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Total alkalinity per unit mass of the water body
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To investigate how the unavoidable physical and chemical perturbations associated with Ocean Alkalinity Enhancement (OAE) could influence marine plankton communities and how potential side-effects compare to impacts of climate change, we conducted 19 ship-based experiments in the Equatorial Pacific, examining three prevalent OAE source (NaOH, olivine, and steel slag) and their impacts on natural phytoplankton populations. Our experiments simulated realistic and moderate alkalinity enhancements between 29-16 μmol kg-1. The monitored parameters included total chlorophyll-a concentrations, macro nutrients, trace elements, total alkalinity, Fv/Fm, pH,and flowcytometry.
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This dataset was generated to assess the biological impacts of ocean alkalinity enhancement (OAE) in the Southern Ocean. Deck-board incubation experiments were conducted at five sites spanning subantarctic to sea-ice regions during the RV Investigator MISO voyage (January–March 2024). Unfiltered surface seawater was incubated for 5–8 days following additions of three alkalinity sources: sodium hydroxide (NaOH), ground olivine, and steel slag, alongside untreated controls. Measurements collected at the beginning and end of each incubation included carbonate chemistry (total alkalinity and pH), macronutrients (nitrate, phosphate, silicate), chlorophyll-a, biogenic silica, photophysiology (Fv/Fm), and plankton community composition. Phytoplankton and bacterial abundances were quantified using flow cytometry, while genus-level phytoplankton composition was determined by light microscopy. A complementary dark leaching experiment quantified dissolved trace metal release from each OAE material using ICP-MS. The purpose of the study was to distinguish the biological effects of alkalinity change alone from those arising from collateral nutrient and trace-metal release, and to evaluate how different OAE materials influence phytoplankton growth and community structure in iron-limited Southern Ocean waters. The dataset supports assessment of ecological risks and co-benefits associated with ocean alkalinity enhancement as a carbon dioxide removal strategy.
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To understand the environmental impacts of added alkaline minerals on plankton communities, we enclosed natural coastal plankton communities using 53L microcosms and exposed these communities to ground factory slag (2g/53L) and olivine (100g/53L). The microcosms of seawater were kept at 13.5 °C with circulations. The biochemical changes and responses in microcosms were monitored and measured for 21 days. The measured parameters are pH, total alkalinity, temperature, macro-nutrients concentrations, total chlorophyll-a, flow cytometry data, POC/PON, BSi, Rapid Light Curves, zooplankton abundance, the dissolved trace metal concentrations, and the particulate trace metal concentrations.