oa Recommendations for Sulfur Species Quantification in Recent Sediments using the Thermal Rock-Eval® 7S Method

The study emphasizes the importance of understanding the sulfur cycle in relation to the carbon cycle in sediments, highlighting the role of microbial activity and sulfate reduction in anaerobic environments. This process influences the production of gases like H2S, CH4, and CO2, affecting biogeochemical fluxes and the preservation of sedimentary organic carbon, which has implications for petroleum generation and gas emissions as well as for metal mobilization.

The temperature ramped Rock-Eval (RE7S®) method, developed for sedimentary rocks, was utilized for the simultaneous quantification of carbon and sulfur. The RE7S analysis involved a two-phase process using different detectors to continuously measure hydrocarbons and gases (CO, CO2, SO2) released by gradual thermal pyrolysis. This method was applied to recent sediments from the Guaymas Basin (Gulf of California) and mixtures of pure compounds offering new insights in distinguishing sulfur and carbon species.

Key findings include the need for prior desalting of sediments for accurate results, the linear but overestimated response of native sulfur quantification, and the identification of interactions between carbonates and metal sulfides. The study proposes new corrections for a better quantification of sulfur species in sediments, highlighting the complex interactions and reactivity of sulfur under varying conditions.