journal
MENU ▼
Read by QxMD icon Read
search

Isotopes in Environmental and Health Studies

journal
https://read.qxmd.com/read/30744417/observation-of-18-o-16-o-isotope-effects-at-the-cathode-of-a-polymer-electrolyte-membrane-fuel-cell
#1
Takao Oi, Kaishu Seki, Yoshikazu Kikawada, Satoshi Yanase
18 O/16 O isotope effects were observed at the cathode of a polymer electrolyte membrane fuel cell at 25 and 35°C. Results of experiments in which the 18 O/16 O isotope ratios of the oxygen gases supplied to and exhausted from the cell were measured revealed that the lighter isotope 16 O reacted more preferentially to form water molecules at the cathode than the heavier one, 18 O. The value of the oxygen isotope separation factor, S1 , defined as the ratio of the 18 O/16 O isotope ratios of the oxygen gases supplied to and exhausted from the cell, ranged from 1...
February 12, 2019: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30626219/source-partitioning-of-atmospheric-methane-using-stable-carbon-isotope-measurements-in-the-reuss-valley-switzerland
#2
Jacqueline Stieger, Ines Bamberger, Rolf T W Siegwolf, Nina Buchmann, Werner Eugster
Measurements of methane ([Formula: see text]) mole fractions and [Formula: see text] [Formula: see text] that resolve the diel cycle in the agriculturally dominated Reuss Valley, Switzerland, were used to quantify the contributions of different [Formula: see text] sources to the atmospheric [Formula: see text] source mix. Both a nocturnal (NBL) and a diurnal convective boundary layer (CBL) approach were employed. A diel course of [Formula: see text] mole fractions was found with a daytime minimum (background around 1900 ppb) and a nocturnal maximum (up to 3500 ppb)...
January 9, 2019: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30621468/chromium-isotopes-tracking-the-resurgence-of-hexavalent-chromium-contamination-in-a-past-contaminated-area-in-the-friuli-venezia-giulia-region-northern-italy
#3
Francesca F Slejko, Riccardo Petrini, Anna Lutman, Claudia Forte, Lisa Ghezzi
The origin of a resurgent hexavalent chromium contamination in groundwater from a phreatic aquifer in the Friuli Venezia Giulia Region plain was investigated by chromium isotopic systematics. The area underwent a severe Cr(VI) contamination by industrial effluents in 1997, when Cr(VI) concentration in groundwater reached 4500 µg/L. In subsequent years the contamination naturally attenuated, totally disappearing in 2003. A renewal of water contamination was observed in 2008, Cr(VI) reaching 1560 µg/L. The δ53 Cr value in groundwater and extracts from sediments was measured in 2009-2011, and it ranges between -3...
January 8, 2019: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30618268/agf-desalination-procedure-for-the-routine-determination-of-oxygen-and-hydrogen-isotopic-composition-of-saline-waters-and-brines
#4
Adam Porowski
The routine methods for stable oxygen and hydrogen isotope analysis of water involve water-CO2 gas equilibration and water reduction on hot metal (e.g. Zn, Cr, U) and subsequent mass spectrometric analysis of the evolved gases of CO2 and H2 for 18 O/16 O and 2 H/1 H ratios, respectively. Precise determination of the isotopic composition of water in brines with application of these standard methods is still problematic and technically often impossible due to detrimental influence of dissolved salts. The new method of brine desalination presented in this study overcomes the problem of the isotope salt effects encountered during the application of the routine techniques for the determination of the isotopic composition of high saline waters...
January 8, 2019: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30602299/field-deployable-measurements-of-free-living-individuals-to-determine-energy-balance-fuel-substrate-usage-through-%C3%AE-13-c-in-breath-co-2-and-diet-through-hair-%C3%AE-13-c-and-%C3%AE-15-n-values
#5
Gwyneth Gordon, Amrita Rhoads
Carbon isotopes of breath CO2 vary depending on diet and fuel substrate used. This study examined if exercise-induced δ13 C-CO2 changes in substrate utilization were distinguishable from baseline δ13 C-CO2 variations in a population with uncontrolled diet, and compared hair isotope values and food logs to develop an isotope model of diet. Study participants included nine women with diverse Body Mass Index (BMI), age, ancestry, exercise history, and diet. Breath samples were collected prior to and up to 12 h after a 5- or 10 K walk/run...
January 2, 2019: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30582824/comparison-of-active-and-passive-radon-survey-in-cave-atmosphere-and-estimation-of-the-radon-exposed-dose-equivalents-and-gamma-absorbed-dose-rates
#6
Songül Akbulut Özen, Uğur Çevik, Halim Taşkın
Radon (222 Rn) measurements were conducted in the Pileki Cave with Radim 3A Active Radon Monitor equipment. Measurements were also done with the passive sampling method with CR-39 nuclear track detectors by exposing them for three months in the cave. Radon concentrations obtained from the active and passive sampling methods showed that, firstly, the concentrations inside the cave measured by the latter method differed greatly due to high humidity levels up to 88%. The total inside radon exposure dose equivalent people were subjected to was estimated to be 19 µSv a-1 for visitors and 24,065 µSv a-1 for guides...
December 24, 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30458650/hydrogeological-responses-in-tropical-mountainous-springs
#7
Jessica Salas-Navarro, Ricardo Sánchez-Murillo, Germain Esquivel-Hernández, José Leonardo Corrales-Salazar
This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18 O and δ2 H in rainfall resulted in a highly significant meteoric water line: δ2 H = 7.93·δ18 O + 10.37 (r2  = 0.97). Rainfall isotopic composition exhibited a strong amount-dependent seasonality. The isotopic variation (δ18 O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs)...
November 20, 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30354800/hans-faust-90th-birthday
#8
Helge Bornhak, Klaus Jung, Peter Junghans, Peter Krumbiegel, Rolf Reinhard, Rolf Russow, Eckart Winkler
No abstract text is available yet for this article.
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30354799/publication-of-the-second-edition-of-the-firms-good-practice-guide-for-isotope-ratio-mass-spectrometry
#9
Philip J H Dunn, James F Carter
No abstract text is available yet for this article.
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30326739/using-the-13-c-12-c-carbon-isotope-ratio-to-characterise-the-emission-sources-of-airborne-particulate-matter-a-review-of-literature
#10
Juan Aguilera, Leah D Whigham
Particulate matter (PM) from atmospheric aerosols contains carbons that are harmful for living organisms and the environment. PM can originate from vehicle emissions, wearing of vehicle components, and dust. Size and composition determine PM transport and penetration depth into the respiratory system. Understanding PM emission characteristics is essential for developing strategies to improve air quality. The number of studies on carbon isotope composition (13 C/12 C) of PM samples to characterise emission factors has increased...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30318924/breath-water-based-doubly-labelled-water-method-for-the-noninvasive-determination-of-co-2-production-and-energy-expenditure-in-mice
#11
Peter Junghans, Solvig Görs, Martina Langhammer, Cornelia C Metges
We explored a novel doubly labelled water (DLW) method based on breath water (BW-DLW) in mice to determine whole body CO2 production and energy expenditure noninvasively. The BW-DLW method was compared to the DLW based on blood plasma. Mice (n = 11, 43.5 ± 4.6 g body mass (BM)) were administered orally a single bolus of doubly labelled water (1.2 g H2 18 O kg BM-1 and 0.4 g 2 H2 O kg BM-1 , 99 atom% (AP) 18 O or 2 H). To sample breath water, the mice were placed into a respiration vessel. The exhaled water vapour was condensed in a cold-trap...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30280592/nitrogen-isotope-fractionation-factors-%C3%AE-measured-and-estimated-from-the-volatilisation-of-ammonia-from-water-at-ph-9-2-and-ph-8-5
#12
Eduardo Cejudo, Sherry L Schiff
This paper examines the nitrogen isotope fractionation factors (α) associated with the volatilisation of ammonia from water under controlled conditions at two pH values (8.5 and 9.2). This experiment assumed the continuous removal of ammonia at a single purge rate of 10 mL air min-1 . The fractionation resulting from the removal of total ammonia from the water into an acid trap was named the observed isotope fractionation factor (αobs ), and it was measured as 1.019 (±0.0025) at pH 8.5 and 1.030 (±0.0025) at pH 9...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30257573/stable-carbon-isotopic-composition-of-peat-columns-subsoil-and-vegetation-on-natural-and-forestry-drained-boreal-peatlands
#13
Hannu Nykänen, Promise A Mpamah, Antti J Rissanen
We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ13 C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ13 C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ13 C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ13 C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the bogs...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30156882/nitrogen-isotope-pattern-in-mongolian-larch-stands-at-the-southern-eurasian-boreal-forest-boundary
#14
Mika Hayashi, Maximo Larry Lopez Caceres, Yoshihiro Nobori, Byambasuren Mijidsuren, Jens Boy
In the last decades a drastic increase in air temperature but a stable precipitation regime in Mongolia has led to gradual drying conditions. Thus, we evaluated the effect of spatial and climatic characteristics on the soil-plant nitrogen dynamics in three representative larch stands (Larix sibirica) with different geographical and climatic conditions using stable nitrogen isotopes. The results showed significant differences in the soil inorganic N content among sites and consequently a different isotopic composition in the plant-soil system...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30081652/stable-isotope-signatures-of-meteoric-water-in-the-cuvelai-etosha-basin-namibia-seasonal-characteristics-trends-and-relations-to-southern-african-patterns
#15
Heike Wanke, Marcel Gaj, Matthias Beyer, Paul Koeniger, Josefina T Hamutoko
The study area is the Namibian part of the Cuvelai-Etosha Basin (CEB), located in central northern Namibia. The CEB is home to 40 % of Namibia's population, and most of the people live in rural areas. These people depend on both surface and groundwater resources which are limited in this dryland (mean annual rainfall ranging from 250 to 550 mm/a). The isotopic signatures of δ18 O and δ2 H from water samples (n = 61) collected over a course of 9 years from various research projects and existing (but mainly unpublished) data of meteoric water of the CEB (10 sites) were evaluated and local meteoric water lines (LMWLs) developed...
December 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30406676/a-guide-for-proper-utilisation-of-stable-isotope-reference-materials
#16
Wolfram Meier-Augenstein, Arndt Schimmelmann
Many scientific publications about stable isotope ratios suffer from flawed practices regarding calibration and normalisation of raw δ values in conjunction with prescribed δ values of reference materials. Violations of the identical treatment principle with regards to samples and standards (i.e. reference materials) and lack of adherence to SI-mandated and IUPAC-recommended nomenclature exacerbate the widespread problem of lackadaisical analytical practice and reporting. Science is supposed to strive for exactness, whereas ambiguity and jargon confound interdisciplinary communication...
November 8, 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30169987/application-of-isotopes-in-the-investigation-of-particulate-matter-pm
#17
Gerhard Strauch
No abstract text is available yet for this article.
October 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30114951/aerosol-source-biomass-traffic-and-coal-emission-apportionment-in-lithuania-using-stable-carbon-and-radiocarbon-analysis
#18
Andrius Garbaras, Justina Šapolaitė, Inga Garbarienė, Žilvinas Ežerinskis, Agnė Mašalaitė-Nalivaikė, Raminta Skipitytė, Artūras Plukis, Vidmantas Remeikis
In the present study, a combination of the stable carbon isotope ratio (13 C/12 C) with radiocarbon data (14 C) allowed us to perform the aerosol source apportionment. Filter samples of PM1 were collected during the warm and cold periods in rural and urban sites in Lithuania. The 14 C/12 C ratio of total carbon (TC) was measured using the single stage accelerator mass spectrometer quantifying of fossil and non-fossil derived aerosol emissions. The δ13 C value was measured using an elemental analyser interfaced with an isotope ratio mass spectrometer...
October 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30081672/anomalous-ratios-of-radioisotopes-in-pm-10-as-tracer-of-global-fallout-impact-in-the-centre-of-mexico
#19
Carmen Grisel Méndez-García, Elizabeth Teresita Romero-Guzmán, Héctor Hernández-Mendoza, Corina Solís Rosales, Efraín Rafael Chávez Lomelí
The monitoring and evaluation of radioactive content in samples of PM10 aerosols have been investigated. The specific radioactivity concentrations (SRC) of 234 U, 235 U, 238 U and 232 Th were determined using inductively coupled plasma-sector field mass spectrometry in 13 samples collected in Mexico City and 8 samples collected in Cuernavaca in the centre of Mexico. The SRC of the radioisotopes analysed in PM10 were larger than those reported in PM2.5 . The enrichment factor was greater than 5, indicating anthropogenic influences in both sites...
October 2018: Isotopes in Environmental and Health Studies
https://read.qxmd.com/read/30081668/isotope-effects-in-the-tyrosinase-catalysed-hydroxylation-of-l-tyrosine-methyl-derivatives
#20
Małgorzata Pająk, Marianna Kańska
To investigate isotope effects in the hydroxylation of [3',5'-2 H2 ]-α-methyl- and [3',5'-2 H2 ]-N-methyl-l-tyrosine, they were synthesised using acid catalysed isotope exchange at high temperature. The kinetic and solvent deuterium isotope effects on Vmax and Vmax /Km parameters of tyrosinase in its action on methylated derivatives of l-tyrosine were determined using the non-competitive spectrophotometric method. Lineweaver-Burk plots were used to consider the inhibition type of O-methyl-l-tyrosine, revealing that it is an uncompetitive inhibitor of tyrosinase...
October 2018: Isotopes in Environmental and Health Studies
journal
journal
32448
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"