Characterisation of atmospheric particulates around a coal-fired power station

The present work focuses on the characterisation of total suspended particu lates (TSP) around the Teruel power station in NE Spain with special emphas is on sulphate aerosols due to their acidification potential. The specific objectives are the determination of the seasonal evolution of TSP levels an d chemistry, and investigation of possible neutralisation processes for aci dic aerosols in the atmosphere. Concentrations of the elements studied in T SP show a marked seasonal trend in the study period (July 1995 to July 1997 ) characterised by higher levels in spring-summer and relative low levels i n autumn and winter. In the case of sulphate aerosols, this pattern may be attributed to higher SO2 oxidation in the summer and autumn, and to the hig her frequency of impact of the emission plume on the surface in this period . A seasonal trend of SO2 oxidation rates is also found. The soil-related e lements show a similar seasonal trend which is interpreted to be a conseque nce of the typical Mediterranean atmospheric dynamics (Sahara air mass intr usions, convective dynamics, and low precipitation scavenging during summer .) In addition to seasonal variations, a clear grain-size fractionation is observed for the different ions determined. SO42- and NH4+ are concentrated in the finest grain-size fraction, while NO3- Cl-, K+, Mg2+, Na+ are conce ntrated in relatively coarser fractions, and Ca2+ levels increase with the particle diameter. Neutralisation of sulphate acidic aerosols is carried ou t by NH4+ and minor amounts of Ca-2(+). The sulphate neutralising compounds are described by different analytical methods. (C) 1999 Elsevier Science B .V. All rights reserved.