Physiological responses of dandelion and orchard grass leaves to experimentally released upwelling soil CO2

• Published in: International journal of greenhouse gas control 2014-05, Vol.24, p.139-148
• Main Authors: Sharma, Bablu, Apple, Martha E., Zhou, Xiaobing, Olson, Jake M., Dorshorst, Carly, Dobeck, Laura M., Cunningham, Alfred B., Spangler, Lee H.
• Format: Article
• Language: English
• Subjects: Chlorophyll; Leaves; Physiology; Stomata; Super-elevated CO2; Surface detection
• ISSN: 1750-5836; 1878-0148
• DOI: 10.1016/j.ijggc.2014.03.006

•Plants are valuable in surface detection of leaks from CO2 sequestration fields.•Hotspots of leaf dieback formed above leaks of CO2 at the ZERT experimental field.•Visible stress responses and disrupted leaf physiology occurred in hotspot plants.•Dandelion leaves were more sensitive to high soil CO2 than grass leaves.•Plants responded quickly to very high soil CO2 at ZERT and can indicate CO2 leaks. Carbon sequestration is an important means of reducing the concentration of atmospheric CO2 by injecting CO2 into subterranean geological reservoirs known as sequestration fields. These deep sequestration fields must be monitored for structural integrity to ensure their long-term efficacy. Stress responses of plants to super-elevated soil CO2 are signatures that we evaluated as potential tools for surface leak detection of CO2 at the Zero Emission Research and Technology (ZERT) site in Bozeman, MT. To mimic a compromised field, CO2 was deliberately released at a rate of 0.15ton/day through a 100m long and 2.0–2.3m deep Horizontal Injection Well (HIW) with intentional leaks, with injections of CO2 taking place on these dates: 7/19–8/15/2010 and 7/18–8/15/2011. Periodically over two years, we measured stomatal conductance, chlorophyll content, and specific leaf area in Taraxacum officinale Wigg. (dandelion) and Dactylis glomerata L. (orchard grass) along a 20m transect perpendicular to a hot spot. Hot spots were visible as circular zones of leaf dieback where T. officinale leaves turned from green to red and became brown and desiccated. CO2 concentrations reached 29% by volume at the edges of hot spots. During CO2 injection, chlorophyll content (as measured with a Hansatech CL-O1 chlorophyll content meter to obtain a unitless measure) decreased significantly (p