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phosphate concentration had been measured by autoanalysers, and nitrite
and silicate by spectrophotometers according to Parsons et.al.
For pore-water chemistry, the sediment had been sampled with box
corers, piston corers or multiple corers. Sediment cores had been
subsampled and put in a nitrogen-filled glove bag. Pore water had been
extracted by centrifugation at 1500 g for 5 min, with a nearly 80% recovery
rate. It had then been passed through 0.45-µm Millipore filters. For redox
conditions, Eh and pH had been measured using Eh/pH electrodes.
For organic and inorganic carbon, sediment had been sampled with
box, piston or multiple corers, then subsampled by cutting the cores evenly,
putting them in bottles and keeping them in freezing conditions until they
had been freeze dried, ground in gauge mortar and placed in a drier. Total
carbon had been measured with an elemental analyser; then, after
treatment to remove inorganic carbon, organic carbon had been measured
with an elemental analyser and inorganic carbon had been calculated by
subtracting organic carbon from the total carbon content.
Methodologies for geology and geophysics
Dr. Sang-Mook Lee, speaking of the geological and geophysical
exploration conducted by the Republic of Korea in the Clarion-Clipperton
Fracture Zone (CCFZ), described some of the instrumentation, sampling
methods, data formats, types of analysis and kinds of estimation involved.
For navigation and logging, KORDI relied on a differential global
positioning system (DGPS) that was slightly different from the kind used
near the coast. Because the satellite transmitted differential data, it
offered a better and more stable performance far out in the CCFZ than a
regular GPS. KORDI had underwater navigation systems to track tow
bodies, but as they were currently limited in range, consideration was being
given to extending this system to full ocean-depth capability. KORDI was
wondering what to do about its marine data-management system,
introduced in 1992 and used to log geophysical and other data, now that it
was becoming obsolete because so many new instruments and types of
measurements had been introduced.
KORDI employed three methods for bathymetric surveys. The first
was a multibeam system, the SeaBeam 2000, which provided up to three
times the water-depth coverage of other systems. In deep water, it had a
resolution of about 100 m, so nothing smaller than that could be properly
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