Analytical results for sulfur and carbon in manganese nodules from the GH80-1 cruise in the north to south central Pacific Ocean

In this study, 111 manganese nodules from the north and south Central Pacific were analyzed for total sulfur and total carbon. The samples had been collected along two tracks of 2000 km long for each, running from east of the Wake island to west of Tahiti in the cruise GH80-1, Geological Survey of Japan. For the purpose of removing adherent sea salt, all nodules were immersed in running water and then ion-free water. Air-dry nodules were ground to under 150 mesh. The ground samples were dried at 110 °C for 3 hours, then removed into 40 ml of plastic bottles and kept in a desiccator. In most cases, the analyzed samples were prepared from the mixture of two or three nodules having different sizes for each group of samples collected with a box corer or a freefall grab. Two instrumental methods were used to determine the concentrations of the elements under consideration: (i) Infrared absorption photometry after combustion at 1800°C for total sulfur, total carbon and non-carbonate carbon; (ii) Atomic absorption spectrometry for manganese, sodium, calcium and barium. The coefficient of variation of the infrared absorption photometry after combustion was 5-10%, and that of the atomic absorption spectrometry was 3-5%.