Trace element and radiological characterisation of ash and soil at a legacy site in the former Raša coal-mining area

Abstract

Coal mined in the shut-down Raša mine in Istria, Croatia had a high organic sulphur content. What has remained of its local combustion is a coal and ash waste (legacy site) whose trace element and radionuclide composition in soil has enduring consequences for the environment. The aim of this study was to follow up on previous research and investigate the potential impact on surrounding soil and local residents by characterising the site’s ash and soil samples collected in two field campaigns. Trace elements were analysed using particle induced X-ray emission (PIXE) analysis. Radionuclides, namely ²³²Th, ²³⁸U, ²²⁶Ra, ²¹⁰Pb, and ⁴⁰K, were analysed with high resolution gamma-ray spectrometry. PIXE analysis confirms previous findings, whereas radionuclide analysis shows higher activity concentrations of ²³⁸U, ²²⁶Ra, and ²¹⁰Pb in ash samples than the worldwide average, and the absorbed dose rates for local residents are up to four times higher than background levels. Our findings confirm the need of investigating coal industry legacy sites and the importance of remediation of such sites.