Dynamic Transport and Distribution of Organic Pollutants in Water and Sediments of the Rur River

Abstract

The distribution and fate of organic pollutants within different compartments of a river system are determined by several key effects and drivers. Within the scope of this study, the aqueous and sedimentary compartments have been analyzed complementary to understand transport and accumulation pathways and to determine temporospatial effects. The bi-annual campaigns allow general statements to be made about relevant processes and effects on pollutant distribution. GC/MS non-target screenings revealed that there is only a minor group of contaminants that occur both in the water and in the riverbed. Nevertheless, for both phases, the main contamination with organic compounds occurred in the anthropogenic, middle to lower course of the river with loads up to 18.3 kg/d (2,4,7,9-tetramethyl-5-decyne-4,7-diol, TMDD) in the water and amounts up to 3.3 mg/gTOC (ƩEPA16 polycyclic aromatic hydrocarbons, PAHs) in the riverbed. Main emission sources were comparable, resulting in a high, almost constant contamination level which also contributes to the pollution of the superior, receiving river. Indeed, the pollution transport of the aqueous and sedimentary phases was closely connected, but with slight temporal and spatial heterogeneities. For the aqueous compartment, seasonal effects were identified while a remarkable change in riverbed contamination occurred due to an extreme flood event. However, dams within the catchment system cause a disconnection of the transport of lipophilic and hydrophilic substances. Overall, the combined investigation of different phases is an important aspect for a comprehensive view of river and environmental contamination.