o:9612 Spatiotemporal variability of heavy metals and metalloid contamination in Danube River sediments (Serbia) based on 23-year integrated monitoring en Contamination of aquatic ecosystems by potentially toxic elements, including heavy metals and metalloid (HMs), is a persistent environmental concern due to their toxicity, persistence, and bioaccumulation. Regulated rivers with large dam systems are particularly vulnerable because altered hydrodynamics and sediment retention promote pollutant accumulation. Here, we present a first 23-year integrated dataset (2001–2023) assessment of HMs in surface sediments of the Serbian Danube River based on 620 samples collected at ten profiles from Novi Sad to Kusjak. Concentrations of Fe, Pb, Zn, Cu, Ni, Cr, As and Cd were determined, and contamination was evaluated using the geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI), SQGs and toxic risk index (TRI). To move beyond routine monitoring, site-specific background values for each element were derived statistically, variability was quantified by coefficients of variation (CV), and multivariate analysis (PCA) was applied to identify geochemical patterns and distinct element behavior. Most HMs showed low to moderate levels, with localized hotspots. Igeo and EF indicated As and Cd as the most critical elements, ranging from unpolluted to locally heavily polluted conditions, whereas Cu, Zn, and Cr generally indicated moderate contamination. PLI and TRI exhibited the highest values in downstream Iron Gate Reservoir profiles highlighting dam-driven sediment trapping. Upstream profiles showed improving temporal trends, likely associated with reduced local anthropogenic inputs, whereas downstream reservoir profiles remained stable or slightly deteriorated due to dam-induced sediment trapping and long-term accumulation of contaminants. Danube River, Sediment quality, Heavy metals 1552101 0269-4042 1552099 10.1007/s10653-026-03213-9 2026-05-20T09:03:14.583Z 44 no 46 Tatjana Mitrović Institute of Physics, University of Belgrade, Belgrade, Serbia 0000-0002-5991-1445 Marija Perović Jaroslav Černi Water Institute, Belgrade, Serbia person 0000-0003-2045-001X Darija Obradović Institute of Physics Belgrade, University of Belgrade, Belgrade, Serbia person Anđelka Petković Jaroslav Černi Water Institute, Belgrade, Serbia person 0009-0006-0162-6920 Jasna Čolić Jaroslav Černi Water Institute, Belgrade, Serbia person 0000-0002-4407-1885 Tanja Nenin Jaroslav Černi Water Institute, Belgrade, Serbia person Saša Lazović Institute of Physics Belgrade, University of Belgrade, Belgrade, Serbia person application/pdf 1546642 https://unilib.phaidrabg.rs/o:9612 no yes 1 70 92000001 71A04 Environmental Geochemistry and Health 48 7 1 21 Springer, Dordrecht, Netherlands 2026 Received: 11 March 2026 Accepted: 21 April 2026 Published online: 28. April, 2026