[Heavy metal pollution in street dusts from different functional zones of Luoyang City and its potential ecological risk].

The concentrations of heavy metals (Cu, Zn, Pb, Cr, Cd) in street dusts were investigated in six different functional zones of Luoyang City, i.e., urban-rural continuum, urban artery, industrial district, urban green space, residential district, and business district. The pollution levels and potential ecological risk of heavy metals were assessed by the methods of potential ecological risk index suggested by Håkanson. The results showed that heavy metal concentrations in street dusts from different functional zones of Luoyang City were all higher than soil background values in Henan, with average concentrations of Zn (1019.75 mg x kg(-1)) > Cr (401.63 mg x kg(-1)) > Cu (240.94 mg x kg(-1)) > Pb (176.04 mg x kg(-1)) > Cd (2.33 mg x kg(-1)). Cd was the most seriously polluted metal in all functional zones, and the average pollution index (Cf(i)) reached 35.84, following by Zn (16.32) > Cu (12.05) > Pb (7.90) > Cr (6.36). Heavy metal concentrations and pollution levels varied greatly in different functional zones, and industrial zone had the highest total contents and the heaviest pollution. The integrated potential ecological risk index (RI) in different functional zones all reached very strong levels, with an order of industrial district (1709.51) > urban green space (1581.50) > business district (1 297.45) > residential district (1 111.25) > urban artery (889.97) > urban-rural continuum (641.39). Among the surveyed heavy metals, Cd accounted for the major potential ecological risk, and the average potential ecological risk index (Er(i)) reached 1075.16 (extremely strong risk level) in all six functional zones. The average Er(i) of Cu and Pb reached 60.23 and 40.77 respectively, belonging to moderate risk level, while Zn (16.32) and Cr (12.71) only reached slight risk level. A reduction in industrial and traffic pollution might be the key measure to decrease the heavy metal pollution and potential risk in street dusts.