September 2018
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- Take a 5 cc headspace sample from every sediment core (non-basement), at the top of a section (try to be consistent). This sample is taken until the total depth objective is met. If doing multiple holes, you do not have to repeat the sampling if the sample is taken at a prior depth but just continue after the prior hole's bottom depth.
- For cores with IW samples, take the headspace sample from the top of the section immediately below the IW sample. Note the core, section and interval of the headspace sample and write it on the Curator's logsheet. The interval will need to be entered into SampleMaster by the Curator/ALO.
- Make sure nobody sprays acetone on the catwalk before sampling is completed. Acetone will contaminate the sample.
- It is recommended to occasionally take a sample of the air on the core deck, so that any change in the headspace sample analysis can be correlated to changes in volatilized acetone.
- Inject a standard (corresponding to a similar concentration seen in the core samples) every fifty injections or so, to check on the instrument calibration.
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- Set the pressure gauge around 3000 lbf and simultaneously push and hold both green (CLOSE) buttons on the hydraulic unit's base until the auto-pressure engages.
- After the first drops flow from the hole in the squeezer's base plate, insert the syringe into the hole. Keep an eye on the syringe to make sure the pressure doesn't push out the syringe or plunger (especially for the first few cores). Keep incrementing the pump pressure in steps of 1000 lbf until 10000; after 10000 lbf, increase in steps of 2000. Do not ever increase the pressure above 30,000lbs.
- Select the correct core, section, and sample, and upload the IW sample splits (using the Excel template) into SampleMaster and distribute the labels.
- When porewater yield is sufficient/no more water is trickling, release the pump by pressing the red OPEN button and remove the syringe from the squeezer.
- Start sample distribution (splits).
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All headspace gas samples will be run on GC3 (C1-C3). Gas void samples or samples containing higher hydrocarbons will be run on the NGA.
Titrations
The ph/alkalinity measures are routinely done (in real-time) by the Scientists with the Technician setting up the instruments. Chlorinity titrations are up to the Scientists as to if they want them done because chloride concentrations are measured on the IC.
IC
To determine anion and cation elemental concentrations. Wait until you have collected enough samples for a batch (ie. end of a hole). The Scientists can assist in preparing the samples but the Technician will set-up and run the instrument.
SPEC
Ammonium and phosphate are routinely measured. It's a good idea to wait until you have enough samples for an entire batch (ie. end of a hole), as it is a time-consuming process.
ICP
The ICP-OES system will measure specific minor and major element concentrations of porewater, sediment (need approval) and hard rock. Wait until you have collected enough samples to run an entire batch (ie. end of a hole). Argon is limited, and the machine requires a significant amount of prep time. The Scientists can help prepare the samples but the Technician will set-up and run the instrument.
Coulometer
Crushing, weighing and running carbonate samples require a significant portion of time. During the initial discussion of the sampling protocol, the Scientists will decide on where they want to take the sample for the carbonate/EA analyses. It can be taken from the IW squeezecake or at the sample table after the core is split. Either way, these samples will have to be freeze-dried (typically for twelve hours) and then crushed/homogenized using a mortar and pestle. Usually the Scientists will prepare and run the analyses and the Technicians will set-up the system.
CHNS
Again, weighing and running the samples on this instrument is time-intensive and it be best to have a good sized batch ready before running. Usually the Scientists will weigh out the samples and the Technician will set-up the instrument and sequences. The combustion column needs to be replaced after approximately 100 samples.
SRA
The SRA is not routinely used but is part of our safety monitoring protocol. You must know how it operates and make sure that it is ready if needed.
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VI. Port call – Off Going
- See General JRSO Shipboard Technical Staff SOP