Integrated study of sediments and fish from Croatian rivers: potentially toxic elements and human health concerns

Aquatic ecosystems are highly vulnerable to contamination by potentially toxic elements (PTEs), with sediments acting as long-term sinks and fish serving as bioindicators of environmental pollution. This study evaluated PTE concentrations in river sediments and three Squalius chub species (S. cephalus, S. squalus, S. svallize) collected from Croatian rivers that belong to the Adriatic and Danube basins. Chemical analyses were performed using inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) following acid microwave-assisted digestion. Principal Component Analysis (PCA) biplot and Self-Organizing Maps (SOM) were applied to explore spatial patterns and associations among PTEs. Environmental implications were assessed using the contamination factor (CF) and ecological risk indices (Eri, RI), while human health risks (non-carcinogenic-HQ, HI and Carcinogenic Risk-CR, R) were estimated for fish consumers. Sediment analyses revealed that most PTE concentrations were below international guideline values, except for Cd, which frequently exceeded regulatory limits and represented the dominant ecological risk contributor. Moderate environmental risk (RI > 150) was observed in sediments from Vidak-Stubičke Toplice and Kupica-Brod na Kupi, both from Danube basin. Multivariate analyses highlighted a clear basin-dependent geochemical signature in sediments, while fishes are more complex with less basin-specific patterns, reflecting the combined influence of environmental exposure and biological processes. Cadmium was identified as the key sediment contaminant, while Pb and Cr in fish represented major food safety concerns. Health risk indices (HI > 1; CR > 1 × 10^-6) show that long-term uncontrolled consumption of the analysed fish is not advisable. The integrated application of analytical and statistical approaches provides a robust framework for environmental monitoring and public health management in Croatia.