Pore-water and solid-phase chemistry for sediment cores with turbidites from the Black Sea

During the PhOxy cruise with R/V Pelagia in June 2013, sediments were collected with a multicorer in the eastern part of the Black Sea. The aim was to determine the geochemical siganture of sediments on the shelf and in the deep basin, and potentially track chemical changes to sediments that are transported into the sulfidic deep basin by turbidity currents. Sediment cores were cut at vertical resolution of 0.5-2.0 cm and the pore-water and solid-phase were separated by centrifugation. After filtration of the pore-water over 0.45 micrometer filter membranes, dissolved inorganic carbon (DIC), Fe, P, Mn, N (ammonium, nitrite, nitrate) and S (sulfate, sulfide) were measured in various sub-samples. After freeze drying and grinding, sub-samples of dry sediment were taken and solid-phase org-C, Al, Ca, Fe, Mn, Mo, P and S were determined by decalcification and combustion (org-C) or ICP-MS analysis of acid digest (other elements). Furthermore, various solid-phase Fe and P pools were determined using sequential chemical extraction protocols. From a second core, 10-mL wet sediment samples were taken at 5-cm resolution from a multicore with pre-drilled holes and transferred into glass vials with gas-tight, crimp-sealed rubber stoppers filled with N2-purged saturated NaCl (no headspace). Later, a N2 headspace was injected and the headspace was analyzed for CH4 by gas chromatography with a flame ionization detector (GC-FID, Thermo Finnigan).