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Asynchronous changes of CO 2 , H 2 , and He concentrations in soil gases: A theoretical model and experimental results
Author(s) -
Di Martino Roberto M. R.,
Camarda Marco,
Gurrieri Sergio,
Valenza Mariano
Publication year - 2016
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2015jb012600
Subject(s) - trace gas , carbon dioxide , gas composition , helium , thermal diffusivity , flux (metallurgy) , chemistry , diffusion , hydrogen , mass transfer , soil gas , analytical chemistry (journal) , thermodynamics , environmental chemistry , soil water , soil science , environmental science , physics , organic chemistry
This paper focuses on the chemical composition changes in soil gases through both a theoretical model and laboratory experiments. The model describes the one‐dimensional mass transfer process, which is triggered by changes in the flux parameters of the system, and the time‐dependent evolution of the composition of the soil gases as a function of (i) the pristine gas mixture, (ii) the diffusivity of the chemicals, and (iii) the thickness of the transited medium. Carbon dioxide (CO 2 ), hydrogen (H 2 ), and helium (He) were used in a laboratory‐scale flux simulator to investigate the evolution of the gas composition profile in an artificial soil of constant thickness. The agreement between the theoretical calculations and the experimental results supports the validity of the model. Our results indicate a good reproducibility of the transient changes in the concentrations of CO 2 , He, and H 2 in CO 2 ‐rich gas mixtures that contain He and H 2 as trace gases. Finally, the theoretical results were used to analyze the H 2 and CO 2 continuous monitoring data collected at Etna volcano in 2010.