim of this study was to determine and evaluate the amounts of major elements (Ca, Fe, K, Na and P), essential trace elements (Cu, Zn, Fe and Mn) and some other trace metals (Ag, Al, Co, Ni, Cr, Sr, Se, Bi, Rb) in eleven species of wild-grown common edible mushrooms from family Boletaceae (Boletus appendiculatus, Boletus edulis, Boletus regius, Boletus fechtneri, Boletus impolitus, Boletus purpureus, Boletus rhodoxanthus, Leccinum crocipodium, Leccinum pseudoscaber, Xerocomellus chrysenteron, Xerocomus badius) from Serbia. The measurements of major elements (Ca, Fe, K, Na and P) were carried out by inductively coupled plasma optical emission spectrometer (ICP-OES), while analytical measurements of the rest of studied elements were performed using an inductively coupled plasma mass spectrometer (ICP-MS), after microwave digestion. The results showed that the element concentrations were species-dependent. Potassium and phosphorous concentrations were found to be greater than those of the other mineral constituents in all tested species. Multivariate analysis included principal component analysis (PCA) and hierarchical cluster analyses (HCA). HCA grouped mushrooms in three statistically significant clusters, while PCA indicated connection between analyzed metals. Also, this paper highlights the importance of essential and nonessential elements of human health and their daily intake.

Development of particle induced X-ray emission-computed tomography in Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency

A new micro-particle induced X-ray emission-computed tomography (PIXE-CT) system was developed at Takasaki Ion Accelerators for Advanced Radiation Application in Japan Atomic Energy Agency. In this system, scanning transmission ion microscopy-CT was performed as well as PIXE-CT for three-dimensional (3D) measurement of major elements' distributions, which are required for corrections of X-ray yields due to energy losses of projectiles and absorption of X-rays. Moreover, maximum likelihood expectation maximization algorithm has been introduced to image reconstruction because higher spatial resolution can be obtained even with less X-ray yields. Consequently, 3D distribution of trace elements in a minute biological cell less than 100 μm has been successfully obtained.

U-series dating of Lake Nyos maar basalts, Cameroon (West Africa): Implications for potential hazards on the Lake Nyos dam

From previously published 14C and K–Ar data, the age of formation of Lake Nyos maar in Cameroon is still in dispute. Lake Nyos exploded in 1986, releasing CO 2 that killed 1750 people and over 3000 cattle. Here we report results of the first measurements of major elements, trace elements and U-series disequilibria in ten basanites/trachy-basalts and two olivine tholeiites from Lake Nyos. It is the first time tholeiites are described in Lake Nyos. But for the tholeiites which are in 238U– 230Th equilibrium, all the other samples possess 238U– 230Th disequilibrium with 15 to 28% enrichment of 230Th over 238U. The ( 226Ra/ 230Th) activity ratios of these samples indicate small (2 to 4%) but significant 226Ra excesses. U–Th systematics and evidence from oxygen isotopes of the basalts and Lake Nyos granitic quartz separates show that the U-series disequilibria in these samples are source-based and not due to crustal contamination or post-eruptive alteration. Enrichment of 230Th is strong prima facie evidence that Lake Nyos is younger than 350 ka. The 230Th– 226Ra age of Nyos samples calculated with the ( 226Ra/ 230Th) ratio for zero-age Mt. Cameroon samples is 3.7 ± 0.5 ka, although this is a lower limit as the actual age is estimated to be older than 5 ka, based on the measured mean 230Th/ 238U activity ratio. The general stability of the Lake Nyos pyroclastic dam is a cause for concern, but judging from its 230Th– 226Ra formation age, we do not think that in the absence of a big rock fall or landslide into the lake, a big earthquake or volcanic eruption close to the lake, collapse of the dam from erosion alone is as imminent and alarming as has been suggested.