Sulfur isotopic composition of H2S and SO4(2-) from mineral springs in the Polish Carpathians.

A number of springs in Carpathian Mts. contain dissolved H2S and SO4(2-) in concentrations above 10 mg/dm3. In this study we have investigated the sulfur isotope composition (delta34S) of the dissolved sulfur species in the springs from the flysch area in the Carpathian Mts. along the tectonic dislocation. It is believed that some of these springs may carry a major fraction of dissolved sulfur species of extremely deep sulfur (of mantle origin), which is subjected to SO4(2-)-H2S isotope exchange at high temperatures. The original isotopic compositions may be modified by reduction/oxidation at low temperatures and by admixture of sulfur from other sources. In order to distinguish the sulfur of mantle origin we investigated delta34S of dissolved sulfide and sulfate and on the basis of known concentrations we calculated delta34S of total dissolved sulfur. The isotope fractionation between sulfate and sulfide helped to distinguish the sulfur origin. Evaluating the sulfur isotope exchange, we selected 4 springs which likely have only weakly disturbed sulfur of mantle origin.

A modified technique for the preparation of SO2 from sulphates and sulphides for sulphur isotope analyses.

A modified technique for the conversion of sulphates and sulphides to SO2 with the mixture of V2O5-SiO2 for sulphur isotopic analyses is described. This technique is more suitable for routine analysis of large number of samples. Modification of the reaction vessel and using manifold inlet system allows to analyse up to 24 samples every day. The modified technique assures the complete yield of SO2, consistent oxygen isotope composition of the SO2 gas and reproducibility of delta34S measurements being within 0.10 per thousand. It is observed, however, oxygen in SO2 produced from sulphides differs in delta18O with respect to that produced from sulphates.

Low-Temperature Thermal Decomposition of Sulfates to SO(2) for On-Line (34)S/(32)S Analysis.

We describe a fast, inexpensive, and safe method of direct SO(2) extraction from BaSO(4) for sulfur isotopic analysis by mass spectrometry. Only two reagents are used: (1) pure NaPO(3), which is mixed with BaSO(4) sample, and (2) Cu foil, from which reaction boats are manufactured. The extraction precedes in the Cu boat placed into a quartz tube connected to a vacuum line. The boat is heated to 650-700 °C while pure SO(2) produced is collected in a "cold finger". Reaction is complete in 7-10 min. We have proven by means of (18)O-enriched BaSO(4) specimens that the oxygen isotopic composition of the SO(2) is totally controlled by (18)O content in NaPO(3), when the weight ratio of the reagent to sample exceeds 6:1. The method described can be used for "on-line" SO(2) preparation for isotopic analysis.