CO₂ leakage simulation: effects of the pH decrease on fertilisation and larval development of Paracentrotus lividus and sediment metals toxicity

Carbon capture and storage has become a new mitigation option to reduce anthropogenic CO₂ emissions. The effects of the CO₂-related acidification, associated with unpredictable leaks of CO₂ during the operational phases were studied using the Paracentrotus lividus sea urchin-liquid-phase-assays (fertilisation and embryo-larval development tests). Besides to the direct effects of the CO₂-associated pH decrease, the possible effects on marine sediment toxicity were studied by exposing the urchin larvae to elutriate of sediments with different metals concentration, which were subjected to various pH treatments. The resulted median toxic effect pH ranged from 6.33 ± 0.02 and 6.91 ± 0.01 for the egg fertilisation, and between 6.66 ± 0.03 and 7.16 ± 0.01 for the larval development assays. Concentrations of Co, Zn, As, Cu, and Fe were detected in the sediment elutriates. For all the sediment elutriates tested the amount of the dissolved Zn increased in parallel with the pH reductions. Correlated effects of acidification, biological response, and the presence of dissolved metals were observed in this work evidencing that the most important factor controlling the reduction of egg fertilisation and larval development success was the combined effects of the reduction of pH and the presence of the contaminants (mainly Zn, Co, and As).