Brief description
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.Lineage
Maintenance and Update Frequency: notPlanned
Statement: Incubation experiments setup
Nineteen incubation experiments were undertaken to assess the impacts of NaOH- olivine- and slag-OAE on phytoplankton growth and community composition. For each experiment, twelve acid-washed 500 mL polycarbonate bottles (Nalgene) were filled with surface seawater collected with a trace metal clean towed water sampling device (so called ‘tow-fish’) after sunset at ~2 m depth. The collection of seawater was conducted in a trace metal-clean plastic tent (the ‘bubble’) that was over-pressurised with HEPA-filtered air to minimize trace metal contamination. Three bottles were left unperturbed and sampled immediately to determine the initial conditions (see below). Three bottles were supplemented with 150 µL of 0.1M NaOH (Analytical grade); three with 0.2 g of ground olivine powder; three with 0.001g of slag powder; and three remained unperturbed as control. These bottles were incubated for 48 h in an on-deck incubator flushed continuously with surface seawater and screened to receive ca. 35% of surface incident light.
Sampling protocol
Initial seawater was stored in dark HDPE bottles before measurements. The pH was carefully measured using a pH meter (914 pH/Conductometer Metrohm), following the procedural reference. Eight mL of sample was filtered (0.2 µm) for macronutrient analysis using a QUAATRO39 (Seal Analytical) autoanalyzer directly after sampling. Alkalinity samples (60 mL) of the control and the NaOH treatment were fixed with 30 µL HgCl2 and stored for 3 months until analysis. Alkalinity samples of the olivine and slag treatments were filtered after sampling (0.22 µm PES syringe filters) to remove remaining particles. In Experiments 3,8 and 9, certain replicate bottles from both the treatment and control groups exhibited lower alkalinity, which could be due to rainwater dilution effects that may have occurred in a patchy manner during seawater collection with the tow-fish. Therefore, we compared the high and low alkalinity samples in the treatment group with the corresponding high and low alkalinity samples in the control group to determine the ∆ alkalinity values in these specific experiments.
After 48 h, experimental bottles were removed from incubators, samples were transferred into dark bottles in the ‘bubble’. Like the initial samples, the following samples were subsampled from the dark bottles from each treatment: pH, flow cytometry (2 mL for phytoplankton and 1 mL for bacteria samples), Chl-a (100 mL), FRRf (5 mL), and total alkalinity (60 mL). Nutrient concentrations of treatment bottles were analysed six times throughout the cruise using a QUAATRO39 (Seal Analytical) autoanalyzer.
Issued: 25 06 2024
Data time period: 2023-04-14 to 2023-06-02
text: westlimit=147.832031; southlimit=-11.872727; eastlimit=-78.574219; northlimit=2.454693
Subjects
ALKALINITY |
Abundance of biota |
BIOGEOCHEMICAL CYCLES |
BIOSPHERE |
Concentration of chlorophyll-a per unit volume of the water body |
Concentration of nitrate and nitrite {NO3 and NO2} per unit mass of the water body |
Concentration of phosphate {PO4} per unit mass of the water body |
Concentration of silicate {SiO4} per unit mass of the water body |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
ECOSYSTEM FUNCTIONS |
EXP |
Global / Oceans | Global / Oceans | Pacific Ocean |
Global / Oceans | Global / Oceans | West Equatorial Pacific Ocean |
OCEAN CHEMISTRY |
OCEANS |
Ocean Alkalinity Enhancement |
Total alkalinity per unit mass of the water body |
biota |
pH (total scale) of the water body |
the maximum potential quantum efficiency of Photosystem II |
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Other Information
(DATA ACCESS - Download OAE incubation data [.zip])
Identifiers
- DOI : 10.25959/BMV8-1K07
- global : 493443ef-be06-40bf-b4af-7f6cd566c1a3
