The shipboard analytical program for inorganic geochemistry focused solely on the chemical characterization of interstitial waters extracted from 5- to 15-cm-long whole-round sediment samples and/or taken with the in-situ sampler (the WSTP tool). During Leg 149, interstitial waters for shore-based analyses of trace elements were obtained by squeezing sediments with a plastic-lined squeezer designed by Hans Brumsack. Interstitial water samples for shipboard analysis and for ODP archives were collected either with the Brumsack squeezer or with a titanium Manheim squeezer.
The whole-round sections were cut from the core immediately after it arrived on deck and were placed in a nitrogen-filled glove bag to prevent oxidation. While in the nitrogen bag, the sediment was removed from the core liner, scraped with a plastic spatula, and loaded into the plastic-lined squeezer. Highly consolidated sediments were broken into small pieces and a portion transferred to the titanium squeezer. The sediment was squeezed at pressures up to 18,000 psi (124 MPa) in the Brumsack squeezer and up to 40,000 psi (276 MPa) in the titanium squeezer. The effluent from the Brumsack squeezer was ejected through a pre-cleaned 0.45-m Millipore polycarbonate membrane placed inside the squeezer. In addition, the effluent was filtered through in-line pre-cleaned 0.22-m acrodisk filters before collection in pre-cleaned syringes. The effluent from the titanium squeezer was filtered through an uncleaned 0.22-m acrodisk filter. Effluent from each sediment sample was collected for shipboard analyses, for ODP archives, and for shore-based analyses of trace elements. The trace-element samples were transferred from the precleaned plastic syringes to pre-cleaned plastic vials acidified with Ultrex HCl and stored. Samples for shipboard analyses were refrigerated, and archive samples were sealed in glass ampules.
Alkalinity and pH were determined in duplicate immediately following sample collection using the Metrohm autotitrator with a Brinkman combination pH electrode. The electrode was calibrated prior to analysis and periodically checked for drift. Salinity was estimated using a Goldberg optical hand refractometer to measure the total dissolved solids. The concentrations of the sulfate and chloride anions and the calcium, magnesium, sodium, and potassium cations were determined in duplicate using a Dionex-DX100 ion chromatograph. All samples were run at 1:200 dilution. Standards were run at the start and end of each run to test for drift in the response of the conductivity detector. Precision of separate dilutions was better than 2%. Concentrations of ammonium, silica, and phosphate were determined by the spectrophotometric techniques described in Gieskes and Peretsman (1986). Concentrations of iron, manganese, and strontium were analyzed by atomic absorption spectrophotometry (AAS).