title: [Content trends of pollutants in street dust of Beijing along the urban-rural gradient and road density gradient].
abstract: In the article, pollutant content of 220 road dust samples within the sixth ring road of Beijing have been investigated by using grid stationing sampling method. The changing characteristics of road nude number per unit area, road network density and pollutant content within buffering areas along urban to rural gradient were also studied. Three following variation trends are presented as each index varies widely within the research areas. Firstly, road nude number per unit area, road network density and Cu, Cr, Pb content decrease along urban to rural gradient, and they decrease sharply in the beginning. Secondly, Mn, Cd content change a little along urban to rural gradient, and mean value remains stable. Thirdly, the content of Ni, TOC, TN decreases along with the distance fluctuations in the beginning and their mean values are then rising slowly in the suburbs. The turning point of pollutant content are found in places 15-20 km away from city center. The article shows that the road index and Cd content are irrelevant, and weak correlations are found between road index, TS, Mn and pH. And other relevance ranking are described as follows: Cu > TN > TOC > Pb > Ni > Cr. In contrast with road network density, higher correlations between road nude number per unit area and each element are fond, and element pollution of Cu, TN, TOC, Pb, Ni and Cr could be indicated by these indicators.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. tangtang832@163.com
authors.forename: Rong-Li
authors.initials: RL
authors.lastname: Tang
authors.forename: Ke-Ming
authors.initials: KM
authors.lastname: Ma
authors.forename: Yu-Xin
authors.initials: YX
authors.lastname: Zhang
authors.forename: Qi-Zheng
authors.initials: QZ
authors.lastname: Mao
mesh_terms: D002681:China; D002947:Cities; D004391:Dust / Q000032:analysis*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis*; D011891:Rain; D012424:Rural Population; D014505:Urban Population; D014872:Water Movements
chemical_list: D004391:Dust; D004785:Environmental Pollutants; D019216:Metals, Heavy