To ensure the safety of carbon capture and storage (CCS) technology, insight into the potential impacts of CO2 leakage on the ecosystem is necessary. We conducted a greenhouse experiment to ...investigate the effects of high soil CO2 on plant growth and the soil environment. Treatments comprised 99.99% CO2 injection (CG), 99.99% N2injection (NG), and no injection (BG). NG treatment was employed to differentiate the effects of O2 depletion from those of CO2 enrichment. Soil CO2 and O2 concentrations were maintained at an average of 53% and 11%, respectively, under CG treatment. We verified that high soil CO2 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 CO2 instead of low O2 or low pH. Our results indicate that high soil CO2 affected the root system, which in turn triggered further changes in aboveground plant tissues and rhizospheric soil water conditions. A conceptual diagram of CO2 toxicity to plants and soil is suggested to act as a useful guideline for impact assessment of CCS technology.
Potential leakages from a carbon capture and storage (CCS) site can have an impact on the unsaturated zone of groundwater, which may affect the saturated zone through leaching. Therefore, the effect ...of possible CO
2
leakage on soil and leachate chemistry were investigated by conducting a leaching experiment from soils that were exposed to 100% CO
2
for 32 days. The leaching was conducted by arranging CO
2
treated mineral and organic soils into two layers in a custom made column. The leachates collected from the leaching were analyzed for pH, base cations and Dissolved Organic Carbon (DOC). Prior to that, the CO
2
treated soils were analyzed for pH, DOC, CEC, exchangeable acidity and Al
3+
. The CO
2
treatment significantly reduced the pH of the organic soil, mineral soil and leachates. After CO
2
treatment, the DOC significantly increased in organic soil, while it decreased in the mineral soil. DOC and base cations significantly increased in the leachates. CEC did not change in the CO
2
treated soils, but significant increases in exchangeable acidity and Al
3+
were observed in the CO
2
treated mineral soil. The results of this study showed that high soil CO
2
can affect the soil chemistry, which can further affect the groundwater chemistry through leaching.
Vegetation monitoring can be used to detect CO2 leakage in carbon capture and storage (CCS) sites because it can monitor a large area at a relatively low cost. However, a rapidly responsive, ...sensitive, and cost-effective plant parameters must be suggested for vegetation monitoring to be practically utilized as a CCS management strategy. To screen the proper plant parameters for leakage monitoring, a greenhouse experiment was conducted by exposing kale (Brassica oleracea var. viridis), a sensitive plant, to 10%, 20%, and 40% soil CO2 concentrations. Water and water with CO2 stress treatments were also introduced to examine the parameters differentiating CO2 stress from water stresses. We tested the hypothesis that chlorophyl fluorescence parameters would be early and sensitive indicator to detect CO2 leakage. The results showed that the fluorescence parameters of effective quantum yield of photosystem II (Y(II)), detected the difference between CO2 treatments and control earlier than any other parameters, such as chlorophyl content, hyperspectral vegetation indices, and biomass. For systematic comparison among many parameters, we proposed an indicator evaluation score (IES) method based on four categories: CO2 specificity, early detection, field applicability, and cost. The IES results showed that fluorescence parameters (Y(II)) had the highest IES scores, and the parameters from spectral sensors (380–800 nm wavelength) had the second highest values. We suggest the IES system as a useful tool for evaluating new parameters in vegetation monitoring.
Vegetation monitoring can be used to detect CO.sub.2 leakage in carbon capture and storage (CCS) sites because it can monitor a large area at a relatively low cost. However, a rapidly responsive, ...sensitive, and cost-effective plant parameters must be suggested for vegetation monitoring to be practically utilized as a CCS management strategy. To screen the proper plant parameters for leakage monitoring, a greenhouse experiment was conducted by exposing kale (Brassica oleracea var. viridis), a sensitive plant, to 10%, 20%, and 40% soil CO.sub.2 concentrations. Water and water with CO.sub.2 stress treatments were also introduced to examine the parameters differentiating CO.sub.2 stress from water stresses. We tested the hypothesis that chlorophyl fluorescence parameters would be early and sensitive indicator to detect CO.sub.2 leakage. The results showed that the fluorescence parameters of effective quantum yield of photosystem II (Y(II)), detected the difference between CO.sub.2 treatments and control earlier than any other parameters, such as chlorophyl content, hyperspectral vegetation indices, and biomass. For systematic comparison among many parameters, we proposed an indicator evaluation score (IES) method based on four categories: CO.sub.2 specificity, early detection, field applicability, and cost. The IES results showed that fluorescence parameters (Y(II)) had the highest IES scores, and the parameters from spectral sensors (380-800 nm wavelength) had the second highest values. We suggest the IES system as a useful tool for evaluating new parameters in vegetation monitoring.
Vegetation monitoring can be used to detect CO
leakage in carbon capture and storage (CCS) sites because it can monitor a large area at a relatively low cost. However, a rapidly responsive, ...sensitive, and cost-effective plant parameters must be suggested for vegetation monitoring to be practically utilized as a CCS management strategy. To screen the proper plant parameters for leakage monitoring, a greenhouse experiment was conducted by exposing kale (
var. viridis), a sensitive plant, to 10%, 20%, and 40% soil CO
concentrations. Water and water with CO
stress treatments were also introduced to examine the parameters differentiating CO
stress from water stresses. We tested the hypothesis that chlorophyl fluorescence parameters would be early and sensitive indicator to detect CO
leakage. The results showed that the fluorescence parameters of effective quantum yield of photosystem II (Y(II)), detected the difference between CO
treatments and control earlier than any other parameters, such as chlorophyl content, hyperspectral vegetation indices, and biomass. For systematic comparison among many parameters, we proposed an indicator evaluation score (IES) method based on four categories: CO
specificity, early detection, field applicability, and cost. The IES results showed that fluorescence parameters (Y(II)) had the highest IES scores, and the parameters from spectral sensors (380-800 nm wavelength) had the second highest values. We suggest the IES system as a useful tool for evaluating new parameters in vegetation monitoring.
Atmospheric carbon dioxide (CO2) concentrations is continuing to increase due to anthropogenic activity, and geological CO2 storage via carbon capture and storage (CCS) technology can be an effective ...way to mitigate global warming due to CO2 emission. However, the possibility of CO2 leakage from reservoirs and pipelines exists, and such leakage could negatively affect organisms in the soil environment. Therefore, to determine the impacts of geological CO2 leakage on plant and soil processes, we conducted a greenhouse study in which plants and soils were exposed to high levels of soil CO2. Cabbage, which has been reported to be vulnerable to high soil CO2, was grown under BI (no injection), NI (99.99% N2 injection), and CI (99.99% CO2 injection). Mean soil CO2 concentration for CI was 66.8–76.9% and the mean O2 concentrations in NI and CI were 6.6–12.7%, which could be observed in the CO2 leaked soil from the pipelines connected to the CCS sites. The soil N2O emission was increased by 286% in the CI, where NO3−-N concentration was 160% higher compared to that in the control. This indicates that higher N2O emission from CO2 leakage could be due to enhanced nitrification process. Higher NO3−-N content in soil was related to inhibited plant metabolism. In the CI treatment, chlorophyll content decreased and chlorosis appeared after 8th day of injection. Due to the inhibited root growth, leaf water and nitrogen contents were consistently lowered by 15% under CI treatment. Our results imply that N2O emission could be increased by the secondary effects of CO2 leakage on plant metabolism. Hence, monitoring the environmental changes in rhizosphere would be very useful for impact assessment of CCS technology.
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•High soil CO2 concentration inhibited plant growth, resulting in lower uptake of soil mineral N.•Accumulation of soil mineral N by stunted plant under high soil CO2 increased the N2O emission.•Monitoring the changes in N2O emission could be utilized for detection of CO2 leakage in the CCS sites.
Potential CO2 leakage is a major concern for carbon capture and storage (CCS). The effects of high soil CO2 concentration on microbes is a major element of impact assessments of CO2 leakage on ...terrestrial ecosystems. We conducted a field experiment to investigate the responses of microbial functional groups of ammonia-oxidizers, methanogens, and methanotrophs in high soil CO2 conditions. A single-point injection gassing plot (2.5 m × 2.5 m in size), which had 52.2% CO2 in the center (radius = 0.5 m) and 5.5% in the edge (radius = 1.7 m) at 10 cm depth, was employed. N2O and CH4 emissions increased after 1 day of injection because injected CO2 was instantly utilized by nitrifiers and methanogens. This suggests that the activities of the selected microbes could be stimulated by high soil CO2 concentrations. Prolonged CO2 injection has toxic effects on aerobic nitrifiers, but may favor anaerobic methanogens. However, the early stimulatory effects of high soil CO2 on N2O and CH4 production did not last to the end of injection. These results imply that increased N2O and CH4 emissions could be the minor side effects of high soil CO2. Microbes responded faster than plants to high soil CO2, with responses observed as late as 7 days after injection. The inhibition of plant absorption of soil water and nutrients by high soil CO2 concentrations may also influence microbial responses. Moreover, high soil water content could retard underground CO2 diffusion, which would magnify CO2 impacts on plants and microbes. Our results suggest that microbial response could be used as an early indicator of the impact assessments of CO2 leakage on soil ecosystems. An understanding of the interaction among soils, plants, and microbes would be helpful in assessing the biological risks of potential CO2 leakage.
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•Extremely high (52.2%) and moderately high (5.5%) soil CO2 concentrations enhanced N2O and CH4 emissions.•One-day responses of microbes were much faster than those of plants (seven days).•Prolonged high soil CO2 concentration negatively affected ammonia-oxidizer populations, but these microbes can recover after injection stopped.•High soil CO2 concentrations were favorable to methanogens.•Interactions among high soil CO2, soil water, plants, and microbes were newly illuminated.
To ensure the safety of carbon capture and storage (CCS) technology, insight into the potential impacts of CO
leakage on the ecosystem is necessary. We conducted a greenhouse experiment to ...investigate the effects of high soil CO
on plant growth and the soil environment. Treatments comprised 99.99% CO
injection (CG), 99.99% N
injection (NG), and no injection (BG). NG treatment was employed to differentiate the effects of O
depletion from those of CO
enrichment. Soil CO
and O
concentrations were maintained at an average of 53% and 11%, respectively, under CG treatment. We verified that high soil CO
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
instead of low O
or low pH. Our results indicate that high soil CO
affected the root system, which in turn triggered further changes in aboveground plant tissues and rhizospheric soil water conditions. A conceptual diagram of CO
toxicity to plants and soil is suggested to act as a useful guideline for impact assessment of CCS technology.
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