SEASONAL EVOLUTION OF SUSPENDED PARTICLES AROUND A LARGE COAL-FIRED POWER-STATION - PARTICULATE LEVELS AND SOURCES

The present work focuses on the seasonal evolution of suspended partic les (TSP and PM10) around the Teruel power station in NE Spain. The sp ecific objectives are the determination of the spatial and time variab ility of levels of suspended particles, and their relationship with th e power plant emissions and other natural or anthropogenic (local or e xternal) particulate sources. The results show a marked seasonal trend , along the study period (July 1995-August 1996) which is characterize d by particulate levels that were higher in spring-summer and decrease d progressively towards winter. This trend may be related to (a) highe r summer oxidation which increased levels of secondary particles, (b) higher convective circulation in summer which raised levels of soil-re lated particles and anthropogenic particles, (c) higher frequency of i ntrusion episodes of Sahara air masses in summer and spring, and (d) l ower aerosol scavenging potential in summer. The similarity between th e seasonal evolutions of daily mean levels of SO, and particulates is due to the fact that both are partially controlled by the solar cycle. The long range transport particulate inputs affecting this area of th e Mediterranean Basin (mainly Sahara air mass intrusions) account for major particulate peaks recorded at the monitoring stations. The influ ence of the emissions from the power plant in the PM10 and TSP levels is evidenced only in periods with a low background particulate levels. The results demonstrate that even PM10 levels are still highly influe nced by the Saharian and European particulate inputs. Therefore, for a n accurate environmental assessment, probably PM2.5 should be monitore d instead of TSP or PM10, in order to quantify the influence of the po wer plant emissions on the bulk atmospheric particulate levels. The re sults obtained from the air back-trajectory analysis and their compari son with the time series of daily PM10 levels allowed the classificati on of the major external particulate inputs as a function of the parti culate levels. (C) 1998 Elsevier Science Ltd. All rights reserved.