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This paper presents a study or the elemental characterization of the Atlanta area aerosol at one rural and several urban sites. It includes a determination of the concentrations of major elemental components of the aerosol and a statistical analysis of the relationships between these components as a means of investigating possible sources. This research has emphasized the study of the graphitic carbon, Ce, and elemental sulfur, S, components of the aerosol (these two components are important in visibility reduction studies). The measurements show that Ce and S represent, respectively 3.1–9.9% and 1.9–4.4% of the total suspended paniculate, TSP, mass. The concentrations of Ce, S and TSP exhibit strong seasonal variations with Ce decreasing from winter to summer and S and TSP increasing over this period. All elemental components exhibit less concentration at the rural site than at the urban sites. Analysis results show that Ce appears to be statistically separate from S, which is assumed to be present as sulfate, indicating that the sources for Ce and particulate sulfate are distinct. S and TSP, however, appear to be linked through common regional scale meteorological processes.

Absorption coefficients of the Arctic aerosol have been measured by means of diffuse transmission techniques using filter samples collected at Barrow, Alaska. These measurements show a highly absorbing aerosol with an average winter absorption coefficient, σ α , of ≈ 1.9 × 10 −6 m −1 . We have used these absorption measurements, concurrent aerosol composition measurements, and estimates of sizes and refractive indices for the individual aerosol components to model the radiative properties of the Arctic aerosol. Our results show good agreement between observed and modeled quantities and indicate that the Arctic aerosol has optical properties that are quite similar to those of an aged pollutionderived mid-latitude tropospheric aerosol. Our results also indicate that particle growth with increasing relative humidity above the surface may cause the overall climatic impact of the Arctic aerosol to be different from that expected solely on the basis of measurements at the surface.