A large number of organic pollutants (OPs) emitted from vehicles and traffic-related activities exhibit environmental persistence and a tendency to bioaccumulate, and may have detrimental long-term effects on aquatic life. The aim of the study was to establish a list of significant sources of OPs occurring in road runoff, identify the OPs emitted from these sources, select a number of priority pollutants (PP), and estimate the quantity of PPs emitted in a road environment case study using substance flow analysis (SFA). The priority pollutants included in the SFA were selected from a list of approximately 1100 compounds found after comprehensive screening, including literature and database searches, expert judgments, the Ranking and Identification of Chemical Hazards method, and chemical analysis of sediments. The results showed the following priority order: polycyclic aromatic hydrocarbons (PAHs)>alkanes C-C>alkylphenols>phthalates>aldehydes>phenolic antioxidants>bisphenol A>oxygenated-PAHs>naphtha C-C>amides>amines. Among these, PAHs were chosen for a SFA, which was performed for a highway case study area in Gothenburg (Sweden). The SFA showed that the main sources of PAHs emitted in the area were vehicle exhaust gases, followed by tyre wear, motor lubricant oils, road surface wear, and brake linings. Only 2-6% of the total 5.8-29kg annually emitted PAHs/ha ended up in the stormwater sewer system. The measured PAH loads were found in much smaller amounts than the calculated loads and the outflow to stormwater contained much more of the hazardous PAHs than the total loads emitted in the catchment area.

Partitioning of organic pollutants is essential to their fate, mobility and removal from water and soil. To study the partitioning behavior of selected alkylphenols, bisphenol A, phthalates and polycyclic aromatic hydrocarbons (PAHs), a method for separating the truly dissolved and colloidal phase of organic pollutants was developed, verified and applied to samples of landfill leachate and stormwater from urban areas and waste-sorting sites. Alkylphenols, bisphenol A, phthalates and PAHs were detected in all the untreated samples (total concentrations), most of the filtered samples and frequently in the colloid-bound phase. Concentrations of alkylphenols and PAHs in urban stormwater were one order of magnitude lower than in the landfill leachates and stormwater from waste-sorting sites. The difference between total, dissolved and colloid-bound concentrations in the water samples was not statistically significant for any phenols or phthalates, but for three of the PAHs; naphthalene (mostly dissolved), phenanthrene and fluoranthene (mostly particulate). These results indicate that in landfill leachates and stormwaters, organic pollutants are predominantly attached to colloids and/or truly dissolved in contrast to their expected strong sorption to particulate matter. Occurrence and concentrations of pollutants in dissolved and colloid-bound phases correlated negatively with the K(OW). However, even highly hydrophobic compounds were frequently detected in filtered samples, i.e. the dissolved phases, and it is suggested that the organic content in the colloids decreases the compounds' partition to particles. The results confirm that the K(OW) values of specific organic pollutants well describe the compounds partition-binding process to dissolved organic carbon (DOC) colloids. Our findings call for a re-assessment of the organic pollutants' mobility and associated risks. This knowledge can also serve as a base for selecting efficient treatment methods for stormwater and landfill leachates.

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