Characterization and diurnal variation of size-resolved inorganic water-soluble ions at a rural background site.
Water-soluble inorganic ions in aerosol samples have been studied. The sample collection took place during summer in 2003 at a European background site which is operating within the framework of the European Monitoring and Evaluation Program. Gent type PM10 stacked filter unit (SFU) samplers were operated in parallel on a day and night basis to collect particles in separate coarse (2.0-10 microm) and fine (<2.0 microm) size fractions. Particulate masses were measured gravimetrically; the filters from one of the SFU samplers were analyzed by particle-induced X-ray emission spectrometry (PIXE) and instrumental neutron activation analysis (INAA). Filters from the other SFU sampler were analyzed by ion chromatography (IC) for major inorganic anions (MSA-, NO2(-), NO3(-), Cl-, Br-, SO4(2-), oxalate) and cations (Na+, K+, NH4(+), Mg2+, Ca2+). The water-soluble inorganic ions measured were responsible for 44% and 16% of the total fine and coarse particulate mass, respectively. In the fine size fraction, the main ionic components were SO4(2-) and NH4(+) accounting for about 90% of fine ionic mass. In the coarse fraction the main ionic components were Ca2+ and NO3(-), followed by SO4(2-). Significant day and night difference in the mass concentrations was observed only for fine NO3(-). The molar ratios of fine NH4(+) to SO4(2-) indicated their complete neutralization to (NH4)2SO4. According to the cation-to-anion ratios the coarse particles were alkaline, while the fine particles were slightly acidic or neutral. By comparing the corresponding concentrations obtained from PIXE/INAA and IC, we determined the water-extractable part of the individual species. We also investigated the effect of long-range transported air masses on the local air concentrations, and we found that the air quality of this background monitoring station was affected by regional pollution sources.
Institute of Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest, Hungary. rita_ocskay@citromail.hu
Rita
R
Ocskay
Imre
I
Salma
Wan
W
Wang
Willy
W
Maenhaut
D000336:Aerosols / Q000737:chemistry*; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D005060:Europe; D007287:Inorganic Chemicals / Q000032:analysis; D010316:Particle Size; D010507:Periodicity; D012995:Solubility; D014867:Water
D000336:Aerosols; D000393:Air Pollutants; D007287:Inorganic Chemicals; D014867:Water