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 1993, in Ankara, Turkey using a stack filter unit (SFU). Collected samples were analyzed for approximately 40 trace elements and major ions using a combination of instrumental neutron activation analysis, atomic absorption spectromerty and ion chromatography. Particle sizing characteristics of the SFU was tested against dichotomous sampler and the sampler was found to be a good alternative for more expensive particle sizing devices. Fossil fuel combustion was found to be the main source of anthropogenic elements in aerosols, including the ones with well-known industrial sources. Atmospheric loading and seasonal variations in the concentrations of crustal elements are determined by the variations in wind speed and moisture of the soil. Short-term episodes in the concentrations of all elements are governed by local meteorology, particularly by the wind speed and mixing height. Concentrations of elements with anthropogenic origin have fairly similar concentrations in all wind sectors as they are distributed uniformly over the city and its suburbs due to low annual average wind speed. However, these elements showed directional preferences in samples which correspond to wind speeds higher than 2.5 m s−1. Change in the concentrations of anthropogenic elements in Ankara atmosphere is consistent with the history of regulatory actions taken to reduce air pollution. Moreover, an unexpected decrease in the concentrations of crustal elements between 1975 and 1993 is related to reduction in exposed earth surface due to rapid urban developments.