| The re-suspended road dust samples from 53 sites that could cover basically the entire Beijing in summer, and aerosol samples from three representative sites in Beijing in four seasons were collected to study concentrations and spatial variations of elements and ions in re-suspended road dust and its contribution to the air-borne particulate pollution. Ca, S, Cu, Zn, Ni, Pb and Cd were main pollution elements, and Ca2+, SO2-4, Cl-, K+, Na+and NO-3 were major ions in re-suspended road dust. Al, Ti, Sc, Co and Mg in re-suspended road dust were mainly originated from crustal source, while Cu, Zn, Ni and Pb were mainly originated from traffic emissions and coal burning, and Fe, Mn and Cd were mainly from industrial emissions and coal combustion. Ca2+ and SO2-4mainly came from construction activities, construction materials and secondary gas-particle conversions, Cl- and Na+were derived from industrial wastewater disposal and chemical industrial emissions, and NO-3 and K+were from vehicle emissions, photochemical reactions of NOx, biomass and vegetable burning. The contribution of mineral aerosol from inside Beijing to the total mineral aerosols was 30% in spring of 2002, 70% in summer of 2002, 80% in autumn of 2003, 20% in winter of 2002. The pollution levels of some major pollution species, Ca, S, Cu, Zn, Ni, Pb, Fe, Mn, and Cd in re-suspended road dust reached 76%, 87%, 75%, 80%, 82%, 90%, 45%, 51%, and 94%, respectively, and their contributions to the related elements in PM10 were 20%-45%， 5%-18%， 4%-50%， 2%-46%， 4%-52%， 5%-20%， 30%-60%， 20%-40% and 2%-25%. Re-suspended road dust from the traffic and construction activities is one of the major sources of the air-born particulate pollution in Beijing. |
