Anthropogenic radioactive particles in the environment

Radioactive particles have been released from multiple sources since the mid-twentieth century. Famous examples include nuclear fuel particles from Chernobyl, glassy microparticles from Fukushima as well as particles from nuclear weapons production facilities (e.g., Windscale, United Kingdom and the facilities in the former Soviet Union), nuclear weapons accidents at Palomares (Spain) and Thule (Greenland), and atmospheric nuclear explosions. Current challenges in environmental research of radioactive particles include the drying of the cooling pond of Chernobyl NPP, which will cause the weathering of previously preserved fuel particles in the (former) sediment of the pond. Environmental aspects of resuspended particles as well as natural particles and aerosols contaminated with radionuclides (e.g., ¹³¹I) are briefly discussed.     

Background of low-level gamma-ray spectrometer due to the atmospheric 220Rn and 222Rn

In connection with low-level gamma-ray counting of natural samples, background due to 220Rn- and 222Rn-daughters was monitored. The results obtained for 4 months showed that the background gamma-ray from 222Rn-daughters was more variable than that of 220Rn-daughters. An efficient air-conditioning was helpful to keep the background stable. It was practically equivalent to the use of N2-gas. Radiometric data for dust samples filtered from the laboratory air suggested that Rn-daughters tended to be removed by air-conditioning.     

A new method for determination of222Rn and220Rn in geothermal steam

The radionuclides²²²Rn and²²⁰Rn are measured by incorporating their daughters²¹⁴Pb and²¹²Pb in a very thin layer of PbS and accumulating the alpha spectrum of their daughter products²¹⁴Po and²¹²Po. The median yield was measured as 88% using a known amount of²¹⁰Pb tracer. A single fumarole and all 23 geothermal wells tested were found to contain²²⁰Rn. As isotopes of Th, Bi, Po and Ra, are also absorbed in the PbS layer, the method can be used for determinations of these in tap-water.     

Measurements of222Rn migration in soil

The concentration of radon (²²²Rn) was measured in the soil near the ground surface, using CR/39 solid state nuclear track detectors. The measurements were carried out in PVC tubes at 0.25 m intervals up to 1.25 m. The detectors were etched in 7N NaOH solutions at 80°C. The -tracks from radon's decay were counted using a microscope. A microscope-camera-computer system developed for automatic counting was also used. The results provide evidence for the non-diffusive transport of radon in soils. A transport length of (46.9±3.2) cm was estimated for radon transport near ground surface. Also the variation of soil's radon concentration was correlate to humidity and atmospheric pressure.     

Rates of Reactive Removal of Anthropogenic Emissions in the Atmosphere

Anthropogenic emissions such as SO₂, CO, NO_x, and hydrocarbons constitute a perturbation of the natural equilibrium of the atmosphere. On a global scale, the extent of this perturbation does not significantly exceed the natural background levels as a result of direct or indirect photochemical “clean-up” processes in the atmosphere. Regionally, however, considerably increased concentrations of these trace components may occur. They are degraded by free radical reactions having widely differing yet substance-specific rates.     

The measurement of222Rn in drinking water by low-level liquid scintillation counting

Radon-222 (Rn) has universally been found in well water. Non-stagnant ground water is collected at the well head while the well is pumping. The water is adjusted to a slow, non-aerated, steady flow through a clear tube, and a 500 ml glass bottle is filled. The sample is tightly capped after a high meniscus has developed. In the laboratory, standard 22 ml glass vials are filled with 10 ml of a toluene based mineral oil LS cocktail. Then, two 5 ml sample aliquots are pipetted into the vial. Vials are capped tightly, shaken vigorously, and placed in the liquid scintillation (LS) counter. Secular equilibrium is established in approximately 4 hours, after which samples are counted for 100 minutes each. The counting efficiency for Rn and progeny ranges between 315 to 345 percent depending on the chosen spectral window. The average background is about 6 cpm. A total of 28 wells were tested for Rn in the Carefree-Cave Creek, Arizona, USA area. The area's geometric average Rn concentration was found to be 46.5 Bq·l^–1. The associated estimated lung dose is 0.51 mSv·y^–1.Deceased 1 June 1991.     

Evolution of persistent Anthropogenic radioactivity in Antarctic ecosystems

The primary objective of this study was to observe the evolution of anthropogenic radioactivity contamination in the Antarctic continent throughout the period 1997–1999. Moreover, results have been compared with those obtained for previous expeditions, starting from 1987. As far as ¹³⁷Cs is concerned, interesting considerations could be made due to the great amount of available data. On the whole, radioactive contamination seems to be higher in continental than in marine environments. For lake algae, contamination seems to decrease gradually in the order: Tarn Flat, Edmondson Point, Carezza Lake. Focusing on ¹³⁷Cs activity data, a clear temporal decreasing trend was observed in all samples: for sea water, values decreased from mean values of 0.9?Bq/m³ in 1987 to 0.5?Bq/m³ in 1999, a 56% decrease (20% of the total is due to natural decay of ¹³⁷Cs). For lake waters and lake algae, the decreases are higher (80 and 30%, respectively) and the same can be assessed for sediments and soils, even if the resulting distributions are more complicated. The highest values for all radionuclides analysed were detected in terrestrial organisms (mosses, lake algae, and lichens). As a consequence, these matrices appear to be good bioindicators of radioactive contamination. Finally, although the Antarctic continent is affected by some degree by anthropogenic radioactive pollution, our results for ¹³⁷Cs show that we are facing a progressive decrease. Moreover, contamination in other parts of the world is much higher: from 6–10 times in the Mediterranean Sea and 20–50 times in the North Sea and Black Sea.     

Measurement of 222Rn and 220Rn decay product deposition velocities using SSNTD based passive detectors

In the present study, the deposition velocities of ²²²Rn/²²⁰Rn decay products were measured experimentally using SSNTD based passive detectors, direct radon progeny sensor (DRPS) and direct thoron progeny sensor (DTPS) and the results were compared with obtained values by Monte-Carlo simulations. In both cases, deposition velocities were found to be log-normally distributed and also the experimentally measured geometric mean (GM) and geometric standard deviation (GSD) of (0.12, 1.85) m h^?1 for radon decay products and (0.07, 1.75) m h^?1 for thoron decay products were found to be in good agreement with the simulated values.     

Charged particle ratio in222Rn indoor atmosphere

The majority of radon daughter products are positively charged; however, their charge is masked by atmospheric ions created along the path of the accompanying -particles. The resulting positive-to-negative particle ratio P, which is usually higher than unity can change during the mitigation of radon daughters; such a change gives evidence that the mechanism is controlled by electric forces.     

New Aspects of the Role of Organisms and Detritus in the Detoxification System of the Biosphere

The review covers new aspects of the participation of organisms in the detoxification system of the biosphere. Problems of detoxification of toxic environmental pollutants are analyzed. New author’s experimental data in combination with a large amount of information in the scientific literature gave rise to a new concept of the role of biogenic detritus and related nutrients in environmental detoxification (ex-living matter concept). This may be useful for the development of new technologies for remediation and decontamination of the environment.     

A continuous monitor for assessment of 222Rn in the coastal ocean

Radon-222 is a good natural tracer of groundwater flow into the coastalocean. Unfortunately, its usefulness is limited by the time consuming natureof collecting individual samples and traditional analysis schemes. We demonstratehere an automated system which can determine, on a continuousbasis, the radon activity in coastal ocean waters. The system analyses ²²²Rn from a constant stream of water passing through an air-water exchangerthat distributes radon from the running flow of water to a closed air loop.The air stream is feed to a commercial radon-in-air monitor which determinesthe concentration of ²²²Rn by collection and measurement of theemitting daughters, ²¹⁴Po and ²¹⁸Po, via a charged semiconductordetector. Since the distribution of radon at equilibrium between the air andwater phases is governed by a well-known temperature dependence, the radonconcentration in the water is easily calculated.     

A survey of 222Rn concentrations in dwellings of Turkey

As part of a national program to determine public exposure to natural radiation, indoor air ²²²Rn concentrations were determined in dwellings of Turkey. The ²²²Rn concentrations were measured with time-integrating passive nuclear etched track detectors in 27 provincial centers. The indoor radon concentrations were found to be in the range of 10-380 Bq^.m^-3. This revised version was published online in August 2006 with corrections to the Cover Date.     

贡嘎山森林水资源水质状况分析

从地表水来源的整个水流过程对森林净化水质功能和影响贡嘎山自然保护区表水水质的因素进行分析,评价了贡嘎山森林流域水质状况,研究了贡嘎山森林生态系统对水域pH和Ca等营养元素的影响,为森林生态系统水质演化研究提供了例证。     

Application of ultra-low level liquid scintillation to the determination of 222Rn in groundwater

A procedure for the determination of ²²²Rn in environmental water samples using liquid scintillation counting (LSC) was applied. The extractive scintillator RADONS^Ò and an ultra-low background 1220 QuantulusÔ were used. A minimum detectable activity of 0.1 Bq·l^?1 in 20 ml was found with low-diffusion polyethylene vials and 200 minute measurement time. Quenching effects and possible interferences due to the existence of other radionuclides in the extraction process were studied. The procedure was controlled by gamma-ray spectrometry of the ²²²Rn daughters. Applications to environmental samples collected from spas, wells, and public springs in Extremadura (Spain) are presented.     

Radiological assessment of 222Rn, 220Rn,EERC, and EETC in residential dwellings of district Palwal,Southern Haryana,India

Journal of Radioanalytical and Nuclear Chemistry - A systematic measurement of radon/thoron concentration by using pin-holes dosimeter and their decay products by deposition based progeny sensors...     

Studies on temporal change in depth profiles of the Rn concentrations in natural water columns

Although radon loss should be taken into account when determining the amount of radon in a water sample, only a few papers have exclusively investigated the factors connected to radon loss. To clarify radon loss behavior, this study examines the temporal changes in depth profiles using a large volume of natural water in a simple system where the effects of external factors (pressure, stirring, air convection, etc.) are suppressed. Analyzing the results using a box model indicates that at low temperature, the depth profile of the residual radon at the surface remarkably decreases, but at high temperature the depth profile is uniform. The exponential decrease of the total residual radon in water depends on the elapsed time and temperature. In addition, the box model analysis provides the activation energies of transfer from water to air and in water. The water depth profiles are formed by the supply balance of radon from deep water to the surface and the discharge of radon from the surface to the air.