Soil pollution of the Labin city area with polycyclic aromatic hydrocarbons derived from Raša coal mining and associated industries

The aim of this study was to determine the mass fraction of polycyclic aromatic hydrocarbons (PAHs) in the soil of the Labin city area (west Croatia) as a consequence of the pollution caused by centuries old Raša coal mining and associated metal processing and foundry industries. Samples of topsoil down to 10-cm depth, following the removal of plant cover, were collected, air-dried, and sieved to <2 mm. Afterwards, they were extracted, and PAH levels were measured by high performance liquid chromatography using a fluorescence detector with a varying wavelength of excitation and emission (HPLC/FLD). The results showed substantially elevated levels of PAHs across the study area. The soil pollution with PAHs increased in the direction towards the Raša Bay, where a former coal separation unit was in operation decades ago. The results demonstrated the presence of pyrolitic PAHs that resulted from Raša coal combustion at high temperatures in power plants, and unburnt coal-derived PAHs formed by Raša coal carbonization. This paper for the first time reports levels of PAHs in soil of the Labin city area, establishing them as higher than the values set by Croatian legislation. Therefore, this study clearly calls for immediate clean-up measures in order to solve the environmental pollution issue of the vulnerable local karst area.