Geochemistry

It is important to follow standard laboratory procedures & rules throughout all analytical operations during both offshore and onshore phases of MSP expeditions.
Keeping the working areas clean is a prerequisite for avoiding contamination of cores and samples.
All deviations in sample handling from routine procedures must be documented to ensure the reproducibility and QA/QC of the resulting data.

Interstitial waters (IW) are either acquired from high pressure squeezing of whole round core samples, or directly from the cores using the non-destructive Rhizone sampling technique (Seeberg-Elverfeldt et al., 2005).

(For detailed information on offshore procedures please see
Offshore core curation and measurements and local sub chapters)

The IW samples are dispensed into aliquots in priority according to:
• IODP minimum measurement policy,
• scientific objective of the expedition,
• the agreed IODP split protocol,
• and the IW amount available.
Onboard MSP platforms, IW aliquots are immediately analyzed for salinity, pH / alkalinity and ammonium (ephemeral properties).

(For detailed information on geochemical analysis offshore IODP-MSP please see Analysis offshore.)

After completion of the offshore operations all IW samples are shipped to the IODP Bremen Core Repository (BCR) in the MARUM - Center for Marine Environmental Sciences building, on the campus of the University of Bremen, Germany. At the BCR/Marum the Onshore Science Party (OSP) takes place.

During the OSP additional shore-based laboratory methods for IW analyses are available.

Major and trace elements of the interstitial waters are analyzed using a PerkinElmer Optima 3300 R simultaneous inductively coupled plasma–optical emission spectrometer (ICP-OES). Measurements are conducted with an acidified IW aliquot (cation split, 4 ml).

Other dissolved components like chloride, bromide, nitrate and sulfate are analyzed by ion chromatography (IC) with the 861 Advanced Compact IC with Sequential Compression by Metrohm AG. Measurements are conducted with a pure IW aliquot (anion split, 4 ml).

(For detailed information on geochemical analysis onshore IODP-MSP please see subchapter Analysis onshore).

For analyzing carbon and sulphur (TOC/TC, S) in grounded and homogenized bulk sediment samples a LECO CS 200 CS-Analyzing System (link to http://www.geo.uni-bremen.de/sedpal/) is used during the OSP.

(For detailed information on geochemical analysis onshore IODP-MSP please see subchapter Analysis onshore).

• Seeberg-Elverfeldt, J., M. Schlüter, T. Feseker, and M. Kölling, (2005): Rhizon sampling of pore waters near the sediment/water interface of aquatic systems, Limnology and oceanography: Methods, 3, 361-371.

For further information on respective IODP Scientific Publications and Reports see:

- IODP – Scientific publications
- MSP Geochemistry during IODP Expedition 302
- MSP Geochemistry during IODP Expedition 310