Bacterial community responses during a possible CO leaking from sub-seabed storage in marine polluted sediments.

Carbon capture and storage (CCS) is a viable option to reduce high concentrations of CO and mitigate their negative effects. This option has associated risks such as possible CO leakage from the storage sites. So far, negative effects deriving from a CO release have been reported for benthic macrofauna in both polluted and nonpolluted sediments. However, bacterial communities has no considered. In this work, risk assessment was carried out in order to evaluate the possible effects in a contaminated area considering bacterial responses (total number of cells, respiring activity, changes in the bacterial community composition and diversity). Four microcosms were placed into an integrated CO injection system with a non-pressurized chamber to simulate four different pH treatments (pH control 7.8, 7, 6.5 and 6). Results showed an impact on bacterial communities because of the CO treatment. Changes in respiring activity, community composition groups and diversity were found. This study highlights the use of respiring bacteria activity not only as bioindicator for environmental risk assessment and monitoring purposes but also as a bioindicador during a CO leakage event or CO enrichment process among all the responses studied.