Carbon Capture and Storage (CCS): Risk assessment focused on marine bacteria.

Carbon capture and storage (CCS) is one of the options to mitigate the negative effects of the climate change. However, this strategy may have associated some risks such as CO2 leakages due to an escape from the reservoir. In this context, marine bacteria have been underestimated. In order to figure out the gaps and the lack of knowledge, this work summarizes different studies related to the potential effects on the marine bacteria associated with an acidification caused by a CO2 leak from CSS. An improved integrated model for risk assessment is suggested as a tool based on the rapid responses of bacterial community. Moreover, this contribution proposes a strategy for laboratory protocols using Pseudomona stanieri (CECT7202) as a case of study and analyzes the response of the strain under different CO2 conditions. Results showed significant differences (p≤0.05) under six diluted enriched medium and differences about the days in the exponential growth phase. Dilution 1:10 (Marine Broth 2216 with seawater) was selected as an appropriate growth medium for CO2 toxicity test in batch cultures. This work provide an essential and a complete tool to understand and develop a management strategy to improve future works related to possible effects produced by potential CO2 leaks.

Response of bacterial communities in Barents Sea sediments in case of a potential CO2 leakage from carbon reservoirs.

Carbon capture and storage sites in Barents Sea shelf are currently in progress as part of climate change mitigation activities. However environmental impacts of a possible CO2 seepage on bacterial community are lacking knowledge. This work addressed potential consequences on bacterial communities from Snøvit region in Barents Sea sediments. Long-term experiment (92 days) was carried out mimicking realistic conditions of pressure (∼30 bars) using the unique hyperbaric chamber (Karl Erik TiTank). The experiment was divided in three stages: i) 21 days of no CO2, ii) 50 days of simulation of carbon dioxide leakage (depletion of pH to 7.0) and iii) 14 days emulating a leakage cessation. Results suggested that bacterial communities can adapt to a CO2 leakage in short term. However, bacteria showed negative effects in terms of activity, community structure, and number of cells after long term CO2 exposure. After CO2 leakage cessation, bacterial communities did not show a significant recovery. These findings highlighted that, even though marine bacteria showed adaptation to the new conditions (acidified environment), in case of a small but continuous CO2 leakage marine bacteria might not be recovered upon pre-exposure status.

A possible CO2 leakage event: Can the marine microbial community be recovered?

Bacterial communities have been studied to a much lesser degree than macrofauna in the case of a CO2 release. The resistance capacity of marine bacteria is well known, but their possible responses and their ability to recover after a CO2 release has not been investigated. Therefore, this work evaluated the responses of a marine bacterial community after 96h of CO2 exposure under diverse pH treatments (7.8 as control without CO2, 7.0, 6.5, and 6.0) and 24h after CO2 exposure. Results showed that the respiration activity and the diversity of the community were affected in all pH treatments. However, after 24h without CO2 enrichment, the respiration activity and diversity increased, showing a partial recovery. Consequently, bacterial responses have the potential to be used as a monitoring tool for risk assessment related to carbon capture and storage techniques or in any similar CO2 enrichment situations.

CO2 leaking from sub-seabed storage: Responses of two marine bacteria strains.

Carbon capture and storage (CCS) in stable geological locations is one of the options to mitigate the negative effects of global warming produced by the increase in CO2 concentrations in the atmosphere. A CO2 leak is one of the risks associated with this strategy. Marine bacteria attached to the sediment may be affected by an acidification event. Responses of two marine strains (Roseobacter sp. CECT 7117 and Pseudomonas litoralis CECT 7670) were assessed under different scenarios using a range of pH values (7.8, 7, 6.5, 6, and 5.5) to mimic a CO2 leak. A CO2 injection system was used to simulate an escape from a stable sub-seabed. Growth rate (µ), cell number, inhibition of Relative Inhibitory Effect (RI CO2) and inhibited population were analysed as endpoints. P. litoralis showed more sensitivity to high CO2 concentrations than Roseobacter sp. Our results highlight the diversity and resistance in marine bacteria and their capacity to adapt under a stressful CO2 leakage.