title: Critical review of heavy metal pollution of traffic area runoff: Occurrence, influencing factors, and partitioning.
abstract: A dataset of 294 monitored sites from six continents (Africa, Asia, Australia, Europe, North and South America) was compiled and evaluated to characterize the occurrence and fate of heavy metals in eight traffic area categories (parking lots, bridges, and three types each of both roads and highways). In addition, site-specific (fixed and climatic) and method-specific (related to sample collection, preparation, and analysis) factors that influence the results of the studies are summarized. These factors should be considered in site descriptions, conducting monitoring programs, and implementing a database for further research. Historical trends for Pb show a sharp decrease during recent decades, and the median total Pb concentrations of the 21st century for North America and Europe are approximately 15 μg/L. No historical trend is detected for Zn. Zn concentrations are very variable in traffic area runoff compared with other heavy metals because of its presence in galvanized structures and crumbs of car tire rubber. Heavy metal runoff concentrations of parking lots differ widely according to their use (e.g., employee, supermarket, rest areas for trucks). Bridge deck runoff can contain high Zn concentrations from safety fences and galvanizing elements. Roads with more than 5000 vehicles per day are often more polluted than highways because of other site-specific factors such as traffic signals. Four relevant heavy metals (Zn, Cu, Ni, and Cd) can occur in the dissolved phase. Knowledge of metal partitioning is important to optimize stormwater treatment strategies and prevent toxic effects to organisms in receiving waters.
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 8, 85748 Garching, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Huber
authors.affiliation: Fachgebiet Siedlungswasserwirtschaft und Hydromechanik, Frankfurt University of Applied Sciences, Nibelungenplatz 1, 60318 Frankfurt am Main, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Welker
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 8, 85748 Garching, Germany. Electronic address: b.helmreich@tum.de.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Helmreich
mesh_terms: D000349:Africa; D001208:Asia; D001315:Australia; D004784:Environmental Monitoring; D005060:Europe; D019216:Metals, Heavy / Q000032:analysis*; D009656:North America; D013020:South America; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical
keywords: Bridge; Dissolved heavy metals; Highway; Parking lot; Road; Site-specific factor