Decoupling environmental contamination from human health risk through selective bioaccumulation: The role of analytical spectrum and physiological modulation.

This study discusses metal(loid) accumulation in the Kızılırmak Delta system (Samsun, Türkiye) using a multilayered approach. Fifteen metal(loid)s, including As, Cd, Hg, Pb, Cr and Ni, were studied in 5 different lagoons, the Kızılırmak River, and the Black Sea as a whole. Environmental pollution, bioaccumulation, and human health risks were evaluated in an integrated manner. While contrasting hydrological seasons were chosen for water and sediment samples, we focused our biotic sampling on the wet season. Data were analyzed using sediment assessment indices such as the enrichment factor (EF) and the contamination factor (CF) (Layer 1), bioaccumulation indices such as BAF, BSAF, and MPI (Layer 2), along with non-carcinogenic (THQ, HI) and carcinogenic risk indices (CR, TCR) that are important for public health (Layer 3). Layer 3, while separated from Layer 1 by the hotspots it revealed, showed closer agreement with Layer 2. Furthermore, the lack of correlation between BAF and BSAF supported this decoupling. The results of this study show that freshwater and saltwater habitats may influence tissue-specific accumulation patterns. Additionally, reducing the analytical spectrum from 15 metal(loid)s to commonly used subsets of 9 and 5 was found to alter tissue hierarchies, suggesting that MPI results are sensitive to the number and selection of elements. Ultimately, the metal(loid) risk in transitional systems is governed by selective biological transfer and analytical resolution, rather than solely by environmental load.