Open AccessIn situ redeposition of trace metals mobilized by CO 2 ‐charged brines
Author(s) -
Wigley M.,
Kampman N.,
Chapman H. J.,
Dubacq B.,
Bickle M. J.
Publication year - 2013
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/ggge.20104
Subject(s) - trace metal , carbonate , aquifer , geology , metal , environmental chemistry , geochemistry , groundwater , mineralogy , chemistry , geotechnical engineering , organic chemistry
Mobilization of contaminants by CO 2 ‐charged brines is one concern relating to injection of CO 2 as part of carbon capture and storage projects. This study monitors the mobility of trace metals in an exhumed CO 2 ‐charged aquifer near the town of Green River, Utah (USA), where CO 2 ‐charged brines have bleached red sandstones, and concentrated trace metals at the bleaching reaction front. Mass balance calculations on the trace metal enrichments are used to calculate time‐integrated fluid fluxes and show that a significant fraction of the metals mobilized by the CO 2 ‐rich brines are redeposited locally. A sequential extraction procedure on metal‐enriched samples shows that these metals are incorporated into secondary carbonate and oxide phases which have been shown to grow at the CO 2 ‐promoted bleaching reaction front. We argue that while CO 2 ‐charged brines are capable of mobilizing trace metals, local metal redeposition implies that the potential for contamination of overlying freshwater aquifers is low.