New Metal Emission Patterns in Road Traffic Environments

Abstract

The increased awareness of traffic as a major diffuse metal emission source emphasizes the need for more detailed information on the various traffic-related sources and how and where the metals are dispersed. In this study, metal emission patterns in the road traffic environment were examined from the perspective of different surrounding factors, e.g. the importance of intersections, deceleration, vehicle speed and traffic density. A total of 148 topsoil samples from 18 south Swedish roads were analysed (using GFAAS) for traffic-emitted metals, i.e. Cd, Cr, Cu, Ni, Pb, Sb and Zn. The roadside topsoil metal concentrations were used to examine correlations between metals and surrounding factors. The studied metals were divided into three groups corresponding to different emission sources: metals from decelerating activities (Cu, Sb and Zn), metals as historical residues from the combustion of petrol (Pb and Cd), and non-source-specific metals (Cr and Ni). It was found that Cu and Sb, despite their rather short history as traffic-emitted metals, have increased more than eightfold in roadside soils compared to background levels. The major source of road traffic related Cu and Sb is brake linings. The significant increase of Cu and Sb in roadside topsoil stresses the need for metal transport studies as well as effect studies of these metals. Metals emitted due to decelerating activities were not correlated to elevated concentrations near road junctions. Emission patterns of traffic-related metals alongside roads are crucial in order to be able to evaluate the optimal localization of storm water treatment ponds.

Pollution Assessment and Health Risk Implication of Human Exposure to Heavy Metals in Road Dusts from Different Functional Areas in Jeddah, Saudi Arabia

“…For Cd, As, Pb, Zn and Cu were more than 10, indicating that they were severely enriched. Cu, Pb and Zn are reported to be multi-source related and their accumulation is commonly found to be anthropogenic and from traffic related materials (brake dust, tires tread and yellow paint) [91]. Moreover, high atmospheric temperature and exposure to weather may accelerate corrosion processes, causing wear of the wares, walls, lamps and railings that often contained the heavy metals such as Zn, Cu, Cd and Cr, then resulting in the release of the metals to the urban environment and accumulation in urban street dust [14,78,92].…”

Metal Accumulation Profile in Roadside Soils, Grass and Caesalpinia Plant Leaves: Bioindicators

“…The same meteorological conditions affect the concentration of same contaminants in the roadside soil [2]. The traffic density determines the lead level in soil and vegetation [11][12][13].…”

A chemometric approach to study the effects of motorway proximity on microelements content in wheat and soil

“…Wheat is often grown in soils along road sides with heavy traffic flow where exhaust gases from motor vehicles are released into the atmosphere and may have harmful effects on the soil and plants (Hjortenkrans et al 2006). Davies and Holmes (1995) found that a Pb content of 0.45 g/l in petrol and the 24-h traffic volume resulted in an increase in the concentration of lead in the air on both sides of the road of 1 lg/m 3 per 1,000 vehicles.…”

“…Traffic-related soil pollution occurs near roads with a traffic density above 20,000 vehicles per day (Hjortenkrans et al 2006). The emission of fine lead particles from automobile exhaust, which may also be adsorbed directly through the leaves, results in lead uptake in roadside vegetation.…”