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.This dataset is included in the OA-ICC data compilation maintained in the framework of the IAEA Ocean Acidification International Coordination Centre (see https://oa-icc.ipsl.fr). Original data were downloaded from the Institute for Marine and Antarctic Studies (IMAS) data catalogue, University of Tasmania (see Source) by the OA-ICC data curator. In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2024) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2026-07-02.