Alpha Activity In Water Samples Research Articles

About development of control levels of specific total alpha-activity in water samples for a number of sources of the centralized economic and drinking water supply in the Republic of Khakassia

The aim of the work is to develop control levels of specific total alpha-activity of water samples for a number of sources of centralized drinking water supply in the Republic of Khakassia on the basis of the results of long-term laboratory studies. Materials and methods. The analysis is carried out on the basis of the results of laboratory studies of water sources of centralized drinking water supply of the population of the Republic of Khakassia, performed by accredited testing laboratories of institutions of the state sanitary and epidemiological service of the Republic for the period from 2001 to 2018, using alpha-beta radiometric, alpha-spectrometric methods with radiochemical preparation of counting samples, gamma-spectrometric method. The control levels of specific total alpha-activity of water samples from the sources of centralized drinking water supply in the Republic of Khakassia were established by the statistical maximum – the sum of the average value with a doubled standard deviation, with the volume of research more than 30, and the maximum value with the volume of research less than 30. Results. About half of the studied water samples from the sources of the centralized drinking water supply of the Republic of Khakassia, annually, are noted with exceeding the control level of specific total alpha-activity (0,2 Bq/kg). The values obtained in the studied samples vary up to 5,57 Bq/kg. During the observation period, samples of water exceeding the reference level of specific total alpha-activity (0.2 Bq/kg) were identified in settlements of the Altai, Askizsky, Beysky, Bogradsky, Ordzhonikidzevsky, Tashtypsky, Ust–Abakansky, Shira districts and the city of Sorsk, smt. Prigorsk (Chernogorsk). In previous studies, it was found that high levels of specific total alpha-activity in the country are mainly due to natural radionuclides uranium-238 (238U), uranium-234 (234U). In a number of settlements of the Republic, the sum of the ratio of specific activities of natural radionuclides to the corresponding levels of intervention exceeds 1,0. Average annual individual effective doses of internal exposure to natural radionuclides of drinking water, at or above 0,1 mSv/year (values in the range of 0,1-0,2 mSv/year), which does not require urgent radiation protection measures. At the same time, monitoring of indicators of radiation safety of water sources of water supply should be carried out in accordance with the established requirements. In this connection, in order to improve control, for the rapid assessment of the radiation situation and making timely decisions to ensure radiation safety of the population, the calculation of control levels of specific total alpha-activity was carried out. As a result of calculations, specific values of control levels for each of water source were obtained. The calculated values range from 0,2 to 2,6 Bq/kg. Conclusion. The control levels are “site standards” and are calculated for each of the source of water supply. Their excess will be considered as a signal of “negative change” of the radiation situation”, which may be associated with an increase of the specific activities of 234U, 238U, or the appearance of highly radiotoxic radionuclides: 226Ra, 210Po, 228Ra.

Selection of the appropriate radionuclide source for the efficiency calibration in methods of determining gross alpha activity in water

Measuring the gross alpha activity in water samples is a rapid, straightforward way of determining whether the water might contain a radionuclide concentration whose consumption would imply a total indicative dose (TID) greater than some reference limit – currently set at 0.1 mSv/y in Europe. There are several methods used for such measurements. Two of them are desiccation with the salts being deposited on a planchet, and coprecipitation. The main advantage of these two methods is their ease of implementation and low cost of preparing the source to measure. However, there is considerable variability in the selection of the most suitable radioactive reference standard against which to calculate the water's gross alpha activity. The goal of this paper is to propose the most appropriate reference radionuclides to use as standards in determining gross alpha activities with these two methods, taking into account the natural radioactive characteristics of a wide range of waters collected at different points in Spain. Thus, the results will be consistent with each other and representative of the sum of alpha activities of all the alpha-emitters contained in a sample.

Sources of variability in the determination by evaporation method of gross alpha activity in water samples

Abstract Determining the gross alpha activity concentration of water samples is one way to screen for waters whose radionuclide content is so high that its consumption could imply surpassing the Total Indicative Dose as defined in European Directive 98/83/EC. One of the most commonly used methods to prepare the sources to measure gross alpha activity in water samples is desiccation. Its main advantages are the simplicity of the procedure, the low cost of source preparation, and the possibility of simultaneously determining the gross beta activity. The preparation of the source, the construction of the calibration curves, and the measurement procedure itself involve, however, various factors that may introduce sufficient variability into the results to significantly affect the screening process. We here identify the main sources of this variability, and propose specific procedures to follow in the desiccation process that will reduce the uncertainties, and ensure that the result is indeed representative of the sum of the activities of the alpha emitters present in the sample.

Gross &#945 and &#946 Activity Concentration and Estimation of Adults and Infants Dose intake in Surface and Ground Water of Ten Oil Fields Environment in Western Niger Delta of Nigeria

The oil and gas rich Niger Delta region of Nigeria is characterized by environmental degradation leading to environmental pollution from oil and gas activities. This study examined the gross α and β activity in thirty (river/stream, well and tap) water samples collected from ten oil fields in the Western Niger Delta region of Nigeria. The counting system employed in this analysis is the Gas-flow proportional counter {Eurisys Measure IN20 low- background multiple (eight) channel counter}. Gross alpha activity concentration range from 0.01±0.002 to 0.7±0.01 (0.15±0.003) Bql-1, 0.01±0.003 to 0.5±0.01 (0.1±0.003)Bql-1and 0.02±0.001 to 35.1±1.1 (4.1±0.1) Bql-1 while beta activity concentration ranged from 1.1±0.04 to 13.2±0.1 (6.0±0.1) Bql-1, 0.7±0.1 to 54.7±1.3 (8.9±0.2)Bql-1 and 0.7±0.03 to 151.2±1.8 (40.1±0.9)Bql-1 for well, tap and river waters respectively. Correlation value between α and β activities in well, tap and river water is 0.025, 0.047 and 0.512 respectively. The results show that except for the alpha activity in the tap water samples, the average natural activity concentrations of α- and β-emitting radionuclides in the samples are slightly above the WHO recommended limit. For all samples the gross β activities are higher than the corresponding gross α activities. The mean effective equivalent dose intake per year due to alpha activity in the water samples for adults and infants are: 76.4±1.8 and 20.9±55μSvy-1, 54.6±1.3 and 14.9±0.4 μSvy-1, and 2118±70 and 584±19.2μSvy-1 in well, tap, and river water samples respectively. The results obtained for dose intake are below the WHO recommended reference level of 0.1mSvy-1, except for the water sample from Uzere river. This study indicates that the water sources evaluated, especially the rivers, are contaminated radiologically. @JASEM