Quantification and molecular characterization of dissolved organic sulfur in water samples obtained during POLARSTERN cruise ANT-XXV (PS73) to the East Atlantic and the Southern Ocean

Although sulfur is an essential element for marine primary production and critical for climate processes, little is known about the oceanic pool of non-volatile dissolved organic sulfur (DOS). We present a basin-scale distribution of solid phase extractable DOS in the East Atlantic Ocean and the Atlantic sector of the Southern Ocean. While molar DOS versus dissolved organic nitrogen (DON) ratios of 0.11 ± 0.024 in Atlantic surface water resembled phytoplankton stoichiometry (S/N ~ 0.08), increasing dissolved organic carbon (DOC) versus DOS ratios and decreasing methionine-S yield demonstrated selective DOS removal and active involvement in marine biogeochemical cycles. Based on stoichiometric estimates, the minimum global inventory of marine DOS is 6.7 Pg S, exceeding all other marine organic sulfur reservoirs by an order of magnitude.

Gridded bathymetry from multibeam echosounder EM122 data of the cruise MSM33 (2013)

Bathymetry based on data recorded during MSM33 between 02.11.2013 -and 10.11.2013 in the Black Sea. The overarching goal of MSM33 was the investigation of the biology and biogeochemistry of the central Black Sea with a special consideration of the processes at pelagic redoxicline. The bathymetric focus laid upon the slope structure especially at the Archangelsky Ridge.