Tar patties are hotspots of hydrocarbon turnover and nitrogen fixation during a nearshore pollution event in the oligotrophic southeastern Mediterranean Sea.

Weathered oil, that is, tar, forms hotspots of hydrocarbon degradation by complex biota in marine environment. Here, we used marker gene sequencing and metagenomics to characterize the communities of bacteria, archaea and eukaryotes that colonized tar patties and control samples (wood, plastic), collected in the littoral following an offshore spill in the warm, oligotrophic southeastern Mediterranean Sea (SEMS). We show potential aerobic and anaerobic hydrocarbon catabolism niches on tar interior and exterior, linking carbon, sulfur and nitrogen cycles.

Tropospheric carbonyl sulfide mass balance based on direct measurements of sulfur isotopes.

Robust estimates for the rates and trends in terrestrial gross primary production (GPP; plant CO uptake) are needed. Carbonyl sulfide (COS) is the major long-lived sulfur-bearing gas in the atmosphere and a promising proxy for GPP. Large uncertainties in estimating the relative magnitude of the COS sources and sinks limit this approach.

Sulfur isotopes ratio of atmospheric carbonyl sulfide constrains its sources.

Carbonyl sulfide (COS) is the major long-lived sulfur bearing gas in the atmosphere, and is used to estimate the rates of regional and global (both past and current) photosynthesis. Sulfur isotope measurements (S/S ratio, δS) of COS may offer a way for improved determinations of atmospheric COS sources. However, measuring the COS δS at the atmospheric concentrations of ~0.

Variability in sulfur isotope composition suggests unique dimethylsulfoniopropionate cycling and microalgae metabolism in Antarctic sea ice.

Sea ice microbial communities produce large amounts of the sulfur metabolite dimethylsulfoniopropionate (DMSP), a precursor of the climate cooling gas dimethylsulfide. Despite their importance to the polar sulfur cycle, drivers and metabolic pathways of sea ice DMSP are uncertain. Here we report the first measurements of sea ice DMSP sulfur isotopic composition (S/S ratio, δS).

Compound-Specific Sulfur Isotope Analysis of Petroleum Gases.

We describe a simple, sensitive, and robust method for sulfur isotope ratio (S/S) analysis of ppm-level organic sulfur compounds (OSCs) in the presence of percent-level HS. The method uses a gas chromatograph (GC) coupled with a multicollector inductively coupled plasma mass spectrometer (MC-ICPMS). The GC, equipped with a gas inlet and a valve that transfers the HS to a thermal conductivity detector (TCD), enables a precise heart cut and prevents the saturation of the MC-ICPMS.

A sensitive method for the sulfur isotope analysis of dimethyl sulfide and dimethylsulfoniopropionate in seawater.

Rationale: Dimethyl sulfide (DMS) is the major volatile sulfur species emitted to the atmosphere from the oceans. The sulfur isotope ratio ((34)S/(32)S) of DMS may offer a way to calculate the contribution of marine DMS to global sulfur cycling. The S-isotopic analysis of DMS is difficult due to its low concentrations in natural seawater and high chemical reactivity.

Sulfur isotope homogeneity of oceanic DMSP and DMS.

Oceanic emissions of volatile dimethyl sulfide (DMS) represent the largest natural source of biogenic sulfur to the global atmosphere, where it mediates aerosol dynamics. To constrain the contribution of oceanic DMS to aerosols we established the sulfur isotope ratios ((34)S/(32)S ratio, δ(34)S) of DMS and its precursor, dimethylsulfoniopropionate (DMSP), in a range of marine environments. In view of the low oceanic concentrations of DMS/P, we applied a unique method for the analysis of δ(34)S at the picomole level in individual compounds.

Compound-specific delta34S analysis of volatile organics by coupled GC/multicollector-ICPMS.

We have developed a highly sensitive and robust method for the analysis of delta(34)S in individual organic compounds by coupled gas chromatography (GC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The system requires minimal alteration of commercial hardware and is amenable to virtually all sample introduction methods. Isobaric interference from O(2)(+) is minimized by employing dry plasma conditions and is cleanly resolved at all masses using medium resolution on the Thermo Neptune MC-ICPMS.

Sulfur isotope fractionation during incorporation of sulfur nucleophiles into organic compounds.

(34)S enrichment is shown to occur during sulfurization reactions and for the first time conclusively attributed to an isotope equilibrium effect rather than selective addition of (34)S enriched nucleophiles.

Sulfur stable isotope distribution of polysulfide anions in an (NH4)2Sn aqueous solution.

Methylation of polysulfides [(NH4)2Sn)] by reaction with CF3SO3CH3 followed by separation of the produced dimethylpolysulfides by liquid chromatography and subsequent highly accurate stable isotope analysis by a continuous-flow isotope ratio mass spectrometer shows that polysulfide anions in an aqueous solution exchange isotopes with the other sulfur species in the system. It demonstrates for the first time that polysulfide anions are 34S-enriched in equilibrium relative to total sulfur as a function of their sulfur chain length.