Source apportionment of heavy metals in urban road dust in a continental city of eastern China: Using Pb and Sr isotopes combined with multivariate statistical analysis

To comprehensively analyze the characteristics and sources of heavy metals (Pb, Cd, Cu, Zn, Sr, V and Co), urban road dust samples from nine roads were collected in Nanchang, China in September 2013. The average concentrations of above heavy metals were 0.4 (V)-5.4 (Cd) times of their corresponding soil background values. The distribution patterns of Cu, Zn, Sr showed higher values mainly located in the northern and eastern parts of the study area, which indicated heavy metals in polluted industry areas migrated easily to near road dust. Enrichment factors (EFs) indicated that Cd, Cu, Sr, Zn and Pb in the road dust of Nanchang presented enrichment to some extent. Although the concentrations of Cd and Cu in the road dust were much lower than those recorded in urban areas of foreign researches, the highest mean EF of Cd (EF = 9) and the maximum EF of Cu (EF = 30) should be taken into consideration seriously. Based on isotopes source apportionment, Pb was mainly from vehicular traffic and industrial emissions, with the contribution rates of 61% and 26%, respectively, and Sr originated from anthropogenic source and soil source, with contributions of 59.7% and 40.3%, respectively. Based on multivariate statistical analysis, total heavy metals primarily originated from vehicular traffic for 43%, industrial emissions for 29%, soil source for 21%, and unknown sources for 7%, and Pb derived from traffic emissions with mean contribution of 62%, and Sr from soil-derived dust with mean contribution of 58%. The isotope tracing results were in good agreement with the multivariate statistical analysis.