New Sulfur Measurement Results for Geological Reference Materials Obtained via Various Pre‐treatment Methods

Total sulfur (TS), chromium‐reducible sulfur (CRS) and HCl‐insoluble sulfur (HCl‐insoluble S) contents (mass fractions), together with their δ 34 S TS , δ 34 S CRS and δ 34 S HCl‐insoluble S values were measured in marine, stream and lacustrine geological reference materials (RMs). These were JMs‐1, JMs‐2, SBC‐1, SCo‐2, JSd‐3, JSd‐4 and JLk‐1, which include modern surface and ancient sediments. Using these data, the mechanisms for driving sulfur isotopic distinctions between the δ 34 S TS , δ 34 S CRS and δ 34 S HCl‐insoluble S values were systematically investigated. Detectable amounts of acid volatile sulfur were not found in all analysed RMs. On the other hand, sulfate in the analysed RMs was found to have the heaviest δ 34 S values compared with other sulfur species, such as elemental sulfur, pyrite and organic sulfur, which is consistent with expectation, based on sulfur oxidation numbers. The most notable finding is that differences between δ 34 S CRS and δ 34 S HCl‐insouble S values can be reasonably explained by the fact that the sulfur isotope ratio of organic sulfur has a wide range compared with that of other sulfur species. Consequently, this data set could contribute to a better understanding of elemental and isotopic S mass fractions of widely used geological RMs by different acid pre‐treatments.