Chemical composition of Southwestern Pacific Ocean surface sediments (Expedition NZOI-Tangaroa_22 and MANGANESE 76, R/V Tangaroa)

Silicon, aluminum, calcium, titanium and iron percentages were obtained by X-ray fluorescence analysis using an EDAX International EXAM system. Sediment samples collected during the Tangaroa cruises have been analyzed for the concentrations of nine elements. Sediments were dried at 80°C for about 48 hours, and ground to a fine powder. After mixing 1:1 by weight with boric acid powder, each sample was pressed into an aluminum \"spec\" cap at about 10,000 psi pressure. Manganese, nickel, copper and cobalt contents were determined by atomic absorption spectrophotometry. Prior to this analysis powdered samples were dried at 110°C to constant weight, and placed in a desiccator to cool. Approximately 0.2-0.3 g of each was weighed into a Teflon beaker, and acidified with 5-15 ml aqua regia (2:1 hydrochloric acid:nitric acid). Samples were heated to a boil and evaporated to near dryness (2-3 hours). About 10-15 ml hydrofluoric acid and 0.5 ml perchloric acid were then added to insure total dissolution. Sample absorbance values were measured with a Perkin-Elmer Model 603 Atomic Absorption Spectrophotometer.