Atmospheric trace elements in Ankara, Turkey: 1. Factors affecting chemical composition of fine particles

Fine and coarse aerosol samples were collected between February and June 19 93, in Ankara, Turkey using a stack filter unit (SFU). Collected samples we re analyzed for approximately 40 trace elements and major ions using a comb ination of instrumental neutron activation analysis, atomic absorption spec tromerty and ion chromatography. Particle sizing characteristics of the SFU was tested against dichotomous sampler and the sampler was found to be a g ood alternative for more expensive particle sizing devices. Fossil fuel com bustion was found to be the main source of anthropogenic elements in aeroso ls, including the ones with well-known industrial sources. Atmospheric load ing and seasonal variations in the concentrations of crustal elements are d etermined by the variations in wind speed and moisture of the soil. Short-t erm episodes in the concentrations of all elements are governed by local me teorology, particularly by the wind speed and mixing height. Concentrations of elements with anthropogenic origin have fairly similar concentrations i n all wind sectors as they are distributed uniformly over the city and its suburbs due to low annual average wind speed. However, these elements showe d directional preferences in samples which correspond to wind speeds higher than 2.5 m s(-1). Change in the concentrations of anthropogenic elements i n Ankara atmosphere is consistent with the history of regulatory actions ta ken to reduce air pollution. Moreover, an unexpected decrease in the concen trations of crustal elements between 1975 and 1993 is related to reduction in exposed earth surface due to rapid urban developments. (C) 2000 Publishe d by Elsevier Science Ltd. All rights reserved.