Helium in old porcelain: The historical variation of the He isotopic composition in air

Abstract

It is still debated whether there is a variation of the atmospheric 3 He/ 4 He ratio, due to the anthropogenic release of radiogenic 4 He contained in fossil fuels, in modern era. In this study, we measured the He isotopic ratios in old Chinese and Japanese porcelains assuming that the old atmosphere might have been preserved in vesicles. The trapped noble gases are elementally but not isotopically fractionated. The 3 He/ 4 He ratios in some old Chinese porcelain are significantly higher than the present air value, indicating that recent human industrial activity might have affected the helium isotopic ratio of the atmosphere. Our result indicates that the rate of change in the atmospheric 3 He/ 4 He ratio was -0.034 ± 0.018 %/year (2σ) in the last 200 years. Results show that porcelain can be used as a time capsule of the paleoatmosphere during historical age.

Atmospheric helium isotopic ratio from 1910 to 2016 recorded in stainless steel containers

“…S-1). In line with this possibility, 3 He excesses (~3-4 % relative to the present R AIR value) have been reported for old air trapped in vesicles of blast-furnace metallurgical slags (Pierson-Wickman et al, 2001;Sano et al, 2010) and in ancient porcelains (Matsuda et al, 2010), suggesting that pre-industrial air contained less 4 He than the present-day air. However, these excesses might also be related to: (i) the release of cosmogenic/nucleogenic 3 He from the sample matrix; (ii) isotope fractionation during helium extraction and (iii) the capture of fractionated R AIR during manufacturing (Pierson-Wickman et al, 2001).…”

No evidence for change of the atmospheric helium isotope composition since 1978 from re-analysis of the Cape Grim Air Archive

“…Studies on the atmospheric helium variations, summarized in Brennwald et al (2013) (e.g., compilation in their Table 1), resulted in contradictory results, indicating either decreases in the 3 He/ 4 He ratio of the order of 0.1-0.3h/yr during the last few decades (Sano et al, 2010;Matsuda et al, 2010), or no detectable change since at least 1973 (Lupton and Evans, 2013) or possibly 1956 (Hoffman and Nier, 1993).…”

Concentrations and isotope ratios of helium and other noble gases in the Earth's atmosphere during 1978–2011

“…While this decrease in the 3 He/ 4 He ratio was interpreted in terms of an anthropogenic input of fossil-fuel derived He into the atmosphere (Sano et al, 1988(Sano et al, , 1989Sano, 1998), other studies questioned the existence of a change in the atmospheric 3 He/ 4 He ratio (Lupton and Graham, 1991;Hoffmann and Nier, 1993;Lupton and Evans, 2004). In light of the resulting controversy on the He isotope composition of the atmosphere (Lupton and Graham, 1991;Hoffmann and Nier, 1993;Sano et al, 1991), recent studies attempted to further constrain the change in the 3 He/ 4 He ratio on longer time scales by analysing the 3 He/ 4 He ratio in air inclusions in ancient porcelain samples or metallurgical slags (Pierson-Wickmann et al, 2001;Matsuda et al, 2010;Sano et al, 2010).…”

“…An effect of geographical differences in the atmospheric 3 He/ 4 He ratio could therefore not be ruled out (Sano et al, 1988(Sano et al, , 1989(Sano et al, , 2010. In addition, the 3 He/ 4 He data obtained from the air inclusions in ancient porcelain and slags may be affected by the release of radiogenic He isotopes from the porcelain or the slags into the air inclusions (Pierson-Wickmann et al, 2001;Matsuda et al, 2010;Sano et al, 2010). Finally, the decrease rates of the 3 He/ 4 He ratio determined from the porcelain and slag samples depend strongly on poorly constrained assumptions on the timing and temporal evolution of the 3 He/ 4 He ratio in the atmosphere.…”