The Study Of Concentration And Migration Characteristics Of Black Carbon In Foliar Dust In Urban Areas

Black carbon, being mainly formed due to incomplete combustion of organic matter such asvegetation or fossil fuel,widly exists in soil, sediment, atmosphere and ice of polar and alpineregions. Past studies have focused on BC in soil,sediment and atmosphere,however, systematicstudy on BC in foliar dust has not been reported.In this paper,we begin experiment aboutdetermining the content of BC in foliar dust.After confirming the reliability of the experiment,wehave chosen six different urban areas with typical plots of trees, including foliar dust,surface dustand surface soil in same areas. The characteristics of BC content in foliar dust was analyzed andcompared with BC content in surface dust and surface soil.The main conclusions of this studycan be summed up as follows：（1）According as the method of determining black carbon from soil and sediment,weanalyze corresponding error in order to check up the reliability of experiment method.Theexperiment can recovery80percent BC from foliar dust,and The relative standard deviation is3.23%.（2）The contents of BC in foliar dusts showed the highest in winter,and the highest value is19.24mg·g-1,lower in autumn, the lowest in both spring and summer and the lowest value is1.10mg·g-1; The contents of BC in commercial and industrial areas were highest.（3）The BC/OC value in commercial and industrial areas were0.65±0.10and0.48±0.15,which means the main source of BC is fossil fuel combustion.A Positive relationshipbetween BC and OC content was found by regression analysis,indicating that BC formation isclose to OC.The Pearson correlation coefficient was0.909,this showed that the increase in BCcan significantly enhance the level of accumulation of OC in foliar dusts.（4）The spatial variance of BC in foliar dust, surface dust and surface soil showed that thecontents of BC abided similar regularity, the contents of them were highest in industrial, andlowest intourism area; there is a trend of foliar dust＞surface dust＞surface soil,which meansthat BC can transfer from each media.