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Title: Evaluating Impacts of CO2 Intrusion into an Unconsolidated Aquifer. I. Experimental Data

Capture and deep subsurface sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Batch and column experiments combined with wet chemical extractions were conducted to evaluate these risks to groundwater quality and to understand effects of CO2 leakage on aquifer chemistry and mineralogy. Sediments from the High Plains aquifer in Kansas, a confined sandstone aquifer, were used to study time-dependent release of major, minor and trace elements when exposed to CO2 gas. Results showed that Ca, Ba, Si, Mg, Sr, Na, and K increased either instantaneously or followed nonlinear increasing trends with time, indicating dissolution and/or desorption reactions controlled their release. Other elements, such as Mn and Fe, were also released from all sediments, creating a potential for redox reactions to occur. Results from acid extractions confirmed sediments had appreciable amounts of contaminants that may potentially be released into the aqueous phase. However, results from the batch and column experiments demonstrated that only a few trace elements (e.g., As, Cu, Cr, Pb) were released, indicating the risk of groundwater quality degradation due to exposure tomore » leakage of sequestered CO2 is low. Concentrations of Mo were consistently higher in the control experiments (absence of CO2) and were below detection in the presence of CO2 indicating a possible benefit of CO2 in groundwater aquifers. These investigations will provide useful information to support site selection, risk assessment, and public education efforts associated with geological CO2 storage and sequestration.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
1233484
Report Number(s):
PNNL-SA--107057
Journal ID: ISSN 1750-5836; AA9010200
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Greenhouse Gas Control; Journal Volume: 44; Journal Issue: 2016
Publisher:
Elsevier
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
CO2 sequestration; sandstone aquifer