Heavy metals toxicity assessment in water and bottom sediments of two tourist lakes of different origin near Gorzów Wielkopolski (western Poland)

Lake tourism includes activities both within the lake itself and in its immediate surroundings. These activities may lead to a range of changes in lake ecosystems, including an increased input of pollutants. Among the most important and still widely studied pollutants are heavy metals (HMs), whose concentrations and potential toxicity were investigated in the waters and bottom sediments of two lakes of different origin near Gorzów Wielkopolski: the natural Kłodawskie Lake and the gravel pit lake Karnin Reservoir. HM concentrations were determined using inductively coupled plasma triple quadrupole mass spectrometry (ICP-QQQ-MS). The results obtained for HMs in water were analyzed in terms of potential toxic effects on humans, whereas HMs in bottom sediments were assessed in terms of their potential toxicity to aquatic biota. The results indicate comparable HM concentrations in the waters of both lakes and show no potential non-carcinogenic and carcinogenic health risk for humans, both in terms of chronic dermal exposure and quantitative assessment. In contrast, HM concentrations in bottom sediments differed significantly between the lakes, with notably higher values recorded in Kłodawskie Lake. The assessment of individual HMs using the modified hazard quotient (mHQ) indicated very low toxicity for Pb and Zn, and to a lesser extent for Cd, Cu, and Ni. Integrated indices indicated no potential combined toxicity of HMs. The presented study provides a basis for conducting similar analyses in lakes used for recreational purposes and highlights the potential of gravel pit lakes for tourism, particularly in regions characterized by a low number of natural lakes.