Potential risks of CO2 removal project based on carbonate pump to marine ecosystem

The development of marine carbon sequestration project has an important potential for carbon neutralization in the short-term (several decades). Marine carbon sequestration technology is based on biological and carbonate pumps to increase particulate organic carbon and authigenic insoluble carbonates to the deep sea or seafloor, aiming to achieve permanent carbon sequestration. Particularly, chemical carbon sequestration technology based on carbonate pump is proposed and considered to achieve short-term marine carbon sequestration in recent years. This technology mainly includes alkaline mineral addition and combining CO32- to insoluble carbonates to improve marine carbon fix-ation capacity. Potential marine ecosystem risks of chemical CO2 removal method should be considered before being a feasible technology. We reviewed the potential effects of marine chemical carbon sequestration project on marine or-ganisms. Marine chemical carbon sequestration had two main effects on marine organisms: released chemicals effect, and particle effect. Released chemicals in mineral weathering directly affected phytoplankton and bacteria commu-nity. Particles formed during carbon sequestration process mainly affected filter feeding organisms. The toxic effects of particles on aquatic organisms increased with decreasing sizes and increasing concentrations of particle. Algae and crustaceans were the most sensitive groups exposed to metal nanoparticles (nm-mu m) in seawaters, thus could be used as target species to evaluate ecological risk of small particles generated in chemical carbon sequestration project. Embryos or larva of filter feeding organisms were more sensitive to large clay and metal microparticles (mu m-mm) than adults, thus could be used as sensitive groups to establish safety concentration of large particles. The relatively inert metal nanoparticles and microparticles had higher safety concentrations than active ones. These particle concentration thresholds could be as a reference to design concentrations and initial sizes of applied minerals in marine chemical carbon sequestration project. This will ensure that the ecological risk is minimized when carbon fixation efficiency is maximized.

Automated summary

The development of marine carbon sequestration project has the potential to neutralize carbon in the short-term. This technology is based on biological and carbonate pumps to increase particulate organic carbon and authigenic insoluble carbonates to achieve permanent carbon sequestration. However, potential risks to marine ecosystems and organisms must be considered. Chemical carbon sequestration through mineral addition and CO32- combination has been proposed to improve the capacity of marine carbon fixation. The effects of this method on marine organisms include the release of chemicals and the formation of particles, which can have toxic effects on phytoplankton, bacteria, and filter feeding organisms.