GI6.5 | Radioactivity in the environment: challenges and opportunities for geoscience

GI6.5

Radioactivity is ubiquitous in the environment a result of i) cosmic radiation from space and secondary radiation from the interaction of cosmic rays with the atmosphere, ii) terrestrial sources from soils and rocks and particularly Potassium, Uranium and Thorium and their decay products among which Radon gas stands out. Artificial radionuclides from nuclear and radiation accidents and incidents provide an additional contribution to the environmental radioactivity.
Nuclear techniques enable the measurement of radioactivity in air, soils and water making it a particularly appealing tool for tracing time-varying environmental phenomena.
The session deals with the measurement and the exploitation of environmental radioactivity in all areas of geosciences including geological surveys, mineral and space resources exploration, atmosphere and groundwater monitoring. Studies about the use of fallout radionuclides as environmental tracers and the relevance of the radioactivity for public health, including the contamination from Naturally Occurring Radioactive Materials (NORM), are welcome. We solicit contributions about novel methods and instrumentation including portable detectors, airborne and drones surveys and geostatistical methods for radioactivity mapping.

Co-organized by NH8
Convener: Virginia StratiECSECS | Co-conveners: Susana Barbosa, Xuemeng ChenECSECS, Anita Erőss, Nesrine MezerregECSECS
Orals
| Fri, 28 Apr, 14:00–15:40 (CEST)
 
Room -2.91
Posters on site
| Attendance Fri, 28 Apr, 10:45–12:30 (CEST)
 
Hall X4
Posters virtual
| Attendance Fri, 28 Apr, 10:45–12:30 (CEST)
 
vHall ESSI/GI/NP
Orals |
Fri, 14:00
Fri, 10:45
Fri, 10:45

Orals: Fri, 28 Apr | Room -2.91

Chairpersons: Virginia Strati, Anita Erőss
14:00–14:10
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EGU23-15860
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GI6.5
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On-site presentation
Sandra Baur, Sabine Schmid, Jacqueline Bieringer, and Andreas Bollhöfer

The German Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) is legally obliged to continuously monitor radioactivity in the environment in Germany. The Atmospheric Radioactivity and Trace Analysis Section of the BfS is operating four different measurement facilities/laboratories in Southern Germany: gamma spectrometry, radiochemistry and noble gas laboratories in Freiburg i.Br. and the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) monitoring station RN33 on Mt. Schauinsland. The three laboratories provide data of radioactive aerosol bound particulates such as Cs, U, Pu or Sr and noble gases (Kr and Xe) for the German Integrated Measurement and Information System (IMIS). The radionuclide station RN33 is monitoring radioactive particulates and Xe for the International Monitoring System (IMS) of the CTBTO. The variation of radioactivity on aerosol bound particles over time and the analysis of their origin, distribution and transport in the environment will be presented.

To collect aerosol bound particles, ground-level air sampling is carried out by high volume air samplers located in Freiburg i.Br. and on Mt. Schauinsland. The high volume air sampler is operated with two filter layers: an upper polypropylene layer with a collection efficiency of about 85% to 95% and a bottom fibre glass layer with a collection efficiency of almost 100%. The fibre glass filter is used as a control for collection efficiency of the polypropylene filter. As required by the German IMIS monitoring programmes, the routine sampling period is seven days, which can be reduced to daily cycles in case of (un)expected enhanced activity concentrations. The filters are separately pressed to pellets and analysed by high resolution γ-spectrometry. In addition, the polypropylene-filters are processed radioanalytically and analysed with a low level α/β-counting system and α-spectrometry.

The applied methods together with atmospheric transport modelling allow to detect smallest amounts of radioactive substances as well as to investigate their origin, distribution and transport in the environment. In addition, the Cs-137/Sr-90 ratios can be used as a geochemical fingerprint for source identification. Current (2022) median activity concentrations in ground-level air for Cs-137 and Sr-90 (2021) are 0.42 µBq m-³ and 0.06 µBq m-³, respectively. Detection limit (LOD) for Cs-137 is on average 0.14 µBq m-³ in weekly samples and 0.01 µBq m-³ in monthly samples for Sr-90. In March 2022 dust blown in from the Sahara towards Southern Germany resulted in slightly higher airborne Cs-137 activity concentrations while Sr-90 did not markedly change. Other sources for increased Cs-137 activity concentrations include past above ground nuclear weapons tests or resuspension of fallout from the Chernobyl accident. Thus, trace analysis is used to track short- and long-term changes in radioactivity in the environment at lowest activity levels.

How to cite: Baur, S., Schmid, S., Bieringer, J., and Bollhöfer, A.: On the trail of Cs-137 and Sr-90 – Trace analysis to monitor radioactivity in air, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15860, https://doi.org/10.5194/egusphere-egu23-15860, 2023.

14:10–14:20
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EGU23-7900
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GI6.5
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ECS
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On-site presentation
Agustín Cerezo, Elena Prieto, Ignasi Reichardt, Ramón Casanovas, and Marçal Salvadó

The Catalan Environmental Radiological Surveillance Network consists of different types of scintillation gamma spectrometry detectors for the continuous and real-time automatic measurement of environmental radiation. The Network has a total of 35 monitors that obtain spectra every 10 minutes: 23 direct measurement monitors (13 with LaBr3(Ce), 5 SrI2(Eu) and 5 NaI (Tl) detectors), 10 particulate filter monitors (9 with LaBr3(Ce) detectors and 1 with SrI2(Eu)) and 2 river water monitors.

A method for the automatic and real-time quantification of the activity concentration of artificial, natural and NORM isotopes was developed and tested in the laboratory. The uncertainties in the activity concentrations, as well as the corresponding detection limits, were calculated applying the ISO-11929 standard. The developed and validated method that is exposed in the present study will be implemented shortly in all the stations of the Network.

The method is based on the analysis by spectral regions or ROIs (Regions of Interest). The method eliminates from the ROIs of the artificial (or NORM) isotopes of study the contributions due to emissions of natural isotopes (overlapping and Compton radiation), the ambient background, the possible intrinsic background of the detector and the contributions of other possible isotopes. As a result, an equation is generated for each isotope that allows us to obtain its net activity concentration (Bq/m3). This procedure is applied to determine the activity concentration of isotopes of natural origin (212Pb, 214Pb and 214Bi), artificial (131I, 137Cs and 60Co) and NORM (234Th).

The method successfully eliminates the contribution of natural elements, intrinsic background and Compton contribution, both in situations with high and low activity of natural isotopes. Therefore, it allows obtaining the net activity concentration of the artificial isotopes of interest and eliminates the presence of false positives that could be produced by the presence of natural isotopes.

How to cite: Cerezo, A., Prieto, E., Reichardt, I., Casanovas, R., and Salvadó, M.: A fast algorithm for real-time monitoring of artificial radioisotopes in presence of variable natural radioactivity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7900, https://doi.org/10.5194/egusphere-egu23-7900, 2023.

14:20–14:30
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EGU23-12074
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GI6.5
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On-site presentation
Dafina Kikaj, Edward Chung, Mareya Saba, Ute Karstens, Alistair Manning, Chris Rennick, Anita Ganesan, Grant Foster, Simon O’Doherty, Angelina Wenger, and Tim Arnold

The unique physical and chemical characteristics of radon make it an excellent tracer of atmospheric mixing and transport processes. As such, it has long been a species of interest to the climate change research communities. However, reliable, high resolution radon flux maps are essential for the use of atmospheric radon in climate studies.

Validation of the existing radon flux maps and inventories is currently limited by the availability of systematic measurements of radon fluxes and other process-relevant parameters (e.g., physical characteristics and moisture content of soil). Localised measurements of radon flux, soil moisture and soil physical properties can provide some information to validate and improve flux maps.  On the other hand, high sensitivity atmospheric radon measurements in conjunction with atmospheric transport models would determine the relative representativeness of radon flux models over larger scales.

To tackle the validation of radon flux maps, atmospheric radon measurements were compared to the results of modelled radon concentrations calculated using the Lagrangian particle model, the Met Office Numerical Atmospheric Modelling Environment (NAME) and two available versions of European radon flux maps1. For this purpose, radon data from three UK greenhouse gases atmospheric monitoring stations located in Heathfield (an inland, 100 m tall tower), Tacolneston (an inland, 185 m tall tower), and Weybourne (a coastal site, 10 m tower) were used. The differences between measured and modelled radon concentrations on diurnal and monthly scales will be presented and discussed. The ratio of measured-modelled radon concentrations shows the potential to objectively assess the reliability of radon flux maps under different wind directions and atmospheric mixing conditions.

 

 

1 2015: doi:10.1594/PANGAEA.854715 and 2022: ICOS data search (icos-cp.eu).

How to cite: Kikaj, D., Chung, E., Saba, M., Karstens, U., Manning, A., Rennick, C., Ganesan, A., Foster, G., O’Doherty, S., Wenger, A., and Arnold, T.: Atmospheric radon measurements to assess the relative representativeness of radon flux models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12074, https://doi.org/10.5194/egusphere-egu23-12074, 2023.

14:30–14:40
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EGU23-12151
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GI6.5
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ECS
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On-site presentation
Mareya Saba, Dafina Kikaj, Edward Chung, Alistair Manning, Ute Karstens, Chris Rennick, Anita Ganesan, Grant Forster, Simon O'Doherty, Angelina Wenger, and Tim Arnold

The vertical mixing state of the atmosphere, as well as the atmospheric boundary layer (ABL) height, are important atmospheric transport model parameters for the accurate simulation of greenhouse gas concentrations. In order to use tall tower greenhouse gas measurements to quantify regional scale emissions (top-down, inverse estimates) an estimate of the atmospheric transport model uncertainty across the time series of study is needed. Several methods have been used to estimate this, often relying on arbitrary thresholds or a combination of parameters (such as vertical gradients if a gas is measured at multiple points). Here we study if radon has potential as an independent measurement to assess model uncertainty.

Radon is a radioactive noble gas present in our atmosphere and is a good tracer of mixing processes in the ABL due to its properties. Hence, measurements of atmospheric radon concentration can provide useful insights into the vertical mixing state of the atmosphere, and in turn may help to calibrate and validate atmospheric dispersion models.

In this study, we use high temporal resolution atmospheric measurements of radon and CH4 from four tall tower sites in the UK, which are part of the Deriving Emissions linked to Climate Change (DECC) network: Heathfield (HFD), Ridge Hill (RGH), Tacolneston (TAC) and Weybourne (WAO). At each site, CH4 is measured at two or three different heights, while radon is measured at one height.

To determine a metric whereby single-height measurements of radon can provide a proxy for vertical mixing states, we compare the diurnal cycle of the measured radon concentration with the modelled radon (calculated by the Met Office Numerical Atmospheric Modelling Environment (NAME) dispersion model and radon flux maps). The largest uncertainties are shown to be before sunrise and after sunset right before the inversion layer was formed/destroyed. The diurnal CH4 vertical gradient at these times is also compared with the modelled CH4 vertical gradient.

How to cite: Saba, M., Kikaj, D., Chung, E., Manning, A., Karstens, U., Rennick, C., Ganesan, A., Forster, G., O'Doherty, S., Wenger, A., and Arnold, T.: Can radon measurements at tall towers provide information on atmospheric vertical mixing states?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12151, https://doi.org/10.5194/egusphere-egu23-12151, 2023.

14:40–14:50
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EGU23-14656
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GI6.5
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On-site presentation
Arnaud Quérel, Tanina Hached, Denis Quélo, Michel Ramonet, Camille Yver Kwok, and Ute Karstens

Atmospheric transport models used for nuclear emergency purposes are dedicated to simulating the atmospheric transport of radionuclides released from a damaged nuclear facility. The quality of this response is crucial and must be constantly improved. However, long-range measurement campaigns for validation are scarce, especially for radioactive pollutants. An effective way to do so is by simulating the radon-222 which is a non-reacting atmospheric tracer species with quite well-known exhalation rate and well-known nuclear transitions.

Radon-222 is naturally emitted. Its flux spatial variation is mainly due to the type of soil and rocks, rather than the vegetation or land use. Temporal variations are mainly led by soil humidity, leading to a monthly variation. The monthly surface radon flux map of Karstens and Levin, 2022 is used in this study.

The availability of the observations at suitable temporal and spatial scales is achieved in this study thanks to the Integrated Carbon Observation System, ICOS (Heiskanen et al. 2021). ICOS provides standardized and open data from more than 39 atmosphere stations that measures greenhouse gases concentrations in the atmosphere. Some stations also provide radon-222 concentrations measurements. Among them, some also include measurements at different heights - from ground level up to 200 meters – which is valuable to validate the vertical atmospheric transport modelling. The limited set of radon-222 stations is not a substitute for performing the comprehensive validation against a large variety of observations but gives valuable information on the performance of air concentration predictions. A previous study using the dose rate measurements network (Quérel et al. 2022), required in addition the need of an accurate deposition modelling to assess gamma dose rates at ground level due to wet deposition of radon-222 decay products.

We evaluate here the overall performance of an air concentration modelling chain: Karstens radon-222 fluxes, Météo-France ARPEGE numerical weather predictions and IRSN LdX operational atmospheric transport model. Simulated radon-222 air concentrations are compared with observations from the ICOS monitoring network over Europe, on an hourly frequency basis over one year. On initial examination, the model appears to under-predict radon-222 concentrations and some possible explanations and sources of improvement are identified.

 

References:

Heiskanen, J., C. Brümmer, N. Buchmann, C. Calfapietra, H. Chen, B. Gielen, T. Gkritzalis, S. Hammer, S. Hartman, M. Herbst, et al. (2021), The Integrated Carbon Observation System in Europe, Bulletin of the American Meteorological Society, 1 - 54, doi:10.1175/bams-d-19-0364.1.

Karstens, U. and Levin, I. (2022). traceRadon monthly radon flux map for Europe 2006-2022 (based on GLDAS-Noah v2.1 soil moisture), https://hdl.handle.net/11676/ge5vMeklvG_Qz43rzcS2wx0-

Quérel, A., Meddouni, K., Quélo, D., Doursout, T., and Chuzel, S. (2022). Statistical approach to assess radon-222 long-range atmospheric transport modelling and its associated gamma dose rate peaks. Advances in Geosciences. 57. 109-124. 10.5194/adgeo-57-109-2022.

How to cite: Quérel, A., Hached, T., Quélo, D., Ramonet, M., Yver Kwok, C., and Karstens, U.: Atmospheric transport modelling of radon-222 at European scale: description and validation against ICOS observations., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14656, https://doi.org/10.5194/egusphere-egu23-14656, 2023.

14:50–15:00
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EGU23-6130
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GI6.5
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ECS
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On-site presentation
David Breitenmoser, Gernot Butterweck, Malgorzata M. Kasprzak, and Sabine Mayer

The objective of the present study is to simulate the spectral gamma-ray response of the Swiss Airborne Gamma-Ray Spectrometry system (SAGRS) using Monte Carlo radiation transport codes. The SAGRS is mounted in the cargo bay of a AS-332M1 Super Puma helicopter from the Swiss Air Force and consists of four prismatic NaI(Tl) scintillation crystals with a total volume of 16.8 l. We developed a high-fidelity Monte Carlo model of the SAGRS including the detector system and the helicopter using the multi-purpose radiation transport code FLUKA. As part of the measurement campaign ARM22c organized by the National Emergency Operations Centre (NEOC), we performed hover and line flights in combination with ground measurements using certified 133Ba and 137Cs point sources to validate our model. The performed measurements revealed a significant impact of the helicopter fuel on the detector response for various solid angles. In general, we found an excellent agreement between the measured and simulated detector response with relative errors in the full energy peak <10%. The validated model presented herein offers a novel way to simulate the spectral detector response of the SAGRS for the generation of fundamental spectra in a full spectrum analysis framework.

How to cite: Breitenmoser, D., Butterweck, G., Kasprzak, M. M., and Mayer, S.: Validation of a High-Fidelity Monte Carlo Model for Airborne Gamma-Ray Spectrometry with Field Measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6130, https://doi.org/10.5194/egusphere-egu23-6130, 2023.

15:00–15:10
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EGU23-12190
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GI6.5
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ECS
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On-site presentation
Elena Prieto, Agustin Cerezo, Ignasi Reichardt, and Marçal Salvadó

This study describes the equipment implementation of a mobile gamma spectrometry unit using LaBr3 detectors and the process followed to obtain a radiological map of Catalonia (Spain). The mobile unit consists of two 2”x2” LaBr3 scintillation detectors mounted on the top of a 4x4 car. To obtain the preliminary map, the extension of Catalonia was divided in 1425 cells of 5x5 km2. Before starting the measurements, we planned a route to ensure a proper distribution and a minimum quantity of spectra within each cell. The car is equipped with a portable computer to control spectra acquisition and a GPS system that associates a position to each spectrum. Each spectrum is stabilised and calibrated. During the acquisition, the computer placed inside the car shows, in real-time, the value of the ambient dose equivalent and the exact location. Therefore, when the software obtains an unexpected high value, the driver of the car can modify the route to acquire more spectra of the area. The first data set of measurements included 70000 spectra obtained during stable weather conditions and represent the preliminary results of the radiological map, as other data campaigns are currently under preparation. In this study, we present the ambient dose equivalent map of Catalonia and isotopic information of interest, such as punctual detections of 137Cs and 131I and other radionuclides. The origin of these detections is analysed and explained in detail.

How to cite: Prieto, E., Cerezo, A., Reichardt, I., and Salvadó, M.: Mapping the environmental radioactivity in Catalonia using a mobile unit with LaBr3 scintillation detectors., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12190, https://doi.org/10.5194/egusphere-egu23-12190, 2023.

15:10–15:20
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EGU23-393
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GI6.5
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ECS
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On-site presentation
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David O Leary, John Connolly, Louis Gilet, Jim Hodgson, Colin Brown, and Eve Daly

Historically, peatlands have acted as globally important carbon sequestration habitats via the storage of organic material. Modern degraded/drained peatlands emit this carbon as CO2 via decomposition of the stored organic material. Through restoration projects, in which the water table is raised, peatlands may become carbon neutral or possibly carbon negative. National restoration plans require a knowledge of peatland extent and spatial distribution across large geographic areas.

Globally, current peatland maps are created in a variety of ways including the use of optical satellite remote sensing or combinations of legacy soil/quaternary maps. However, optical remote sensing cannot detect peatlands under landcover such as forest or grassland. Legacy maps are often created from sparse in-situ augur, borehole, or trial pit data. These types of measurements do not allow for accurate measurement of peatland boundaries.

Radiometrics, a geophysical method that measures radiation emitted from geological materials, is particularly suited to peatland studies. Modelling of radiometric attenuation shows that a statistical difference is present in recorded potassium, equivalent uranium and equivalent thorium counts acquired over peat, compared to those acquired over a non-peat/mineral soil. Mineral soils contain geological material which acts as a source of gamma radiation. Peat, being a mostly organic material, is generally not considered a source of radiation. Peat also tends to be saturated and water acts to attenuate the recorded gamma signature. These effects combined means that peatlands are represented as a “low” radiometric signal in the landscape.

In Ireland, the Tellus survey, acquired by the Geological Survey, Ireland (GSI) aims to acquire airborne data including electromagnetic, magnetic, and radiometric data, consistently across the country (flight line spacing of 200m). This study uses Tellus airborne radiometric data in combination with machine learning classification techniques, to identify peatlands under modified landcover, such as forestry and grasslands and to increase the spatial resolution of existing peatland map to 50 x 50 m. The methodology is robust and can be applied in all areas where these data exist. The results may update national and international carbon inventories of peatlands area and geographic distribution and inform European policy.

How to cite: O Leary, D., Connolly, J., Gilet, L., Hodgson, J., Brown, C., and Daly, E.: Using environmental radioactivity to create a national scale peatlands map: a case study from Ireland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-393, https://doi.org/10.5194/egusphere-egu23-393, 2023.

15:20–15:30
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EGU23-16827
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GI6.5
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On-site presentation
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Leticia Gaspar, Iván Lizaga, Arturo Catalá, and Ana Navas

Proximal gamma-ray spectroscopy is an effective technique for monitoring the spatial and temporal distribution of terrestrial radioelements like 40K, which is inversely proportional to the volumetric soil water content SWC (m3/m3). In recent years, PGRS has become a promising sensor to infer topsoil water content at an intermediate field scale supported by adequate calibration and corrections, but to date, it has not yet been used in Spain. The aim of this contribution is to test the response of mobile ground-based gamma measurements conducted while walking over an agricultural plot of 400 m2 of bare soil. Two surveys were conducted, a day before and a day after a 16-liter rain episode, allowing us to i) evaluate the information obtained when using the mobile mode, ii) test the response of the PGRS to dry and wet soil conditions, and iii) compare mobile measurements with stationary records taken during one hour at the 4 vertices of the study plot. A scintillator detector of 0.3 L sodium iodide (NaI) crystal was used to evaluate the region of interest for total counts of 40Potassium (1461 KeV). The mobile measurements were conducted 0.5 m above the soil surface and taken in stop-and-go mode (instead on-the-go mode) with two sets of 5 transects spaced 5 m apart placed in a perpendicular direction to cover the study plot. While walking we stopped every 1m for 10 sec. to collect a total of 21 measurements per transect, obtaining 210 data for geostatistical interpolation. These preliminary results show higher content of 40K (cps) during the dry compared to the wet survey, and some differences in the spatial distribution of 40K for both surveys. Similarities and parallel trends were observed when comparing mobile and stationary measurements, supporting the promising use of PGRS technique.

How to cite: Gaspar, L., Lizaga, I., Catalá, A., and Navas, A.: Testing mobile ground-based gamma-ray spectroscopy for measuring 40K in an agricultural field (Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16827, https://doi.org/10.5194/egusphere-egu23-16827, 2023.

15:30–15:40
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EGU23-7988
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GI6.5
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ECS
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On-site presentation
Sophia M. Becker and Trenton E. Franz

Detection of gamma-rays emitted by K-40 decay demonstrates potential for reliable soil moisture estimation for agricultural and hydrological applications. With a circular footprint of roughly 20 m radius, gamma-ray spectroscopy (GRS) provides a continuous, non-invasive average measurement that fills the scale gap between point and satellite data. GRS sensors have also been successfully integrated with Unmanned Aerial Systems opening the potential for soil moisture mapping.  Current theoretical models of gamma-ray spectra and soil moisture have not been extensively tested with empirical data. An existing soil moisture model for NaI gamma-ray spectra includes a method for biomass water content correction and was tested with five sampling campaigns in a tomato field, while another soil moisture model was tested with a single sampling campaign in a sugar beet field using CsI gamma-ray spectra. We hypothesize that testing existing theoretical models with thorough empirical data over a range of soil moisture and vegetative conditions will increase our understanding of the relationship between gamma-ray spectra, soil moisture, and biomass, and will allow us to validate and/or improve the soil moisture calibration function.

In this study we conduct a robust calibration of a stationary CsI gamma-ray soil moisture sensor (gSMS, Medusa Radiometrics) against gravimetric water content samples at a long term agricultural experimental field in eastern Nebraska, United States. Additional measurements include an Eddy Covariance tower, a Cosmic-Ray Neutron Sensor, in-situ soil moisture sensors, and destructive vegetation sampling every 10 days during the growing season. In total, 18 sampling campaigns were conducted between June 2021 and October 2022 under bare soil, maize, and soybean conditions. Soil samples were collected in a radial pattern at 0, 2, 5, and 12 m from the sensor, every 60 degrees following the expected spatial sensitivity of the gSMS. Samples from the 19 locations surrounding the sensor were aggregated in 5 cm intervals from 0 to 35 cm depth. Both a depth-weighting function and the arithmetic mean were used to calculate the average gravimetric water content within the sensing volume.

We then leverage the relatively large experimental data set of gravimetric water content and K-40 counts to test current theoretical approaches to soil moisture estimation with GRS. Data from both bare soil and vegetated conditions allow us to investigate and potentially remove the biomass water content signal from the soil moisture estimation. Comparison with the existing theoretical calibration functions shows large deviations with the empirical data.  Cosmic-ray Neutron Sensor data recorded at the site shows a high degree of correlation (R > 0.7 for hourly data) between the K-40 counts and neutron counts under changing biomass conditions. Lastly, comparison of the GRS derived soil moisture data with the in-situ soil moisture sensors, rainfall, and evapotranspiration result in good correspondence with soil moisture state and water fluxes at the study site.

How to cite: Becker, S. M. and Franz, T. E.: Theoretical vs experimental relationship between K-40 counts and gravimetric water content at a well instrumented agricultural research station in Nebraska, USA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7988, https://doi.org/10.5194/egusphere-egu23-7988, 2023.

Posters on site: Fri, 28 Apr, 10:45–12:30 | Hall X4

Chairpersons: Virginia Strati, Susana Barbosa
X4.186
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EGU23-2800
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GI6.5
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ECS
Virginia Strati, Matteo Albéri, Enrico Chiarelli, Tommaso Colonna, Enrico Guastaldi, Andrea Iannarone, Nicola Lopane, Alice Magnoni, Andrea Maino, Fabio Mantovani, Dario Petrone, Kassandra Giulia Cristina Raptis, Filippo Semenza, Mattia Taroni, and Giacomo Zambelli

In industrial waste management the on-site and real-time automatic radiological characterization represents a significant improvement in disposal procedures, minimizing processing times and operators exposure. In a steel mill the accidental fusion of radioactive sources in contaminated metals is an event with a non-negligible extent. In these radiological emergency situations, significant issues arise for the environment protection with negative consequences on the mill’s production. The contamination of the separate structures (e.g., furnaces, filtering systems) force a stop on the production and a complex management of the storage and disposal of the contaminated materials. In these situations, a representative sampling is an extremely time-consuming and expensive operation which increases the risks of further radiological contamination both to the environment and the involved personnel.

BlueSky is an innovative measurement system developed and validated in a steel mill for the in-situ characterization of filtering and dust suppression systems contaminated with Cs-137 which were stocked in about 400 containers with an approximate mass of 100 kg each. BlueSky was conceived with the goal of identifying, in-situ and with a 95% confidence level, the containers with an activity concentration lower than 100 Bq/kg, the clearance level which determines their disposal without radiological relevance. A single 20-minute measurement, realized positioning the detector on the top of each container, permits to achieve this objective with a Minimum Detection Activity of 22 Bq/kg.

The BlueSky system includes a 2 x 2 inches cerium bromide (CeBr3) detector partially collimated with a lead shielding to decrease by 60% the signal contribution from the surrounding environment. The in-situ measurement process has been streamlined by the development of an Android App that, thanks to the Bluetooth module coupled to the detector, manages the data taking process, analyzes the acquired spectrum, displays the results and sends them to the Cloud Storage Platform.

How to cite: Strati, V., Albéri, M., Chiarelli, E., Colonna, T., Guastaldi, E., Iannarone, A., Lopane, N., Magnoni, A., Maino, A., Mantovani, F., Petrone, D., Raptis, K. G. C., Semenza, F., Taroni, M., and Zambelli, G.: BlueSky: a system for in-situ identification of 137Cs in industrial waste, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2800, https://doi.org/10.5194/egusphere-egu23-2800, 2023.

X4.187
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EGU23-3918
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GI6.5
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Mattia Taroni, Andrea Iannarone, and Giacomo Zambelli

The characterization of NORM/TENORM materials must be performed using different nuclear techniques, able to show the complete scheme of the equilibrium of the radionuclides in the different natural chains. The characterization must be done in order to be able to determine the levels of radionuclides present in them, in order to verify the clearance levels for the correct management of the material, of the area management in which they are located and determine any breakage of the natural chains to identify NORM/TENORM pollution phenomena in the environment where these materials are stored. All this is particularly important in order to organize the remediation of polluted sites.

In the site of national interest of Tito Scalo (South Italy), "ex Liquichimica" Area, following specific samplings, characterizations were carried out for the determination of Uranium, 226Ra, 210Pb and 210Po as well as the gamma emitters with various analytical techniques and through specific radiochemical procedures.

The above determinations were performed on various matrices, including surface and groundwater, soils, silt-sediments and plants, for a total of 257 soil samples, 47 groundwater samples, 8 surface water samples, 8 silt-sediment and 10 plant samples.

The analyzes were conducted using radiochemical procedures, such as the IAEA/AQ/34:2014 procedure, accredited according to the UNI EN ISO 17025 standard, specific for the determination of U, Ra, Pb and Po in phosphogypsum.

The analytical techniques used are complex and involve multiple steps for the treatment of the sample and the sequential separation of the radionuclides for their determination: in particular, the above procedure involves the use of liquid scintillation, alpha and gamma spectrometry after radiochemical treatment of the starting matrix. Processes of this type require, in addition to specific skills, a qualitative process that guarantees the goodness of the entire process.

This work shows in detail the IAEA/AQ/34 procedure for the radiological characterization of the phosphogypsum basin of the "ex Liquichimica" area of Tito Scalo, as well as analytical data for each group of analyzed matrices.

 

How to cite: Taroni, M., Iannarone, A., and Zambelli, G.: NORM-TENORM: Characterization of Uranium, Radium, Lead and Polonium levels in the area of the phosphogypsum basin in South Italy. Radiochemical measurement techniques, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3918, https://doi.org/10.5194/egusphere-egu23-3918, 2023.

X4.188
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EGU23-4703
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GI6.5
Pierre-Alexis Chaboche, Olivier Evrard, Anthony Foucher, Pierre Sabatier, and Marcos Tassano

Sedimentary sequences have received a growing interest as a support for conducting climatic and environmental reconstructions covering the 20th century period, which has been highly impacted by socio-environmental changes. South-America is one of the regions of the world the most impacted by these changes (e.g. agricultural expansion, extreme climatic events) which induce many deleterious consequences (e.g. increase of soil erosion, transfer of contaminants). However, quantitative information regarding soil erosion and sediment accumulation processes at the catchment scale is currently lacking to determine the magnitude of these phenomena and promote effective policies to mitigate their environmental and economic impacts.

Fallout of anthropogenic radionuclides (137Cs, 239Pu and 240Pu) emitted by atmospheric nuclear weapon tests conducted between 1945 and 1980 provides an opportunity to overcome this lack of information. Indeed, artificial radionuclides bound to fine-grained sediment have been increasingly recognized as powerful tools to conduct environmental, climatic and soil redistribution rate reconstructions during the Anthropocene. Although spatial and temporal reconstructions of this fallout have been conducted worldwide, this information remains scarce in South America. In addition, scientific controversies emerged regarding the contribution of French atmospheric nuclear tests to the deposition of artificial radionuclides in this region of the world, requiring further investigation.

Based on a compilation of 137Cs inventories in undisturbed soil profiles (n=96) and a digital soil mapping approach, an open-access baseline map of 137Cs fallout at the subcontinental scale of South America was created. The results showed that the 137Cs inventory technique should be appropriate to reconstruct soil erosion in intensive agricultural landscapes of Chile, Argentina, Uruguay and southern Brazil and theoretically applicable in Paraguay, Bolivia and Peru. Compared to previous estimations, higher levels of 137Cs fallout were observed between 20 and 60° South latitude. Additional measurements were therefore conducted in undisturbed soils and lake sediment cores collected at these latitudes by analyzing the 240Pu/239Pu atomic ratios, which is a powerful tool to determine the sources and their respective contributions to the deposition of anthropogenic radionuclides. Significantly lower plutonium atom ratios were found and attributed to the higher contribution (up to 60% in Uruguay) of the fallout following French atmospheric nuclear tests between 1966 and 1974.

This refined chronology and spatial distribution of bomb-derived fallout will undoubtedly be useful to avoid misinterpretations of sediment core dating and reconstruct soil redistribution rates during the Anthropocene in South America.

How to cite: Chaboche, P.-A., Evrard, O., Foucher, A., Sabatier, P., and Tassano, M.: A refined chronology and spatial distribution of artificial radionuclide fallout (239,240Pu, 137Cs) in South America, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4703, https://doi.org/10.5194/egusphere-egu23-4703, 2023.

X4.189
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EGU23-549
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GI6.5
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ECS
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Highlight
Paballo Moshupya, Seeke Mohuba, Tamiru Abiye, and Ian Korir

Naturally occurring radionuclides arises mainly from natural sources and anthropogenic activities such as mining. In South Africa, gold mining in the goldfields of the Witwatersrand Basin has resulted in numerous tailing dams that have high concentrations of NORM bearing residue. The aim of this study was to evaluate the surface radioactivity levels in and around the gold tailing dams of Gauteng Province in South Africa and further determine the consequential radiological exposure to the public. The portable BGO SUPER-SPEC (RS-230) spectrometer, with a 6.3 cubic inches Bismuth Germanate Oxide (BGO) detector was used to measure the activity concentrations for 238U, 232Th and 40K in mine tailings, soils and underlying rocks. This work was conducted on a regional scale and covered the West Rand, East Rand and Central Rand Districts of the Gauteng Province, which are dominated by the abandoned gold tailings dams. Of the three radionuclides that were studied, 238U was found to be the most significant radioactive contaminant of radiological concern. High 238U concentrations (209.95 to 2578.68 Bq/kg) were found in the mine tailings than in the surrounding soils (9.88 to 941.07 Bq/kg) and rocks (11.12 to 71.63 Bq/kg). In surface soil, the radionuclides show significant spatial variability with high activities recorded in soils located in close proximity to tailings thus signifying the adverse environmental impacts of mining in the study area. The annual effective dose estimations indicate that the mine tailings found in the area and soils impacted by tailings significantly contribute to the external gamma radiation received by members of the public. This therefore highlight the need for further monitoring and regulatory control measures targeting these affected areas, in order to ensure the protection of persons and the environment within the areas.

Keywords: activity concentration; gold mine tailings; in situ gamma ray spectrometry; radiological

exposures; South Africa

 

How to cite: Moshupya, P., Mohuba, S., Abiye, T., and Korir, I.: Mapping of radioactivity levels in and around the gold mine tailing dams of Gauteng Province, South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-549, https://doi.org/10.5194/egusphere-egu23-549, 2023.

X4.190
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EGU23-15199
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GI6.5
Anita Molnár, Róbert Janovics, Mihály Veres, and Mihály Molnár

The determination of 14C in dissolved inorganic carbon (DIC) fraction has important task in nuclear environmental monitoring and water base protection. The aim of my research is to develop a preparation method for the 14C determination of dissolved organic carbon (DOC) and to develop sample preparation of total carbon containing both organic and inorganic fractions. In practice, the measurement of dissolved inorganic carbon (DIC) 14C is of essencial importance for example in environmental studies, as the amount of DIC is usually more than 100 times the amount of DOC and there is an easy, rapid preparation method. However, it is often difficult to interpret water dating and water residence time by measurement of dissolved inorganic fraction, because DIC dissolved in water can come from several sources: deep CO2 uptake and bedrock dissolution, not only from the surface biogenic environment at the time of seepage. Therefore, the measurement of dissolved organic carbon (DOC) component gets more importance around nuclear facilities because of its efficiency in detection of anthropogenic effect. To this aim, preparation methods have been developed that are suitable to determine the specific 14C activity concentration of the total dissolved carbon (TD14C) as well as of the dissolved organic form (non-purgeable organic fraction). The measurement of 14C in organic form is a difficult task, the amount of material is usually very small (only a few µg) and samples are difficult to handle furthermore the necessary sample volume usually is more than 500 mL. One of the solutions for DO14C sample preparation is an application of wet oxidation method. In this case the organic components are oxidized by acid and CO2 is extracted. This type of sample preparation technique is basically very sensitive about modern and fossil carbon contamination. However, the method has the additional disadvantage of high chemical demand (hence the contamination introduced) and a complicated and long sample preparation process. These disadvantages can be overcome by testing the total dissolved fraction 14C, which contains both fraction: inorganic and organic forms. Sample preparation can be performed in a significantly shorter time and at lower cost and can be used effectively alongside DI14C for the detection and monitoring of organic forms, for example in environmental monitoring of nuclear facilities. By determining DI14C and TD14C and carbon concentrations, DO14C can be estimated with a good approximation (±10% rel. error).

 

,,Prepared with the professional support of the Doctoral Student Scholarship Program of the Co-operative Doctoral Program of the Ministry of Innovation and Technology financed from the National Research, Development and Innovation Fund.”

The research was supported by the European Union and the State of Hungary, co-financed by the European Regional Development Fund in the project of GINOP-2.3.4-15-2020-00007 “INTERACT”.

How to cite: Molnár, A., Janovics, R., Veres, M., and Molnár, M.: Water preparation methods of dissolved organic fraction determination for C-14 AMS measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15199, https://doi.org/10.5194/egusphere-egu23-15199, 2023.

Posters virtual: Fri, 28 Apr, 10:45–12:30 | vHall ESSI/GI/NP

Chairpersons: Virginia Strati, Susana Barbosa
vEGN.10
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EGU23-537
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GI6.5
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ECS
Carolina L Zilli Vieira and Petros Koutrakis

Radon is a naturally occurring radioactive gas formed from the decay of primordial radionuclides (Uranium and Thorium) in the Earth's crust. It infiltrates into homes from soil, water, and construction materials. Indoor radon is one of the leading cause of lung cancer. Our recent studies have showed short- and middle-term exposures to indoor radon are also related to increased risk of cardiovascular, pregnancy and respiratory morbidity and mortality. These findings bring a new direction for radon exposures and health outcomes studies.  In this overview, we will present our most recent studies on radon exposures and non-cancer outcomes, describing from biological mechanisms to future directions for public health policies.

How to cite: Zilli Vieira, C. L. and Koutrakis, P.: Impact of radon exposures on non cancer outcomes and future perspectives , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-537, https://doi.org/10.5194/egusphere-egu23-537, 2023.

vEGN.11
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EGU23-5501
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GI6.5
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ECS
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Ayane Kan, Maria Heiling, Arsenio Toloza, Franck Albinet, Takuro Shinano, and Gerd Dercon

The release of radiocaesium radionuclides (RCs) has affected food safety after the accidents at Chernobyl and Fukushima Daiichi nuclear power plants. 137Cs, in particular, is of major concern in terms of agriculture due to its relatively long half-life (30.2 years for 137Cs), its strong fixation by the soil, and easy absorption by plants. Therefore, several countermeasures have been undertaken. For instance, topsoil removal and potassium fertilizer successfully reduced the level of RCs contamination in agricultural products. However, the relation between the transfer factor and exchangeable potassium (Kex) differs depending on the soil, meaning that there are several parameters including Kex that influences caesium (Cs) uptake by plants. The reason remains unclear, but a previous studies suggested that exchangeable 137Cs could be a crucial factor in explaining the variation. Also, some factors such as solid/liquid distribution coefficient (Kd) of Cs, or the ratio of exchangeable 137Cs versus total 137Cs (137Csex / 137Cstotal) in the soil could be involved in the determination of the risk of 137Cs uptake by plants. Furthermore, a rapid risk assessment is needed while these parameters can take a huge amount of time to be determined. Hence, Mid-Infrared Spectroscopy (MIRS), being faster, more cost-effective, and non-destructive, may be utilized for the determination of these parameters. However, the prediction of these parameters using MIRS has yet to be assessed. In this study, we aimed to assess whether MIRS can predict Cs-related parameters in the soil such as Kd, 137Csex / 137Cstotal, Kex and other parameters that may be of influence on the behaviour of RCs in the soil, such as CEC, pH, and soil organic carbon.

In total about 1700 soil samples were collected from agricultural fields in the Fukushima Prefecture in Japan. The soil samples were air-dried and ground. The MIRS data were obtained using a Thermo Scientific Nicolet iS20 spectrometer. Using Partial Least Squares Regression as a baseline, the spectra data and the wet chemistry data including Kd, 137Csex / 137Cstotal, and Kex, among other soil parameters, were used for modelling and prediction. Even though until present (at submission of this abstract) only 176 samples have been measured, we found that balancing the range of values between training and validation sets enabled Partial Least Regression Estimation methods to provide a relatively high R2 valid score for the prediction of each wet chemistry data, especially soil organic carbon, CEC, Mgex and Caex, ranging between 0.73 and 0.88. Using less than 200 samples, however, the validation scores of Cs -related parameters were less than 0.5. Further MIRS data are expected for up to about 1600 soil samples, for 137Csex / 137Cstotal in the soil. Additional processing and modelling techniques will be tested aiming at further improving the validation scores, and results will be shown at EGU.

How to cite: Kan, A., Heiling, M., Toloza, A., Albinet, F., Shinano, T., and Dercon, G.: Prediction of caesium dynamics in soil using Mid-Infrared Spectroscopy (MIRS), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5501, https://doi.org/10.5194/egusphere-egu23-5501, 2023.

vEGN.12
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EGU23-3353
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GI6.5
Nuno Dias, Guilherme Amaral, Carlos Almeida, António Ferreira, António Camilo, Eduardo Silva, and Susana Barbosa

Gamma radiation measured over the ocean is mainly due to airborne radionuclides, as gamma emission by radon degassing from the ocean is negligible. Airborne gamma-emitting elements include radon progeny (Pb-2114, Bi-214, Pb-210) and cosmogenic radionuclides such as Be-7. Radon progeny attaches readily to aerosols, thus the fate of gamma-emitting radon progeny, after its formation by radioactive decay from radon, is expected to be closely linked to that of aerosols.

Gamma radiation measurements over the Atlantic Ocean were made on board the ship-rigged sailing ship NRP Sagres in the framework of project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer). The measurements were performed continuously with a NaI(Tl) scintillator counting all gamma rays from 475 keV to 3 MeV.  

The counts from the sensor were recorded every 1 second into a computer system which had his time reference corrected by a GNSS pulse per second (PPS) signal. The GNSS was also used to precisely position the ship. The measurements were performed over the Atlantic ocean from January to May 2020, along the ship’s round trip from Lisboa - Cape Verde – Rio de Janeiro – Buenos Aires – Cape Town – Cape Verde - Lisboa.

The results show that the gamma radiation time series displays considerable higher counts and larger variability in January compared to the remaining period. Reanalysis data also indicate higher aerosol concentration. This work investigates in detail the association between the temporal evolution of the gamma radiation measurements obtained from the SAIL campaign over the Atlantic Ocean and co-located total aerosol concentration at 550 nm obtained every 3 hours from EAC4(ECMWF Atmospheric Composition Reanalysis 4) data.

How to cite: Dias, N., Amaral, G., Almeida, C., Ferreira, A., Camilo, A., Silva, E., and Barbosa, S.: Temporal variability of gamma radiation and aerosol concentration over the North Atlantic ocean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3353, https://doi.org/10.5194/egusphere-egu23-3353, 2023.

vEGN.13
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EGU23-6207
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GI6.5
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ECS
María López Pérez, Elisa Gordo, Francisco Javier Hernández Suárez, Gabriel Castelló, Pedro Ángel Salazar Carballo, Cristina González, Francisco Javier Expósito, Juan Pedro Díaz, and Esperanza Liger

Understanding the mechanisms for transport and deposition of pollutants in the atmosphere is essential for the modelling of air quality. Air quality Radio-indicators (or radio-tracers) such as 40K and 137Cs may be useful to identify and differentiate natural and anthropogenic inputs of pollutants as well as forcing mechanisms (such as dust plumes, nuclear accidents, etc…).  

Spain, due to its proximity to the African continent, is especially affected by African dust plumes which have a remarkable impact on air quality. These events, in addition to large amounts of aerosols, bacteria, virus, seeds, etc.., are usually accompanied by relatively high concentration of 40K (t1/2 = 1.25·109 years) and 137Cs, a fission product with a half-live of 30.2 years. The deterioration of the air quality during such events often has large socio-economical and medical implications to the population.

In this work we analyse and discuss the variations of these two radio-indicators in aerosol samples collected at 7 different monitoring stations over a period of 10 years (2009-2018). The monitoring stations were all located in Spain and operated by the Spanish Nuclear Safety Council. These stations were: Tenerife (28º27′18′′N; 16º17′29′′W), Málaga (36º43’40’’N; 4º28’80’’W), Sevilla (37°22′51″N; 5°59′28″O), Cáceres (39°28'36"N; 6°22'06"O), Madrid (40°27′16″N; 3°43′42″W), Barcelona (41°23′12″N; 2°09′50″E) and Bilbao (43°16′07″N; 2°56′16″O).

40K and 137Cs activity concentrations in atmospheric aerosols were recorded from January 2006 to July 2018. Sampling was carried out weekly using high-flow collectors that operate at about 600 m3/h.  Polypropylene square filters were used to collect atmospheric aerosols. These filters have an efficiency of approximately 96% for the collection of radionuclides.

40K activity concentrations were detected between 39% (Tenerife) and 100% (Bilbao and Madrid) of the samples measured. However, 137Cs activity concentrations appeared in between 3% (Sevilla) and 19% (Bilbao) of the aerosol samples. The simultaneous detection of both radio-indicators in the monitoring stations located in the south of Spain were mostly linked to African dust plumes.

During the weeks after the Fukushima nuclear power plant accident in 2011, 137Cs was detected between 70% (Málaga) and 100% (Madrid, Barcelona and Bilbao) of the samples analyzed. Other fission products such as 131I and 134Cs were also recorded in the same samples during this period.

This work highlights the proper functioning of the Spanish environmental radiological monitoring network but also its usefulness for the study of atmospheric processes impacting air quality such as African dust plumes.

Acknowledgements

This study was supported by the Spanish Nuclear Safety Council (CSN).

How to cite: López Pérez, M., Gordo, E., Hernández Suárez, F. J., Castelló, G., Salazar Carballo, P. Á., González, C., Expósito, F. J., Díaz, J. P., and Liger, E.: VARIATIONS OF AIR QUALITY RADIO-INDICATORS 40K AND 137Cs IN ATMOSPHERIC AEROSOLS IN SEVERAL LOCATIONS IN SPAIN., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6207, https://doi.org/10.5194/egusphere-egu23-6207, 2023.

vEGN.14
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EGU23-6491
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GI6.5
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Highlight
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M. Candelaria Martin-Luis, Pedro A. Salazar-Carballo, María López-Pérez, Xiomara Duarte-Rodríguez, José L. Rodríguez-Marrero, José M. Lorenzo-Salazar, and Antonio Catalán-Acosta

On 19 September 2021, the largest historic eruption of La Palma began, named the Tajogaite volcano. It was active for 85 days, ending on 13 December 2021. During eruptions, the exposure to natural pollutants rises above background levels due to gas emissions and particulate matter (ash and aerosols) into the atmosphere. Moreover, rock fracturing due to magma injection and seismic activity associated with the eruptive phenomena can increase the ground permeability, having a potential effect on radon (222Rn) emissions. During the eruptive and post-eruptive period of the Tajogaite volcano, 222Rn measurements were performed across the affected areas to assess the possible radiological impact of this volcanic episode on La Palma inhabitants.

During the first weeks of the eruption, 88 Solid State Nuclear Track (CR-39-SSNT) detectors were deployed at workplaces and dwellings, mainly located in the vicinity of the eruption, though several detectors were also placed in more distant areas for comparison. These detectors were exposed for ca. 90 days, from September 2021 to January 2022, though only 77 detectors could be retrieved as the rest were buried by the lavas. In addition, 3 portable RadonScout devices (SARAD GmbH) were used for continuous monitoring (1 h integration time) of radon and environmental parameters (air temperature, humidity and barometric pressure). They were installed inside 3 buildings located 2.8-5 km from the volcano.

Eighty percent of the CR-39-SSNT radon data were below the reference level of 300 Bq/m3 (Directive 2013/59/Euratom). Of the remaining detectors, a large percentage of radon levels were above 300 Bq/m3 in the Aridane valley, an area close to the volcano, and with a clear spatial pattern showing higher levels of 222Rn at shorter distances to the eruptive centre. Continuous monitoring of radon showed low 222Rn levels (< 300 Bq/m3) at the two sites furthest from the volcano, with fluctuations highly correlated with environmental variables. Several anomalies of 222Rn reaching up to 4000 Bq/m3 were detected during the eruptive period in the monitoring station located closer to the eruptive centre, unrelated to the observed environmental variables. These anomalies were synchronous with the occurrence of large explosive events and phreatomagmatic pulses during the eruption.

The computed effective dose due to the contribution of 222Rn during the 3 months of eruption was 0.3 mSv, which, extrapolated to the annual reference value, provides an estimated effective dose of 0.9 mSv/year. This value is 50% lower than the estimated worldwide annual average dose from natural and artificial radiation sources (2.4 mSv/year) (UNSCEAR 2000). Thus, radon levels during the Tajogaite eruption did not lead to a significant increase in exposure level to this radioactive gas. However, transient radon bursts have been recorded associated with several phases of the volcanic activity.

 Acknowledgments

This study was supported by the Spanish Ministry of Science and Innovation (BOE-A-2021-20262).

References:

Council Directive 2013/59/Euratom laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom.

UNSCEAR (2000), Sources and effects of ionizing radiation. UNITED NATIONS, New York.

How to cite: Martin-Luis, M. C., Salazar-Carballo, P. A., López-Pérez, M., Duarte-Rodríguez, X., Rodríguez-Marrero, J. L., Lorenzo-Salazar, J. M., and Catalán-Acosta, A.: Radon gas emissions during the 2021 Tajogaite eruption at Cumbre Vieja Volcano (La Palma, Canary Islands), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6491, https://doi.org/10.5194/egusphere-egu23-6491, 2023.