GI6.2
vPICO presentations: Fri, 30 Apr
Ambient radioactivity reflects a wide range of physical processes, including atmospheric and geological processes, as well as space weather and solar conditions. Gamma radiation near the Earth’s surface comes from diverse sources, including space (cosmic radiation), the earth’s atmosphere, and solid earth. In addition to the terrestrial gamma radiation originating from the radioactive decay of primordial radionuclides present in every soil and rock, gamma radiation is also continuously produced in the atmosphere from the interaction of secondary cosmic rays and upper-atmosphere gases, as well as from the decay of airborne radon (Rn-222) progeny. Therefore the temporal variability of gamma radiation contains information on a wide range of physical processes and space-earth interactions, but disentangling the different contributions remains a challenging endeavor. Continuous monitoring of gamma radiation at sea enables to remove both the terrestrial and radon exhalation contributions, allowing to examine in detail the space and atmospheric sources of ambient gamma radiation.
Gamma radiation over the Atlantic Ocean was measured on board the ship-rigged sailing ship NRP Sagres in the framework of the SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer) project. The measurements were performed continuously (every 1-second) with a NaI(Tl) scintillator counting all the gamma rays from 475 keV to 3 MeV. The casing of the instrument was adapted in order to endure the harsh oceanic conditions and installed in the mizzen mast of the ship. The counts were linked to a rigorous temporal reference frame and precise positioning through GNSS.
Here preliminary results based on the gamma radiation measurements performed from January 5th to May 9th 2020 are presented, corresponding to the journey of the ship from Lisboa to Cabo Verde, Rio de Janeiro, Montevideu, Cape Town, and back to Lisboa. The data exhibit a clear transition from the coastal to the marine environment, enabling to study in detail the temporal variation of gamma radiation in the marine boundary layer, as well as the interface between land and marine conditions in terms of environmental radioactivity.
How to cite: Barbosa, S., Amaral, G., Almeida, C., Dias, N., Ferreira, A., Camilo, M., and Silva, E.: Environmental radioactivity in the Atlantic marine boundary layer from the SAIL monitoring campaign , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1264, https://doi.org/10.5194/egusphere-egu21-1264, 2021.
Radioactivity soundings have been performed in Finland since the early 1960s to measure radiation and radioactivity levels in the atmosphere up to the height of 40 km. A sonde package based on a Geiger-Müller (GM) tube is carried up to the stratosphere by a balloon filled with hydrogen or helium. En route the GM tube count rate values are sent to the ground station with a radio transmitter.
Vaisala Corporation developed a radioactivity sounding system in the early 1960s. Radioactivity soundings were performed at the company's aerological test station in Helsinki as a part of development and quality assurance activities. At least once, in October 1962, these radioactivity soundings revealed the presence of abnormal radioactivity in the stratosphere over Finland due to atmospheric nuclear tests.
The Finnish Defence Forces acquired the Vaisala's radioactivity sounding system in 1963. This system was placed at the Finnish Meteorological Institute's (FMI) meteorological observatory of Jokioinen. The staff of the observatory operated the system. Initially radioactivity soundings were performed once a week but later sparser and sparser so that in 1980 only one sounding, in November after the so far last atmospheric nuclear test, was performed. Only a couple of publications have been produced from the artificial radioactivity observations in the upper atmosphere, perhaps due to the sensitive nature of the subject. After 1980 no more radioactivity soundings were performed in Finland during the 1980s, not even during the 1986 Chernobyl accident.
In the aftermath of the Chernobyl accident Vaisala developed a new generation of radioactivity sondes that are incorporated into the company's meteorological sounding systems. The FMI has performed these radioactivity soundings since the early 1990s at its sounding stations at Jokioinen, Tikkakoski and Sodankylä. Usually one or two soundings are performed per year, often during nuclear accident preparedness exercises.
The radioactivity soundings described above have brought information on cosmic radiation even if the main motivation was the surveillance of artificial radioactivity in the upper atmosphere. However, balloon soundings dedicated to cosmic radiation research have been made by the University of Oulu. These sounding activities were coordinated by SPARMO organization (Solar Particles and Radiation Monitoring Organization), later with the name SBARMO (Scientific Ballooning and Radiation Monitoring Organization). Altogether 114 soundings were performed from 1965 to 1979. In addition to scientific results these activities helped the then new university to network with the international scientific community.
Balloon-borne radiation sondes have shown to be a flexible and a cost-efficient method to obtain data on the radiation environment of the upper atmosphere. The information about the vertical distribution of a radioactive plume provided by soundings is essential for a reliable atmospheric dispersion estimation. This, in turn, helps to plan and execute protective measures, e.g. stable iodine prophylaxis. On the other hand, the altitude information about observed airborne radioactivity of unknown origin benefits the inverse modeling to find out the possible source areas of the release. This can be useful for example in detecting clandestine nuclear activities.
How to cite: Paatero, J., Hatakka, J., Kivi, R., and Immonen, J.: Radioactivity soundings of the upper atmosphere in Finland 1962-2020, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11452, https://doi.org/10.5194/egusphere-egu21-11452, 2021.
The SMEAR Estonia station (58.277663 N, 27.308266 E, 36 m a.s.l.) was established in south-east of Estonia at the Järvselja Experimental Forestry in 2012 to investigate the atmosphere-biosphere interactions and atmospheric aerosol formation and growth.
In summer 2019, the gamma-radiation monitor GammaTRACER XL2-3 (Saphymo GmbH) was set up at Järvselja station and the rain sensor DRD11A (Vaisala Oyj) in autumn 2019. These devices enable to measure the gamma-radiation dose rate and precipitation intensity, which affect the ionization rate of atmospheric air close to ground, with high accuracy and time resolution, and complement our measurement system of atmospheric ions and aerosol particles.
The gamma-radiation dose rate measurements at about 1.2 m above the ground reveled on relatively steady background about 70 nSv/h occasional events with increase up to about 110 nSv/h, which correlated well with rainfall intensity. Commonly such events last 3-4 hours, but in specific meteorological situation with continuous long-lasting rain and air mass movement from southerly directions the effect can last 2-3 days, resulting in gradual increase in gamma-radiation dose rate level during about 24 h.
Such a phenomenon is known to occur due to wet deposition of radioactive aerosol particles during rain, namely due to the radon (222 Rn) short-lived daughter progeny products (Po-218, Pb-214, Bi-214) attached to atmospheric aerosol particles. The radon (222 Rn) daughter progeny involvement is confirmed by simultaneous gamma-spectrometric measurements with SARA AGS711F (Envinet GmbH) at Tõravere station (58° 15' 52,9" N, 26° 27' 42,1", 72 m), located about 50.3 km west from the Järvselja SMEAR station. The gamma dose rates showed very similar temporal behavior when both stations were affected by the same air mass with precipitation zone passing over the stations.
To our best knowledge, the details of rain-induced enhancement of gamma-radiation dose rate and atmospheric processes behind the phenomenon are not well known and are worth future investigations. The events of rain induced gamma-radiation dose rate enhancement at Järvselja SMEAR and Tõravere station are analyzed and discussed in more detail in the presentation and the spatial representativity of the phenomenon is estimated based on the gamma-radiation monitoring network data of Estonian Early Warning System.
How to cite: Hõrrak, U., Chen, X., Hõrrak, K., Rand, U., Komsaare, K., Vana, M., Luts, A., and Junninen, H.: The rain induced gamma-radiation dose rate enhancement at Järvselja SMEAR station, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15644, https://doi.org/10.5194/egusphere-egu21-15644, 2021.
Air ions are ubiquitous in the atmosphere. These charge carriers can be found in various forms as charged molecules, nanoclusters as well as aerosol particles. The population of air ions normally concentrates in the cluster size range (0.8 – 1.7 nm in mobility equivalent diameters) in the absence of particle formation processes. A concentration burst in the intermediate size range (1.7 – 7 nm) can be typically observed during atmospheric new particle formation (NPF) and in precipitation episodes 1. Contrary to the intermediate ions formed during NPF that favour growth to larger sizes, intermediate ion bursts resulting from precipitation tend to shrink 2,3. The production of intermediate ions during precipitation has been attributed to the Lenard effect and they are usually referred to as the balloelectric ions 3.
During precipitation the rain-out and wash-out of radon progeny increase the gamma dose at ground level 4. Being a type of ionising radiation, gamma creates positive and negative charges in the air. These charges are either lost in recombination or transformed into air ions. It is therefore interesting to understand whether the precipitation-associated elevation in gamma radiation plays any role in forming or neutralising the balloelectric ions. At SMEAR II station in Hyytiälä, Finland 5, we have conducted measurements of air ions, gamma radiation, precipitation together with other meteorological parameters. A similar establishment of the measurement set stands also at SMEAR Estonia station in Jarvseljä, Estonia 6. The data collected at Hyytiälä from 2017.7 to 2018.8 show that the intermediate ion concentration correlates with rainfall only when the precipitation intensity is greater than 1 mm/h. For milder rainfall with the precipitation intensity being 0.1-1 mm/h, the intermediate ion concentration increases with an increase in the gamma counts. The work is under progress and we intend to extend the analysis to Jarvseljä data for a comprehensive understanding of the observations.
Acknowledgements: This work received financial supports from European Regional Development Fund (project MOBTT42) under the Mobilitas Pluss programme and from Estonian Research Council project PRG714.
References:
1. Tammet, H., Komsaare, K. & Hõrrak, U. Intermediate ions in the atmosphere. Atmospheric Research 135-136, 263-273, doi:10.1016/j.atmosres.2012.09.009 (2014).
2. Hõrrak, U. et al. Formation of Charged Nanometer Aerosol Particles Associated with Rainfall: Atmospheric Measurements and Lab Experiment. Report Series in Aerosol Science 80, 180-185 (2006).
3. Tammet, H., Hõrrak, U. & Kulmala, M. Negatively charged nanoparticles produced by splashing of water. Atmos. Chem. Phys. 9, 357–367 (2009).
4. Paatero, J. & Hatakka, J. Wet deposition efficiency of short-lived radon-222 progeny in central Finland. Boreal Env. Res. 4, 285-293 (1999).
5. Hari, P. & Kulmala, M. Station for measuring ecosystem-atmosphere relations (SMEAR II). Boreal Environ. Res. 10, 315-322 (2005).
6. Noe, S. M. et al. SMEAR Estonia: Perspectives of a large-scale forest ecosystem – atmosphere research infrastructure. Forestry Studies 63, doi:10.1515/fsmu-2015-0009 (2015).
How to cite: Chen, X., Barbosa, S., Paatero, J., Kulmala, M., and Junninen, H.: Investigation on the role of elevated gamma radiation in ion production during precipitation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11909, https://doi.org/10.5194/egusphere-egu21-11909, 2021.
The natural radioactive noble gas radon (222Rn) is originated from the decay of radium into the soil and then continuously exhaled to the lower atmosphere. Its diffusion and exhalation rate depend both on the physical and environmental conditions of the soil layers and on the meteorological conditions. With a half-life of 3.8 days and a very limited chemical activity, the 222Rn is nowadays being used as an atmospheric tracer for: i) the improvement of atmospheric transport models used, among others, to identify greenhouse gas (GHG) emission sources; ii) for the indirect estimation of GHG fluxes by the Radon Tracer Method (RTM). These previous applications need high sensitivity and precision at low radon concentrations range (< 100 Bq m-3).
A new monitor, based on alpha spectrometry of 218Po electrostatically collected on a PIPs detector, has been designed and developed at the Institute of Energy Technologies (INTE) of the Universitat Politecnica de Catlunya (UPC) in the mark of the project ‘High efficiency monitor of atmospheric radon concentration for radiation protection and environmental applications (MARE2EA), reference: 2019-LLAV-00035, funded by the Catalan Agency for Management of University and Research Grants. The aim is building an instrument able to measure atmospheric radon concentration activities with high precision in order to be running at GHG atmospheric networks for the RTM applications.
The monitor is an improved version of a previous prototype instrument (Grossi et al., 2012, 2020). The new instrument will allow a higher efficiency, robustness and portability. In addition, it will have a GUI interface to be user friendly. Finally, in order to reduce the air sample humidity within the detection volume of the instrument which affects the 218Po collection, a portable drying system has also been built to keep the instrument ongoing without maintenance during several weeks.
References
Grossi, C., Arnold, D., Adame, J. A., López-Coto, I., Bolívar, J. P., De La Morena, B. A., & Vargas, A. (2012). Atmospheric 222Rn concentration and source term at El Arenosillo 100 m meteorological tower in southwest Spain. Radiation Measurements, 47(2), 149–162. https://doi.org/10.1016/j.radmeas.2011.11.006
Grossi, C., Chambers, S. D., Llido, O., Vogel, F. R., Kazan, V., Capuana, A., Werczynski, S., Curcoll, R., Delmotte, M., Vargas, A., Morguí, J.-A., Levin, I., & Ramonet, M. (2020). Intercomparison study of atmospheric 222Rn and 222Rn progeny monitors. Atmospheric Measurement Techniques, 13(5). https://doi.org/10.5194/amt-13-2241-2020
How to cite: Curcoll Masanes, R., Grossi, C., and Vargas, A.: High efficiency and portable monitor of atmospheric radon concentration activity for environmental applications, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4497, https://doi.org/10.5194/egusphere-egu21-4497, 2021.
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The IRSN operates a framework capable of modelling the occurrence of gamma dose rate peaks due to Radon-222 progeny scavenged by precipitations. This framework includes a Radon-222 exhalation flux and meteorological data as inputs to a long range atmospheric transport model (ldx), and specific post-processes for reporting or performance analysis. Ldx is used in nuclear emergency preparedness and response, and it is applied to Radon-222 and its progeny to simulate both their air concentration and deposition onto the ground. This framework is successful at forecasting, in timing and intensity, around half of the peaks actually observed by the IRSN radiation monitoring stations over France. Understanding and analysing the failures is the starting point to improve the modelling.
For a statistical evaluation of the framework performance, we confronted its results to observations of gamma dose rates over a period of six months gathering more than 12,000 peaks. We used two sets of metrics to assess the agreement between model and observations: punctually (peak by peak) and continuously (whole six months’ time series of gamma dose rate and air concentration). We also performed statistical significance tests to identify the influence of some input parameters on the results.
We found that considering a factor 5 instead of a factor 2 between observed and simulated peak values increases the percentage of successfully forecasted peaks from around 50% to above 90%, whereas increasing the permissible time lag between the two has no such effect. Overall, the model shows better recall than precision: i.e. a tendency to produce more false positives than false negatives. ANOVA tests did not point out any performance difference across factors such as land cover or time of the day. Using weather radar measurements for precipitation instead of meteorological model data also improves the reanalysis performances.
This statistical evaluation serves as a gauge to measure the benefits expected from future developments of our current framework, and by that way the future evolutions of our long range module and methodology of use in case of an emergency response, and helps to determine the relevance of alternative simulation options regarding key parameters or processes, such as exhalation and soil moisture. A well-validated framework is of interest as to assess outdoor concentrations of Radon-222.
How to cite: Quérel, A., Meddouni, K., Quélo, D., Doursout, T., and Chuzel, S.: Statistical approach to improve Radon-222 long-range atmospheric transport modelling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9081, https://doi.org/10.5194/egusphere-egu21-9081, 2021.
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Croatian Science Foundation MARRES project (MARine lake (Rogoznica) as a model for EcoSystem functioning in a changing environment) aims to investigate the unique environment (slow exchange of seawater with the sea; atmospheric input is the only source of freshwater) of the marine lake which is an example of highly stratified (permanent anoxia bellow 9 m depth), and by climate changes affected marine system in the middle of the eastern Adriatic coast (43.53° N, 15.95° E). The area of the lake is characterized by the extensive tourism and mariculture, and the low impact of local industrial activities. It is also affected by the combined influence of long-range transport of air masses and local emissions (open-fire events).
An important part of the project is focused on the exchange and interaction between atmosphere, water column and sediment by measuring the atmospheric input (wet and dry deposition) of sulphur compounds, organic carbon, trace metals and radionuclides (Be-7, Pb-210).
This work for the first time will present the current state of the measurements of radioactivity in the Rogoznica lake area, including samples of aerosol particulate matter, PM2.5 < 2.5 um, rainwater and lake water column. Namely, the concentrations of Be-7 and Pb-210 in PM2.5 are measured to determine and correlate the dynamics of particle transport, meteorological information, especially origin of air masses and seasonal variation of PM2.5. While presence of Be-7 indicates the recent wet or dry deposition from the upper parts of the atmosphere, Pb-210 may be used as a tracer for continental air masses. Therefore, it can also indicate the influence of the pollution induced by human activity. Regarding that, special attention will be paid to compare results before and during the Covid-19 lockdown periods.
So far, preliminary results do not show significant difference in PM2.5 masses and measured radionuclide activity concentrations for the lockdown period. Be-7 and Pb-210 were regularly detected in aerosols collected on a glass fiber filters during a one-week sampling periods with the air flow rate of 2.3 m3/h. Their activity concentrations are determined by gamma spectrometry using High Purity Germanium detectors. The results are found to be correlated with PM2.5 masses, ranging from 2.9 to 12.2 Bq/m3 for Be-7 and from 0.5 to 2.5 Bq/m3 for Pb-210. First analyses show that the highest values can be related to the long-range transport of air masses and to the recorded near open-fire event. As expected, Be-7 is also detected in almost every rainwater sample (event), with the activity concentration up to 5.6 Bq/L, while low activities of Pb-210 are detected only sporadically. Related to that, Be-7 is detected in lake water column as well, but only in the surface layer and in samples collected during, or immediately after the rain events.
Dynamics and seasonal variation of radionuclide activity concentrations in here studied samples will be discussed, and the relationships with some meteorological parameters (temperature, wind speed, relative humidity, precipitation level) as well as local and long-range transport and physico-chemical conditions in the lake water column will be established.
How to cite: Tucaković, I., Mateša, S., Coha, I., Marguš, M., Čanković, M., and Ciglenečki, I.: Radioactivity measurements in the atmosphere and water column of Rogoznica Lake (central Adriatic), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12269, https://doi.org/10.5194/egusphere-egu21-12269, 2021.
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An overlapping need exists between the climate science, air quality and radiological protection communities for a robust, portable and direct monitor of atmospheric 222Rn concentrations typical of the ambient outdoor atmosphere. To reliably characterise afternoon radon concentrations, or resolve daytime vertical radon gradients in the atmospheric boundary layer (requirements for radon measurements to be used to evaluate the performance of chemical transport models), detection limits of ≤0.2 Bq m-3 at an hourly temporal resolution are required. Commercial portable radon detectors are mainly designed for indoor use, and the best of these has a detection limit of ≥2 Bq m-3 for hourly sampling, with an approximate uncertainty of 60% at typical outdoor daytime radon concentrations. Here we introduce a portable (200 L) version of the two-filter dual-flow-loop radon detector, designed and built by ANSTO in collaboration with the EMPIR 19ENV01 traceRadon project. While not as compact as commercial monitors (standing 1.6 m tall, and 0.48 m wide), its longest component is 1.2 m, enabling transportation in a standard utility vehicle or 4x4 (and can fit inside a 19” instrument rack). Constructed of marine grade stainless steel, it is weather resistant, robust, and suitable for long-term, continuous, autonomous deployment; in fact it is fully remotely controllable if a networked computer is available. The estimated lower limit of detection is 0.17 Bq m-3 for hourly observations, and the counting uncertainty at typical ambient outdoor radon concentrations is around 7%. Additional uncertainty associated with current calibration techniques, which inject calibration gas on top of ambient sampled air, varies from 2-6%. Some objectives of the traceRadon project include establishing direct calibration traceability to the SI and developing an improved closed-loop calibration technique, using a new, low activity Radium-226 source. If successful, the absolute accuracy of the 200 L radon detector at typical ambient outdoor concentrations could be kept well below 15% for hourly observations. This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. 19ENV01 traceRadon denotes the EMPIR project reference.
How to cite: Chambers, S., Morosh, V., Griffiths, A., Williams, A., Röttger, S., and Röttger, A.: Field testing of a portable two-filter dual-flow-loop 222Rn detector, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-196, https://doi.org/10.5194/egusphere-egu21-196, 2021.
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More than 23 million workers worldwide are exposed occupationally to ionizing radiation in the workplace and all people in the world are exposed to environmental radiation. Due to developments in healthcare and changes in living conditions, radiation exposure from artificial and natural sources has been increasing for years. Accurate measurement of radiation dose is key to ensuring safety, but there are two challenges to address. First, new standards and reference fields are needed due to the rapid developments in medical imaging, radiotherapy and industrial applications. Second, communication channels are needed to ensure that information on best practice in measurements reaches the people concerned effectively and quickly.
It is therefore necessary to provide access to identified problems and solutions on an international level. A European Metrology Network (EMN) under the roof of EURAMET is in the foundation phase prepared by the project supportBSS[1]. This project will prepare this future EMN by addressing this issue through the identification of stakeholder research needs and implementing a long-term ongoing dialogue between them and the metrology community. The EMN will serve as a single point of contact to address all metrological needs related to radiation protection and will relate to all environment processes in which ionising radiation and radionuclides are involved.
A Strategic Research Agenda and two roadmaps are under development, covering the metrology needs of both the Euratom Treaty and the EU Council Directive 2013/59/EURATOM (laying down basic safety standards for protection against the dangers arising from exposure to ionizing radiation). Furthermore, long-term knowledge-sharing and capacity building will be supported and a proposal for a joint and sustainable European metrology infrastructure is in the development. This will significantly strengthen radiation protection metrology and support radiation protection measures. The final goal of the network project is a harmonised, sustainable, coordinated, and smart specialised infrastructure to underpin the needs expressed in the European regulation for radiation protection.
[1] This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. 19NET03 supportBSS denotes the EMPIR project reference.
How to cite: Röttger, A., Veres, A., Sochor, V., Pinto, M., Derlacinski, M., Ioan, M.-R., Sabeta, A., Bernat, R., Adam-Guillermin, C., Gracia Alves, J. H., Glavič-Cindro, D., Bell, S., Wens, B., Persson, L., Živanović, M., and Nylund, R.: Metrology for radiation protection: A new European network in the foundation phase, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-82, https://doi.org/10.5194/egusphere-egu21-82, 2021.
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Radon gas is the largest source of public exposure to naturally occurring radioactivity, and concentration maps based on atmospheric measurements aid developers to comply with EU Safety Standard Regulations. Atmospheric radon can also be used as a tracer to evaluate transport models important for supporting successful greenhouse gas (GHG) mitigation strategies. One of the most common techniques currently applied for this propose is the Radon Tracer Method (RTM). To increase the accuracy of both radiation protection measurements and those used for GHG modelling, traceability to SI units for radon exhalation rates from soil, its concentration in the atmosphere and validated models for its dispersal are needed. Thus, atmospheric networks such as the Integrated Carbon Observation System (ICOS) are interested in integrating atmospheric radon concentration measurements. The EMPIR project 19ENV01 traceRadon[1] started to provide the necessary measurement infrastructure for atmospheric radon activity concentration and radon flux measurements, with benefits for both large scientific communities. This is particularly important for GHG emission estimates that support national reporting under the Paris Agreement on climate change.
Compared to the large spatiotemporal heterogeneity of GHG fluxes, radon is emitted almost homogeneously over ice-free land and has a negligible flux from oceans. Atmospheric measurements of radon activity concentrations can be used for the assessment and improvement of atmospheric mixing and transport models.
Similarly, for radiological data, all European countries have installed networks of automatic gamma dose rate and atmospheric concentration level monitoring stations and report the information gathered to the European Radiological Data Exchange Platform (EURDEP). Currently, EURDEP exchanges real-time monitoring information from 39 countries collected from more than 5500 automatic surveillance systems. Therefore, improving contamination detection requires greater accuracy in determining environmental radon concentrations and their movement in the atmosphere.
An overlapping need exists between the climate research and radiation protection communities for improved traceable low-level outdoor radon measurements, combining the challenges of collating and modelling large datasets, with setting up new radiation protection services. The project traceRadon works on this aspect for the benefit of two large scientific communities. An overview will be presented, and first results with respect to radionuclide metrology will be discussed.
[1] This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. 19ENV01 traceRadon denotes the EMPIR project reference.
How to cite: Röttger, S., Röttger, A., Grossi, C., Karstens, U., Cinelli, G., and Rennick, C.: Radon metrology for use in climate change observation and radiation protection at the environmental level, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-173, https://doi.org/10.5194/egusphere-egu21-173, 2021.
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Tenerife is the largest and most populated island of the Canary Islands; with a surface of 2,034 km2 and 917,841 inhabitants (in January 2019), it hosts 43% of the total population of the archipelago.
Large amounts of 137Cs, an artificial radionuclide with a half-life of 30.2 years, were released into the environment due to the nuclear weapon tests carried out from the 1950s to the 1970s and by nuclear power plant accidents, such as the Chernobyl in 1986. The most recent 137Cs release into the environment was due to the Fukushima Daiichi Nuclear Power Plant accident, following the earthquake and tsunami of 11 March 2011. Radionuclides released by this accident were measured in air filters collected in the Canary Islands despite the tremendous distance to the source (López-Pérez et al., 2013).
In this work, we provide the concentrations of 137Cs measured in 73 soil samples collected in 2013 in Tenerife. Besides, a second dataset of 137Cs concentrations recorded in 103 soil samples collected in 1991 (22 years before) have been used to provide information on the spatial and temporal variability of this anthropogenic radionuclide at this site.
In both surveys, sampling sites were randomly selected on a predefined 3x3 km sampling grid covering the whole island and superficial samples were collected from uncultivated fields. Radiometric measurements were performed by gamma spectrometry with a coaxial-type germanium detector (Canberra Industries Inc., USA). The activity concentration of 137Cs was directly measured by its gamma-ray photopeak at 661.65 KeV. The Minimum Detectable Activity was 0.08 Bq kg-1.
137Cs activity concentrations in the 1991 survey ranged from 0.08 to 100.90 Bq kg-1 and from 0.08 to 88.85 Bq kg-1 in 2013. Comparing the results of both campaigns, 137Cs activity concentrations were found to be rather similar, despite the 22 years gap between the measurements. We believe that, in addition to the 137Cs atmospheric fallout, there is an additional contribution to the inventory of this radionuclide in the soils of this island produced by the deposition of 137Cs-loaded dust particles frequently transported from the Sahara Desert as dust storms (Karlsson et al, 2008).
In terms of radiological risk, in some few locations, the contribution to the outdoor gamma absorbed dose from the 137Cs activity concentrations present in the soils were as high as 50%. Therefore, it is important to identify the various sources of this radionuclide to the studied sites in order to enhance the understanding of the radiological hazard produced by this man-made radionuclide.
References:
Karlsson L, Hernandez F, Rodríguez S, López-Pérez M, Hernandez-Armas J, Alonso-Pérez S, Cuevas, E. (2008). Using 137Cs and 40K to identify natural Saharan dust contributions to PM10 concentrations and air quality impairment in the Canary Islands. Atmospheric Environment, 42: 7034-7042
López-Pérez M, Ramos-López R, Perestelo NR, Duarte-Rodriguez X, Bustos JJ, Alonso-Pérez S, E. Cuevas, J. Hernández-Armas. (2013). Arrival of radionuclides released by the Fukushima accident to Tenerife (Canary Islands). Journal of Environmental Radioactivity, 116: 180-186
How to cite: López Pérez, M., Salazar Carballo, P. Á., Martín Luis, M. C., Hernández, F. J., Liger, E., Fernández de Aldecoa, J. C., Catalán Acosta, A., and Gordo, E.: Radiocesium distribution in soils of Tenerife Island (Canary Islands, Spain), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3171, https://doi.org/10.5194/egusphere-egu21-3171, 2021.
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Lichen and moss samples were collected from Russian Arctic areas (Kola Peninsula, Franz Josef Land and few other locations) in the 1990s. In 2020, 137Cs was determined by HPGe gamma spectrometry from these samples after which isotopes of Pu and U were radiochemically separated from the samples. Mass ratios 240Pu/239Pu and 235U/238U were determined by ICP-MS for utilizing the characteristic isotopic fingerprints of different nuclear events. The aim of the work was to survey radioactive contamination sources in terrestrial environment in Russian Arctic regions, which have not yet been completely explored in respect to anthropogenic isotopes and their origin in the environment.
How to cite: Salminen-Paatero, S., Dutheil, P., Sundström, T., Rodushkin, I., and Paatero, J.: Determination of anthropogenic contamination by 137Cs, 240Pu/239Pu and 235U/238U in lichens and mosses from Russian Arctic areas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12997, https://doi.org/10.5194/egusphere-egu21-12997, 2021.
Safecast has been initiated in 2011 in Japan as response to the perceived inadequacy of official information policy about radioactive contamination. It is based on measurements of ambient dose rate (ADR) by numerous volunteers using a standardized monitor, called SAFECAST bGeigie Nano. In essence, it consists of a Geiger counter and a GPS module, data (ADR, GPS coordinates, date/time) are recorded on an SD card if operated in its survey mode.
The project quickly expanded world-wide and by end 2020, over 150 million measurements were recorded, however by far not uniformly distributed over the world (https://map.safecast.org/ ). Evidently, such amount of data cannot be reasonably acquired by institutional surveying. On the other hand, professionals can be expected to follow metrological quality assurance (QA) standards, which is usually not the case for members of the public who are mostly laypeople in metrology.
Thus, impressive as the Safecast map is, it raises questions related to QA. This is relevant for interpretation of the ADR values shown on the map, and their uncertainty and resulting reliability. We propose to distinguish between two aspects of metrological QA regarding monitoring in the context of citizen science.
(1) Metrology proper, which pertains to characterization of the measurement procedure, from sampling protocols to physical behaviour of the instrument and resulting uncertainty; this is of course equally true also for professional measuring.
(2) Real-world handling: not being familiar with metrological QA concepts, in general, it can be expected that citizen scientists deviate from QA standards more frequently and more severely than professionals. This adds to the uncertainty budget of reported values. Uncertainty impairs interpretability.
In this contribution, we report current metrological knowledge of the bGeigie Nano in the sense of aspect (1). Further, we discuss how QA in the sense of aspect (2) can be approached. We report experiments of repeated realistic handling, i.e. without caring for particularly controlled laboratory or well-defined field conditions (as in (1)) and of intentional mishandling.
It appears that QA type (2) is the more serious issue, both by contribution to the uncertainty budget and by difficulty in handling it. While the Safecast map provides – in some regions - an astonishing dense database, one must be cautious about interpreting local data, if the measurement circumstances are not known, which is the usual case. One element of addressing the problem consists in instruction of participants about correct usage.
In response to certain technical issues of the bGeigie Nano which derogate its performance, SÚRO developed an alternative but conceptually similar device called CzechRad (details in https://github.com/juhele/CzechRad) whose metrological characterization is ongoing.
How to cite: Kuča, P., Helebrant, J., and Bossew, P.: Safecast – a Citizen Science initiative for ambient dose rate mapping; Quality assurance issues., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1343, https://doi.org/10.5194/egusphere-egu21-1343, 2021.
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Natural radioactivity depends on primordial radionuclides which decay across a chain of transformations to achieve a stable nuclear state. Transformations involve the emission of particles and photons whose energy can be harmful to organisms even at low-dose. K-40, Th-232 and U-238 are responsible for most of the natural emission of gamma rays from the earth’s crust and volcanic rocks are, in general, the most emissive materials.
Volcanic rocks and related volcano-sedimentary lithified deposits have been quarried for construction purposes and for road paving, since the Greek times, in the area where the city Naples is located, halfway between the volcanic districts of Phlegrean Field and Mt. Somma-Vesuvius, respectively. For centuries, lithified pyroclastic products, such as grey or yellow tuffs, have been used mainly for buildings and vertical structures; lava blocks from Phlegrean Fields and, since 18th century, from Vesuvian effusive materials have been historically used to pave the roads of the old town.
However, in the last few decades, deteriorated historical paving materials of some roads serving areas undergoing renovation have been partially replaced by volcanic materials of Etnean origin (proceeding from Sicily, indeed) or covered/replaced by non-geologic materials (NGMs) (e.g., asphalt).
Considering that 120,000 people live in the old town (over an area of 4 sqkm) being potentially exposed to low-dose ionizing gamma radiations, a survey to estimate the contribution of geological materials to the ambient dose equivalent rate (ADER) was completed. A radiological risk assessment was also completed.
Specifically, 2548 measurements of ADER (µSv/h) were made in the open air at 0.2 (ADER0.2) and at 1 m (ADER1) above the ground, respectively, using a handheld gamma-ray spectrometer. Besides, a total of 13 samples of paving materials were collected and analyzed by means of a high purity germanium detector at the Center for Ecological-Noosphere in Armenia.
Results revealed a significant activity of all materials, except for NGMs. ADER1 and ADER0.2 values showed a strong dependence on the distance from the ground in the streets paved with geologic materials, while the distance from the ground resulted to be not relevant for ADER in areas paved by NGMs .
Based on the ADER1 data, a Monte Carlo simulation was conducted to calculate the outdoor excess lifetime cancer risk (ELCRout) for the population of the study area and for each district belonging to the old town.
In one of the districts showing the highest average ELCRout, 51 additional ADER1 measurements were also conducted inside private dwellings to assess the indoor ELCR (ELCRin). Finally, the total excess lifetime cancer risk (ELCRtot) was estimated by summing values of ELCRout to ELCRin.
The average ELCRout obtained for the entire study area (1.33E-03) and for individual districts (from 5.20E-04 to 1.44E-03) exceeds the world average reference value (2.9E-04).
ELCRin (4.35E-03) and ELCRtot (5.79E-03) are also higher than the average reference values proposed in the literature.
This study revealed that low-dose gamma radiations, emitted by paving or building materials of volcanic origin can pose a radiological risk to human health.
How to cite: Aruta, A., Guarino, A., Ebrahimi, P., Dominech, S., Belyaeva, O., Tepanosyan, G., and Albanese, S.: Low-level ionizing radiation and associated risk in an urban environment: the importance of both paving and building materials, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5566, https://doi.org/10.5194/egusphere-egu21-5566, 2021.
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The absorbed dose rate due to natural radioactivity arises from terrestrial and cosmic sources, both contributing to the individual effective dose rate per fraction of time spent outdoor. Rocks and soils are the main reservoirs of terrestrial gamma-emitting radionuclides (e.g. 40K and radioisotopes of the 232Th and 238U chains) while high-energy particles originated from astrophysical phenomena produce a cascade of nuclear interactions which contributes to cosmic radiation decreasing in intensity with the atmosphere depth. Following the UNSCEAR 2008 report, the average exposure of the world population to the different natural radioactivity sources corresponds to about 2420 μSv/yr and the external effective dose of terrestrial and cosmic origin is 870 μSv/yr.
The Umbria region (Italy), with its high variability of sedimentary and igneous rocks (e.g. limestone, sandstone, volcanic tuff) and a population of about 880000 inhabitants well distributed between 100 m and 1000 m a.s.l., represents the ideal case for mapping the effective dose from natural sources in a multifaceted environment. The outdoor effective dose rate from terrestrial radionuclides is studied by analysing 7439 gamma spectra measuring rock and soil samples in laboratory and carrying out about 20 hours of airborne radiometric surveys. Collocated CoKriging is used for the spatial interpolation of the sparse data, adopting a high-resolution geological map as ancillary information. The obtained numerical map is integrated with the cosmic radiation effective dose rate calculated considering the effects of altitude, latitude and the solar magnetic activity cycle. The resulting map of the outdoor effective dose rate shows a median value of 632 mSv/yr and only 3% of the territory is characterized by values higher than 814 mSv/yr.
How to cite: Serafini, A., Albéri, M., Bisogno, S., Chiarelli, E., Cicala, L., De Cesare, M., Maino, A., Montuschi, M., Motti, A., Natali, N., Ogna, M., Raptis, K. G. C., Simone, G., Strati, V., and Mantovani, F.: Mapping the outdoor effective dose: the case study of the Umbria region (Italy), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7284, https://doi.org/10.5194/egusphere-egu21-7284, 2021.
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As a consequence of Council Directive 2013/59/EURATOM and its transposition into national law, the German States (Länder) had to define radon-prone areas where special rules apply in order to assure protection against excessive exposure to Radon-222 in living spaces and at work. The state of Saxony-Anhalt has chosen to define these areas based on datasets of long-term average indoor Rn concentration and Rn concentration in soil-air, complemented by ambient dose rate (ADR), whose values were acquired by a measurement campaign throughout the state territory.
Saxony-Anhalt is characterized by sabulous lowlands in its northern part with little Rn exhalation, but also by granite in the secondary mountains of the Harz massif and copper-shale dominated areas in the south. Radon prone areas can therefore be expected in the latter regions.
ADR was measured from vehicles carrying both a bGeigie nano pancake detector (the standard device of the Safecast mapping project, https://safecast.org/) with automatic GPS geo-referencing and a Thermo Eberline ESM FHZ 672-2 plastic scintillator. The latter device features a natural-background rejection system which could be used to determine high ADR levels as a consequence of K-40 anomalies that needed to be rejected. An ADR map could be created which was statistically linked to geogenic Rn data and soil geochemistry.
The purpose of the resulting model is to develop an algorithm that makes ADR a predictor for identifying radon-prone areas, which is sufficiently accurate for the objective of Rn legislation. It can be used in regions lacking of indoor Rn concentration or soil-sample data, on which the identification of such areas is usually based, but whose acquisition is too time and labour consuming to be achievable in the time frame allowed for implementation of Rn legislation.
It could be demonstrated that the gamma-dose rate can be used as an additional predictor for the identification of radon-prone areas with an algorithm that applies selective averaging on the data obtained on 2 500 km of measuring trips throughout the entire state of Saxony-Anhalt.
In this contribution, the algorithm is presented together with the areas the State of Saxony-Anhalt has finally determined as radon prone, with the legal consequence for employers to do quality assured Radon measurements and take action with respect to radon mitigation, if necessary. Special emphasis is put on establishing a statistically significant relationship between the measured dose rate on the one hand and geological information and radon exhalation, on the other.
How to cite: Ilgner, C., Bossew, P., and Schneider, P.: Ambient dose rate as an additional predictor for the identification of radon-prone areas as used in the German State of Saxony-Anhalt, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15633, https://doi.org/10.5194/egusphere-egu21-15633, 2021.
The Nuclear Engineering Laboratory of the National Technical University of Athens (NEL-NTUA) is among the oldest laboratories conducting radioactivity mesurements in Greece, founded in the early sixties. One of the main activities at NEL-NTUA is environmental radioactivity studies, mainly based on gamma spectroscopic analysis. For this purpose NEL-NTUA is equipped with a variety of Germanium detectors for in-vitro and in-situ measurements. Starting back in the early eighties, environmental radioactivity studies at NEL-NTUA were significantly boosted after the Chernobyl accident in 1986 when they focused on the Chernobyl fallout radionuclides, as well as some natural radionuclides typically determined in environmental studies, namely 232Th, 226Ra and 40K. As a result of these studies maps of nine Chernobyl fallout radionuclides and the three natural radionuclides in continental Greece surface soils were produced.
Since natural radioactivity in soil is in most cases relatively low, high volume samples had to be analyzed. Over the years, the acquisition of detectors capable of detecting low energy photons (LEGe) along with the development of techniques to correct for self-absorption of low energy photons within the sample, allowed for the accurately determination of radionuclides emitting such photons, like 234Th (63.29keV), 210Pb (46.52keV) and 241Am (59.54keV). These newer studies showed that a significant disruption of radioactive equilibrium in surface soil between 226Ra and 210Pb is very common, while radioactive equilibrium disruption between 238U and 226Ra is common as well. It is interesting to notice that the mean activity ratio 210Pb/226Ra as obtained from ~300 sample measurements is of the order of ~4, while the mean activity ratio 226Ra/238U was estimated to be around one. A mapping of radioactive equilibrium disruption that followed provided interesting results.
In the years to follow studies focused on the vertical distribution of natural (210Pb) and artificial (137Cs) radionuclides in soil and sea sediments and the study of radionuclides fractionation in soil as well as NORM. Both types of studies require the analysis of small volume samples – of the order of 20-50g or even less. Therefore, the development of techniques for sampling of soil vertical profile and the accurate analysis of small samples was of great importance. These analyses require high efficiency detectors, such as XtRa detectors, background reduction techniques, such as Compton Suppression Systems, optimized sample geometries for higher full energy peak efficiency. Sophisticated techniques for background determination and subtraction, in order to obtain accurate results for natural radionuclides which are often detected in the background, are also required.
Another field of research at NEL-NTUA is the development and improvement of techniques for monitoring of 222Rn daughters outdoors using on-line detector systems, as well as for monitoring of natural and artificial radionuclides in atmospheric precipitations and aerosols (7Be, 210Pb, 22Na) using high volume air samplers.
Aim of this work is to present the research conducted at NEL-NTUA over the years with regard to the environmental radioactivity, as well as the current activities in the field and those planned for the future.
How to cite: Anagnostakis, M.: Environmental radioactivity studies at the Nuclear Engineering Laboratory of the National Technical University of Athens, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9934, https://doi.org/10.5194/egusphere-egu21-9934, 2021.
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Polonium-210 (Po-210) is a naturally occurring high-energy alpha emitter with a high dose coefficient compared to other natural radionuclides. In groundwater, Po-210 concentrations usually are low due to its high surface reactivity and tendency to readily adsorb onto mineral surfaces. The nationwide median in drinking water in Germany is 1.4 mBq/L as shown by investigations of the Federal Office for Radiation Protection (BfS). However, some sites in southern Sachsen-Anhalt in Germany were revealed to have Po‑210 activity concentrations far above 100 mBq/L. This is of particular relevance, since the EU Council Directive 2013/51/Euratom and its national implementation in the German Drinking Water Ordinance specifies requirements for drinking water quality with regard to artificial and natural radioactive substances. These high values of Po-210 would require reduction measures according to legislation.
In order to gain a better understanding of the occurrence and origin of Po-210 in groundwater, further groundwater wells and water supply facilities in southern Sachsen-Anhalt were selected for analysis, taking into account the regional geology. The investigated aquifers pertain to the rock sequences of the Lower, Middle and Upper Buntsandstein (Lower Triassic), the Lower Muschelkalk (Middle Triassic) and Cenozoic stratigraphic units. Unfiltered water samples from 50 sites in total were analyzed for their content of natural radionuclides, major and trace elements as well as their oxygen and hydrogen isotope composition and supplemented by the examination of drill core material from these rock sequences.
The data indicate that the elevated Po-210 activity concentrations are limited to the aquifer of the Middle Buntsandstein. The simultaneous absence of the parent nuclides lead-210 (Pb-210) and radon-222 in the water samples indicate a local release mechanism in the rock. In the Middle Buntsandstein the amount of Pb-210 would be sufficient to provide the amount of Po-210 found in solution and the available clay minerals like illite, chlorite, hematite and muscovite could serve as potential hosts for Pb-210 and Po-210. Redox-indicators and a relatively high content of dissolved organic material (DOC >1 mg/L) found in the water samples of the Middle Buntsandstein aquifer could be interpreted as an indication of microbially induced reduction processes.
Understanding the geochemical processes responsible for the mobilization of Po-210 could provide necessary information helping to minimize the human exposure caused by drinking water consumption. Therefore, further investigations will focus on the size distribution of Po-210-bearing particles, the presence of the short-lived mother nuclide bismuth-210 and the sulfate isotope distribution at selected Po-210-rich groundwater sites in this study area.
How to cite: Hofmann, P., Wagner, F., Lucks, C., and Wittwer, C.: Occurrence and origin of polonium-210 in a sandstone aquifer in Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-69, https://doi.org/10.5194/egusphere-egu21-69, 2021.
The August, 2 2017 Decree, which standardized the health protection requirements from the presence of radioactive substances in the waters intended for human consumption, provides for the obligation to verify the value of two parameters relating to the radioactivity content in drinking water: the concentration of tritium, which must be less than 850 UT (unit of tritium), and the total indicative dose, related to ingestion, which must be less than 0.1 mSv / year.
Tritium atoms produced in the atmosphere, by combination with oxygen in the air, tritiated water (HTO) which, having greater molecular mass than the H2O molecule, has a shorter residence time in the atmosphere from which it tends to be removed with precipitation. The short periods of residence in the atmosphere and the short period of decay mean that the concentrations of tritium in the rains are low and almost constant, as there is a balance between the speed of formation, the removal by the rains and the total quantity of natural tritium in the environment which is ∼ 70 × 106 Ci (US Department of Energy, 2002). This means that in groundwater with a long residence time in subsoil, infiltrated before 1950 (nuclear test period), the concentration of tritium is below the analytical detection limit.
In 1960, rainwater had an abnormal concentration (due to the emission into the atmosphere following nuclear tests) corresponding to an average value of 1000 UT. In the subsoil the decay of tritium produces its continuous loss which, in the absence of rainwater recharge and without the compensation of new atmospheric inputs, causes a decrease. To date, in the absence of any infiltration, this water would contain 35 UT.
Given that waters with over 50 years generally have dilution factors from 10 to 20 times with tritium-free fossil water, today we expect, due to mixing, detectable UT values but lower than 4. Aquifer values greater than 9 UT would therefore be related to recent anthropogenic recharge or surface percolation factors.
In the case of recharge with rain water rich in tritium, the concentration reflects the balance between the loss due to decay and the supply of rain water enriched with tritium. Based on the abundance of tritium, in the absence of sources of anthropogenic contamination it is possible to establish the average age of groundwater under the age of 50. This data is very important, because by analyzing the concentrations of tritium present in groundwater it is possible to trace the age of the aquifer and / or define if the aquifer is polluted by anthropogenic activities.
ENEA's Environmental Traceability and Radiometry Laboratory is at the forefront of the analysis of radioisotopes in the environment, including low-concentration of tritium analyzes. In this regard, an activity with ARPAV of Treviso was started for the determination and evaluation of the concentrations of tritium found in groundwater samples of the area around the city of Treviso.
How to cite: Telloli, C., Rizzo, A., Salvi, S., and Ubaldini, A.: Characterization and analysis of groundwater recharge through tritium measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-490, https://doi.org/10.5194/egusphere-egu21-490, 2021.
Radon-222, 222Rn, is a naturally radioactive noble gas with a half-life of 3.82 days. It is a product of the 238U disintegration chain with 226Ra as parent isotope. Radon gas has traditionally been linked to magmatic and seismic activity.
In order to improve volcanic surveillance networks, 222Rn monitoring in volcanic areas is carried out by measuring its concentration in air and soils. Also, since radon-222 is soluble in water, the gas may also be dissolved into groundwater flows. The quantity of dissolved 222Rn depends on different factors such as the characteristics of the aquifer, water-rock interaction, water residence time and material content of radium.
In Tenerife there are a vast number of excavated galleries, subhorizontal water mining tunnels, that drain the main aquifer in the island. Thirteen of them have been selected in order to monitor the dissolved radon-222 concentration since October 2019 every three months. This set of galleries surrounds the main volcanic complex in the island, Teide-Pico Viejo, located in Las Cañadas caldera in central Tenerife.
Before sampling, 10 ml of Opti-Fluor O scintillation cocktail for selective extraction of radon-222, two-phase counting method, was transferred into a 20 ml vial. During the sampling, 10 ml of water were injected into the bottom of the vial. The vial was then tightly capped, vigorously shaken and transported to the laboratory for analysis. Water samples were measured using the liquid scintillation system Quantulus 1220 from PerkinElmer.
In this work, we show the main and preliminary results, which includes both spatial and temporal distribution of the dissolved radon concentration measured in the selected sampling points for the studied period. There are galleries showing a high stability, with radon-222 activity concentrations around 20 Bq/L, whereas others show a clear seasonal influence. The maximum dissolved 222Rn value detected was 29.2 ± 2.1 Bq/L. The detection limit is 0.5 Bq/l using a 30 minutes counting time. Besides, this dataset has been compared to data previously reported by other authors, in order to find changes in dissolved radon-222 emission across time. Finally, in the aim of finding interesting relationships, dissolved 222Rn values have been studied together with in situ groundwater parameters measured in the field (temperature, pH and electric conductivity) and, in some of the sampling points, also with dissolved CO2 concentration and isotopic ratio 3He/4He corrected for air contamination, (R/Ra)c, which are parameters directly related to volcanic activity.
How to cite: Torres González, P. A., Luengo Oroz, N., and Pujol, L.: Monitoring dissolved radon-222 in groundwater in a volcanic island (Tenerife, Canary Islands), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5233, https://doi.org/10.5194/egusphere-egu21-5233, 2021.
Groundwater represents a vast majority of the readily accessible fresh water on Earth and satisfies the demand for drinking water for a large portion of the world population. However, groundwater quality can be seriously threatened by geogenic and anthropogenic contamination with elevated concentrations of hydrocarbons, pesticides, metal(loid)s or radionuclides. Understanding the controls of the release and mobility of these contaminants including radionuclides is critical in proper groundwater management. In the southern foreland of a granitic outcrop in Hungary, gross alpha activity exceeding the 0.1 Bq L–1 limit was measured in drinking water wells. Nuclide-specific measurements for uranium, radium and radon isotopes were involved. The sampling activities indicate that excess of uranium (3−753 mBq L−1) is mainly responsible for the natural radioactivity measured in drinking water. Radium was measured in low activity concentrations (<5–63 mBq L−1) with the exception of three specific wells (285–695 mBq L−1). Notable radon activity was measured in the spring waters from Velence Hills (101–314 Bq L−1 ) and in interrelation with the high radium activities. These observations were interpreted in a “groundwater flow system” context. A conceptual model explaining the elevated radioactivity of groundwater was delineated. A geochemical modeling analysis involving redox-controlled kinetic reactions and a surface complexation model was developed to support the conceptual model of uranium mobility. The results suggest that uranium distribution is sensitive to redox changes in the aquifer. Its mobility in groundwater depends on the residence time of water compared to the reaction times controlling the consumption of oxidizing species. The longer the flow route from the recharge point to an observation point where U is measured, the higher the likelihood of finding aquifer reducing conditions and low U concentrations. It is concluded that the joint application of nuclide-specific measurements, hydrogeological approach and geochemical modeling can support safe drinking water management when dealing with the excess of radionuclides in groundwater.
This topic is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 810980. This study was also supported by the ÚNKP-17-4-III-ELTE-73 New National Excellence Program of the Ministry of Human Capacities (Hungary). The results here presented have been developed in the frame of the MIUR Project “Dipartimenti di Eccellenza 2017—Le Geoscienze per la società: risorse e loro evoluzione”.
How to cite: Baják, P., Csondor, K., Pedretti, D., Muniruzzaman, M., Izsák, B., Vargha, M., Horváth, Á., Pándics, T., and Erőss, A.: The controls of radionuclide mobility in a siliciclastic aquifer in Hungary: Hydrogeological investigations and geochemical modeling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8804, https://doi.org/10.5194/egusphere-egu21-8804, 2021.
This study assesses how internal dose rate in quartz grains impacts luminescence dating. In 2018, the Gliwice Luminescence Laboratory implemented innovative μDose system which combines advantages of alpha and beta counting measurement techniques with additional radioactive identification capabilities. The device allows measurements of small samples and results verification with an independent high-resolution gamma spectrometry method.
All measurements of internal dose rate were made on pure quartz grains after standard chemical pretreatment. Grains with diameters between 125 and 200 μm were selected for measurements. This material was dried and grounded to approx. 20 μm using a planetary ball mill prior to measurements on the μDose systems.
Internal dose rate reported here is particularly important because of low (about 0.8-0.9 Gy/ka) or very low (0.4-0.6 Gy/ka) external dose rates. Internal dose rate in quartz grains in our measurements is a significant fraction of the total dose rate, often exceeding 10%. Ignoring this correction would make luminescence ages in our study artificially older.
Presented results were obtained with support of Polish National Science Centre, contract number 2018/30/E/ST10/00616
How to cite: Poręba, G., Szymak, A., Moska, P., Tudyka, K., and Adamiec, G.: Internal dose rate in quartz grains: Implications for luminescence dating, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14208, https://doi.org/10.5194/egusphere-egu21-14208, 2021.
The objective of this work is to simulate the spectral gamma-ray response of NaI(Tl) scintillation detectors for airborne gamma-ray spectrometry (AGRS) using Monte Carlo radiation transport codes. The study is based on a commercial airborne gamma-ray spectrometry detector system with four individual NaI(Tl) scintillation crystals and a total volume of 16.8 l. Monte Carlo source-detector simulations were performed in an event-by-event mode with the commercial multi-purpose transport codes MCNP6.2 and FLUKA. Validation measurements were conducted using 241Am, 133Ba, 60Co, 137Cs and 152Eu radiation sources with known activities and source-detector geometries. Energy resolution functions were derived from these measurements combined with additional measurements of natural Uranium, Thorium and Potassium sources. The simulation results are in good agreement with the experimental data with a maximum relative error in the full-energy peak counts of 10%. In addition, no significant difference between the two Monte Carlo radiation transport codes was found with respect to a 95% confidence level. The validated detector model presented herein can be adopted for angular detector response analysis and calibration computations relating radionuclide activity concentrations with spectral detector counts.
How to cite: Breitenmoser, D.: Experimental and Simulated Spectral Gamma-Ray Response of a NaI(Tl) Scintillation Detector used in Airborne Gamma-Ray Spectrometry, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1345, https://doi.org/10.5194/egusphere-egu21-1345, 2021.
Glaciers are temporary repositories for radionuclides and other airborne contaminants (eg. heavy metals). Retreat of glaciers results in the release of these contaminants to downstream ecosystems where they can be accumulated by biota, with further consequences along the trophic chain. Fallout radionuclides, and especially Pu released from nuclear weapons testing and nuclear accidents, concentrates on glacier surfaces in cryoconite granules. These aggregates of mineral and organic components are associated with biological consortia composed of archaea, algae, cyanobacteria, fungi and heterotrophic bacteria (Cook et al., 2016). Cryoconite is also responsible for local decrease ice albedo and is responsible for formation of water-filled holes. Contaminants are effectively trapped in cryoconite granules for long periods (up to decades) due to the “sticky” nature of the material. Cryoconite can thus be useful in monitoring of radionuclide deposition on glaciers (Łokas et al., 2019; Giovanni et al., 2020).
Our collective research reveals widespread incidence of Pu isotopes in cryoconite across multiple sites on both hemispheres, including Svalbard, Sweden, Norway, Iceland, Greenland, British Columbia, Alaska, the European Alps, the Caucasus, Siberia, Tien Shan, Altai, South America and Antarctica. The levels of plutonium isotopes (238,239,240Pu) found in cryoconite at these sites are orders of magnitude higher than those detected in non-glaciated environments, raising important questions around the role of glaciers, and specifically cryoconite, in concentrating levels of Pu isotopes above those found in the surrounding environment. The activity ratios of 238Pu/239+240Pu show that the plutonium-related radioactivity of cryoconite from the Northern hemisphere is compatible with the worldwide signal from the global radioactive fallout (0.025) but in some samples from Svalbard higher activity ratios are associated with an additional source of pure 238Pu, pointing to an influence of the SNAP-9A satellite burn up in the atmosphere occurred in 1964. Also activity ratios from South America and Antarctica are consistent with the global radioactive fallout ratio (including SNAP 9 re-entry) in the southern hemisphere (0.14), with an exception concerning cryoconite from the Exploradores Glacier (Chilean Patagonia, ratio 0.35). There are no known nuclear test sites near this glacier which could explain this anomalous value. However, there is also no information about the atmospheric re-entry of the automatic Interplanetary Station “Mars’96” which was launched on 16 November 1996. It fell off the coast of Chile near the border with Bolivia and was not found so far. There were considerable quantities of 238Pu on board of the station, with a total activity of 174 TBq (IAEA, 2001). We hypothesize that this event could explain the anomaly observed at Exploradores Glacier, confirming the unmatched potential of cryoconite to study environmental radioactivity in glacial contexts.
Acknowledgements
This study was supported by the National Science Center grant no. NCN 2018/31/B/ST10/03057.
References
Cook et al., 2016. Progress in Physical Geography, 40(1), 66-111.
Giovanni et al., 2020. CATENA, 191, 104577.
IAEA, 2001. International Atomic Energy Agency IAEA, Vienna).
Łokas et al., 2019. The Cryosphere, 13(7), 2075-2086.
How to cite: Łokas, E., Baccolo, G. B., Clason, C., Wachniew, P., Takeuchi, N., Zawierucha, K., Beard, D., Ambrosini, R., Pittino, F., Franzetti, A., Owens, P., Poniecka, E., Blake, W., Nastasi, M., and Buda, J.: Deposition of plutonium isotopes in glacial environments in the Northern and Southern Hemispheres, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8795, https://doi.org/10.5194/egusphere-egu21-8795, 2021.
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