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At least 973 records · Page 54Linked to original sources
PubMed2002

The potential of lichens as long-term biomonitors of natural and artificial radionuclides.

Lichens were used as biomonitors of Chernobyl fallout 137Cs, of cosmogenic 7Be and of radioactive members of the natural uranium and thorium decay chains. Samples were taken from two locations in France, including lichens sampled at different distances of a coal fired power plant and close to a uranium ore processing waste disposal site. All samples were analyzed gamma-spectrometrically after equilibrium concentrations of short-lived isotopes had been attained. Activity concentrations of the members of the uranium and thorium decay chains in Parmelia sulcata sampled 1994 decrease with distance from the plant, whereas in lichens taken at the waste disposal site a decrease with time was observed. Comparison of 7Be activity concentrations measured in lichens with atmospheric deposition rates confirms that P. sulcata can be used as a quantitative biomonitor of radioactive trace substances. Retention half-lives calculated with a simple one-compartment model are 2.6 +/- 1.2 years for cesium, which was detected in all samples even more than a decade after the Chernobyl accident, and of 0.7 (+/- 0.1) to 3.3 (+/- 0.7) years for lead. Consequences of our results for model identifiability and parameter estimation of a two-compartment model are discussed.

Environmental Monitoring↗
PubMed1962

Strontium-90 fallout from the 1961 Soviet nuclear detonations.

A steady increase in the strontium-90 concentration in rain was observed at Fayetteville, Arkansas, after the 1961 Soviet nuclear test series. Experimental data indicate that the nuclear weapons tested in 1961 were "cleaner" on the average by a factor of five than those exploded in 1957 and 1958.

Arkansas↗
PubMed1985

Comparison of environmental radiation dosimetry and gamma-ray spectroscopy.

During the period 1975-1980, direct radiation dose rates were measured at 16 fixed locations in the vicinity of the Joseph M. Farley Nuclear Plant, Houston County, AL, by exposure of TLDs which were read quarterly. The average quarterly dose rates using LiF chips varied widely over the 6-yr period and were divided into 2 distinct population groups of 4 and 2 yr each, corresponding to the vendor labs supplying and reading the TLDs. The simultaneous exposure of CaSO4:Dy TLDs for 2 yr gave a third set of values which fell between the 2 LiF groups. During the period December 1976-November 1980, simultaneous pressurized ion chamber (PIC) and in situ Ge(Li) gamma-ray spectroscopy measurements were made at the same locations at approx. 6-month intervals. The PIC exposure rate values were relatively constant for each location except for 1 measurement at the end of a long dry period broken by showers of rain. The average PIC dose rate values were in good agreement with the average 2-yr LiF TLD values. Also, good agreement resulted from converting the in situ radioactivity values to dose rates using conversion values previously published. Using the in situ Ge(Li) gross gamma count rates, and a new equation developed by the authors for calculating exposure rate, resulted in excellent agreement with both individual and average PIC values. The natural radioactivity and fallout 137Cs in the soil showed little variation for a specific site, but varied widely between some sites. With the event of rain at the end of a long dry period, there was a large increase in 214Bi and 214Pb activity detected. Short half-life manmade radionuclides were seen for a few months following several atmospheric nuclear tests by the People's Republic of China.

Alabama↗