Impact assessment of high soil CO2on plant growth and soil environment: a greenhouse study

To ensure the safety of carbon capture and storage (CCS) technology, insight into the potential impacts of CO 2 leakage on the ecosystem is necessary. We conducted a greenhouse experiment to investigate the effects of high soil CO 2 on plant growth and the soil environment. Treatments comprised 99.99% CO 2 injection (CG), 99.99% N 2 injection (NG), and no injection (BG). NG treatment was employed to differentiate the effects of O 2 depletion from those of CO 2 enrichment. Soil CO 2 and O 2 concentrations were maintained at an average of 53% and 11%, respectively, under CG treatment. We verified that high soil CO 2 had negative effects on root water absorption, chlorophyll, starch content and total biomass. Soil microbial acid phosphatase activity was affected by CG treatment. These negative effects were attributed to high soil CO 2 instead of low O 2 or low pH. Our results indicate that high soil CO 2 affected the root system, which in turn triggered further changes in aboveground plant tissues and rhizospheric soil water conditions. A conceptual diagram of CO 2 toxicity to plants and soil is suggested to act as a useful guideline for impact assessment of CCS technology.