Sulfur compounds in bottom sediments and interstitial waters of the Pacific Ocean to the east of Japan

In near-shore Pacific bottom sediments to the east of Japan unusually high content of free H2S ocurs. H2S resulting from bacterial reduction of sulfates from interstitial waters has a number of derivatives; pyrite dominates among them. Contents of other derivatives of H2S: sulfide sulfur and organic sulfur do not exceed 0,01%, content of organic sulfur does not exceed 0.1%. Due to reduction content of sulfates can reduce to 0,03% S. Capacity of the process of sulfate reduction, estimated by sum of all reduced forms of S - derivatives of H2S, is a function of organic matter content in sediments. Ability of bottom sediments to accumulate free H2S depends on content of reactive forms of Fe. Spatial distribution of reduced forms of S in the studied sediments is considered.

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.