scholarly journals Recent Progresses in Stable Isotope Analysis of Cellulose Extracted from Tree Rings

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2743
Author(s):  
Silviu-Laurentiu Badea ◽  
Oana Romina Botoran ◽  
Roxana Elena Ionete
Keyword(s):  
Stable Isotope ◽  
Hydrogen Isotope ◽  
Environmental Changes ◽  
Isotope Analysis ◽  
Isotope Ratio Mass Spectrometry ◽  
Hydrogen Atoms ◽  
Surrounding Water ◽  
Analytical Tools ◽  
Technical Sample

In this work, the challenges and progression in stable isotope investigation, from the analytical tools and technical sample preparation procedures to the dendroclimatological experiments, were reviewed in terms of their use to assess tree physiological responses to environmental changes. Since the isotope signature of whole wood is not always a reliable tool in studying the climate changes, cellulose is often preferred as the study material in paleoclimatic studies. Nevertheless, the isotope analysis of cellulose is challenging due to the difficulty to remove the other wood components (extractives, lignin, pectin, and hemicelluloses). Additionally, in the case of hydrogen isotope analysis, about 30% of the hydrogen atoms of cellulose are exchanged with the surrounding water, which complicates the isotope analysis. In recent years, more automated isotope analysis methods were developed based on high temperature pyrolysis of cellulose, followed by the chromatographic separation of H2 from CO and by their individual isotope analysis using isotope ratio mass spectrometry. When used to investigate climate factors, the combined isotope analysis δ13C and δ18O appears to be the most promising isotope tool. In contrast, the role of δ2H values is yet to be elucidated, together with the development of new methods for hydrogen isotope analysis.

scholarly journals Mass spectrometric measurement of hydrogen isotope fractionation for the reactions of chloromethane with OH and Cl

2018 ◽  
Author(s):  
Frank Keppler ◽  
Enno Bahlmann ◽  
Markus Greule ◽  
Heinz Friedrich Schöler ◽  
Julian Wittmer ◽  
...  
Keyword(s):  
Hydrogen Isotope ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Isotope Analysis ◽  
Isotope Ratio Mass Spectrometry ◽  
Detailed Knowledge ◽  
Mass Spectrometric Measurement ◽  
Isotopic Analyses ◽  
Chlorine Radicals ◽  
Stable Hydrogen Isotope

Abstract. Chloromethane (CH3Cl) is an important provider of chlorine to the stratosphere but yet lacks detailed knowledge of its budget. Stable isotope analysis is potentially a powerful tool to constrain CH3Cl flux estimates. The largest degree of isotope fractionation is expected to occur for deuterium in CH3Cl in the hydrogen abstraction reactions with its main sink reactant tropospheric OH and its minor sink reactant Cl atoms. We determined the isotope fractionation by stable hydrogen isotope analysis of the fraction of CH3Cl remaining after reaction with hydroxyl and chlorine radicals in a 3.5 m3 Teflon smog-chamber at 293 ± 1 K. We measured the increasing stable hydrogen isotope values of the unreacted CH3Cl using compound specific thermal conversion isotope ratio mass spectrometry. The isotope fractionations of CH3Cl for the reactions with hydroxyl and chlorine radicals were found to be −242 ± 7 mUr (or ‰) and −280 ± 11 mUr, respectively. For comparison, we performed similar experiments using methane (CH4) as the target compound with OH and obtained a fractionation constant of −205 ± 6 mUr which is in good agreement with values previously reported. The observed large kinetic isotope effects are helpful when employing isotopic analyses of CH3Cl in the atmosphere to improve our knowledge of its atmospheric budget.

Dietary composition of endangered seahorses determined by stable isotope analysis

2017 ◽  
Vol 68 (5) ◽  
pp. 831 ◽  
Author(s):  
S. Valladares ◽  
D. X. Soto ◽  
M. Planas
Keyword(s):  
Stable Isotope ◽  
Environmental Changes ◽  
Conservation Status ◽  
Management Strategies ◽  
Isotope Analysis ◽  
Primary Source ◽  
Habitat Characteristics ◽  
Conservation Actions ◽  
Isotope Mixing Models ◽  
North Western

The lack of integrated measures for assessing the feeding ecology of seahorses may restrict the effectiveness of conservation actions on wild populations of worldwide threatened seahorse species. Identifying dietary sources will allow researchers to determine their degree of vulnerability to environmental changes, redefine their conservation status and apply appropriate management strategies. The resource use of the seahorse Hippocampus guttulatus inhabiting coastal waters of Galicia (north-western Iberian Peninsula) was assessed for three populations and 2 years using stable isotope mixing models. The Bayesian mixing model (MixSIAR) estimated the relative contributions of the dietary sources to the seahorse diet and revealed that Caprellidea were the primary source, followed by Gammaridea and Caridea. Mysidae and Annelida represented the less dominant prey. This prey preference can be explained by the foraging behaviour of seahorses. Different contributions of Gammaridea and Caridea to the diet were found among sites, indicating different habitat characteristics and hence different habitat use by seahorses within each site. In addition, differences were encountered among sexes. Caprellidea was the dominant prey for females, whereas Gammaridea was the dominant prey for males. The findings of the present study will contribute to the knowledge of feeding patterns of H. guttulatus, providing relevant data for conservation of this endangered species.

Pedogenic, palustrine and groundwater dolomite formation in non-marine bentonites (Bavaria, Germany)

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 163-183 ◽  
Author(s):  
M.H. Köster ◽  
H.A. Gilg
Keyword(s):  
Stable Isotope ◽  
Isotope Geochemistry ◽  
Isotope Analysis ◽  
X Ray Diffraction ◽  
Wetting And Drying ◽  
C3 Plant ◽  
Carbonate Formation ◽  
Data Points ◽  
Dolomite Formation

AbstractDolomite and calcite in Bavarian bentonites, southern Germany, were investigated using petrography, field-emission scanning electron microscopy and stable isotope geochemistry to explore the role of authigenic carbonate formation during bentonitization. Pedogenic, palustrine and groundwater carbonates were distinguished on the basis of X-ray diffraction, micromorphological and stable isotope analysis. The δ13CV-PDB and δ18OV-PDB values of dolomite range from −8.0% to −6.1% and −5.4% to −3.4%, respectively. Calcites show a range from −11.9% to −8.1% for carbon and from −9.1% to −6.2% for oxygen. Carbon isotope compositions imply a C3-plant-dominated carbon source and repeated wetting and drying cycles. The oxygen isotope data points to an evaporation and temperature controlled δ18OV-SMOW value of meteoric water of −7.0% to −4.8%. A syngenetic to early diagenetic timing of dolomitization is indicated, suggesting both dolomite and bentonite formation in non-saline, non-arid and repeatedly partially-oxygenated and reducing soil and groundwater environments during pedogenesis.

scholarly journals Estimation of nutrient contributions from the ocean across a river basin using stable isotope analysis

2015 ◽  
Vol 12 (7) ◽  
pp. 5535-5557
Author(s):  
K. Nakayama ◽  
Y. Maruya ◽  
K. Matsumoto ◽  
M. Komata ◽  
K. Komai ◽  
...  
Keyword(s):  
Stable Isotope ◽  
River Basin ◽  
Stable Isotope Analysis ◽  
Chum Salmon ◽  
Ursus Arctos ◽  
Isotope Analysis ◽  
Oncorhynchus Gorbuscha ◽  
River Ecosystem ◽  
River Channels

Abstract. Since marine derived nutrients (MDN) are transported not only in river channels but also across the entire river basin, including via ground water and migratory animals, it is necessary to investigate the contribution of MDN to the forest floor (soils) in order to quantify the true role of MDN at the river ecosystem scale. This study investigated the contribution of pink (Oncorhynchus gorbuscha) and chum salmon (O. keta) to total oceanic nitrogen (TN) input across a river basin using stable isotope analysis (SIA) of nitrogen (δ15N). The contribution of TN entering the river basin by salmon was 23.8 % relative to the total amount of TN exported from the river basin, providing a first estimate of MDN export for a river basin. The contribution of nitrogen from the ocean to the river basin soils was between 22.9 and 23.8 %. Furthermore, SIA showed that the transport of oceanic TN by sea eagles (Haliaeetus spp.) was greater than that by bears (Ursus arctos), which had previously been that bears are thought to be the major animal transporter of nutrients in the northern part of Japan.

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