Characteristics of Heavy Metal Pollution and Health Risk Assessment in Subway Station Dust in Beijing
|Keywords||Metro dust Heavy metals To accumulate Index Health Risk Assessment Spatial distribution characteristics Beijing|
With the increasing urbanization process in China continue to promote and city transport pressure, subway traffic has increased annually, and increasingly showing a trend of high-speed. Increase in the number of subway traffic and driving inevitably lead to the subway air quality degradation, part of the Metro has been operating in the process, there were frequent passenger on board fainted. The subway dust concentration of heavy metal pollutants on operators, passengers and staff in order to improve the subway quality of the environment and the promotion of health to provide reliable reference, also has important practical significance to improve the air quality inside the station and take the environment comfort. In this paper, as the object of study, 16 in Beijing subway stations dust After an investigation, sample collection and experimental analysis, system to study the physical and chemical properties of the dust in the Beijing subway station, Park dust of heavy metals As, Cd, Cu, Ni, Hg , Pb and Cr content. Use accumulated index, the consolidated potential ecological risk index and the U.S. EPA human health evaluation of heavy metal pollution of dust samples, the potential risks and human health risk analysis, and correlation analysis and principal component analysis and discussion of the physical and chemical properties of dust The relationship between heavy metal content, dust, possible sources of heavy metals, the following conclusions: (1) Heavy metals Cr, Cd, Cu, Ni, Hg, Pb, As the average content of 131.92,1.11,67.33,41.77,0.35,437.41 and 9.09 mg kg -1 sup>, more than the soil background value, Pb, Hg and Cd contents were more than 23.29,19.24 and 7.38 times the background value of soil, formed an important threat to the health of people . (2) dust pH range of 8.32 to 8.93, an average of 8.63, alkaline, easier adsorption of heavy metal elements found lt; weighing process; 60 purpose dust samples such as sand particles and debris, GT; 100 mesh particle mass fraction of 43.24%, while gt; 150 Head of the total mass fraction of 35.59%. Shows that subway particles greater than 100 mesh particle size exist, taking into account the fine particles large specific surface area greater harm to the human body, so this is mainly particle size lt; 106 um fine particulate matter is the main object of study, an analysis of the major heavy metal contaminants and human health risks. (3) cumulative index Pb gt; Hg GT; Cd GT gt; Cr; Cu GT; Ni gt; AS, which Pb, Hg, Cd, respectively 3.77,3.12,2.16, serious pollution, in addition to the routes cumulative index the order of the 1st line gt; 2 Line GT; 13 line gt; 4 Line GT; 10 line; ecological risk of potential ecological risk index of each element in turn to Hg GT; Cd GT; Pb GT; Cu GT ; As gt; Ni gt; Cr, Hg and Pb potential ecological risk of the strongest, so should be strengthened Hg and Pb pollution control. (4) Human Health Risk Assessment of the risk of non-carcinogenic Pb GT; Cr gt; As GT; Ni GT; Cu gt; Hg gt; Cd, does not constitute a significant risk except Pb, Cr, Cd, Ni, As carcinogenic risk below the risk threshold, the body does not pose a health hazard. (5) the spatial distribution of heavy metals by the Beijing subway dust difference, serious pollution of the local area. Especially Pb and Hg; principal component analysis and Spearman correlation coefficient analysis showed that Cd, Cu, Ni, As and Cr and Hg six heavy metals: Metro dust comes mainly from human activities into the surface dust; actually only Pb in the subway station severe cumulative, this seriously tired positive may be derived from the train and the track friction and brake systems to the formation of particulate matter, the coating off the subway station, the repair of the wall, the subway line material wear and the plating metal corrosion and other reasons.