Seasonal distribution, source identification, health and eco-toxicological risk assessment of PAHs in water and sediment from the Danube River in Hungary

Abstract

The Danube is one of the largest transboundary rivers word-wide, having several tributaries. The discharges from industrial activities and wastewater treatment facilities affect the river's aquatic environment. These discharges pose a serious risk to aquatic life by degrading the water and sediment quality. Therefore, 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds in six different locations were examined along the river over 12 months to investigate the temporal and special variations of the compounds in water and sediment. The findings highlighted a broad variance range in PAHs concentration in water within a year, ranging from 224.85 ng/L in summer to 365.87 ng/L in winter, whereas PAHs in sediment samples recorded values ranging from 316.72 ng/g in dry weight in summer to 422.98 ng/g in dry weight in winter. The overall results indicate that the putative anthropogenic sources of PAHs were of pyrolytic and pyrogenic origin; with pyrogenic sources being more prominent. Generally, except for Acenaphthylene and Fluorene concentrations, the eco-toxicological concerns for the aquatic environment of the Danube River do not pose a significant threat. In addition, the combined impact of the 16 PAHs pollutants in sediments suggests a low chance for negative biological impacts and low ecological risk. The total ILCR for both children and adults is more than 1/104 in all seasons, with the highest values recorded in spring followed by winter time, which becomes a matter of urgency.