The impacts of introduced CO2 flux on maize/alfalfa and soil

Carbon capture and storage (CCS) is a technology of strategic importance to global carbon reduction. However, studies indicate that CCS may likely lead to CO2 leakage in the long term. In the present study, the potential impacts of introduced CO2 fluxes on the growth and development of selected crops and soil are described. Plants were grown in restructured pots with platform bottoms to simulate stored and introduced CO2. In the initial growth stages, pure CO2 gas was continuously injected into maize and alfalfa root zones at five different fluxes, ranging between 0 g/(m2 d) and 2000 g/(m2 d), for a minimum of 30 days. The results showed inhibition of plant growth and development, and soil modification, based on introduced CO2 and control (absence of CO2) scenarios. Maize and alfalfa showed decreased height, leaf number, leaf area, and root length trends as the introduced CO2 flux increased. Photosynthesis and transpiration rates decreased, accumulated dry matter was significantly reduced, and soil pH and O2 concentrations were reduced. The results indicated alfalfa was less tolerant than maize. The relationship between soil O2 concentration and injected CO2 flux was expressed as a linear equation. Most plant indicators did not change significantly when introduced CO2 was within a flux of 500 g/(m2 d), but when introduced CO2 was between 500 g/(m2 d) and 2000 g/(m2 d) all indicators exhibited notably decreased values. Maize and alfalfa exposed to a 2000 g/(m2 d) flux rapidly approached zero (0) in terms of all physiological indicators, and plant growth and development ceased, i.e. Maize and alfalfa showed a tolerance threshold of 500-2000 g/(m2 d) flux for introduced CO2. This provided the tolerance thresholds for maize and alfalfa under different scenarios of introduced CO2, and clarified how the simulated introduction of CO2 interfered with plant growth and development. The results of this study can inform future preventative and remedial actions in response to potential CCS leakage.