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C Papastefanou

Publications and source records attributed to C Papastefanou.

30 records · Page 2Linked to original sources
PubMed1995

Atmospheric deposition of cosmogenic 7Be and 137Cs from fallout of the Chernobyl accident.

Atmospheric (tropospheric) depositional fluxes of the naturally occurring 7Be of cosmogenic origin and 137Cs from fallout of the Chernobyl accident were measured over a 7-year period (January 1987-December 1993) at Thessaloniki, Greece (40 degrees 38' N, 22 degrees 58' E). The annual total deposition fluxes of 7Be varied between 854 Bq/m2 (1987) and 1242 Bq/m2 (1992), showing a minimum in the years 1988-89. The annual total deposition fluxes of 137Cs varied between 183 Bq/m2 (1987) and 16.4 Bq/m2 (1992), showing a significant decrease as expected for natural removal and radioactive decay and no new releases from nuclear facilities or weapons testing. The annual average total deposition velocity for 7Be was from 0.3 cm/s (1988) up to 0.8 cm/s (1991), while for 137Cs the corresponding values were much higher, hence 137Cs was associated with larger atmospheric particles. High 7Be concentrations in air were related to the very little solar activity (1987-88 and 1993-94), while low 7Be concentrations in air related to the high solar activity (1989-91). Maximum 137Cs concentrations in air were registered during the spring 1991 and 1992, reflecting some stratospheric inputs. An unusual highly elevated value of 137Cs concentration in air, reaching 0.25 mBq/m3, was observed during the summer 1990.

Air Pollutants, Radioactive↗
PubMed1994

Indoor radon concentrations in Greek apartment dwellings.

Radon concentrations indoors were determined in 24 typical occupied apartments in the city of Thessaloniki, North Greece (40 degrees 38'N, 22 degrees 58'E), by means of 12 surveys, each 2 mo long, over a 2-y period starting October 1989. The ratio of the winter and summer averages for the first year of measurements was 1.8 +/- 0.78, and for the second year of measurements was 1.6 +/- 0.61. The indoor radon concentration in the summer (1990) period ranged between 8 and 81 Bq m-3, while in the winter (1989-1990) it ranged between 20 and 143 Bq m-3 for the first year of measurements or between 8 and 92 Bq m-3 in the summer (1991) period and between 12 and 119 Bq m-3 in the winter (1990-1991) for the second year of measurements. These results were obtained by type CN-85 alpha track detectors. Some parameters that influenced the concentrations, such as precipitation rates and use of fly ash in building materials, are discussed.

Air Pollution, Indoor↗
PubMed1991

Seasonal variations of 137Cs content of milk after the Chernobyl accident.

Results are presented on monthly measurements of 137Cs content in cows' milk over a 3-y period after the Chernobyl reactor accident. It was observed that, in an annual cycle of measurements, the 137Cs concentration of milk increased between December and August, peaking in April each year, due to the dependency of the 137Cs content of cattle feed on the fallout activity of 137Cs. There was a consistent correlation between the 137Cs concentration of milk and surface air.

Accidents↗
PubMed1989

The radioactivity of coloured rain in Thessaloniki, Greece.

The radioactivity of coloured rain precipitated over Thessaloniki, Greece, on 4-5 April 1988 was determined. The long-lived fission product radionuclides such as 137Cs, 134Cs, 144Ce, 106Ru and 125Sb were identified in dust originating from the Sahara desert which was precipitated with the rain to produce coloured rain. Caesium-137 concentrations reached 1000 Bq kg-1, resulting in a deposition of 3.03 Bq m-2, which is four orders of magnitude lower than measured on 5-6 May 1986 after the Chernobyl reactor accident.

Air Pollution, Radioactive↗
PubMed1989

Time-dependent radioactive concentrations of fallout following the Chernobyl reactor accident.

The levels of Chernobyl-derived 137Cs, 134Cs, 106Ru and 103Ru were measured at Thessaloniki, Greece, in air, rain, soil, grass and milk samples for more than 2 years after the accident. The data were analysed in conjunction with 7Be (produced in the atmosphere by cosmic rays) measurements and show that significant variations were observed, particularly in the spring and in the autumn measurements. In interpreting these variations we took into consideration the tropospheric, or possibly stratospheric, fallout injections into the atmosphere due to the Chernobyl accident, nuclear weapons testing or other releases from nuclear reactors operating world-wide. Useful information can be derived for determining the periodicity of global circulation of the fallout radionuclides.

Accidents↗
PubMed1988

Silver-110m and 125Sb in Chernobyl fallout.

Measurements of the two unusual nuclides 110mAg and 125Sb in soils and grass, derived from fallout, were made in Greece after the Chernobyl reactor accident. The 110mAg concentrations ranged from 4.5 to 46.1 Bq kg-1 (average 14.3 Bq kg-1) in soils and from 0.2 to 1.5 Bq kg-1 (average 0.8 Bq kg-1) in grass. The 125Sb concentrations ranged from 15.7 to 284.6 Bq kg-1 (average 105.0 Bq kg-1) in soils and from 1.1 to 19.6 Bq kg-1 (average 4.4 Bq kg-1) in grass.

Accidents↗
PubMed1987

Aerodynamic size associations of 212Pb and 214Pb in ambient aerosols.

The aerodynamic size distributions of short-lived Rn daughters (reported as 214Pb and 212Pb) in ambient aerosol particles were measured using low-pressure as well as conventional low-volume and high-volume impactors. The activity distribution of 214Pb and 212Pb, measured by alpha spectroscopy, was largely associated with submicron aerosols in the accumulation mode (0.08 to 2 microns). The activity median aerodynamic diameter ranged from 0.09 to 0.37 micron (mean 0.16 micron) for 214Pb and from 0.07 to 0.25 micron (mean 0.13 micron) for 212Pb. The mean values of the geometric standard deviation (sigma g) were 2.97 and 2.86, respectively. By comparison, the median diameters of cosmogenic 7Be and ambient SO4(2-) were about 0.24 micron higher. In almost 70% of the low-pressure impactor measurements, the activity distribution of 214Pb showed a small shift to larger particle sizes relative to 212Pb. This shift probably results from alpha-recoil detachment of parent 218Po, which preferentially depletes 214Pb from smaller particles. The subsequent recondensation of 214Pb causes an enrichment of larger aerosols. Early morning and afternoon measurements indicated that similar size associations of 214Pb occur, despite humidity differences and the potential for fresh particle production in the afternoon. Health physics implications of the results are also discussed.

Aerosols↗
PubMed1984

On the escaping radioactivity from coal power plants (CPP).

The escaping radioactivity from Greek coal power plants (CPP) was studied. For the case studied the radioactivity is due to the uranium series. The major part (99%) escapes as very fine particles, while the rest is fly ash. The total escaping 226Ra activity is of the order of 40 Ci/yr. The particulate dispersion of fly ash in sites around the stacks of CPP is described. The hazards from the escaping radioactivity are evaluated.

Air Pollution, Radioactive↗