On site determination of sulfur concentrations of sedimentary rock by XRF analysis

Determination of sulfur concentrations of sedimentary rocks is very important for tunnel constructions, because construction waste soils containing high sulfur may lead acid water pollution. We determined X-ray intensities of S Kα of certified standards for sediments and sedimentary rocks. The ratios of X-ray intensity of S Kα to its sulfur concentration for JMS-1 and JMS-2 (AIST marine sediment standards) are significantly higher than JSd-2 (AIST river sediment standard obtained from the downstream of the a mining site) containing sulfide minerals, suggesting that the ratio of X-ray intensity of S Kα to its sulfur concentration is controlled by the sulfur bearing minerals in these standards. The ratios of X-ray intensities of S Kα to their sulfur concentrations for the in-house standard obtained by mixing kaolinite and sulfate (CaSO₄) powders are significantly higher than those of the in-house standards obtained by mixing of kaolinite and sulfide minerals (FeS₂, ZnS) powders. These differences may be caused by the higher X-ray absorptions of S Kα in sulfide than sulfate. (author)