Leakage from geologic CO₂ sequestration (GCS) reservoirs to overlying underground sources of drinking water (USDW) is a tangible risk. This study is an integrated assessment that combines column experiments and reactive transport simulations of sediments sampled from the Ogallala aquifer above an active commercial‐scale GCS site (the Farnsworth Unit in northern Texas). Experimental and simulation results suggest that carbonate mineral (calcite and dolomite) dissolution is the most significant reaction following CO₂ intrusion, and is also the dominant source of trace metal release. Cation exchange is another key mechanism controlling trace metal release by cation interference. Most of the trace metals, including Ba, Sr, As, Pb, and Zn, show a short‐term release and quickly drop to the baseline values, suggesting low risk to the overlying USDW quality. Other trace metals, such as Mn and U, exhibit a tangible increase of their concentrations in the beginning, and drop to a higher level compared to the baseline, which may become a potential concern of long‐term USDW quality change with CO₂ introduction. This study provides a comprehensive example of combining laboratory experiments and simulations for assessment of CO₂‐sediment interactions with combined release mechanisms in shallow groundwater aquifers. Data presented here provides useful insights for quantitative risk assessment and effective public education regarding CO₂ geological sequestration, and trace metal reactive transport studies in shallow groundwater aquifers.

中文翻译：

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地下二氧化碳的潜在化学影响：Ogallala含水层案例研究的综合实验和数值评估

从地质CO ₂封存（GCS）储层泄漏到上层地下水（USDW）的泄漏是明显的风险。这项研究是一项综合评估，结合了柱实验和从活跃商业规模GCS站点（德克萨斯州北部的Farnsworth单元）上方的Ogallala含水层采样的沉积物的反应性输运模拟。实验和模拟结果表明，碳酸盐矿物（方解石和白云石）的溶解是CO _2之后最显着的反应入侵，并且也是微量金属释放的主要来源。阳离子交换是通过阳离子干扰控制痕量金属释放的另一关键机制。大多数痕量金属，包括Ba，Sr，As，Pb和Zn，都显示出短期释放并迅速下降至基线值，这表明覆盖USDW质量的风险较低。其他微量金属（例如Mn和U）在开始时就显示出明显的浓度增加，并且与基线相比下降到更高的水平，这可能成为长期引入USD ₂随CO ₂引入质量变化的潜在问题。这项研究提供了结合实验室实验和模拟评估CO ₂的综合实例。浅层地下水含水层中沉积物与联合释放机制的相互作用。此处提供的数据为定量风险评估和有效的公众教育提供了有用的见解，涉及有关CO ₂地质隔离和浅层地下水含水层中痕量金属反应性迁移研究。