scholarly journals Water content and hydrogen isotopic composition of glassy bronzite andesite (sanukite) and glassy rhyolite from Goshikidai and Kanayama, northeast Skikoku, Japan.

1991 ◽  
Vol 97 (9) ◽  
pp. 755-758 ◽  
Author(s):  
Hiroaki Sato ◽  
Minoru Kusakabe
Keyword(s):  
Isotopic Composition ◽  
Water Content ◽  
Hydrogen Isotopic Composition

scholarly journals New clues to ancient water on Itokawa

2019 ◽  
Vol 5 (5) ◽  
pp. eaav8106 ◽  
Author(s):  
Ziliang Jin ◽  
Maitrayee Bose
Keyword(s):  
Isotopic Composition ◽  
Water Content ◽  
Water Loss ◽  
Parent Body ◽  
Terrestrial Planets ◽  
Nominally Anhydrous Minerals ◽  
Potential Source ◽  
Impact Events ◽  
Hydrogen Isotopic Composition ◽  
Water Contents

We performed the first measurements of hydrogen isotopic composition and water content in nominally anhydrous minerals collected by the Hayabusa mission from the S-type asteroid Itokawa. The hydrogen isotopic composition (δD) of the measured pyroxene grains is −79 to −53‰, which is indistinguishable from that in chondritic meteorites, achondrites, and terrestrial rocks. Itokawa minerals contain water contents of 698 to 988 parts per million (ppm) weight, after correcting for water loss during parent body processes and impact events that elevated the temperature of the parent body. We infer that the Bulk Silicate Itokawa parent body originally had 160 to 510 ppm water. Asteroids like Itokawa that formed interior to the snow line could therefore have been a potential source of water (up to 0.5 Earth’s oceans) during the formation of Earth and other terrestrial planets.

scholarly journals Seasonal changes in the D  /  H ratio of fatty acids of pelagic microorganisms in the coastal North Sea

2016 ◽  
Vol 13 (19) ◽  
pp. 5527-5539 ◽  
Author(s):  
Sandra Mariam Heinzelmann ◽  
Nicole Jane Bale ◽  
Laura Villanueva ◽  
Danielle Sinke-Schoen ◽  
Catharina Johanna Maria Philippart ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Isotopic Composition ◽  
North Sea ◽  
Phytoplankton Bloom ◽  
Isotopic Fractionation ◽  
Spring Phytoplankton Bloom ◽  
Fractionation Factor ◽  
Culture Studies ◽  
Hydrogen Isotopic Composition

Abstract. Culture studies of microorganisms have shown that the hydrogen isotopic composition of fatty acids depends on their metabolism, but there are only few environmental studies available to confirm this observation. Here we studied the seasonal variability of the deuterium-to-hydrogen (D / H) ratio of fatty acids in the coastal Dutch North Sea and compared this with the diversity of the phyto- and bacterioplankton. Over the year, the stable hydrogen isotopic fractionation factor ε between fatty acids and water (εlipid/water) ranged between −172 and −237 ‰, the algal-derived polyunsaturated fatty acid nC20:5 generally being the most D-depleted (−177 to −235 ‰) and nC18:0 the least D-depleted fatty acid (−172 to −210 ‰). The in general highly D-depleted nC20:5 is in agreement with culture studies, which indicates that photoautotrophic microorganisms produce fatty acids which are significantly depleted in D relative to water. The εlipid/water of all fatty acids showed a transient shift towards increased fractionation during the spring phytoplankton bloom, indicated by increasing chlorophyll a concentrations and relative abundance of the nC20:5 polyunsaturated fatty acids, suggesting increased contributions of photoautotrophy. Time periods with decreased fractionation (less negative εlipid/water values) can potentially be explained by an increased contribution of heterotrophy to the fatty acid pool. Our results show that the hydrogen isotopic composition of fatty acids is a promising tool to assess the community metabolism of coastal plankton potentially in combination with the isotopic analysis of more specific biomarker lipids.

Hydrogen isotopic composition of the water in CR chondrites

2013 ◽  
Vol 106 ◽  
pp. 111-133 ◽  
Author(s):  
L. Bonal ◽  
C.M.O’D. Alexander ◽  
G.R. Huss ◽  
K. Nagashima ◽  
E. Quirico ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Hydrogen Isotopic Composition

scholarly journals Disentangling temporal and population variability in plant root water uptake from stable isotopic analysis: when rooting depth matters in labeling studies

2020 ◽  
Vol 24 (6) ◽  
pp. 3057-3075 ◽  
Author(s):  
Valentin Couvreur ◽  
Youri Rothfuss ◽  
Félicien Meunier ◽  
Thierry Bariac ◽  
Philippe Biron ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Content ◽  
Soil Water ◽  
Physical Model ◽  
Transpiration Rate ◽  
Temporal Dynamics ◽  
Plant Root ◽  
Root Water Uptake ◽  
Rooting Depth ◽  
Stable Isotopic

Abstract. Isotopic labeling techniques have the potential to minimize the uncertainty of plant root water uptake (RWU) profiles estimated using multisource (statistical) modeling by artificially enhancing the soil water isotopic gradient. On the other end of the modeling continuum, physical models can account for hydrodynamic constraints to RWU if simultaneous soil and plant water status data are available. In this study, a population of tall fescue (Festuca arundinacea cv. Soni) was grown in amacro-rhizotron and monitored for a 34 h long period following the oxygen stable isotopic (18O) labeling of deep soil water. Aboveground variables included tiller and leaf water oxygen isotopic compositions (δtiller and δleaf, respectively) as well as leaf water potential (ψleaf), relative humidity, and transpiration rate. Belowground profiles of root length density (RLD), soil water content, and isotopic composition were also sampled. While there were strong correlations between hydraulic variables as well as between isotopic variables, the experimental results underlined the partial disconnect between the temporal dynamics of hydraulic and isotopic variables. In order to dissect the problem, we reproduced both types of observations with a one-dimensional physical model of water flow in the soil–plant domain for 60 different realistic RLD profiles. While simulated ψleaf followed clear temporal variations with small differences across plants, as if they were “onboard the same roller coaster”, simulated δtiller values within the plant population were rather heterogeneous (“swarm-like”) with relatively little temporal variation and a strong sensitivity to rooting depth. Thus, the physical model explained the discrepancy between isotopic and hydraulic observations: the variability captured by δtiller reflected the spatial heterogeneity in the rooting depth in the soil region influenced by the labeling and may not correlate with the temporal dynamics of ψleaf. In other words, ψleaf varied in time with transpiration rate, while δtiller varied across plants with rooting depth. For comparison purposes, a Bayesian statistical model was also used to simulate RWU. While it predicted relatively similar cumulative RWU profiles, the physical model could differentiate the spatial from the temporal dynamics of the isotopic composition. An important difference between the two types of RWU models was the ability of the physical model to simulate the occurrence of hydraulic lift in order to explain concomitant increases in the soil water content and the isotopic composition observed overnight above the soil labeling region.

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