中国公路交通的重金属排放及其对土地污染的初步估算

本文研究了全国各省市机动车Pb、Cu、Zn、Cd排放总量和公路两侧土壤中Pb含量的分布及其面积。结果表明,东部发达省份机动车的重金属排放量较西部地区大。使用含铅汽油的1990~1996年期间,北京市公路两侧土壤中Pb的年输入量为2.48~3.17 mg/ (kg · a)、累积量为11.4 mg/kg;1997~2003年使用无铅汽油后,两者分别下降到0.26~0.29 mg/(kg · a)和1.30 mg/kg。公路两侧的土壤中Pb含量随垂直距离的外延呈指数形式下降。公路交通对道路两侧土壤产生严重和轻度Pb污染的范围分别为距公路0~10 m和10~65 m。2003年北京市和全国受公路交通Pb污染的土地面积为2310 km²和28900 km²。公路交通的重金属排放是导致我国土地污染的重要原因之一。

Emissions of heavy metals from road traffic and effect of emitted lead on land contamination in China: A primary study

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.