ZMT - Leibniz Zentrum für Marine Tropenforschung

13/05/2024 | ZMT's seawater test facility is currently running an exciting series of experiments with a mineral that could be used to remove CO₂ from the atmosphere (Carbon Dioxide Removal - CDR). Olivine is a green iron-magnesium silicate and is found in the Earth's upper mantle and in volcanic melts. When it weathers in nature, CO₂ is removed from the atmosphere.

Prof Dr Nils Moosdorf and Dr Murugan Ramasamy from the Submarine Groundwater Discharge working group at ZMT are working with Master's student Husna Sheikh to find out which environmental influences affect the weathering rates - i.e. the speed of weathering.

In their experimental setup, the researchers have placed a layer of olivine on sediment in large tubes and filled the tubes with seawater.

• Versuchsaufbau bestehend aus 14 Säulen, die mit einer bestimmten Menge grob- und feinkörnigen Sediments am Boden und einer gesetzten Menge Dunitsand gefüllt waren, sowie einem bestimmten Volumen gefilterten natürlichen Meerwassers. Die Olivin-Behandlungen wurden in dreifacher Ausführung durchgeführt, und eine Meerwasser-Kontrolle ohne Olivin wurde in zweifacher Ausführung eingerichtet. / Experimental set-up consisting of 14 columns filled with a fixed amount of coarse and fine-grained sediment at the bottom and a fixed amount of dunite sand, along with a fixed volume of filtered natural seawater. Olivine treatments were conducted in triplicate, and a seawater control without olivine was set up in duplicate.
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• Messung der physikalischen In-situ-Parameter (Temperatur, pH-Wert, Salzgehalt und Leitfähigkeit) in der Wasserphase der einzelnen Säulen. / Measuring the in-situ physical parameters (Temperature, pH, Salinity, and Conductivity) in the water phase of each column.

  versuche retake maree ag sdg n moosdorf web
  

• Messung der physikalischen In-situ-Parameter (Temperatur, pH-Wert, Salzgehalt und Leitfähigkeit) in der Wasserphase der einzelnen Säulen. / Measuring the in-situ physical parameters (Temperature, pH, Salinity, and Conductivity) in the water phase of each column.

  versuche retake maree nils moosdorf a daschner web

• Es wurden Wasserproben entnommen; das Meerwasser wurde mit einer 20-ml-Spritze gesammelt und aus jeder Schicht der Säule (Wasser, Olivin und Sedimentporenwasser) gefiltert. / Water sampling was conducted; seawater was collected with a 20 ml syringe and filtered from each layer of the column (water, olivine, and sediment porewater).

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• Die gefilterten Proben wurden in Fläschchen aufbewahrt, um pH-Wert, Gesamtalkalität (TA), Nährstoffe, Metalle und gelösten anorganischen Kohlenstoff (DIC) zu bestimmen. pH-Wert und TA wurden nach der Probenahme gemessen, während die anderen Proben für spätere Messungen im Gefrierschrank gelagert wurden. / Filtered samples were stored in vials for pH, Total Alkalinity (TA), nutrients, metals, and dissolved inorganic carbon (DIC). pH and TA were measured after sampling, while other samples were stored in the freezer for later measurement.

  versuche retake maree ag sdg n moosdorf web

• Das Foto zeigt den Aufbau der Säule nach der Einleitung des Meerwassers: Am Boden wurden 3 kg Feinsediment hinzugefügt, darüber 600 g Olivin und 10 cm Meerwasser. Die Gezeiten wurden alle 6 Stunden durch das Rohr simuliert, wobei sich hinter der Säule ein Gezeitentank befand. Für die tägliche und wöchentliche Probenahme aus jeder Schicht der Säule (Wasser, Olivin und Porenwasser des Sediments) wurde eine 20-ml-Spritze angebracht. / The photo depicts the column setup after seawater introduction: at the bottom, 3 kg of fine sediment was added, above which 600 g of olivine and 10 cm of seawater were placed. Tidal conditions were simulated every 6 hours through the tube, with a tidal tank behind the column. A 20 ml syringe was fixed for daily and weekly sampling purposes from each layer of the column (water, olivine, and sediment porewater).

  versuche retake maree ag sdg n moosdorf web

• Porenwasserproben, die mit einer 20-ml-Spritze aus dem Bodensediment entnommen wurden, um die Anreicherung der Gesamtalkalität (TA) zu beobachten / Pore water sampling collected from the bottom sediment using a 20 ml syringe to observe the accumulation of Total Alkalinity (TA)

  versuche retake maree nils moosdorf a daschner web

• TA-Proben werden in 5-ml-Fläschchen zur Messung gesammelt. / TA samples are being collected in 5 ml vials for measurement.

  versuche retake maree nils moosdorf a daschner web

Versuchsaufbau bestehend aus 14 Säulen, die mit einer bestimmten Menge grob- und feinkörnigen Sediments am Boden und einer gesetzten Menge Dunitsand gefüllt waren, sowie einem bestimmten Volumen gefilterten natürlichen Meerwassers. Die Olivin-Behandlungen wurden in dreifacher Ausführung durchgeführt, und eine Meerwasser-Kontrolle ohne Olivin wurde in zweifacher Ausführung eingerichtet. / Experimental set-up consisting of 14 columns filled with a fixed amount of coarse and fine-grained sediment at the bottom and a fixed amount of dunite sand, along with a fixed volume of filtered natural seawater. Olivine treatments were conducted in triplicate, and a seawater control without olivine was set up in duplicate.

Messung der physikalischen In-situ-Parameter (Temperatur, pH-Wert, Salzgehalt und Leitfähigkeit) in der Wasserphase der einzelnen Säulen. / Measuring the in-situ physical parameters (Temperature, pH, Salinity, and Conductivity) in the water phase of each column.

Messung der physikalischen In-situ-Parameter (Temperatur, pH-Wert, Salzgehalt und Leitfähigkeit) in der Wasserphase der einzelnen Säulen. / Measuring the in-situ physical parameters (Temperature, pH, Salinity, and Conductivity) in the water phase of each column.

Es wurden Wasserproben entnommen; das Meerwasser wurde mit einer 20-ml-Spritze gesammelt und aus jeder Schicht der Säule (Wasser, Olivin und Sedimentporenwasser) gefiltert. / Water sampling was conducted; seawater was collected with a 20 ml syringe and filtered from each layer of the column (water, olivine, and sediment porewater).

Die gefilterten Proben wurden in Fläschchen aufbewahrt, um pH-Wert, Gesamtalkalität (TA), Nährstoffe, Metalle und gelösten anorganischen Kohlenstoff (DIC) zu bestimmen. pH-Wert und TA wurden nach der Probenahme gemessen, während die anderen Proben für spätere Messungen im Gefrierschrank gelagert wurden. / Filtered samples were stored in vials for pH, Total Alkalinity (TA), nutrients, metals, and dissolved inorganic carbon (DIC). pH and TA were measured after sampling, while other samples were stored in the freezer for later measurement.

Das Foto zeigt den Aufbau der Säule nach der Einleitung des Meerwassers: Am Boden wurden 3 kg Feinsediment hinzugefügt, darüber 600 g Olivin und 10 cm Meerwasser. Die Gezeiten wurden alle 6 Stunden durch das Rohr simuliert, wobei sich hinter der Säule ein Gezeitentank befand. Für die tägliche und wöchentliche Probenahme aus jeder Schicht der Säule (Wasser, Olivin und Porenwasser des Sediments) wurde eine 20-ml-Spritze angebracht. / The photo depicts the column setup after seawater introduction: at the bottom, 3 kg of fine sediment was added, above which 600 g of olivine and 10 cm of seawater were placed. Tidal conditions were simulated every 6 hours through the tube, with a tidal tank behind the column. A 20 ml syringe was fixed for daily and weekly sampling purposes from each layer of the column (water, olivine, and sediment porewater).

Porenwasserproben, die mit einer 20-ml-Spritze aus dem Bodensediment entnommen wurden, um die Anreicherung der Gesamtalkalität (TA) zu beobachten / Pore water sampling collected from the bottom sediment using a 20 ml syringe to observe the accumulation of Total Alkalinity (TA)

TA-Proben werden in 5-ml-Fläschchen zur Messung gesammelt. / TA samples are being collected in 5 ml vials for measurement.

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Nils Moosdorf explains the experimental procedure: "We influence the water chemistry and measure it regularly to check which chemical reactions are taking place. We measure the salinity and pH value of the water every day."

"At the same time, we take samples so that we can then take a close look at how the water chemistry has changed in the laboratory," adds Murugan Ramasamy.

With the experiments, the researchers want to try to mimic the effect of the tides and find out the effects of different types of seabed on the weathering rates. In a further step, the influence of microbiology, i.e. the algae and bacteria already present on the mineral, on the weathering rate of the olivine will also be investigated.

The series of experiments is scheduled to run for two months. At the end, the researchers hope to gain new insights into the use of olivine as a CDR measure.

"If you know how olivine reacts to which environmental influences accelerate the weathering process in particular, you can find the best places for this method.

The series of experiments is part of the CDR-Mare project RETAKE of the German Marine Research Alliance (DAM).

About RETAKE: CO₂ removal by alkalinity enhancement: potential, benefits and risks

The research consortium RETAKE, coordinated by Andreas Oschlies from GEOMAR Helmholtz Centre for Ocean Research Kiel, will assess the potential, feasibility and side effects of various forms of marine alkalinity enhancement (AE) as a means to reliably and sustainably remove CO₂ from the atmosphere. Increased ocean alkalinity reduces the activity of CO₂ in seawater, and prompts an enhanced flux of CO₂ from the atmosphere into the ocean, thereby reducing the atmospheric CO₂ concentrations. RETAKE will examine a range of mineral alkalinity sources with respect to dissolution kinetics, CO₂ sequestration potential and side effects on chemistry and biology. Laboratory studies and mesocosm experiments of AE in benthic and pelagic systems will simulate realistic environments with focus on the Baltic and the North Sea. A hierarchy of numerical models will be used to simulate deployment in German coastal waters and elsewhere, and to extrapolate experimental results from local to regional and global scales. Permanence and accounting of carbon storage as well as monitoring, detection and attribution issues will be examined against the background natural variability. An investigation of economic aspects and the relation to the U.N. sustainability goals will complete the comprehensive assessment in order to inform policymakers about the feasibility, overall sequestration potential and environmental risks of ocean alkalinity enhancement.

More about the research consortium: https://retake.cdrmare.de/en/