A whole‐core squeezer for interfacial pore‐water sampling1

Abstract

The “whole‐core squeezer” is a simple pore‐water sampler designed for millimeter depth resolution 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 does not smear the profiles by more than a few millimeters. Benthic fluxes of SiO2 calculated from interfacial concentration gradients resolved with the whole‐core squeezer in San Clemente Basin are in good agreement with “bell‐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 interfacial gradients and (by calculation from models) fluxes of O2, NO3−, SiO2, 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 pore‐water profiles of trace metals and other particle‐reactive chemicals.