Co-occurrence of microplastics and polycyclic aromatic hydrocarbons in the Júcar River basin (E Spain): The benchmark before 2024's floods

The south of the province of Valencia (Spain) is characterised by high flood risk and, in October 2024, Júcar River tributaries were partially responsible for catastrophic floods in the area related to the influence of global warming. The floods carried large amounts of water and sediment and, with them, many pollutants such as microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs). Co-occurrence of MPs and PAHs was investigated in water, sediment and fish samples from the Júcar River basin to set a benchmark of pollution in this flood susceptible area, only four months before the October 2024 catastrophe. Extractions were optimized based on matrix and compound type. Analyses were performed by micro-FTIR, Pyrolysis coupled with Gas Chromatography-Mass Spectrometry (Py-GC–MS) and GC–MS/MS, and ecological and human health risks were, also, estimated for the determined pollutants. Both MPs and PAHs were detected in the majority of samples, with higher concentrations near the river mouth (up to 100 ± 3.8 MPs Kg −1 and 2017.4 ± 107.8 ng g −1 of total PAHs), located close to the metropolitan area of Valencia and its industrial zone. One fish sample ( A. alburnus ) presented a concentration of 19.97 ± 1.1 μg g −1 of polypropylene (PP) and was contaminated by 11 PAHs, including benzo[ a ]pyrene (14.2 ± 1.2 ng g −1 ). Incremental life cancer risk values for MPs and PAHs ranged from 1.7 × 10 −6 to 3.1 × 10 −4 for all water samples where PAHs were detected, and for the highly polluted fish sample (14.5 × 10 −3 and 7.7 × 10 −5 ), indicating potential risk. Principal component analysis (PCA) suggested positive correlation between PP, benzo[ a ]pyrene and potential cancer risk. This is the first study that provides data on both MPs and PAHs ecological and human health risk assessment in the same environmental samples from a river catchment and establish a benchmark for these pollutants before flooding. • MPs and PAHs were determined in the Jucar River basin by μFTIR, Py-GC–MS and GC–MS/MS. • Both pollutants were more abundant in sediment and fish compared to water. • PAHs´ RQ values point to potential ecological risk at the final part of the river. • ILCR MPs / ILCR PAHs > 10 −6 indicated potential cancer risk through water/ fish consumption. • PCA showed positive correlation between PP, benzo[ a ]pyrene and potential cancer risk.