Meeting 30: 16 November 2023
Meeting Minutes
Date: 16 November 2023; 10:00 – 10:30 CT; via Zoom
Attendees: Gary Acton, Carlos Alvarez-Zarakian, Bridgette Cervera, Laurel Childress, Lisa Crowder, Emily Estes, Bill Gilhooly, Jennifer Hertzberg, David Houpt, Brad Julson, Leah LeVay, Chang Liu, Aaron Mechler, John Miller, Algie Morgan, Beth Novak, Chieh Peng, Michelle Penkrot, Vinny Percuoco, Thomas Ronge, Jeff Ryan, de JR, Johanna Suhonen, Elizabeth Trembath-Reichert, Kara Vadman, Trevor Williams
1) Expedition review: 399
Issue G153) Tabletop pH meter did not work.
LWG RECOMMENDATION: No action. Unit was fixed shipboard during expedition.
Issue G154) Coulometer did not have sufficient instructions for measuring low percent carbonate (we had to wait for atmospheric CO2 to be purged).
LWG RECOMMENDATION: David Houpt will review protocols in Confluence and add a sentence about increasing sample mass for analysis of low carbonate samples.
2) Expedition review: 400
Issue G155) Some of the methods could need a little bit of optimization, e.g., the coulometer software needs some improvement to improve analysis of dolomite.
- can’t calculate CaCO3% because the instrument can’t know the fraction Mg
- dolomite may dissolve more slowly, need to adjust instrument run time
LWG RECOMMENDATION: TAS will follow up with the scientist who submitted comment for suggestions on how to improve the methods.
Issue G156) It would be great to have the opportunity to analyze organic carbon directly, not indirectly.
- lack of lab space and time limits shipboard ability to do this
- we can acidify CHNS samples shipboard in silver cups – this is documented in tech materials. But it’s time consuming. And acid in samples will also cause faster column deterioration, need to remake column more often, etc. and it is generally better to make these measurements on-shore.
LWG RECOMMENDATION: No action.
Issue G157) An upgrade of the weighing system for coulometry and EA would be great (e.g., a digital marine micro scale), and could accelerate the work processes and make weight measurements more precise.
- David has reached out to the scientist for more information/recommendations.
- We have previously investigated the Cahn Model/36 and Mettler-Toledo XP56DR DeltaRange microbalances.
- Cahn Model/36 was researched just before Cahn went out of business, but because it’s a classical pan-with-needle apparatus, it wouldn’t work at sea.
- We also tried a pair of Mettler-Toledo XP56DR DeltaRange microbalances (which on shore, can weigh down to 1 µg), but were unable to get masses <100 mg because the mass of the stage dominates the averaging below that mass; since we need to weigh down to <1 mg at times, they didn’t work, so we had to keep using the Cahn Model/29 and Model/31 balances.
LWG RECOMMENDATION: Wait for response from scientist; options are limited. Cahns work best in shipboard environments.
3) Future of shipboard chemistry lab
David gave a short update:
- Equipment on JR will be demobilized Aug/Sept 2024, coming back to GCR. Lab spaces at the GCR are under renovation. Physical properties, paleomagnetics, and geochemistry instrumentation will be set up on shore.
4) Emily will circulate LWG recommendation document for coordinating microbiology and petrology sampling in basements
- this is simply a restructured document from the past circulation; no content changes.
5) Updates from Gary on dry dock
6) Next meeting
- After Expedition 401, ~March 2024