Interstitial waters were extracted from whole-round sections 5-10 cm long cut immediately after core retrieval on deck. Samples were gathered with a frequency of one per core in the upper 50 mbsf, and then every third core to the bottom of the hole. After extruding the sediment from the core liner, the surface of each whole-round section was carefully scraped with a spatula to remove potential contamination. Interstitial waters were extracted by placing the sediment in a titanium squeezer and applying pressures up to 40,000 lb (~4150 psi) using a hydraulic press. Water samples were collected into plastic syringes and filtered through 0.45-µm Gelman polysulfone disposable filters. Samples for shipboard analyses were stored in plastic vials. Aliquots for shore-based analyses were stored in heat-sealed acid-washed plastic tubes and/or glass vials.
Interstitial water analyses followed the procedures outlined by Gieskes et al. (1991). Salinity was measured with a Goldberg optical handheld refractometer. The pH and alkalinity were measured by Gran titration with a Brinkmann pH electrode and a Metrohm autotitrator. The Cl- concentration was measured by titration. The H4SiO4, HPO42-, and NH4+ concentrations were measured by spectrophotometric methods with a Milton Roy Spectronic 301 spectrophotometer. The K+, Mg2+, Ca2+, and SO42- concentrations were calculated by ion chromatography using a Dionex DX-100 instrument. The Li+ and Sr2+ concentrations were measured by flame atomic absorption spectrophotometry using a Varian SpectrAA-20. The Mg2+ and Ca2+ concentrations were gauged by titration at Site 1143 to assess the reproducibility of the results from ion chromatography.
We used sample replicates
(NH4+ and HPO42-) and the
International Association of Physical Sciences Organizations standard seawater
(all other elements) to determine 1 
standard deviation. The standard deviations were alkalinity, <1.5%; Cl-,
1 mM; Ca2+, 0.9 mM; Mg2+, 0.8 mM; Si+, 0.7 µM;
NH4+, 0.2 mM; K+, 0.8 mM; SO42-,
0.4 mM; Na+, 5 mM; HPO32-, 0.1 µM; Li+,
1 µM; and Sn2+, 2 µM. Reproducibility for Mg2+ and Ca2+
concentrations measured by titration was 0.03 mM.
