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SUMMARY:Approach-dependent Effects of Ocean Alkalinity Enhancement on Part
 icle Sinking Velocities
DTSTART:20260715T111500Z
DTEND:20260715T123000Z
DTSTAMP:20260716T203600Z
UID:indico-event-1139@events.geomar.de
CONTACT:office-fb2@geomar.de\;- 4445
DESCRIPTION:Speakers: Emily Raab (FB2-BI)\n\nAbstract:\nMitigating the env
 ironmental impacts of global warming requires carbon dioxide removal\, e.g
 .\, via ocean alkalinity enhancement (OAE). However\, before OAE can be de
 ployed on a large scale\, our understanding of the environmental impacts o
 f the method must be improved. OAE has been investigated across different 
 experimental settings and application methods to narrow this knowledge gap
 . Here\, we conducted an across-study statistical comparison of three meso
 cosm experiments\, applying liquid or particulate treatment to enhance the
  alkalinity within the mesocosms using a CO2-equilibrated or unequilibrate
 d approach. We measured and analyzed particle sinking velocities and expor
 t fluxes of particulate inorganic carbon in all studies. Both are drivers 
 of the biological carbon pump\, the main mechanism for carbon sequestratio
 n in the ocean and are of particular importance for the CO2 removal effici
 ency of OAE. Consistent with previous studies\, our findings indicate that
  liquid OAE\, regardless of the equilibration state\, had no impact on the
  selected parameters\, provided that the precipitation thresholds for calc
 ium carbonate are not crossed. For the particulate OAE approach\, enhanced
  values were observed in both parameters\, raising multiple concerns. Diss
 olution kinetics of the feedstocks and calcium carbonate precipitation wer
 e identified as the drivers of the observed changes. In a real-world scena
 rio\, the application of particulate OAE or liquid OAE at TA >1\,800 μmol
  kg-1 could lead to alkalinity loss in surface waters caused by either fee
 dstock particles sinking out of the mixed layer or by calcium carbonate pr
 ecipitation producing CO2. Consequently\, surface waters could become over
 saturated and leak CO2 into the atmosphere.\nOur findings suggest that par
 ticulate OAE poses a greater risk of reducing the approach’s efficacy th
 an liquid OAE. Both approaches should be further tested in different exper
 imental settings\, prioritizing precipitation thresholds and assessing the
  context-dependency of our findings and their implications for the large-s
 cale deployment of OAE.\nMeeting link:https://geomar.webex.com/geomar/j.ph
 p?MTID=ma1a0f968b01c74ed3a49c91d3eb51a04\n \n\nhttps://events.geomar.de/e
 vent/1139/
LOCATION:5-1.213 - PAZIFIK / PACIFIC- Rechte Seite - Großer\, unterteilba
 rer Konferenzraum (GEOMAR - Standort Ostufer  / GEOMAR - East Shore)
URL:https://events.geomar.de/event/1139/
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