A study on aerosol residence time in El-Minia, Egypt

Journal of Environmental Radioactivity, 2004

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 longlived ( 222 Rn) decay products 214 Pb and 210 Pb. The samples were taken by using a single-filter technique and c-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214 Pb and 210 Pb 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 214 Pb and 210 Pb within the whole year was found to be 1:4 AE 0:27 Bq m À3 and 1:2AE 0:15 mBq m À3 , respectively. Different 210 Pb: 214 Pb activity ratios during the year varied between 1:78 Â 10 À4 and 1:6 Â 10 À3 with a mean value of 8:9 Â 10 À4 AE 7:6 Â 10 À5 . From the ratio between the activity concentrations of the radon decay products 214 Pb and 210 Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10:5 AE 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. #

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1999

The main goal of the present study was to evaluate the in¯uence of meteorological conditions on short range transport of trac-related aerosols. Samples were collected at ®ve dierent distances from one of the main transit arteries in Krak ow during the day (high trac intensity) and night (low trac intensity). The concentrations of 27 elements were determined using PIXE. The results showed that rainfall and wind direction and velocity are the most important factors in¯uencing the elemental concentrations. If these parameters are not taken into account comparison of the data obtained at dierent locations during various meteorological conditions can lead to biased conclusions. Therefore, a simple standardisation of the results with respect to wind direction and velocity was applied which resulted in the determination of the range of transport of coarse trac-related particles.

Atmospheric Chemistry and Physics, 2009

Particle number concentration and size distribution are important variables needed to constrain the role of atmospheric particles in the Earth radiation budget, both directly and indirectly through CCN activation. They are also linked to regulated variables such as particle mass (PM) and therefore of interest to air quality studies. However, data on their long-term variability are scarce, in particular at high altitudes. In this paper, we investigate the diurnal and seasonal variability of the aerosol total number concentration and size distribution at the puy de Dôme research station (France, 1465 m a.s.l.). We report a variability of aerosol particle total number concentration measured over a five-year (2003-2007) period for particles larger than 10 nm and aerosol size distributions between 10 and 500 nm over a two-year period (January 2006 to December 2007). Concentrations show a strong seasonality with maxima during summer and minima during winter. A diurnal variation is also observed with maxima between 12:00 and 18:00 UTC. At night (00:00-06:00 UTC), the median hourly total concentration varies from 600 to 800 cm −3 during winter and from 1700 to 2200 cm −3 during summer. During the day (08:00-18:00 UTC), the concentration is in the range of 700 to 1400 cm −3 during winter and of 2500 to 3500 cm −3 during summer. An averaged size distribution of particles (10-500 nm) was calculated for each season. The total aerosol number concentrations are dominated by the Aitken mode integral concentrations, which drive most of the winter to summer total concentrations increase. The night to day increase in dominated by the nucleation mode integral number concentration. Because the site is located in the free troposphere

Nucleus

Be-laden aerosols, thus obtained, were 5.29 ± 0.91 days and 7.18 ± 0.97 days respectively.

Journal of Environmental Radioactivity, 2017

Variations of aerosol radionuclides (2001e2015) in the groundelevel air in Bratislava (Slovakia) showed 7 Be maxima in spring/early summer and minima in winter, however, an inverse trend was observed for 210 Pb, 137 Cs and 40 K. A decreasing amplitude and splitting of summer maxima for 7 Be in the last years has been found. A temporal behavior of the 7 Be/ 210 Pb activity ratio showed higher levels during warm seasons due to vertical convection of air masses from higher altitudes. The 137 Cs activity concentration in the surface air between 2003 and 2010 was decreasing with an effective half-life of 1.9 ± 0.3 years. The yearly average 137 Cs concentrations during 2009e2014 were almost constant, disturbed only by the Fukushima accident in 2011. The increased atmospheric 137 Cs and 40 K levels observed during the autumn ewinter season may be due to surface soil resuspension, biomass burning and radionuclide transport by winds. Seasonal variations of 222 Rn activity concentrations were found with maxima at the end of autumn and in winter, and minima in spring. The variability of the average annual course of 222 Rn has been larger than that of 210 Pb. The 210 Pb/ 222 Rn activity ratio was highest at the end of winter and in the spring, while from June to December remained nearly constant. More intensive atmospheric mixing in spring months caused a decrease in the 222 Rn activity concentration, while the aerosol component of the atmosphere has been affected mainly during the autumn and winter seasons. The mean residence time of aerosols in the atmosphere was calculated using the 210 Pb/ 222 Rn method to be 4.5 ± 0.9 days.

Atmospheric Chemistry and Physics, 2011

Detailed investigations of the chemical and microphysical properties of atmospheric aerosol particles were performed at the puy-de-Dôme (pdD) research station (1465 m) in autumn (September and October 2008), winter (February and March 2009), and summer (June 2010) using a compact Time-of-Flight Aerosol Mass Spectrometer (cToF-AMS)

This research program "Climate Change in relation to Aerosols" was financed by the Dutch ministry of Economic Affairs in the period 1998-2002 (fasnumber 64115), in cooperation with TNO.

Atmospheric and Oceanic Optics, 2010

Measurements of the temperature dependence of aerosol optical characteristics during controlled heating of an aerosol medium are analyzed. The annual motion of characteristic thermooptical parameters of submicron aerosol are discussed; their stability for different observation years is shown. Correlation of the thermooptical characteristics with the refractive index of dry particles and with the parameter of condensa tion activity is determined.

Atmospheric Environment, 2001

Ambient concentrations of aerosol radioactivity in ground-level air were measured weekly in a low-industrialized city (Salamanca, Spain). Means of about 6.9;10\ and 4.83;10\ Bq m\ were found for gross and activities, respectively, averaged over three years. The measured activities, which include contributions from several radionuclides in the ground atmosphere, were evaluated to determine the relationship between the meteorology and the aerosol activities in air. We have studied the in#uence of diverse meteorological parameters such as temperature, pressure and wind direction, as well as the e!ect of the less often considered terrestrial electrostatic "eld. Concentrations of gross and activities were greatly a!ected by the meteorological conditions, showing pronounced di!erences between seasons. The study reveals that much of the variability (approximately 50%) in the activities is explained by the electrostatic "eld, its in#uence being higher in winter. About 40% of the and variability is explained by both the temperature and the humidity. The in#uence of the wind direction is only statistically signi"cant for radioactivity. A simple mathematical model based on these variables is developed to describe globally the dynamics in air of radioactive particles enabling us to estimate the air radioactive background level.