Ex situ respiration rates measured in water column samples during the James Cook cruise JC087 in June 2013

Oxygen concentration and rate of change of oxygen were measured using the Unisense Oxygen Microsensor System. Water from different depth was taken from CTD attached niskin bottle. Measurements were conducted in 2 ml vials provided by Unisense and lasted for a minimum of two minutes after a stable rate was achieved. The sampling interval was 6 seconds. Transport containers, tubes and vials for measurements were covered with light proof black foil for dark-measurements.

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.