A whole-core squeezer for interfacial pore-water sampling1
Résumé
The "whole-core squeezer" is a simple pore-water sampler dcsigncd for millimeter depth rcsolution near the sediment-water interface. Various tests have been done to determine how accurately true gradients are reproduced by whole-core squeezing. Tracer studies show that any mixing associated with squeezing dots not smear the profiles by more than a few millimeters. Benthic fluxes of SiO, calculated from interfacial concentration gradients resolved with the whole-core squeezer in San Clcmente Basin are in good agreement with "beil-jar" values measured with the benthic chambers of a bottom lander. Oxygen profiles determined with the whole-core squeezer are very similar to values determined with an oxygen microelectrode. These comparisons confirm that intcrfacial gradients and (by calculation from models) fluxes of 02, N03-, SiO,, and other particle-unreactive ions and molecules can be determined with the instrument. On the other hand, the composition of squeezed pore waters is very susceptible to rapid alteration by solid-solution reactions. Therefore the method is not suitable for determining port-water profiles of trace metals and other particle-reactive chemicals.
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