scholarly journals Changes in the atmospheric helium isotope ratio over the past 40 years

2013 ◽  
Vol 40 (23) ◽  
pp. 6271-6275 ◽  
Author(s):  
J. Lupton ◽  
L. Evans
Keyword(s):  
Isotope Ratio ◽  
Helium Isotope ◽  
The Past

scholarly journals The atmospheric helium isotope ratio: Is it changing?

2004 ◽  
Vol 31 (13) ◽  
pp. n/a-n/a ◽  
Author(s):  
John Lupton ◽  
Leigh Evans
Keyword(s):  
Isotope Ratio ◽  
Helium Isotope

scholarly journals Atmospheric helium isotope ratio.

1988 ◽  
Vol 22 (4) ◽  
pp. 177-181 ◽  
Author(s):  
Yuji Sano ◽  
Hiroshi Wakita ◽  
Xu Sheng
Keyword(s):  
Isotope Ratio ◽  
Helium Isotope

Helium isotope ratio measurement by a single focusing mass spectrometer with large incident and exit angles

1989 ◽  
Vol 91 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Yuji Sano ◽  
Hiroshi Wakita ◽  
Kikuo Wakino ◽  
Michihiro Murata ◽  
Hiroshi Yamamoto ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Isotope Ratio ◽  
Helium Isotope ◽  
Isotope Ratio Measurement ◽  
Ratio Measurement

scholarly journals Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems

2020 ◽  
Vol 16 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Ryu Uemura ◽  
Yudai Kina ◽  
Chuan-Chou Shen ◽  
Kanako Omine
Keyword(s):  
Fluid Inclusion ◽  
Isotope Ratio ◽  
Isotopic Exchange ◽  
Quantitative Estimation ◽  
Depth Interval ◽  
Exchange Effect ◽  
Fractionation Factor ◽  
The Past ◽  
Isotopic Compositions ◽  
Quaternary Climate

Abstract. The oxygen and hydrogen isotopic compositions of water in fluid inclusions in speleothems are important hydroclimate proxies because they provide information on the isotopic compositions of rainwater in the past. Moreover, because isotopic differences between fluid inclusion water and the host calcite provide information on the past isotopic fractionation factor, they are also useful for quantitative estimation of past temperature changes. The oxygen isotope ratio of inclusion water (δ18Ofi), however, may be affected by isotopic exchange between the water and the host carbonate. Thus, it is necessary to estimate the bias caused by this postdepositional effect for precise reconstruction of paleotemperatures. Here, we evaluate the isotopic exchange reaction between inclusion water and host calcite based on a laboratory experiment involving a natural stalagmite. Multiple stalagmite samples cut from the same depth interval were heated at 105 ∘C in the laboratory from 0 to 80 h. Then, the isotopic compositions of the inclusion water were measured. In the 105 ∘C heating experiments, the δ18Ofi values increased from the initial value by 0.7 ‰ and then remained stable after ca. 20 h. The hydrogen isotope ratio of water showed no trend in response to the heating experiments, suggesting that the hydrogen isotopic composition of fluid inclusion water effectively reflects the composition of past drip water. We then evaluated the process behind the observed isotopic variations using a partial equilibration model. The experimental results are best explained by the assumption that a thin CaCO3 layer surrounding the inclusion reacted with the water. The amount of CaCO3 that reacted with the water is equivalent to 2 % of the water inclusions in molar terms. These results suggest that the magnitude of the isotopic exchange effect has a minor influence on paleotemperature estimates for Quaternary climate reconstructions.

A ten-year decrease in the atmospheric helium isotope ratio possibly caused by human activity

1989 ◽  
Vol 16 (12) ◽  
pp. 1371-1374 ◽  
Author(s):  
Yuji Sano ◽  
Hiroshi Wakita ◽  
Yoshihiro Makide ◽  
Takeshi Tominaga
Keyword(s):  
Human Activity ◽  
Isotope Ratio ◽  
Helium Isotope
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