title: Seasonal variations of aerosol residence time in the lower atmospheric boundary layer.
abstract: During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.
authors.affiliation: Physics Department, Faculty of Science, El-Minia University, El-Minia, Egypt.
authors.forename: A A
authors.initials: AA
authors.lastname: Ahmed
authors.forename: A
authors.initials: A
authors.lastname: Mohamed
authors.forename: A E
authors.initials: AE
authors.lastname: Ali
authors.forename: A
authors.initials: A
authors.lastname: Barakat
authors.forename: M
authors.initials: M
authors.lastname: Abd El-Hady
authors.forename: A
authors.initials: A
authors.lastname: El-Hussein
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001272:Atmosphere / Q000737:chemistry*; D004534:Egypt; D006813:Humidity; D007856:Lead Radioisotopes / Q000032:analysis / Q000737:chemistry*; D011886:Radon / Q000032:analysis / Q000737:chemistry*; D012621:Seasons; D013696:Temperature; D014919:Wind
chemical_list: D000336:Aerosols; D000396:Air Pollutants, Radioactive; D007856:Lead Radioisotopes; D011886:Radon