| Objective: To understand the concentration, spatial distribution, to evaluate the pollution level of lead in urban soils and road dusts of China, and to provide a scientific and feasible method for control of lead pollution.Methods: Collect papers by keywords "urban soils/topsoil/road dusts/ lead / heavy metal /pollution" in CNKI, Wanfang, CQVIP and Science Direct, Pub Med published during 2000 to 2014. Calculate the weighted average of lead concentration in urban soils. Map the spatial distribution of lead by the software of Arc Gis. Evaluate the pollution level of lead in urban soils by geo-accumulation index and single-factor pollution index method. The ratio of enrichment was from the average of lead concentration in urban soils divided by the background values.Results:1 A total of 92 articles were included in the study, involved 48 cities of 27 metropolises and included 10,925 samples, sampling time was in the year of 1999 to 2014. The studies about lead in urban soils were reported in 64 articles about 39 cities of 25 metropolises and included 8,702 samples. The studies about lead in road dusts were reported in 33 articles about 21 cities of 15 metropolises and included 2,223 samples.2 There were similar spatial distribution in urban soils, urban road dusts in China. Lead content in the eastern regions was higher than central and western regions. There were also obvious differences among different functional areas the city.3 The mean concentrations of lead in urban soils was 53.6 mg/kg, with the range of 22.2~257mg/kg, median was 53.5mg/kg, 92.3%(36/39) of the cities higher than the background value of soil lead in China(26mg/kg), which were Luoyang, Shenyang and Hangzhou, but Guiyang, Taiyuan and Shijiazhuang under local background value. The mean concentrations of lead in urban road dusts was 206.3mg/kg, with the range of 38.5 to 956.0mg/kg, median was 174.7mg/kg, 21 of the cities higher than the background value of soil lead in China(26mg/kg) and local background value, where Zhuzhou, Zhenjiang, Baoji, Shanghai and Baoding, with high lead content. The result of geo-accumulation index(Igeo) showed that pollution index of lead in urban soils in China was 1.27, ranged from-1.47 to 4.07, at the secondary pollution level. There were 25.5%(19/47) of the cities, at middle pollutant level. There were 8.51%(4/47) of the cities, only in cities of Baoji and Baoding, at heavy pollution level. There was only one city, Zhenjiang, was in severely polluted.4 The value of geo-accumulation index(Igeo) of lead in urban soils in China was 0.49, ranged from-1.35 to 3.13, in slightly contaminated. There were 28.2% of the cities, not be polluted; and 56.4% of the cities, in slightly polluted. There were 15.4% of the cities, in partialy moderate polluted, and only in Shenyang, in moderate polluted. There was no city, and was in severely polluted. The value of geo-accumulation index(Igeo) of lead in urban road dusts in China was 1.92, ranged from 0.26 to 4.07, in slightly moderate contaminated. There were 23.8% of the cities, in slightly polluted. There were 28.6% of the cities, in partialy moderate polluted. There were 23.3% of the cities, in moderate polluted. There were two cities(Baoding and Baoji), with 3<Igeo≤4, only Zhenjiang city, was in severely polluted.5 The single-factor pollution index of lead in urban soils was 1.07, ranged from 0.44 to 5.14. There were about 38.5% of the cities, which single-factor pollution index was below 1, not be polluted. There were 48.7% of the cities, which pollution index between 1 and 2, in slightly contaminated. And there were two cities(Quanzhou and Luoyang), with lead pollution index over 3, in heavily polluted. The single-factor pollution index of lead in urban road dusts was 4.27, ranged from 0.77 to 19.12.Two cities(Haerbin and Xuchang), not be polluted,with lead pollution index lower than 1, There were 23.8% of the cities, which pollution index between 1 and 2, in slightly contaminated. There were two cities, which pollution index between 2 and 3, in moderate contaminated. There were 57.1% of the cities, which pollution index over 3, in heavily contaminated.Conclusions:1 The mean concentration of lead in urban topsoils and in urban road dusts, were both higher than soil background values of lead in China. Lead in road dusts >in topsoils.2 There was similar spatial distribution in urban topsoils and road dusts. Lead content in the eastern regions was higher than central and western regions.3 There were also obvious differences among different functional areas in the city. Traffic and industrial regions were heavily contaminated inspite for urban topsoils and road dusts.4 Urban topsoils were in slightly contaminated and road dusts were between moderate and severe pollution. |
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