2016_11_29

Geochemistry/Microbiology LWG

Meeting minutes

29 November 2016

0900-1015 CST in A105

Participants: Jason Sylvan, Brad Julson, Lorri Peters, David Houpt, Lisa Brandt, Kara Bogus, Trevor Williams, Tobias Höfig, Algie Morgan, Don Sims

Via Zoom: Erik Moortgat, Becky Robinson

Updates

1. Olympus Delta handheld XRF (David)

· Quantitative analyses on homogenized discs; qualitative on core surface

· Quantitative data stored as ppm

· Scientists can covert majors to %oxide on their own

· Qualitative data stored as %element

· Vinny writing up UserGuide – will distribute when ready

· Two techs trained on it per crew – XRD tech responsible for sample prep and thin section tech is secondary

· Training during Guam port call (December 2016)

2. Update on ICP analyzer application (Vinny, via email, and Erik)

· Current external software (ICPAnalyzer) has had complaints from sailing geochemists

· To address this, Vinny created a new Excel-based program

· Was available for Exp 362, but not used

· On board Exp. 363, it has been used at each new site thus far for IW minors. There were one or two bugs that were worked out and two new features were added:

1. Allows the user to import a curatorial report from LORE in order to automatically generate depth profiles

2. Generates a table which lists all the samples which have line intensities that exceed the greatest calibration standard.

· The program puts all sample concentrations into spreadsheet uploader format automatically; uploading to the database has worked like a charm.

· Scientist response has been very positive thus far

· They like being able to see how the data is being generated/reduced as opposed to sole presentation of the final concentrations.

· One comment they have is on the calculation of detection limits (LOD). There is some functionality in the program that will flag sample raw intensities that fall within the instrument LOD as determined from the standard deviation of the most recently run blank, as well as filter out these data for subsequent calculations. However, they would like to be able to report a minimum concentration detectable by the ICP. For our methods, the LOD will change during a run because of instrument drift/contamination on the torch/etc. Becky Robinson recommended that we should have methodological LOD.

ACTION: Prepare best approach on how to report a single methodological LOD

Discussion items

3. Cruise evaluation review of 362 (Sumatra Seismogenic Zone)

· Comments from two sailing geochemists and one of the co-chiefs

· All identified the same single issue with the IC that required re-measurements and troubleshooting. No action required, issue was fixed on board and working fine on Exp. 363

· All other comments were positive.

4. Open action items

· Numerous items either closed or transferred to “in progress” – see https://sites.google.com/a/scientific-ocean-drilling.org/lwg-geochemistry-mbio/action-items/open-action-items

· Highlight:

· Contamination control for microbiology – recommendation from Jason for JRSO to host a face-to-face discussion one day in April 2017 (28 April tentatively identified) with microbio representatives to produce formal recommendation for JRSO – LWG in agreement.

ACTION: Kara to prepare recommendation to send to management