Spatial variability of carbonaceous aerosols and associated source tracers in two cites in the Midwestern United States

摘要: Abstract Semi-continuous and 24-h averaged measurements of fine carbonaceous aerosols were made concurrently at three sites within each two U.S. Midwestern Cities; Detroit, Michigan Cleveland, Ohio; during two, one-month intensive campaigns conducted in July 2007 January & February 2008. A comparison revealed substantial intra-urban variability consistent with the influence local sources, excesses both PM2.5 organic carbon (OC) elemental (EC) identified individual city. High time-resolved black (BC) indicated that concentrations higher adjacent to freeways busy surface streets, temporal patterns suggested excess EC to freeways was dominated by mobile source emissions while away from traffic corridors point/area emissions. The site-to-site OC approximately 7% neighborhood scale (0.5–4 km) between 4 27% urban (4–100 km). In contrast, tracers, conjunction a Chemical Mass Balance (CMB) source-apportionment model, spatial variation contribution stationary sources often exceeded mass concentration factor 3 or more. Markers for biomass smoke, natural gas, coal combustion differed as much 60% greater than 200% scale. observations this study suggest is more complex has been previously reported rigorous, source-oriented approach should be taken order assess risk associated exposure industrialized environments United States.