First assessment of the impact of pH equilibrated Ocean Alkanlinity Enhancement technology on marine biota in the Gulf of La Spezia (north-west Italy)

Abstract

Throughout the past decades, the rise of atmospheric carbon dioxide (CO2) levels has been one of the most important global issues. Higher CO2 concentrations contribute to a strengthened greenhouse effect, resulting in elevated temperatures and a severe acidification of the oceans. Recently, the Intergovernmental Panel on Climate Change (IPCC) highlighted the need to develop CO2 removal approaches, as an essential support to mitigate the ongoing climate change. To this purpose, Negative Emission Technologies (NETs) are capable of extracting CO2 from the atmosphere, keeping it stored in geological reservoirs for long periods. Among NETs, Limenet s.r.l. is proposing a pH equilibrated Ocean Alkalinity Enhancement (OAE) process which involves the permanent storage of carbon dioxide in seawater in the form of bicarbonates using calcium hydroxide and releasing a carbon enriched solution at the same pH of natural seawater. The life cycle assessment conducted on this process demonstrated that the advantages of CO2 capture and storage outweigh the greenhouse gas emissions produced by the entire process. Although this technology is economically promising and the chemical analysis has shown that CO2 stored in the form of bicarbonates in the seawater is quite stable, it’s necessary to assess any possible impact of the pH equilibrated OAE on marine organisms. In light of this, the aims of this project are: 1) To assess the short-term response of the biota after the treatment. 2) To study the effects of a prolonged exposure to the treated water on planktonic and benthic communities through mesocosms experimentation. All experiments are conducted in the Gulf of La Spezia (North-West Italy).