Results 101 to 110 of about 241,523 (262)

Preparation and Certification of Reference Materials for Hydrogen and Oxygen Isotopes in Water

Yankuang ceshi, 2013
Certified reference materials of water for stable hydrogen and oxygen isotopes were developed and have been used for more than 30 years. However, they no longer meet the requirements for newly developed technologies. New reference materials of water have
ZHANG Lin, LIU Fu-liang, JIA Yan-kun, LIU Jun   +3 more
doaj  

Late Holocene environmental history of Dojran, Macedonia: Investigating the interplay of imperial dynamics and climatic change

Journal of Quaternary Science, EarlyView.
ABSTRACT This study presents a high‐resolution, multi‐proxy reconstruction of environmental and land‐use change from Lake Dojran over historical times (last 2500 years), combining pollen, biomarkers, radiocarbon dating, Ottoman taxation records and other historical data.
Alessia Masi, Lucrezia Masci, Georgios C. Liakopoulos, Monica Bini, Alexander Francke, Ilaria Isola, Carlo Ricotta, Laura Sadori, Alexander Sarantis, Sławomir Sprawski, Jakub Sypiański, Irene Tunno, Cristiano Vignola, Bernd Wagner, Giovanni Zanchetta, Adam Izdebski   +15 more
wiley   +1 more source

Qualitative Analysis of Biogas by Raman Spectroscopy: Effect of Pressure on Major Components

Journal of Raman Spectroscopy, EarlyView.
Raman spectra of major and selected minor biogas components were studied under pressures up to 100 bar. Pressure‐induced shifts and band broadening were quantified for methane, carbon dioxide, and nitrogen, while Raman spectra of ammonia and hydrogen sulfide are presented in the context of biogas quality monitoring.
Dominik Tománek, Matouš Kuneš, Tomáš Hlinčík   +2 more
wiley   +1 more source

Detection of Acoustic Phonons in Carbon by Raman Spectroscopy

Journal of Raman Spectroscopy, EarlyView.
Acoustic phonons in graphite and diamond are detected by Raman spectroscopy through disorder‐induced relaxation of selection rules. Comparison with calculated phonon densities of states enables assignment of the observed Raman features to acoustic phonon branches.
Konstantin Iakoubovskii, Andrey Katrusha, Weihua Peng, Jianguo Peng   +3 more
wiley   +1 more source

A systematic 15N‐amino‐acid tracer framework to identify sources of pelagic marine organic matter

Limnology and Oceanography: Methods, EarlyView.
Abstract Accurately tracing organic matter sources in marine systems remains challenging, particularly where natural and anthropogenic inputs coexist. Compound‐specific stable isotope analysis of amino acids (CSIA‐AA) offers strong potential for organic matter source discrimination, but its application is limited by the small number of validated δ15N ...
E. Cepeda, S. Bodé, P. Boeckx, J. Vanaverbeke, U. Braeckman, I. Lizaga   +5 more
wiley   +1 more source

Depositional and Hydrological Relationships Between Buried Dead Ice and the Active Layer in the McMurdo Dry Valleys, Antarctica: A Study of Sediment Geochemistry and Cation Concentrations

Permafrost and Periglacial Processes, EarlyView.
ABSTRACT The McMurdo Dry Valleys, the largest ice‐free region in Antarctica, are home to a cold‐desert hydrologic system of glaciers, snowbanks, streams, and lakes. Freshwater is also stored as dead glacial ice, which is poorly constrained in terms of ion concentrations and interactions with both in situ and overlying sediments.
Matthew C. Witscheber, Kate M. Swanger
wiley   +1 more source

Zoning and contamination rate of magnesium and heavy metals of iron, zinc and copper in the north and northwest aquifer of Khoy (Zourabad) based on GIS and determining the contaminated source

Journal of Economic Geology, 2015
Introduction Heavy metals are the most toxic pollutants in aquatic ecosystems. This contamination can result from the release of heavy metal elements during alteration and weathering of ultramafic and mafic rocks (ophiolite zones).
Fariborz Khodadadi, Abdolnaser Fazlnia, Hossein Pirkharrati   +2 more
doaj  

Thallium Isotopes Across the Smithian-Spathian Boundary: Evidence for Anoxia Throughout Most of the Early Triassic. [PDF]

Geobiology
ABSTRACT Following the largest known Phanerozoic extinction, the end‐Permian mass extinction, the Early Triassic is often considered an interval of slow biotic recovery. During this time, the minor Smithian‐Spathian extinction occurred, further delaying the biotic recovery of this epoch.
Newby SM, Owens JD, Young SA, Hammer Ø.
europepmc   +2 more sources

Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes

, 2009
Geochemical data1,2,3,4 suggest that oxygenation of the Earth’s atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between ∼2.45 and 2.2 Gyr ago1,5, leading to a significant increase in atmospheric ...
Claudio Gaucher, Gaucher, Claudio, Robert Frei, Poulton, Simon W., Don E. Canfield, Simon W. Poulton, Canfield, Donald Eugene; id_orcid, Poulton, S.W., Canfield, D.E., Frei, Robert   +9 more
core   +1 more source

University teaching of mass spectrometry as a key practical technique within the context of a fully integrated, spiral curriculum

Rapid Communications in Mass Spectrometry, EarlyView.
Rationale Mass spectrometry (MS) is introduced to high school students in the UK in many pre‐university course syllabi. As such, we have identified the use of MS as a key technique that should be taught practically to undergraduates from the outset of their studies.
Andrew F. Worrall, Craig D. Campbell, Megan O. Midson, Malcolm I. Stewart   +3 more
wiley   +1 more source