Inverse Modeling of Water-Rock-CO2 Batch Experiments: Potential Impacts on Groundwater Resources at Carbon Sequestration Sites

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• 作者：Changbing Yang ; Zhenxue Dai ; Katherine D. Romanak ; Susan D. Hovorka ; Ram贸n H. Trevi帽o
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：March 4, 2014
• 年：2014
• 卷：48
• 期：5
• 页码：2798-2806
• 全文大小：380K
• 年卷期：v.48,no.5(March 4, 2014)
• ISSN：1520-5851

文摘

This study developed a multicomponent geochemical model to interpret responses of water chemistry to introduction of CO₂ into six water-rock batches with sedimentary samples collected from representative potable aquifers in the Gulf Coast area. The model simulated CO₂ dissolution in groundwater, aqueous complexation, mineral reactions (dissolution/precipitation), and surface complexation on clay mineral surfaces. An inverse method was used to estimate mineral surface area, the key parameter for describing kinetic mineral reactions. Modeling results suggested that reductions in groundwater pH were more significant in the carbonate-poor aquifers than in the carbonate-rich aquifers, resulting in potential groundwater acidification. Modeled concentrations of major ions showed overall increasing trends, depending on mineralogy of the sediments, especially carbonate content. The geochemical model confirmed that mobilization of trace metals was caused likely by mineral dissolution and surface complexation on clay mineral surfaces. Although dissolved inorganic carbon and pH may be used as indicative parameters in potable aquifers, selection of geochemical parameters for CO₂ leakage detection is site-specific and a stepwise procedure may be followed. A combined study of the geochemical models with the laboratory batch experiments improves our understanding of the mechanisms that dominate responses of water chemistry to CO₂ leakage and also provides a frame of reference for designing monitoring strategy in potable aquifers.