Distribution and interaction profiles of metal(loid)s and microplastics in lake sediments: Lake Iznik (NW Türkiye)

Abstract Purpose Sediments are often the first areas to be examined in order to understand the behavior, transport, transformation, and accumulation of pollutants in freshwater systems. This study was designed to determine: (1) the distribution, source, and ecological risks of metal(loid)s (Ms); (2) the polymer types, distribution, and ecological risks of microplastics (MP); and (3) the potential for microplastics to function as carriers of metal(loid) in Lake Iznik sediment. Materials and Methods The concentrations of 14 selected metal(loid)s were determined by ICP-MS, the size and morphological characteristics of MPs were examined using a stereomicroscope, and polymer identification was performed using FTIR. The adsorption of Ms onto the MP surface was examined using SEM-EDX. The environmental risks of the detected Ms amounts in sediment were investigated using sediment quality guidelines and indices, along with multivariate statistical analyses. Results and discussion Fe and Al were the elements with the highest concentrations in the sediment and As was the element posing the highest ecological risk. Al, Fe, and Mn were of geogenic origin, while Cd, Cu, and Zn were of anthropogenic origin, as supported by principal component, clustering, and correlation analyses. As, grouped with Ba and Sr and having the highest relative toxicity, was not detected on the surface of MPs, despite being the most abundant element in sediments along with Fe and Mn. Cationic metals such as Cd, Cr, Cu, Pb, and Zn were found to be adsorbed onto the surfaces of MPs. Conclusion The findings demonstrate that the behavior of MPs, specifically their ability to selectively adsorb cationic metals while failing to bind with As oxyanions, is governed by chemical speciation and surface-level interactions within the water. This selectivity controls the distribution and potential mobility of Ms in lake sediments, providing significant data for environmental risk assessments.