Preliminary results from the first national in situ gamma spectrometry survey of the United Kingdom

In situ gamma spectrometry was introduced as part of a national soil and herbage pollution survey of the United Kingdom (UK) in 2002, to evaluate its potential for complimenting or even replacing the conventional soil sampling approach in environmental monitoring. A total of 128 points were measured across the whole of the UK on a 50-km grid, including 11 calibration sites, encompassing a complete spectrum of soil types, geology and depositional environments. Good comparisons are demonstrated between in situ and soil sample derived estimates of environmental radioactivity from spatially matched sampling plans. Air kerma results and the contributions to air kerma rate are also presented and compared with calibrated conventional single parameter GM based instruments. The preliminary results are presented here and show that in situ gamma spectrometry provides a rapid and robust approach, providing spatially integrated estimates for environmental monitoring purposes.     

The use of ambient air quality modeling to estimate individual and population exposure for human health research: a case study of ozone in the Northern Georgia Region of the United States

Ambient monitors are commonly used to estimate exposure for epidemiological studies, and air quality modeling is infrequently applied. However air quality modeling systems have the potential to alleviate some, although not all, of the limitations of monitoring networks. To investigate this application, exposure estimates were generated for a case study high ozone episode in the Northern Georgia Region of the United States based on measurements and concentration estimates from an air quality modeling system. Hourly estimates for 2268 4-km by 4-km gridcells were generated in a domain that includes only eight ozone monitors. Individual and population-based ozone exposures were estimated using multiple approaches, including area-weighted average of modeled estimates, nearest monitor, and spatial interpolation by inverse distance weighting and kriging. Results based on concentration fields from the air quality modeling system revealed spatial heterogeneity that was obscured by approaches based on the monitoring network. With some techniques, such as spatial interpolation, monitoring data alone was insufficient to estimate exposure for certain areas, especially for rural populations. For locations far from ozone monitors, the estimates from the nearest monitor approach tended to overestimate exposure, compared to modeled estimates. Counties in which one or more monitors were present had statistically higher population density and modeled ozone estimates than did counties without monitors (p-value <0.05). This work demonstrates the use of air quality modeling to generate higher spatial and temporal resolution exposure estimates, and compares the advantages of this approach to traditional methods that use monitoring data alone. The air quality modeling method faces its own limitations, such as the need to thoroughly evaluate concentration estimates and the use of ambient levels rather than personal exposure.     

Increased environmental gamma-ray dose rate during precipitation: a strong correlation with contributing air mass

It has long been observed that the environmental gamma-ray dose rate increases noticeably during precipitation intervals. This increase, due to the presence of radon progeny in the rain droplets (or snow flakes), can affect the reliability of the monitoring of artificial radioactivity and long term estimates of exposure to ambient natural radionuclides in surveillance network. Predicting the amplitude of the dose increase has been shown to be surprisingly challenging. In this work, standard air mass back trajectory analysis is used to show that the amplitude of the increase can be quantitatively linked to the history of the air mass where the precipitation is occurring. Furthermore, we show how back trajectory analysis, environmental gamma and rain data can be used to obtain estimations of relative radon emanation rates for locations far from the actual point of detection.     

Pollutant loads from the drainage basin to the Venice Lagoon (Italy)

In order to assess the actual pollutant loads from the drainage basin, the twelve major tributaries of the Venice Lagoon were monitored and studied in the period 1998-2000 in the framework of the DRAIN project. A specific sampling scheme was designed to investigate the effects of the different regimes, including floods, in the transport of total and dissolved metals, nitrogen and phosphorous species as well as organic micropollutants. The loads were calculated from data collected during the year of 1999, since this year displayed a value close to the mean in terms of the distribution of total rainfall on the drainage basin. The annual values for the different pollutants are reported and discussed. A comparison with the estimates of previous investigations highlights the significant advancement provided by the DRAIN project results in the understanding of the drainage basin contribution to the pollution of the lagoon. Finally, the importance of flood events on the overall balance of materials and pollutants delivered to the lagoon is emphasized.     

The concentration of Cs in the surface of the Greek marine environment

The radiological status of the Greek marine environment, prior to the Chernobyl accident, was characterized mainly by the fallout from nuclear weapon tests. However, the release of radioactivity into the environment from the accident in the Chernobyl Nuclear Power Plant and its deposition in the Greek marine environment resulted in an increase of the ¹³⁷Cs activity concentration by approximately one order of magnitude. In addition, the direct transport of radiocaesium into the North Aegean Sea has been further influenced by the late impact of the Chernobyl accident on the Greek marine environment, related to the transfer of ¹³⁷Cs, mainly through the Dnieper but also the Danube rivers, to the Black Sea and further to the North Aegean Sea through the Straits of Dardanelles. The aim of this work is to provide a present day picture of the geographic variation of the concentration of ¹³⁷Cs in the surface layer of the Greek marine environment and hence, to evaluate the annual committed effective dose delivered to humans through the ingestion pathway from marine sources.     

Geostatistics for environmental monitoring and survey design

Geostatistics is a field of statistics which development to solve estimation problems in the mining industry. Geostatistical techniques, however, can also be useful in the environmental sciences. For example, one geostatistical technique, called kriging, can be used to obtain unbiased, minimum variance estimates of the spatial distribution of a pollutant. In this discussion, an introduction to kriging is presented. In addition, a brief review of some of the applications of kriging in the fields of hydrology and geohydrology, soil science, agronomy, and contaminant monitoring is presented.     

Development of a new aerosol monitoring system and its application in Fukushima nuclear accident related aerosol radioactivity measurement at the CTBT radionuclide station in Sidney of Canada

A high volume aerosol sampler ("Grey Owl") has been designed and developed at the Radiation Protection Bureau, Health Canada. Its design guidance is based on the need for a low operational cost and reliable sampler to provide daily aerosol monitoring samples that can be used as reference samples for radiological studies. It has been developed to provide a constant air flow rate at low pressure drops (∼3 kPa for a day sampling) with variations of less than ±1% of the full scale flow rate. Its energy consumption is only about 1.5 kW for a filter sampling over 22,000 standard cubic meter of air. It has been demonstrated in this Fukushima nuclear accident related aerosol radioactivity monitoring study at Sidney station, B.C. that the sampler is robust and reliable. The results provided by the new monitoring system have been used to support decision-making in Canada during an emergency response.     

Results of the European Commission Marina II study: part II--effects of discharges of naturally occurring radioactive material

Enhanced levels of naturally occurring radioactive materials (NORM) are produced through various industrial operations and may lead to discharges to the marine environment. A recent study, called MARINA II, carried out for the European Commission considered discharges of radionuclides from the NORM industries to north European marine waters and their consequences. There are two main sources that were considered in the study. The use of phosphogypsum during the production of phosphoric acid by the fertiliser industry and the pumping of oil and gas from the continental shelf in the North Sea which produces large quantities of water contaminated with enhanced levels of naturally occurring radionuclides. Discharges of alpha emitting radionuclides from these two industries have contributed significantly to the total input of alpha emitters to north European waters over the period 1981-2000 (data were not available prior to 1981). Discharges due to the use of phosphogypsum have declined since the early 1990s and are now very low. Discharges from the oil and gas industries stabilised in the second half of the 1990s and are now the major contributor to alpha discharges to the region. As most European countries do not report discharges of radioactivity with the water produced during extraction, there is considerable uncertainty in the discharges used in the study. The impact of the discharges has been estimated both in terms of the effect on non-human biota and the radiological impact for people. In the 1980s the radiation dose rates to marine biota in the region around a phosphate plant on the north-west coast of England were as high due to the discharges from the phosphate plant as those near to the Sellafield reprocessing plant due to its discharges. In recent years the additional dose to marine biota in this region due to the past NORM discharges is of the same order of magnitude as the natural background. The collective dose rate was estimated to determine the radiological impact on people. The peak collective dose rate from the NORM industries occurred in 1984 and was just over 600 manSv y(-1). The collective dose rate fell with time as discharges from the phosphate industry reduced and was estimated as under 200 manSv y(-1) in 2000.     

Seabed gamma-ray spectrometry: applications at IAEA-MEL

The technique of underwater gamma-ray spectrometry has been developed to complement or replace the traditional sampling-sample analysis approach for applications with space-time constraints, e.g. large areas of investigation, emergency response or long-term monitoring. IAEA-MEL has used both high-efficiency NaI(Tl) and high-resolution HPGe spectrometry to investigate contamination with anthropogenic radionuclides in a variety of marine environments. Surveys at the South Pacific nuclear test sites of Mururoa and Fangataufa have been used to guide sampling in areas of high contamination around ground zero points. In the Irish Sea offshore from the Sellafield nuclear reprocessing plant, a gamma-ray survey of seabed sediment was carried out to obtain estimates of the distribution and subsequently, for the inventory of 137Cs in the investigated area.     

Environmental monitoring and radioecology: a necessary synergy

Environmental monitoring primarily aims through sampling or by the use of direct detection equipment to quantify the levels of radioactive substances and ionising radiation resulting from human activities and natural sources in the different compartments of the environment. Its objectives are very practical and include the quantification of the environmental sources of ionising radiation and the verification of compliance with regulatory requirements and permit limits for industrial, research and medical activities, as stated by their specific licence. Radioecology is a multidisciplinary science, which attempts to understand and to quantify the behaviour of radionuclides in the environment and the processes ruling their transport through natural and agricultural ecosystems to various receptors such as plants, animals and humans. A second facet of this science covers the assessment of the radiological dose to and effects on man and its environment from present, past or future, even hypothetical, nuclear activities. Despite their different immediate objectives, environmental monitoring and radioecology are complementary. Many examples illustrate the connections between these two approaches. For instance, transfer parameters generated by radioecological studies are necessary to estimate through models the radiological exposure of population, derive from the contamination level measured in a bio-indicator the quantity of radioactivity released from a nuclear installation, or identify potentially important pathways to be monitored. On the other hand, monitoring data will confirm important pathways suggested by radioecological modelling and provide site-specific data for the estimation of model parameters or actual data sets for the validation of transfer models.     

On the occurrence of radioactive fallout over Norway as a result of the Windscale accident, October 1957

A fire at the Windscale plant at Cumbria in the UK between the 10th and the 11th of October 1957 resulted in the first publicised release of radioactivity to the wider environment. The cloud of contamination passed to the southeast of England before travelling northwards on the 14th of October as a result of weather fronts in Europe. Monitoring of radioactive fallout in Norway was at the time conducted by the Norwegian Defence Research Establishment (FFI) using a network of air and precipitation monitoring stations. This article presents results from these monitoring activities which were originally contained in laboratory journals and a series of internal reports produced by FFI. Although mainly classified during the 1950s and 1960s, recent years have seen the incremental declassification of these reports and as the 50th anniversary of the accident approaches, a distillation and reanalysis of this information has been conducted. Results indicate that radioactivity from Windscale was first detected at Bergen and Sola in the south west of Norway and a little later at Vaernes, significant amounts of radioactivity being deposited at these locations during the second and third weeks of that month. Results relating to concentrations of activity in air and precipitation and fallout levels are presented for the relevant period and discussed in relation to fallout levels in Norway during the period 1957-1960.     

Assessment of persistent toxic substances in the environment of Egypt

The objective of this review is to provide a comprehensive assessment of the threats posed by persistent toxic substances (PTS) to the environment and human health in Egypt and to identify priorities, data gaps and recommendations for future intervention to control, reduce or eliminate releases of PTS. Data on available concentrations of persistent toxic substances in the different environmental compartments and their impacts on the ecosystem, and humans have been assembled and summarized. Despite extensive studies, most of the data available deal with limited studies or hot spot situations. Localized inputs of PTS have been identified from freshwater discharges in coastal areas (e.g., Nile estuaries and coastal lakes) and near sewage outfalls from highly industrialized and populated cities. Data are often missing for certain contaminants and in some compartments and geographical areas. The lack of standardized methodologies makes it difficult to compare and use existing data to provide exact conclusions on spatial and temporal trends. In spite of these restrictions, available data indicate that it is unlikely that present levels of cyclodiene pesticides would adversely affect marine organisms. Compounds which are proven to be of concern are DDT, PCBs, gamma-HCH, PAHs, HCB and organotin compounds. Other compounds are suspected to be ubiquitous but data are lacking. Based on few recent data, the reported levels of organochlorine pesticides in fish and human milk samples suggest a concentration decline during the 1990s consistent with the regulatory restrictions on the use of these compounds. It is essential to activate monitoring programs to fill data gaps in appropriate abiotic and biotic. Monitoring programs should be follow standard procedures and include improved QA/QC protocols.     

A soil sampling intercomparison exercise for the ALMERA network

Soil sampling and analysis for radionuclides after an accidental or routine release is a key factor for the dose calculation to members of the public, and for the establishment of possible countermeasures. The IAEA organized for selected laboratories of the ALMERA (Analytical Laboratories for the Measurement of Environmental Radioactivity) network a Soil Sampling Intercomparison Exercise (IAEA/SIE/01) with the objective of comparing soil sampling procedures used by different laboratories. The ALMERA network is a world-wide network of analytical laboratories located in IAEA member states capable of providing reliable and timely analysis of environmental samples in the event of an accidental or intentional release of radioactivity. Ten ALMERA laboratories were selected to participate in the sampling exercise. The soil sampling intercomparison exercise took place in November 2005 in an agricultural area qualified as a “reference site”, aimed at assessing the uncertainties associated with soil sampling in agricultural, semi-natural, urban and contaminated environments and suitable for performing sampling intercomparison. In this paper, the laboratories sampling performance were evaluated.     

A simple model for describing the concentration of 212Pb in the atmosphere

The implementation of the Comprehensive Test Ban Treaty is resulting in the construction of a world-wide system of 80 monitoring stations that will be able to detect air-borne radioactivity, not only from atomic bombs but also from other anthropogenic and natural sources. A prototype monitoring station has been operating since April 1996 in Vancouver, BC, Canada. This station provides daily reports of natural radioactivity, including 7Be and decay products of 220Rn (thoron). Data for 212Pb concentrations have been analyzed over a 6-month period. The concentration is reduced by rainfall, high wind velocity, and low temperatures and it also depends on the wind direction, but atmospheric inversions appeared to have little impact. We present a relatively simple model, which is easy to use and which offers predictive powers that can be applied to other similar environmental situations.     

210Pb as a tool for establishing sediment chronologies: examples of potentials and limitations of conventional dating models

For aquatic sediments, the use of ²¹⁰Pb originating from the decay of atmospheric ²²²Rn is a well-established methodology to estimate sediment ages and sedimentation rates. Traditionally, the measurement of ²¹⁰Pb in soils and sediments involved laborious and time-consuming radiochemical separation procedures. Due to the recent development of advanced planar (‘n-type’) semi-conductors with high efficiencies in the low-energy range which enable the gamma-spectrometric analysis of the 46.5 keV decay line of ²¹⁰Pb, sediment dating using this radionuclide has gained renewed interest.In this contribution, potentials and limitations of the ²¹⁰Pb methodology and of the models used for estimating sediment ages and sedimentation rates are discussed and illustrated by examples of freshwater and marine sediments. Comparison with the use of ¹³⁷Cs shows that the information which may be gained by these two tracers is complementary. As a consequence, both radionuclides should be used in combination for dating of recent sediments. It is shown that for various sedimentation regimes additional information from other sources (e.g. sediment lithology) may be needed to establish a reliable chronology. A strategy for sediment dating using ²¹⁰Pb is recommended.     

Distribution and sources of (129)I in rivers of the Baltic region

The concentration of (129)I was measured in 54 river waters discharging into the Baltic Sea from Sweden, Finland, Estonia, Latvia, Lithuania, Poland and Germany. Sample collection was performed during a well-bracketed time interval (June-July 1999), thus allowing comparison of the rivers over a wide latitude range without the effect of long temporal spread. Although there is no direct input of anthropogenic (129)I in the watersheds, the concentration of the isotope is about two to three orders of magnitude higher than the expected pre-nuclear era natural values in the rivers of Finland and northern Sweden, and in the rivers of southern Sweden, Lithuania, Estonia, Latvia, Poland and Germany; the (129)I concentration may reach five orders of magnitude higher. Furthermore, there are significant correlations between the (129)I concentration and latitude and/or distance from the North Sea and between (129)I and Cl. These findings suggest seawater as a main source of (129)I to the rivers through atmospheric transport. Of the many chemical parameters investigated, the pH may account for some of the variability in (129)I concentrations of the rivers. The contribution from nuclear weapon tests and the Chernobyl accident to the riverine (129)I is insignificant compared to the releases from the nuclear fuel reprocessing facilities. The total flux of (129)I by rivers to the Baltic Sea and related basins represents minor amounts of the isotope pool in these marine waters. External radioactivity hazards from (129)I are considered to be negligible in the Baltic region. However, as the main (129)I intake to the human body is likely through water, due to the large amount of daily water consumption, more concern should be given to internal radioactivity hazard that may be associated with the isotope's localized elevated concentration in the human organs.     

A critical evaluation of the cost-effectiveness of radon protection methods in new homes in a radon Affected Area of England

In the UK, building new homes in areas prone to radon gas is currently subject to regulations that require installation of radon-proof membranes. These membranes are not, however, the only way to protect residents of new homes against radon's potential to cause lung cancer. Alternative regulatory regimes can be constructed that would achieve the same end.The purpose of this paper is to examine the cost-effectiveness of four alternative regimes and so determine if building regulations for new homes could be altered to protect residents from the effects of radon more cost-effectively than at present. In addressing this question, the paper also contributes to the wider debate on how best to reduce the effect on public health of exposure to radon.The measure of cost-effectiveness used, cost per quality-adjusted life-year gained, is determined from radon test results obtained in properties in Brixworth, England, UK, a radon Affected Area. Confidence intervals for the cost-effectiveness estimates are also derived using bootstrap techniques.The central estimates of cost-effectiveness range from £2870 per quality-adjusted life-year gained for the most cost-effective of the alternative regimes to £6182 for the current regime. These results suggest that alternative regimes may be more cost-effective in tackling the radon problem. A definitive assessment of the most suitable to adopt will require extensive negotiation between government departments, the construction industry, and other interested parties to ensure acceptance of any new regime. The paper offers suggestions for future research that should help in the process of identifying the key features of a new regulatory approach.     

Quality assurance for the measurements and monitoring of radioactivity in the environment

During the Fifth Framework Programme (FP5) of the European Commission--according to an institutional programme in support to the policy of the European Commission for the implementation of Art. 35 and 36 of the Euratom Treaty as well as in the framework of the OSPAR Convention for the protection of marine environment of the north-east Atlantic--at the Institute for Transuranium Elements (ITU--General Directorate Joint Research Centre--European Commission), a reference laboratory for the measurement of radioactivity in the environment (MaRE laboratory) has been set up. In this paper, the principles and philosophy in order to improve the quality and reliability of analytical data for the measurement and monitoring of radioactivity in the environment under a quality assurance (QA) programme are presented. Examples of how a QA programme at the MaRE laboratory is developed and applied are given. Internal and external quality control (QC) programmes are also discussed.     

Monitoring of radiation and radioactivity in the environment

This report lists the programs for monitoring radiation and radioactivity in the environment that are known to be in operation or to have been in operation recently. It is intended as a guide to be used when seeking information on the programs of other institutions. Sources of the data have been the literature and personal correspondence and discussions.The programs are divided into the categories of weapons test fallout, natural activity and environmental monitoring of releases from specific facilities. Where possible, the types of measurements being made are also listed. While the data are as up to date as possible the field is changing rapidly and there may be ommissions.     

Radiological characteristics and investigation of the radioactive equilibrium in the ashes produced in lignite-fired power plants

Coal- and lignite-fired power plants produce significant amounts of ashes, which are quite often being used as additives in cement and other building materials. In many cases, coal and lignite present high concentrations of naturally occurring radionuclides, such as 238U, 226Ra, 210Pb, 232Th and 40K. During the combustion process, the produced ashes are enriched in the above radionuclides. The different enrichment of the various radionuclides within a radioactive series, such as that of 238U, results in the disturbance of radioactive secular equilibrium. An extensive research project for the determination of the natural radioactivity of lignite and ashes from Greek lignite-fired power plants is in progress in the Nuclear Engineering Department of the National Technical University of Athens (NED-NTUA) since 1983. This paper presents detailed results for the natural radioactivity, the secular radioactive equilibrium disturbance and the radon exhalation rate of the fly-ash collected at the different stages along the emission control system of a lignite-fired power plant as well as of the bottom-ash. From the results obtained so far, it may be concluded that 226Ra radioactivity of fly-ash in some cases exceeds 1 kBq kg(-1), which is much higher than the mean 226Ra radioactivity of surface soils in Greece (25 Bq kg(-1)). Furthermore, the radioactivity of 210Pb in fly-ash may reach 4 kBq kg(-1). These results are interpreted in relation to the physical properties of the investigated nuclides, the temperature in the flue-gas pathway, as well as the fly-ash grain size distribution. It is concluded that towards the coldest parts of the emission control system of the power plant, the radioactivity of some natural nuclides is gradually enhanced, secular radioactive equilibrium is significantly disturbed and the radon exhalation rate tends to increase.