Influence of traffic in the heavy metals accumulation on urban roads: Torrelavega (Spain)-Soacha (Colombia)

Abstract

High concentrations of heavy metals have been detected in soils associated with a high density of traffic. The road users and those living in nearby environments are potentially exposed. This paper presents a study of the behavior of heavy metals concentration associated with the sediment accumulated on road surfaces (Torrelavega-Spain and Soacha-Colombia). Two types of samples are distinguished: aspired directly and collected after sweeping. The particle size distribution (63-2800 μm) and heavy metals concentration (Pb, Zn, Cu, Cr, Cd and Ba) associated with each size fraction were determined by means of flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry. The results showed that the sediment with a longer residence time on the surface was more exposed to crushing generated by traffic (i.e., finer particle size distribution). As a result, this sediment probably tended to present a greater susceptibility to the suspension by the wind and traffic turbulence. In this sense, the size fraction of less than 63 μm presented the highest concentrations. The larger the residence time of the sediment on the road surface, the higher the metal concentrations associated with it. Areas with a higher traffic density tend to have the highest concentrations. Furthermore, the roads with greater use as parking zones tend to have the highest concentrations, despite registering a lower density of traffic. In the researched cities, Pb exceeds the limits established by law used as reference.