Integrated monitoring of particle associated transport of PAHs in contrasting catchments

Water quality of rivers depends often on the degree of urbanization and the population density in the catchment. This study shows results of a monitoring campaign of total concentration of polycyclic aromatic hydrocarbons (PAHs) and suspended particles in water samples in adjacent catchments in Southern Germany with similar geology and climate but different degrees of urbanization. Defined linear relationships between total concentrations of PAHs in water and the amount of suspended solids were obtained indicating predominance of particle-facilitated transport. The slopes of these regressions correspond to the average contamination of suspended particles (Csus) and thus comprise a very robust measure of sediment pollution in a river. For the first time, we can show that Csus is distinct in the different catchments and correlates to the degree of urbanization represented by the number of inhabitants per total flux of suspended particles.

► PAHs in water samples show a linear correlation with the total suspended solids.
► PAHs on suspended solids correspond to mean concentrations in sediments sampled.
► Degree of urban pressure per particle flux drives PAH loads on suspended particles.
► Dilution of particle associated pollutants requires “clean background” particles.