Meeting 28: 29 November 2022

Meeting Minutes

Date: 29 November 2022; 09:00 – 10:00 CT; via Zoom

Attendees: Gary Acton, Peter Blum, Bridgette Cervera, Laurel Childress, Emily Estes, Bill Gilhooly, Jennifer Hertzberg, David Houpt, Brad Julson, Leah LeVay, Eric Moortgat, Algie Morgan, Chieh Peng, Vinny Percuoco, Thomas Ronge, Jeff Ryan, The JR (Carlos, Alvarez-Zarikian, Lisa Crowder, Aaron Mechler), Kara Vadman, Trevor Williams


1) Tracer pumping

- We have traditionally pumped perfluorocarbon tracers (PFTs) downhole for microbiological contamination tracer purposes. The older compound, perfluoromethylcyclohexane (PFMCH, C7F14), was problematic in that it was highly volatile and so the entire workspace would quickly become contaminated.

- While we still need to determine the effectiveness as a microbiological tracer, we are now currently stocking perfluoromethyldecalin (PFMD, C11F20) onboard the JR. PFMD is at best 85-90% purity and much of its impurities are perfluorodecalin (PFD, C10F18); furthermore, both PFD and PFMD have two isomers (cis- and trans-) which have different chromatographic retention times.

- Unfortunately, the cost of PFMD is skyrocketing and if an expedition were to pump during 100% of its coring time, that’s ~$80,000-100,000 in cost for PFD ($850/kg; $1240/kg for PFMD).

- Our technicians have performed a detection limit study for PFD and PFMD and the gas chromatograph, equipped with a micro-electron capture detector (GC-µECD) has a method detection limit (MDL) of approximately 1 part per billion (w/v). This implies that we can reduce the amount of PFT we’re pumping from 1000 ppb (w/v) to 200 ppb and still see the tracer in contaminated samples while still having the ability to detect it at low contamination levels.

- However, this has not been proven to work yet, and testing will occur during Expedition 398. JRSO technical staff will prepare samples and run the instrument while guided by the microbiologist on where/how to take samples.

- Testing during Expedition 398 will include:

  • Pump 24 hours at 20% of the normal pump rate.

  • Pump 24 hours at 40% of the normal pump rate.

  • Pump 24 hours at 60% of the normal pump rate.

  • For each day, the microbiologist would guide the technicians on where (and how) to take contamination testing samples for the GC analysis.

  • If the 20% works, then we could lower the pump rate back down; the higher rates are there are in case we’re not seeing peaks.


  • LWG RECOMMENDATION: Test PFD/PFMD and pumping rate as planned (above) during Expedition 398. Results will be presented to the LWG in March 2023 and any needed further recommendations needed can be made.


2) HF Onboard

- HF onboard the JR presents a variety of safety concerns, including: the transportation, storage, and disposal of a hazardous material, staff and scientist time required for safety, additional medical supplies onboard, the use of an entire fume hood, and the limited working space within this fume hood. Therefore, TAS has asked to revisit the use of HF on the JR.

- In October 2018, with input from the LWG, management developed the Guidelines for Use of Hydrofluoric (HF) Acid on the JOIDES Resolution: https://wiki.iodp.tamu.edu/download/attachments/116687356/HF-Guidelines-2018-10-04.pdf?version=2&modificationDate=1640095809000&api=v2

- Included in this document are several guidelines that have not been completely implemented in subsequent expeditions:

  • If HF is requested for use on an expedition, evidence shall be provided that HF palynological processing is necessary for drilling decisions.

  • The requestor will also provide a rationale why non-HF methods would be considered ineffective and a plan of use for HF that limits quantities as much as possible and cannot exceed 10 liters.

  • Requests from the science party to use HF during an expedition should be evaluated by the EPM, co-chiefs, and Technical & Analytical Services.


  • LWG RECOMMENDATION: The LWG recommends that EPMs/TAS rely more on the guidelines document and follow the specifications within. The use of HF should be limited to instances where ages are required to make a drilling decision and can only be determined using HF methods, and the requestor will need to provide evidence that alternative methods are ineffective. If ages are not required for drilling decisions, HF will not be used onboard. Alternative methods can instead be used to gather preliminary ages which can be refined post-expedition.



3) Expedition review: 393

Issue G144) protocol and safety of microbiological sampling of hard rock

General protocol:

- The Foldio imaging system used during Expeditions 390 & 393 was tedious, but the results were popular.

- Each expedition will need to determine the level of contextual image required prior to destructive hard rock sampling (‘Hard rock’ defined as when a piece can be removed and replace in the section). This may be as basic as the overhead image standardly collected when a piece is removed for destructive sampling (uncleaned, but with a color card), or as complex as 360° imaging of the piece (cleaned prior to imaging).

Safety/Sampling:

- Destructive hard rock sampling by current methods is loud, pieces can fly across the room, and hands/fingers can get smashed.

- A Dremel is now available and TAS will develop an SOP for use that includes some way to stabilize the tool and make it safe.

- Another possible option for hard rock sampling would be some type of press system, which TAS will investigate.


  • LWG RECOMMENDATION: Maintain the Foldio imaging system as an option for science parties. Decisions about using this system should be made well in advance of the expedition, alongside other recommended discussion points for pre-expedition destructive microbiological sampling (see next recommendation). TAS will add a page to the wiki about the Foldio system.

  • LWG RECOMMENDATION: Science parties should be presented with the document “Recommendations for destructive sampling of igneous/metamorphic/sedimentary (“hard”) rocks for microbiology studies” during pre-expedition discussions, with a focus answering the questions found in the ‘Important decisions for microbiologists and core describers’ section of the document as early as possible. Emily Estes will re-write portions of the questions section for clarity and it should then be posted to the Lab Manuals Confluence Wiki. [Note: this will now be overseen by the Geology LWG]

  • LWG RECOMMENDATION: TAS development of methods and SOP for use of the Dremel hard rock tool, including a means of stabilizing the tool and making it safe to operate.

  • LWG RECOMMENDATION: TAS investigation of options available for some type of press system to break rocks, keeping in mind that cleaning/contamination and size of unit (ex. To fit inside clean area) are considerations.


4) Next meeting

- After Expedition 398, ~mid/late March 2023