Emissions of heavy metals from road traffic and effect of emitted lead on land contamination in China: A primary study
中国公路交通的重金属排放及其 对土地污染的初步估算

The rapid development of motor traffic in China increases the heavy metal concentrations of the dust, and might contaminate the soils along the roads. In order to quantify the effects of motor traffic on the heavy metal concentrations of roadside soils, the traffic emissions of Pb, Cu, Zn and Cd in individual provinces of China, and the pollution index of Pb in roadside soils, as well as the contaminated areas caused by traffic were calculated by the models induced from the reviews of researches at home and abroad. Results showed that the emissions of Pb, Zn, Cu and Cd from traffic in developed eastern provinces were higher than those in the western provinces. During the years of 1990 to 1996, Pb inputs of the roadside soils in Beijing City ranged from 2.48 to 3.17 mg · kg-1 · a-1, and Pb accumulation was 11.4 mg · kg-1 along the roads because of the use of lead in gasoline. After inverting to lead free gasoline, Pb inputs of the roadside soils in Beijing City decreased to 0.26 ~ 0.29 mg · kg-1 · a-1 from 1997 to 2003, and Pb accumulation was only 1.30mg·kg-1. Lead concentrations in roadside soils decreased rapidly with the increase of distance from road. The land with the distance up to 10 m from road was heavily contaminated by Pb emitted from traffic, and that moderately contaminated between 10 and 65 m. According to the models, the areas of contaminated lands by Pb from motor traffic in Beijing and China were 289 km2 and 3.63×104 km2 in total, respectively. The results revealed that the traffic emission is one of the important reasons of heavy metal contamination of soils in China. This study provides both the models for the relationship between motor traffic and heavy metal concentrations in roadside soils, and the practical guiding for the prevention of heavy metal contamination by motor traffic.