Assessing heavy metal bioavailability and ecological risks in river sediments: A case study of the Dłubnia River, Poland

The Dłubnia River plays a vital role in the water supply for the residents of Kraków. The Geoaccumulation Index (I geo ), Pollution Load Index (PLI), Environmental Risk Factor (ERF) and the forms of heavy metals (HMs) were used to assess the environmental hazard of HMs in the bottom sediments (BS) of the Dłubnia River. Total concentrations of HMs were determined in BS collected at Imbramowice, Grzegorzowice Wielkie, Iwanowice, Podskale, Michałowice, Młodziejowice and Raciborowice: Cd (0.00–0.825 mg∙kg −1 d.m); Cu (0.00–36.057 mg∙kg − 1 d.m), Cr (3.04–18.145 mg∙kg −1 d.m), Ni (2.002–12.141 mg∙kg −1 d.m), Pb (2.326–46.489 mg∙kg −1 d.m) and Zn (21,659–489.49 mg∙kg −1 d.m). The highest concentrations of the HMs were found in Imbramowice . I geo values ranging from −3.8–2.8 revealed that the BSs are not polluted only in Grzegorzowice Wielkie. The PLI revealed that the BSs in Imbramowice are polluted with HMs (1.8–3.5). ERF values ranging from 0.00 to 0.40 showed a low risk of HMs contamination throughout the length of the Dłubnia River. The results of the speciation of HMs analysis indicated that the dominant form of HMs in the BSs was the immobile form, that is, bound to silicates. The results confirmed that surveying watercourses that are Level 2 river catchments and drain into main rivers is justified.