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Title: Experimental observation of signature changes in bulk soil electrical conductivity in response to engineered surface CO2 leakage

Journal Article · · International Journal of Greenhouse Gas Control

Experimental observations of signature changes of bulk soil electrical conductivity (EC) due to CO{sub 2} leakage were carried out at a field site at Bozeman, Montana, to investigate the change of soil geophysical properties in response to possible leakage of geologically sequestered CO{sub 2}. The dynamic evolution of bulk soil EC was measured during an engineered surface leakage of CO{sub 2} through in situ continuous monitoring of bulk soil EC, soil moisture, soil temperature, rainfall rate, and soil CO{sub 2} concentration to investigate the response of soil bulk EC signature to CO{sub 2} leakage. Observations show that: (1) high soil CO{sub 2} concentration due to CO{sub 2} leakage enhances the dependence of bulk soil EC on soil moisture. The bulk soil EC is a linear multivariate function of soil moisture and soil temperature, the coefficient for soil moisture increased from 2.111 dS for the non-leaking phase to 4.589 dS for the CO{sub 2} leaking phase; and the coefficient for temperature increased from 0.003 dS/C for the non-leaking phase to 0.008 dS/C for the CO{sub 2} leaking phase. The dependence of bulk soil EC on soil temperature is generally weak, but leaked CO{sub 2} enhances the dependence, (2) after the CO{sub 2} release, the relationship between soil bulk EC and soil CO{sub 2} concentration observes three distinct CO{sub 2} decay modes. Rainfall events result in sudden changes of soil moisture and are believed to be the driving forcing for these decay modes, and (3) within each mode, increasing soil CO{sub 2} concentration results in higher bulk soil EC. Comparing the first 2 decay modes, it is found that the dependence of soil EC on soil CO{sub 2} concentration is weaker for the first decay mode than the second decay mode.

Research Organization:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE SC OFFICE OF SCIENCE (SC)
DOE Contract Number:
DE-AC02-98CH10886
OSTI ID:
1048202
Report Number(s):
BNL-98155-2012-JA; R&D Project: 2014-BNL-EE536EEDA-Budg; KP1702010; TRN: US201216%%798
Journal Information:
International Journal of Greenhouse Gas Control, Vol. 7; ISSN 1750-5836
Country of Publication:
United States
Language:
English