Impacts of CO₂ leakage on plants and microorganisms: A review of results from CO₂ release experiments and storage sites

Carbon capture and storage (CCS) technology, a process consisting of the separation and capture of CO₂ from point sources and injection into deep geological reservoirs for long-term isolation from the atmosphere, is considered to be a promising technology that can mitigate global climate change. However, the risk of CO₂ leakage from storage sites exists, and thus its impact on ecosystem functions needs to be understood for safe implementation of CCS. Plant and microbial parameters were monitored in artificial CO₂ release experiments in the field and in greenhouses. In addition, plants and microorganisms were monitored in CO₂ storage sites. We review the findings from these studies and suggest directions of future research for determining the impact of potential CO₂ leakage from CCS sites on plants and microorganisms. Our review showed that under high levels of soil CO₂, (i) plant stress response was visible within short period of time; (ii) dicots were more sensitive than monocots in most studies; and (iii) the responses of microorganisms were more diverse and harder to generalize than those of plants. Only a limited number of field and greenhouse experimental studies have been conducted so far, and thus more field and greenhouse experimental studies are needed to better understand the plant and microbial response to elevated soil CO₂ levels and elucidate specific mechanisms underlying these responses. Determining the ecological impacts of geological CO₂ storage and ensuring its environmental safety via such research will make CCS a more viable technology.