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

Abstract

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. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Suggestions for plant parameters to monitor potential CO2 leakage from carbon capture and storage (CCS) sites

“…Soil CO 2 concentration from the pipelines could increase to around 20–40% due to slow, insidious seepage and up to extremely high levels (100%) if there is a sudden accidental release. This leakage scenario is supported by results obtained from the Artificial Soil Gassing and Response Detection (ASGARD) site in the UK, the Zero Emissions Research and Technology (ZERT) site in the USA, and the Environmental Impact Evaluation Test (EIT) facility in South Korea . During CO 2 injection from 0.6–2.5 m below the soil surface, soil CO 2 concentrations ranged from 10–80% at a 30 cm depth within 1.5 m from the leakage points .…”

“…During CO 2 injection from 0.6–2.5 m below the soil surface, soil CO 2 concentrations ranged from 10–80% at a 30 cm depth within 1.5 m from the leakage points . Compared to microbial and soil physico‐chemical reactions, plant responses were more sensitively and consistently changed within 1–1.5 m from the CO 2 injection points . These results indicate that plant observation could be a promising method for monitoring CO 2 because it is relatively cost effective and suitable for the monitoring of extensive areas near CO 2 transport pipelines.…”

“…To utilize plant responses for CO 2 monitoring, it is essential to select a plant indicator with morphological and physiological parameters that meet the following qualification criteria: CO 2 ‐specific reactivity, non‐specific responses across plant species, and early changes in parameters . In an extensive review of artificial CO 2 release experiments, most plant metabolic processes, such as photosynthesis, stomatal conductance, and transpiration rate were affected by soil CO 2 concentration higher than 20% . Extremely high soil CO 2 concentration (>40%) caused leaf discoloration and chlorophyll decomposition within one to two weeks, followed by leaf dieback after 15 days .…”

“…This leakage scenario is supported by results obtained from the Artificial Soil Gassing and Response Detection (ASGARD) site in the UK, the Zero Emissions Research and Technology (ZERT) site in the USA, and the Environmental Impact Evaluation Test (EIT) facility in South Korea. 4,11 During CO 2 injection from 0.6-2.5 m below the soil surface, soil CO 2 concentrations ranged from 10-80% at a 30 cm depth within 1.5 m from the leakage points. 8,10,[12][13][14][15][16] Compared to microbial and soil physico-chemical reactions, plant responses were more sensitively and consistently changed within 1-1.5 m from the CO 2 injection points.…”

“…8,10,[12][13][14][15][16] Compared to microbial and soil physico-chemical reactions, plant responses were more sensitively and consistently changed within 1-1.5 m from the CO 2 injection points. 9,11,[17][18][19] These results indicate that plant observation could be a promising method for monitoring CO 2 because it is relatively cost effective and suitable for the monitoring of extensive areas near CO 2 transport pipelines.…”