Multivariate Assessment of Heavy Metal and Boron Levels in Međuvršje Lake Water: Implications of Long-Term Upstream Metal Processing Industry

This study investigates trace element concentrations in surface waters of Lake Međuvršje and evaluates their environmental relevance within Serbian and EU regulatory frameworks. Seventy-five samples were analyzed for B, Ba, Cu, Mn, Ni, Pb, and Zn. Multivariate analyses (Pearson correlation, PCA, and hierarchical clustering) revealed distinct geochemical groupings, indicating both natural lithogenic influences and potential anthropogenic inputs. Censored data analysis showed that Ni, Pb, Zn, and B were dominated by values below the analytical detection limit, rendering conventional geostatistical interpolation inappropriate. These elements were therefore assessed using detection-based spatial analyses, whereas Cu, Mn, and Ba exhibited sufficient variability for quantitative spatial interpolation. This study highlights the importance of integrating regulatory assessment, multivariate statistics, and censoring-aware spatial analysis to ensure reliable interpretation of freshwater trace element distributions.