The Level of As and Ni in Street Dust Fractions of Different Sizes and Its Contributions in Guiyang

Based on the land use status in Guiyang,a total of 66 dust samples from industrial area(IA),residential area(RA),traffic area(TA),city square(CS),school area(SA),commercial area(CA) and garbage stations(GS) were collected within the central urban area of Guiyang for assessing the distribution of As and Ni and its difference.The results showed that the industrial area represented the highest mean level of As and Ni,and the commercial area and school area had relatively low mean level of As and Ni.The mass percentage of street dust fractions of different sizes follows the order of fine fraction(105 μm) medium fraction(105～250 μm) coarse fraction(250～425 μm).Differences in the distribution of As in street dust fractions of different sizes in Guiyang are not significant,while Ni in street dust fractions of different sizes in Guiyang decreases with increasing particle size.Street dust of Guiyang shows a relatively high mass percentage of As(42%) and Ni(47%) in fine fractions(105 μm).Except garbage stations,the mass percentage of street dust fractions of different sizes in other function areas decreases with increasing particle size,and the traffic area has the highest value of mass percentage in fine fractions.The mass percentage of street dust fractions of different sizes in garbage stations increases with increasing particle size.The contributions to As and Ni in street dust fractions of different sizes in garbage stations follows the increasing order of e medium fraction coarse fractionfine fraction.In the other function areas,the contributions to As and Ni from fine fractions of dust in Guiyang are higher than those from the medium and coarse fractions.