Molar gas ratios of air entrapped in ice: A new tool to determine the origin of relict massive ground ice bodies in permafrost

• Published in: Quaternary Research
• Main Authors: Cardyn, Raphaelle, Clark, Ian D., Lacelle, Denis, Lauriol, Bernard, Zdanowicz, Christian, Calmels, Fabrice
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2007
• Subjects: Arctic; Ice; permafrost
• Online Access: http://dx.doi.org/10.1016/j.yqres.2007.05.003; http://api.elsevier.com/content/article/PII:S0033589407000695?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:S0033589407000695?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400014174

Abstract The molar ratios of atmospheric gases change during dissolution in water due to differences in their relative solubilities. We exploited this characteristic to develop a tool to clarify the origin of ice formations in permafrost regions. Extracted from ice, molar gas ratios can distinguish buried glacier ice from intrasedimental ground ice formed by freezing groundwaters. An extraction line was built to isolate gases from ice by melting and trapping with liquid He, followed by analysis of N 2 , O 2, , Ar, 18 O O2 and 15 N N2 , by continuous flow mass spectrometry. The method was tested using glacier ice, aufeis ice (river icing) and intrasedimental ground ice from sites in the Canadian Arctic. O 2 /Ar and N 2 /Ar ratios clearly distinguish between atmospheric gas in glacial ice and gases from intrasedimental ground ice, which are exsolved from freezing water. δ 15 N N2 and δ 18 O O2 in glacier ice, aufeis ice and intrasedimental ground ice do not show clear distinguishing trends as they are affected by various physical processes during formation such as gravitational settling, excess air addition, mixing with snow pack, and respiration.