Paper Title
BIOAVAILABILITY OF HYDROPHOBIC ORGANIC CONTAMINANTS IN DANUBE SEDIMENTS: INSIGHTS FROM PASSIVE SAMPLING

Abstract
This study assesses the effectiveness of passive sampling for monitoring priority pollutants in aquatic environments. Using silicone rubber strips as sorption media, passive samplers collected hydrophobic organic compounds from sediment samples. Results showed organochlorine pesticide (OCP) concentrations in pore water ranged from 0.001 to 0.040 ng/L for pentachlorobenzene and 0.05 to 0.2 ng/L for hexachlorobenzene, with the highest mean at RatnoOstrvo (1.25 ng/L) and the lowest at Dubravica (0.29 ng/L), indicating no new pesticide input. Polycyclic aromatic hydrocarbons varied between 0.02 and 15 ng/L, with peak levels at Belegiš (199.54 ng/L). Organophosphate flame retardants ranged from 0.1 to 50 ng/L, and polycyclic aromatic musks were detected from 0.79 ng/L at Pančevo to 5.55 ng/L at Belegiš. Elevated concentrations correlated with high organic carbon content, reflecting significant sediment sorption capacity. Most pollutant levels in pore water were notably lower than annual average Environmental Quality Standards for water, demonstrating the method's precision and sensitivity. Passive samplers effectively predicted pollutant concentrations in aquatic organism tissues, highlighting their utility in assessing bioavailability and ecological impact. This approach offers a reliable alternative to traditional methods for preliminary contamination assessments and supports regulatory frameworks such as the EU Water Framework Directive. Keywords - Sediment, Passive sampling, Hydrophobic organic pollutants, Danube River