JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

A (Atmospheric and Hydrospheric Sciences) » A-OS Ocean Sciences & Ocean Environment

[A-OS25] [JJ] Oceanic responses to global warming and ocean acidification in coastal regions

Mon. May 22, 2017 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall HALL7)

convener:Tsuneo Ono(Fisheries Research Agency), Masahiko Fujii(Faculty of Environmental Earth Science), Takeshi Yoshimura(Central Research Institute of Electric Power Industry)

[AOS25-P04] The dynamics of pore water in subsurface sediments at the site of controlled CO2 release experiment

*Ayumi Tsukasaki1, Natalie Hicks2, Peter Taylor2, Masahiro Suzumura1, Anna Lichtschlag3, Henrik Stahl4, Rachael H James3 (1.AIST - National Institute of Advanced Industrial Science and Technology, 2.SAMS - Scottish Association for Marine Science, UK, 3.NOC - National Oceanography Centre, UK, 4.Zayed University, UAE)

Keywords:CCS, global warming, sediment, pore water

Carbon capture and storage (CCS) in sub-seabed geological formations is a mitigation strategy that can aid the reduction of anthropogenic CO2 emissions. In 2012, the QICS (Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage) project was undertaken by researchers from the UK and Japan. The project conducted a field-scale controlled CO2 release experiment in order to examine the impacts on the marine ecosystem and evaluate the methods for detection and impact monitoring, should CO2 leakage occur. Changes in the chemical composition of water and seabed sediment were detected, in particular, pH and dissolved inorganic carbon (DIC) of the sediment pore water during the CO2 release. After the gas release was stopped, concentrations of all pore water constituents rapidly returned to pre-release values. The QICS team concluded that the environmental impacts from small-scale leakage is not ecologically significant.
We address two unsettled issues from QICS: (1) the mechanism behind the rapid recovery of pore water parameters to pre-release levels, and (2) the fate of the released CO2 potentially remaining in the subsurface sediments. To settle these issues, we conducted field observation measurements at the QICS site, Ardmucknish Bay, in 2016, four years after the CO2 release. Time series in situ monitoring of pore water chemistry in the subsurface sediments was conducted in order to investigate pore water dynamics. To characterize pore water behaviour more precisely, we conducted a tracer test using the custom-made pore water extractors. To trace the injected CO2, carbonate content and stable carbon isotope ratio of the sediment and pore water were compared between the area close to the CO2 release point and the unaffected reference site. In this presentation we focus on the pore water dynamics at the QICS site and show the results of field observation that influence benthic recovery from a CO2 leak.