This study examined a mountainous area with two hydrochemically distinct CO₂-rich springs to understand the origin, flow, and leakage of CO₂, which may provide implications for precise monitoring of CO₂ leakage in geological carbon storage (GCS) sites. The carbon isotopic compositions of dissolved inorganic carbon (DIC) in CO₂-rich water (δ¹³C_DIC) and those of soil CO₂ (δ¹³C_CO2) indicated a deep-seated CO₂ supply to the near-surface environment in the study area. The hydrochemical difference (e.g. pH, total dissolved solids) for the two CO₂-rich springs separated by 7 m, despite similar δ¹³C_DIC and partial pressure of CO₂, was considered as the result of different evolution of shallow groundwater affected by deep-seated CO₂ preferentially rising along fracture zones. Electrical resistivity tomography also suggested flow through fracture zones beneath the CO₂-rich springs, showing low resistivity compared to other surveyed zones. However, soil CO₂ efflux was low compared to that in other natural CO₂ emission sites, and in particular it was noticeably low near the CO₂-rich springs, whereas δ¹³C_CO2 was high close the CO₂-rich springs. The dissolution of CO₂ in the near-surface water body seemed to decrease the deep-seated CO₂ leakage through the soil layer, while δ¹³C_CO2 imprinted the source. End-member mixing analysis was performed to assess the contribution of deep-seated CO₂ to the low soil CO₂ efflux by assuming that atmospheric CO₂ and soil CO₂ (by respiration) as well as deep-seated CO₂ contribute to the soil CO₂ efflux. For each end-member, characteristic δ¹³C_CO2 and CO₂ concentrations were defined, and then their apportionment to soil CO₂ efflux was estimated. The resultant proportion of deep-seated CO₂ was up to 8.8%. Unlike the spatial distribution of high soil CO₂ efflux, high proportions exceeding 3% were found around the CO₂-rich springs along the east-west valley. The study results indicate that soil CO₂ efflux measurement should be combined with carbon isotopic analysis in GCS sites for CO₂ leakage detection because CO₂ dissolution in the underground water body may blur leakage detection on the surface. The implication of this study is the need to quantitatively assess the contribution of deep-seated CO₂ using the soil CO₂ concentration, soil CO₂ efflux, and δ¹³C_CO2 at each measurement site.

本研究山区具有两个不同hydrochemically CO ₂富弹簧了解原点，流，和CO的泄漏₂，这可以提供对CO的精确监控的影响₂在地质碳存储（GCS）位点泄漏。在CO溶解的无机碳（DIC）的碳同位素组成₂富水（δ ¹³ C ^ _DIC）和那些土壤CO的₂（δ ¹³ C ^ _CO2）表示的深层次的CO ₂供应到近表面在环境学习区。两种CO ₂的水化学差异（例如pH，总溶解固体）富弹簧分离由7米，尽管类似δ ¹³ Ç _DIC和CO的分压₂，被认为是浅层地下水受到根深蒂固CO的不同进化的结果₂沿断裂带优先上升。电阻层析成像也表明流过富含CO _2的弹簧下方的断裂带，与其他调查区域相比，电阻率低。然而，土壤CO ₂流出物低相比于其他天然CO ₂发射点，并且特别是显着地低附近的CO ₂富弹簧，而δ ¹³ Ç _CO2高位关闭富含CO _2的弹簧。CO的溶解₂在近地表水体似乎降低根深蒂固CO ₂通过土壤层的泄漏，而δ ¹³ Ç _CO2印迹源。通过假设大气中的CO ₂和土壤CO ₂（通过呼吸作用）以及深层的CO ₂对土壤的贡献，进行了末端成员混合分析，以评估深层的CO ₂对土壤低CO ₂排放的贡献。 CO ₂外排。对于每个端构件，特性δ ¹³ Ç _CO2和CO ₂确定浓度，然后估算它们对土壤CO ₂外流的分配。产生的深层CO ₂比例高达8.8％。与高土壤CO ₂外排的空间分布不同，在东西谷地周围富含CO _2的泉水周围发现了超过3％的高比例。研究结果表明，应在GCS站点中将土壤CO ₂外流测量与碳同位素分析结合起来进行CO ₂泄漏检测，因为地下水体中的CO ₂溶解可能会使表面的泄漏检测变得模糊。该研究的意义在于需要定量评估深层二氧化碳的贡献。₂使用土壤CO ₂浓度，CO土壤₂流出，和δ ¹³ Ç _CO2在每个测量部位。