Trace metals in CO2-rich Green River Springs, Utah, USA: an analogue for engineered storage

Mark Wilkinson*, Kit Carruthers, Robert Stuart Haszeldine

*Corresponding author for this work

Research output: Contribution to journalSpecial issuepeer-review

Abstract / Description of output

Sedimentary rocks with high natural CO2 concentrations provide invaluable analogues for the engineered storage of CO2. Some previous studies have reported high trace metal concentrations in sandstone aquifers exposed to CO2, a cause for concern should stored CO2 leak into underground sources of drinking water. However, the intensively studied Jurassic sandstone aquifer in the San Rafael – Green River (Utah, USA) area has trace metal concentrations that are within USA Environmental Protection Agency’s limits for drinking water. Exceptions are As which is plausibly introduced into the aquifer by saline brines external to the aquifer, and salinity which largely is. This shows that CO2 in aquifers does not inevitably cause trace metal contamination. CO2-water-rock batch experiments elucidated the controls on the trace metal concentrations. After the addition of CO2, the experiments reproduce well Cu, Cd, Hg, Ni and Zn, with less good agreement for Cr and Pb although these are still low compared to drinking water standards. Major cations used as fingerprints for mobilisation mechanisms suggest that the trace metals are largely derived by desorption, possibly from grain-coating Fe-oxides, rather than by the dissolution of mineral phases. Possible exceptions are Pb and Ni, plus As which is derived from saline brines.
Original languageEnglish
JournalGeological Society Special Publications
Volume528
DOIs
Publication statusPublished - 22 Aug 2022

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