PANGAEA_996213 KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: Microbial metabolic rates Marín-Samper, Laura; Arístegui, Javier; Faucher, Giulia; Kittu, Leila; Boersma, Maarten; Riebesell, Ulf KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: Microbial metabolic rates 2026-07-27 PANGAEA Dataset https://doi.pangaea.de/10.1594/PANGAEA.996213 Investigator Laura Marín-Samper laura.marin@ulpgc.es Earth Science Type of study Event label Day of experiment DATE/TIME Identification number Treatment: dilution type Treatment: alkalinity, total Treatment Sample code/label Respiration rate, oxygen, community Net community production of oxygen Gross community production of oxygen Balance Depth, description geoscientificInformation KOSMOS_2023 KOSMOS_2023_Mesocosm-M1 KOSMOS_2023_Mesocosm-M10 KOSMOS_2023_Mesocosm-M11 KOSMOS_2023_Mesocosm-M12 KOSMOS_2023_Mesocosm-M2 KOSMOS_2023_Mesocosm-M3 KOSMOS_2023_Mesocosm-M4 KOSMOS_2023_Mesocosm-M5 KOSMOS_2023_Mesocosm-M6 KOSMOS_2023_Mesocosm-M7 KOSMOS_2023_Mesocosm-M8 KOSMOS_2023_Mesocosm-M9 Mesocosm experiment metabolic rates ocean alkalinity enhancement Ocean Alkalinity Enhancement (OAE) Phytoplankton Primary production 2023-03-14 2023-04-17 Complete 54.183300000000024 54.183300000000024 7.900000000000001 7.900000000000001 RETAKE DAM CDRmare - RETAKE: CO2 removal by alkalinity enhancement: potential, benefits and risks OceanAlkAlign Ocean Alk-Align OceanNETs Ocean-based Negative Emission Technologies CDRmare Research Mission of the German Marine Research Alliance (DAM): Marine carbon sinks in decarbonisation pathways access rights needed CC-BY-4.0: Creative Commons Attribution 4.0 International (License comes into effect after moratorium ends) English PANGAEA Data Publisher for Earth & Environmental Science https://www.pangaea.de/ Data Center Contact Michael Diepenbroek info@pangaea.de

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Bremen Bremen 28359 Germany online 2798 data points text/tab-separated-values Marín-Samper, Laura; Arístegui, Javier; Faucher, Giulia; Kittu, Leila; Boersma, Maarten; Riebesell, Ulf (in press): Microbial metabolic rates under ocean alkalinity enhancement: A step towards a safe operating space. Communications Earth & Environment

Ocean alkalinity enhancement (OAE) is a marine carbon dioxide removal (mCDR) approach that can also mitigate ocean acidification. However, its biological impacts are expected to depend on the magnitude, timing, and dilution of alkalinity additions. To investigate these factors, a mesocosm experiment simulated hydrated lime additions using two six-level alkalinity gradients (up to ΔTA 1250 µmol kg⁻¹): one with immediate full-column mixing and another with mixing delayed by two days. These treatments simulated rapid (e.g. from a moving vessel in open ocean) and slow (e .g. point source or land-based applications in poorly mixed environments)dilution scenarios, representing different hydrodynamic conditions that may occur following real-world alkalinity additions. Gross production (GP), net community production (NCP) and community respiration (CR), determined from in vitro oxygen production and consumption, together with chlorophyll a, were monitored over a 35-day period. Spring bloom initiation was delayed non-linearly at low fCO₂, with reduced absolute and biomass-normalized production occurring in treatments exposed to fCO₂ below ~70 and 30 µatm respectively. These findings indicate that phytoplankton communities may be generally resilient to realistic OAE scenarios while helping to define ecologically relevant fCO₂ thresholds for safe OAE deployment. ** For all details see the full metadata description at "https://doi.pangaea.de/10.1594/PANGAEA.996213"!

http://en.wikipedia.org/wiki/ISO_8601 DATE/TIME http://invabio.wdc-mare.org/mesocubi.jpg Mesocosm experiment https://alkalign.ocean.dal.ca/ OceanAlkAlign https://cdrmare.de/en/ CDRmare https://doi.org/10.1029/2007GB003095 Net community production of oxygen https://retake.cdrmare.de/en/ RETAKE https://www.oceannets.eu OceanNETs DIF 9.4 2026-07-27 2026-07-27