Monitoring of a Simulated CO<sub>2</sub> Leakage in a Shallow Aquifer Using Stable Carbon Isotopes Alexandra Schulz Carsten Vogt Hendrik Lamert Anita Peter Ben Heinrich Andreas Dahmke Hans-Hermann Richnow 10.1021/es3026837.s001 https://acs.figshare.com/articles/journal_contribution/Monitoring_of_a_Simulated_CO_sub_2_sub_Leakage_in_a_Shallow_Aquifer_Using_Stable_Carbon_Isotopes/2477950 Artificial carbon dioxide leakage into a shallow aquifer was monitored using stable carbon isotope measurements at a field site near the town of Wittstock, Brandenburg, Germany. Approximately 400 000 L of CO<sub>2</sub> were injected into a shallow aquifer at 18 m depth over 10 days. The <sup>13</sup>C/ <sup>12</sup>C ratios of the CO<sub>2</sub> were measured in both groundwater and soil gas samples to monitor the distribution of the injected CO<sub>2</sub> plume and to evaluate the feasibility and reliability of this approach to detect potential CO<sub>2</sub> leakage, for example from carbon capture and storage (CCS) sites. The isotopic composition of the injected CO<sub>2</sub> (δ<sup>13</sup>C −30.5 ‰) was differentiable from the background CO<sub>2</sub> (δ<sup>13</sup>C −21.9 ‰) and the artificial CO<sub>2</sub> plume was monitored over a period spanning more than 204 days. The results demonstrate that this stable isotope monitoring approach can be used to identify CO<sub>2</sub> sources and detect potential CO<sub>2</sub> migration from CCS sites into overlying shallow aquifers or even into the upper subsurface. A significant difference between the isotope ratios of the natural background and the injected CO<sub>2</sub> is required for this monitoring approach to be effective. 2012-10-16 00:00:00 Stable Carbon IsotopesArtificial carbon dioxide leakage CCS CO 2 leakage CO 2 migration Simulated CO 2 Leakage 400 000 L CO 2 CO 2 plume soil gas samples CO 2 sources carbon isotope measurements isotope monitoring approach 18 m depth