Response of Marine Primary Producers to Olivine Additions

Abstract. Carbon dioxide removal (CDR) technologies are gaining increasing attention as a potential solution to reduce atmospheric CO₂ concentrations and combat climate change. Ocean alkalinity enhancement (OAE) seeks to enhance the ocean's CO₂ absorption capacity by introducing powdered minerals or dissolved alkaline substances into the surface ocean. Nevertheless, the impact of OAE on marine ecosystems remains largely uncharted. In this study, we explored the impact of olivine on a diversity of cosmopolitan primary producers, including Coccolithophores, Diatoms, Dinophyceae, Micromonas sp., Prochlorococcus sp., and Synechococcus sp. Here, we show that most primary producers were not impacted negatively by the concentrations of olivine additions that were applied despite olivine additions increasing nickel concentrations in our cultures. Additions of olivine did not lead to growth inhibition but resulted in a slight increase in growth in most cultures, with picoplankton benefiting the most. However, phytoplankton responses were species-specific and subject to the media used in a combination with the olivine addition. Additionally, it is essential to mention the pitfalls and concerns associated with our experimental setup, particularly regarding the impact of the medias and considerations of carbonate chemistry. Our findings raise confidence in applying olivine for carbonation to generate CO₂ removal without harming primary producers; however, future studies should include tests on an ecosystem level to investigate potential effects on different trophic levels and natural settings.