[H-SC05] CCUS (Carbon Dioxide Capture, Utilization, and Storage) for Climate Mitigation

[HSC05-13] Development of a biological impact database on marine organisms

*Jiro Suekuni¹, Keisuke Uchimoto¹, Yuji Watanabe¹, Ziqiu Xue¹ (1.Research Institute of Innovative Technology for the Earth)

Keywords:Database, Sub-seabed CO2 storage, Marine monitoring, CO2 leakage

When CO₂ leaks from the seabed into the sea, the CO₂ concentration in seawater increases and pCO₂ rises. This result affects marine organisms. In assessing the potential environmental impact of leaked CO₂, which is required by law, it is important to collect data on the relationship between pCO₂ and biological impact, and organize them into a usable form. In this study, we developed a biological impact database for the purpose of searching and managing data on the biological impact of CO₂. When developing the system, we first defined the system requirements. This includes consideration of data volume, search items, search time, maintainability, and so on. We also aimed for an easy-to-use interface. In addition, graphing function was installed in the system using search results so that the impact threshold level can be confirmed on the screen. In parallel with the development of the database system, impact data were extracted from various papers related to biological impacts and inputted into the database. The species to be stored in the database were selected in consideration of various stakeholders. As a result, 150 lethal records and 661 sub-lethal records were collected. Biological impact is determined by a pCO₂ value and exposure time. Therefore, the lethal index was organized as LC50 and LT50 that are ΔpCO₂ (pCO₂ increment from the natural state) and exposure time, respectively, for half of the organisms to be killed . Although various items related to sublethal impact have been reported, in this database they have been classified into eight categories: growth, life and death, proliferation, metamorphosis, hatching, infection, malformation, and behavior. As the sublethal index, LnRR and Hedges' d were calculated to allow mutual comparison between the categories. LnRR is the logarithmic of the ratio of a variable in a category between the control group and the experimental group, and Hedges' d is another index calculated from the average value, the number of samples, and the standard deviation of both the control and experimental groups. Environmental impact assessment has a step to describe the biological composition of the target sea area. Based on the results obtained in this step, the information required for the target sea area can be searched and extracted from this database. By combining ΔpCO₂ distribution estimated from a simulation calculating leaked CO₂ dispersion based on a leakage scenario with the results from the database, it is possible to predict an area of biological impacts caused by CO₂ leakage. In addition, the results obtained from the biological impact database can be used to select organisms and items that should be focused on in monitoring.