@article {26381,
	title = {Tracking natural CO2 migration through a sandstone aquifer using Sr, U and C isotopes: Chimay{\'o}, New Mexico, USA},
	journal = {International Journal of Greenhouse Gas Control},
	volume = {104},
	year = {2021},
	pages = {103209},
	abstract = {<p id="spar0120">
	The geochemical and isotopic characteristics of groundwaters in Chimay{\'o}, New Mexico, reflect processes that affect water quality in the Tesuque Aquifer, which overlies a leaking natural CO<sub>2</sub>\&nbsp;source in a structurally complex region. In this study, select isotopes (δ<sup>13</sup>C,\&nbsp;<sup>87</sup>Sr/<sup>86</sup>Sr,\&nbsp;<sup>234</sup>U/<sup>238</sup>U) are applied to groundwaters to better understand CO<sub>2</sub>\&nbsp;transport mechanisms and related water-rock interactions that impact Chimay{\'o} groundwater. Carbon stable isotope ratios of dissolved inorganic carbon (DIC; δ<sup>13</sup>C<sub>DIC</sub>\&nbsp;= -15.10{\textperthousand} to 4.50{\textperthousand}) identify a distinct source of upward-migrating CO<sub>2</sub>\&nbsp;that interacts with the groundwater. Groundwater\&nbsp;<sup>87</sup>Sr/<sup>86</sup>Sr compositions (0.7098 to 0.7154) reflect intrusion of varying amounts of saline water associated with the high CO<sub>2</sub>\&nbsp;source, while\&nbsp;<sup>234</sup>U/<sup>238</sup>U ratios corroborate presence of deep groundwater and suggest impacts from distinctive natural uranium sources are affecting groundwater. Previous work proposed two CO<sub>2</sub>\&nbsp;transport mechanisms at the site: (1) dissolved in deep brine that underlies the aquifer and (2) in the gas phase; this study uses isotope mixing models to identify wells that are affected by these CO<sub>2</sub>\&nbsp;transport mechanisms and demonstrates that both transport mechanisms are associated with impaired groundwaters. Overall, this study demonstrates that applying multiple isotope systems (δ<sup>13</sup>C<sub>DIC</sub>,\&nbsp;<sup>87</sup>Sr/<sup>86</sup>Sr,\&nbsp;<sup>234</sup>U/<sup>238</sup>U) is a dynamic tool for identifying and measuring the impact of CO<sub>2</sub>\&nbsp;leakage from a sequestration site.
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},
	url = {https://doi.org/10.1016/j.ijggc.2020.103209},
	author = {JB Gardiner and RC Capo and DL Newell and BW Stewart and TT Phan and EH Keating and GD Guthrie and JA Hakala}
}
