Assessing sediment contamination status in Important Bird and Biodiversity Areas in Spain

River sediments constitute the physical habitat of aquatic ecosystems and are an important food resource for species and provide a source of life. Yet, sediments are also sinks of chemicals released from the many anthropogenic activities occurring along the river basin. The objective of this study is to determine the presence and risk of 52 legacy and emerging organic pollutants in sediments of 140 Important Bird and Biodiversity Areas (IBAs) located throughout the Spanish territory. In each IBAs, landscape observations including the existence of wastewater treatment plant (WWTP) discharges, picnic areas, landfills, agriculture, industry, urban areas, and human-generated waste (trash) abandoned in nature were recorded and served to determine the main pressures and impact. Sediments were analysed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The total sum of contaminants in sediments ranged from 0.07 to 31076 ng/g and the most ubiquitous pollutants were polycyclic aromatic hydrocarbons (PAHs), DDTs, and polychlorinated biphenyls (PCBs), while plasticizers and organophosphate esters (OPEs) were detected at the highest concentration, likely due to their recent use and dumping of plastics associated with garbage. Currently used pesticides were seldom detected. The concentrations detected have been compared to sediment quality standards and Predicted No-Effect Concentrations (PNEC) to evaluate the potential risk for the aquatic ecosystem. Risk compounds and pollution hotspots have been identified and mapped. Threshold concentrations are provided to protect habitats and species that live in IBAs, and we highlight the need for sediment monitoring to preserve biodiversity.