Time-resolved measurements of water-soluble ions and elements in atmospheric particulate matter for the characterization of local and long-range transport events.

Chemical composition of atmospheric PM(10) was determined at 2-h resolution during a 10-d field study carried out in the urban area of Rome, Italy. Extractable and residual fractions of elements were determined on 2-h samples by inductively coupled plasma mass spectrometry, a rather widespread analytical technique; daily chemical characterization of macro- and micro-components was also carried out and the mass closure was obtained. Interpretation of the variations in PM(10) composition was carried out in the light of the meteorological conditions and, in particular, of the mixing properties of the lower atmosphere, evaluated by monitoring natural radioactivity due to radon 222 decay. The combination of time-resolved sampling, chemical fractionation and monitoring of the dilution properties of the atmosphere allowed a reliable identification of long-range transport events and of local phenomena, which could not be detected by daily samplings. This kind of study can be effective for gathering detailed information about tracers at local scale, which are really valuable for interpreting the results of traditional low-resolution monitoring studies. Copyright (c) 2010 Elsevier Ltd. All rights reserved.