Fractionation and bioavailability of heavy metal contamination of urban surface dusts in Shanghai city

This paper presents data on size fractionation and bioavailability of heavy metal characteristics of urban surface dusts in Shanghai City. Result shows that medium size of surface dust is 132 μm, < 75 μm fraction has the highest volume percentage. Particle size distribution has the important influence on pollutant concentrations. With particle size decreasing, the heavy metal concentration increase, and the < 75 μm fraction contains the highest levels of all of the heavy metals, and the order refers to Cr > Pb > Cd > Zn > Ni > Cu. A five-step sequential extraction of roadside sediments showed that Zn is predominantly in the carbonate fraction; Pb is highest in the Fe/Mn oxide fraction; Cu and Cd are mainly distributed in the organic fraction; Cr and Ni are predominantly associated with residual fraction. Considering the proportion of metals bound to the exchangeable and carbonate fractions, the comparative mobility of metals probably decreases in the order of Zn > Pb > Ni > Cd > Cu > Cr. Comparing with literature data abroad, the labile fraction of heavy metal bioavailability in Shanghai is higher for Zn, Pb and Ni, lower for Cu and Cd, and the same level for Cr.