Meeting 27: 7 July 2022

Meeting Minutes

Date: 07 July 2022; 09:00 – 10:00 CT; via Zoom

Attendees: Jeanine Ash, Oscar Cavazos, Laurel Childress, Lisa Crowder, Emily Estes, Bill Gilhooly, David Houpt, Sandra Herrmann, Jack Longman, Amy McWilliams, Aaron Mechler, Eric Moortgat, Algie Morgan, Johanna Suhonen, Jeff Ryan, Elizabeth Trembath-Reichert, the JR [other participants unclear]

1) Update on the new pXRF unit from Jeff Ryan on the ship

- Bruker pXRF onboard for Expedition 393, trial run.

- The instrument is wonderful – runs lots of elements with good results, including rubidium. It generates good working curves, and is stable for elements it does well. Excellent at energies higher than potassium.

- However care must be taken with data for Si, Al, Mg, where the data looks good but can vary day-to-day. A calibration could be applied daily, but this might not be worthwhile. it looks good but varies from day-to-day, calibration changes daily, we could calibrate daily, but maybe not worthwhile. The pXRF is not in a controlled atmosphere, therefore these daily differences might be caused by changes in temperature/humidity.

• LWG RECOMMENDATION: TAS incorporate information into the Wiki User Guide about how to properly analyze the low-energy elements

2) Other instrument updates

- The old coulometers are coming back to shore; new coulometers are on the ship and working well

- The new SEM-EDS will go to the ship during the tie-up, with further set-up and testing during Expedition 397T

- The old source rock analyzer is going to the vendor for repair, and will be installed onshore when returned [unless needed to swap with the ship; see Issues Tracking Item G141]

- The old CHNS analyzer will also be installed on shore

3) Helium shortage

- Helium is becoming harder to obtain and more expensive. TAS has been investigating alternatives.

- N2 and Ar were investigated as carrier gasses for the GC, but will not be feasible due to retention time and peak interference. If we cannot get He, we will need to use hydrogen which presents safety needs that will have to be addressed.

- The SRA requires helium. The CHNS could use Ar.

- There is currently no timeline for when this will become an issue, but we need to be prepared and continue to explore other options now.

4) Expedition review: 391

Issue G137) the pXRF unit has no capacity for matrix corrections - issue closed

Issue G138) due to the time and labor intensive process to switch the ICP-OES between water/sediment and hard rock geochemistry, could a tabletop XRF system be used instead?

- this is unlikely to happen before a new vessel; at that time a wavelength dispersive instrument would be superior to an energy dispersive unit

- the handheld pXRF unit with powdered samples provides a good alternative currently (used on Exps 390 and 392)

- external member Jeff Ryan notes that having an ICP-OES and a WDS XRF onboard would be redundant. These instruments generate the same data and well. There are some trace elements that each does better than the other. However, the pXRF works better for Ni, Zn (which are near detection limit on the ICP-OES).

- issue closed

5) Expedition review: 392

Issue G139) HF safety concerns: lack of isolated space and additional chemistry technical personnel

- the chemistry lab and the paleo prep lab each have an HF hood; the chemistry lab has less general foot traffic, does not stop other micropaleontology prep work, and provides for the chemistry technician to be in closer proximity to the work.

- in the next meeting we will revisit whether HF may no longer be used onboard. While this would hinder a small number of cruises from generating age models onboard, this could be done immediately post-cruise. Drilling decisions have rarely (if ever) been made using this data.

- external member Elizabeth Trembath-Reichert notes that microbiologists also use HF for cell counts, however that it is not necessary to do this shipboard.

- Other external members reiterated the safety hazards (which include waste disposal, which was not discussed) including space and staff needs.

- issue closed (however will be revisited separately)

Issue G140) some chemistry lab computers crashing during analysis

- 100 new computers going to the ship for instrument hosts during the tie-up

- issue closed

Issue G141) issues with the performance of the source rock analyzer

- Bruno (SRA company representative) is working with Oscar and Johanna and shipboard theyare checking through voltages at different points

- if this does not solve the issue, David and Aaron will work on it during the tie-up

- if this does not solve the issue the other, refurbished, SRA will be returned to the ship

- issue closed

Issue G142) request for extraction and GC capabilities

- This requires space not currently available on the JR, however could be implemented on a new vessel. Currently scientists can collect and freeze samples for later biomarker analysis.

- it would also be difficult to provide capabilities for the wide range of biomarkers studied on IODP samples and the ensure quality measurements, is better done on shore.

- issue closed

6) Expedition review: 390

Issue G143) problems with ventilation and temperature control in the rad van

- issue is primarily in the smaller back room; these problems were not observed during Exp 385, which in a very warm environment and suggests a possible issue with the air handling

• LWG RECOMMENDATION: discuss with Siem about inspecting the A/C unit to ensure it is working properly; inspect the air inlet on the side of the van which may be where smoke is entering from the smoking area below [consider redirection or addition of a filter].

7) Next meeting

- After Expedition 393, likely in fall 2022