Timeline: 2003 – 2005
Funding Source: Oswald Schulze Foundation
Study Location: “Mittlerer Ring” (high capacity ring road in the center) in Munich and Laboratory of the Technical Supervisory Organization of the institute for Water Quality Control and Waste Management.
Role: Primary Researcher

Background:
The National Water Quality Inventory reports that runoff from urbanized areas is the leading source of water quality impairments to surveyed estuaries and the third-largest source of impairments to surveyed lakes (EPA 2003). Since road surfaces comprise the largest proportion of all impervious urban surfaces significant loads of pollutants originate from these surfaces such as nutrients, heavy metals and hydrocarbons (Ngabe et al., 2000; Davis et al., 2001; Farm, 2002). Their runoff is considered a major source of the pollution in the environment (Brezonik and Stadelmann, 2002; Lee et al., 2004). Under certain conditions, related to the nature and characteristics of the road, the runoff event and the receiving water body or ecosystem, pollutants in highway runoff may exert an acute or chronic impact on the receiving soil or water-based ecosystem (Opher et al., 2009). For example in urban receiving waters, the principal pollutants are suspended solids, heavy metals, hydrocarbons and de-icing salts (Mungur et al., 1995). Traffic characteristics (mean vehicle speed, traffic load, etc.), long dry weather periods, climate, rain intensity and rain duration are regarded as important factors in generating pollutions in road runoff (Lee et al., 2004; Crabtree et al., 2006). Therefore, the quality of urban runoff is of increasing concern to communities (Ball et al., 1998).
Unfortunately, significant differences concerning pollutant constituents in stormwater runoff have been found between studies carried out in different countries. The variability from one location to another caused by differences in land-use, climatic influences, traffic density, atmospheric deposition, maintenance, road drainage designs and vehicular traffic density indicates the need for local data (Marsalek et al., 1999; Brezonik and Stadelmann, 2002). Study areas comprise locations in Australia and New Zealand (Ball et al., 1998; Drapper et al., 2000; Mosley and Peake, 2001; Brown and Peake, 2006), North America (Sansalone et al., 1996; Brezonik and Stadelmann, 2002; Lee et al., 2004), Asia (Lee et al., 2002) and Europe (Farm, 2002; Westerlund et al., 2003; Gnecco et al., 2005; Mangani et al., 2005). However, specific data on urban road runoff for Germany are scarce.
On-site treatment plants for elimination of polluted runoff are under consideration and a part of best management practices (BMPs) to replace existing combined or separated sewer systems

(Nanbakhsh et al., 2007). For the development of effective treatment systems knowledge about the occurrence of metals and their attribution to the dissolved or particulate phase is crucial (Sansalone et al., 1996). Many already used treatment systems (geo-textile bags, slow sand filters, etc.) rely on the retention of particulate matter, which is, however, not removed from the runoff flow but remains as passive filter in the systems. A change in runoff composition like e.g. an increase of ionic strength of the runoff due to de-icing salt or a significant pH change within the filter cake due to biological degradation of organic compounds application has the potential of remobilizing these accumulated pollutants at once and thus posing a higher risk than untreated runoff.
The aim of the project was to characterize water quality of heavily polluted urban road runoff for the development of BMPs for climate conditions of the most European countries. Therefore, the concentrations and speciation of the most common heavy metals (Zn, Cu, Pb, Ni, and Cd), organic carbons in general as well as PAHs specifically, de-icing salts, and standard water quality parameter have been analyzed and correlated with climatic and locational factors. Moreover the remobilization potential of heavy metals associated to the particulate portion has been assessed.

This project supported two Research Associates to combine engineering and chemical backgrounds. While his project partner Dr. Rita Hilliges focused on engineering aspects of treatment systems Dr. Schriewer was responsible for the analysis for PAHs, analysis of remobilization capacities for particulate heavy metals and design of laboratory experiments. The responsibility for the overall project management and monitoring schedule was shared by both.

Publications:

Helmreich B., Hilliges R., Schriewer A., Horn H. (2010). Runoff pollutants of a highly trafficked urban road – Correlation analysis and seasonal influences. Chemosphere (80) 991-997.

Schriewer A. (2006): Pollutants in urban storm water runoff and their impact on decentralized treatment systems. Original title (German) Schadstoffpotentiale urbaner Niederschlagsabläufe mit Hinblick auf Behandlungsmöglichkeiten in dezentralen Systemen, Berichte aus Wassergüte- und Abfallwirtschaft der Technischen Universität München“. No 191, Hieronymus Verlag. SSN 0942-914X.