222Rn as a tracer for air mass transport characterization at 100-m-high tower in the south-west Spanish coast

Es los últimos años se han llevado a cabo importantes trabajos de investigación, tomando el gas radón como elemento de evaluación en modelos de transporte atmosférico y así estimar el flujo de partículas. Además la utilización del radón ha encontrado otras aplicaciones en el estudio de las emisiones de gases de efecto invernadero a escala regional; en la actualidad en algunos proyectos europeos como el Ttorch y el InGOS se realizan medidas en continuo de radón atmosférico junto con otros gases de efecto invernadero. En este marco de actuación, la presente tesis quiere caracterizar una nueva estación de radón atmosférico en El Arenosillo, en la cuenca sur de España, llevando a cabo medidas de radón a diferentes alturas gracias a una torre de 100 metros. Además otro objetivo de la tesis ha sido la caracterización del flujo de radón en esta área geográfica. Este trabajo incluye, además de un análisis de las concentraciones de radón mediante un sistema de esfera por electrodeposición, las observaciones de los parámetros meteorológicos en la estación de El Arenosillo. El flujo de radón en la misma área ha sido estudiado tanto con métodos directos como indirectos. Para poder estudiar el origen de las masas de aire ricas o pobres en radón que llegan a la estación, se ha realizado un análisis cualitativo con retro trayectorias.An intensive research has been carried out during the last decade on a global scale using 222Rn for global atmospheric transport models evaluation as well as for estimating fluxes of atmospheric constituents. Furthermore, a new application in recent years has been the use of radon for estimating regional scale greenhouse gas emission. Nowadays, some European projects and data base, such as the TTtorch and the InGOS, are carrying out continuous measurements of the atmospheric 222Rn gas concentrations together with others greenhouse gases measurements at tall towers. In this framework, the present thesis aims to characterize a new atmospheric radon station at the El Arenosillo station, in the Southwest coast of Spain, by performing atmospheric radon concentration measurements at different heights thank to the presence of a 100 m tall tower. Furthermore, the study wants to properly characterize the radon flux background in this area. Therefore, this work includes the analysis of atmospheric radon gas concentration by electrostatic chamber method under seasonal meteorological parameters at two heights and the characterization of the radon flux of the El Arenosillo station area by direct and by indirect radon flux inventories. Finally, a qualitative back trajectories analysis has been performed to study the origin of air masses rich or poor in radon and to confirm the specific regions as radon source regions. During the Autumn season the geometric mean of radon data at 10 m is 4.48 Bq m-3 with a st. dev. of 2.03 Bq m-3 .and at 100 m is 2.93 with 1.98 Bq m-3 . In the Winter season the geometric mean of radon concentration data at 10 m is 3.82 Bq m-3 with a st. dev. of 2.34. At 100 m the geometric mean is and 3.06 Bq m-3 with 1.72. These radon concentrations are not as high as would be expected for winter and can be explained by the high frequency of radon-poor air masses coming from the Atlantic Ocean and from South Portugal during this season. The Spring season shows a geometric mean of radon concentration data at 10 m of 3.60 Bq m-3 with a st. dev. equal to 2.18 and at 100 m is 2.05 Bq m-3 with 2.20. These average radon concentrations indicate good atmospheric layer separation during this season. Finally, during the summer season the radon concentration data at 10 m is 2.64 Bq m-3 with a st. dev. of 1.86. At 100 m height, the geometric mean is 2.41 Bq m-3 with standard deviation of 1.88. These values indicate good statistics for this season and a strong mixing layer, as was expected for an unstable summer. The local radon flux contribution at el Arenosillo station is really low, of 5.3 ± 1.8 Bq m-2 h-1 which means that the atmospheric radon concentrations data will not have any strong noisly radon background and can be used in order to estimate remote radon source. The 222Rn flux observed from the close phosphogypsum pile and confirmed by different monitors and methods shows an average value of 33.5 ± 5.6 Bq m-2 h-1 , which is really low if compared with material 226Ra activity concentration of 550 Bq kg-1. The experimental analysis of atmospheric radon behaviour at El Arenosillo station has pointed out the existence of specific regions poor/rich in radon where the air masses use to come from such as the Sierra Morena system, the Betic system, the North of Portugal, the Atlantic Ocean, the Marocco area and the Guadalquivir Valley. A back-trajectory analysis has been performed by the transport model HYSPLIT4 in order to confirm the air masses origin from specific sectors and to justify the poor/rich radon concentrations transported and measured at El Arenosillo station.Postprint (published version

Radon

Radon isotopes (222Rn, 220Rn) are noble, naturally occurring radioactive gases. They originate from the alpha decay of radium isotopes (226Ra, 224Ra), which occur in most materials in the environment, i.e. soil, rocks, raw and building materials. Radon is also found in ground and tap water. The two radon isotopes are chemically identical, but they have very different halflives: 3.82 days for radon (222Rn) and 56 seconds for thoron (220Rn). Thus, they behave very differently in the environment. Both isotopes are alpha-emitters; their decay products are polonium, bismuth and lead isotopes.Peer ReviewedObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaPostprint (published version

Ancient use of the knuckle-bone for rituals and gaming piece

In ancient times the knuckle-bone had probably both a ritual function linked to the practice of divination and a profane use as game piece for infants and adults. This bone can derive from different animal species and when found in large numbers is invariably associated with cultic, funerary or public spheres. A fair amount of worked and unmodified knuckle-bones has recently come to light in Italy from the cemeteries of Le Grotte near Populonia (4th-3th BC) and of Poggio Picenze in Abruzzo (3rd-2nd BC). Zooarchaeological analysis of these knuckle-bone groups contributes to our understanding of several aspects of the ancient use of this particular bone, such as the choice of the animal the different types of modifications and the effects and significance of the different types of deposition

Pathogenesis of the obstetric antiphospholipid syndrome: the key role of beta 2 glycoprotein I

Antiphospholipid syndrome (APS) is defined by recurrent pregnancy morbidity and/or vascular thrombosis associated with the persistent presence of antibodies against anionic phospholipid-binding proteins. Beta 2 glycoprotein I (β2GPI) and prothrombin (PT) are the major antigens for antiphospholipid antibodies (aPL) detectable by functional coagulation [lupus anticoagulant (LA)] or solid-phase assays [anti-β2GPI-dependent cardiolipin (aCL) and anti-β2GPI]. β2GPI-dependent aPL are responsible for the positivity of the three classification laboratory criteria. While medium/high titers of antibodies against β2GPI are risk factors for both the vascular and the obstetric manifestations of APS, persistent low titers are also associated with pregnancy complications. There is evidence from animal models of aPL-dependent fetal loss and from in vitro systems that β2GPI-dependent aPL can be pathogenic. β2GPI is physiologically found in large quantities at the placental level being available for the specific antibodies circulating in the maternal blood. Once bound to the protein, the antibodies trigger a local inflammation via the activation of the complement cascade and affect trophoblast and decidual function. The final result is represented by defective placentation, while thrombotic events are apparently less important. β2GPI is a pleiotropic molecule with scavenging properties towards several molecules including apoptotic material and displays anti-oxidant activity. These functions may explain the β2GPI placental localization in an area of intensive tissue remodeling and low oxygen tension. Since β2GPI interacts also with the complement and the coagulation cascade, its binding with specific antibodies may affect the physiology of placentation in several ways

Intercomparison study of atmospheric 222Rn and 222Rn progeny monitors

The use of the noble gas radon (222Rn) as a tracer for different research studies, for example observation-based estimation of greenhouse gas (GHG) fluxes, has led to the need of high-quality 222Rn activity concentration observations with high spatial and temporal resolution. So far a robust metrology chain for these measurements is not yet available. A portable direct atmospheric radon monitor (ARMON), based on electrostatic collection of 218Po, is now running at Spanish stations. This monitor has not yet been compared with other 222Rn and 222Rn progeny monitors commonly used at atmospheric stations. A 3-month intercomparison campaign of atmospheric 222Rn and 222Rn progeny monitors based on different measurement techniques was realized during the fall and winter of 2016–2017 to evaluate (i) calibration and correction factors between monitors necessary to harmonize the atmospheric radon observations and (ii) the dependence of each monitor's response in relation to the sampling height and meteorological and atmospheric aerosol conditions. Results of this study have shown the following. (i) All monitors were able to reproduce the atmospheric radon variability on a daily basis. (ii) Linear regression fits between the monitors exhibited slopes, representing the correction factors, between 0.62 and 1.17 and offsets ranging between -0.85 and -0.23¿Bq¿m-3 when sampling 2¿m above ground level (a.g.l.). Corresponding results at 100¿m¿a.g.l. exhibited slopes of 0.94 and 1.03 with offsets of -0.13 and 0.01¿Bq¿m-3, respectively. (iii) No influence of atmospheric temperature and relative humidity on monitor responses was observed for unsaturated conditions at 100¿m¿a.g.l., whereas slight influences (order of 10-2) of ambient temperature were observed at 2¿m¿a.g.l. (iv) Changes in the ratio between 222Rn progeny and 222Rn monitor responses were observed under very low atmospheric aerosol concentrations. Results also show that the new ARMON could be useful at atmospheric radon monitoring stations with space restrictions or as a mobile reference instrument to calibrate in situ 222Rn progeny monitors and fixed radon monitors. In the near future a long-term comparison study between ARMON, HRM, and ANSTO monitors would be useful to better evaluate (i) the uncertainties of radon measurements in the range of a few hundred millibecquerels per cubic meter to a few becquerels per cubic meter and (ii) the response time correction of the ANSTO monitor for representing fast changes in the ambient radon concentrations.Postprint (published version

Variability of methane fluxes at the Ebro Delta due to rice field: comparison between inventories and Radon Tracer Method based results.

The Ebro River Delta, in the northwestern Mediterranean basin, has an extension of 320 km2 and is mainly covered by rice fields. Rice fields are known to be one of the main sources of anthropogenic methane emissions, and a better estimation of its temporal variability in relation to the different rice cultivation phases is important to help with the implementation of emission reduction strategies (Àgueda et al., 2017), In the framework of the ClimaDat network, an atmospheric station was installed in the middle of the Ebro Delta in 2012. A Picarro G2301 for greenhouse gases (GHG) atmospheric concentrations and an ARMON (Atmospheric Radon Monitor) for atmospheric 222Rn concentrations were collocated among other instruments. Nocturnal hourly atmospheric observations of CH4 and 222Rn measured between 2013 and 2019 were used to apply the Radon Tracer Method (RTM) for retrieving CH4 fluxes over the footprint area. The Ebro River Delta has a reduced dimension and a complex meteorological regime highly influenced by the Ebro channelled winds and the sea breezes, making it difficult to calculate GHG fluxes using global or regional inversion models. However, the use of high-resolution backtrajectories (model WRF-Flexpart) coupled with the traceRadon daily radon flux maps for Europe (Karsten et al., 2022), with a resolution of 0.05 degrees, has allowed the use of the RTM in this complex area. Methane fluxes estimated by RTM were compared with fluxes directly measured with chambers in past studies (Martínez-Eixarch et al., 2018) and with data obtained by the EDGAR inventory (Crippa et al., 2022). Results show a promising agreement between methane fluxes obtained with different methods, and a variability clearly governed by the rice crop cycle which is not reflected in the methane emissions values reported in EDGAR inventories.Peer ReviewedPostprint (published version

Metrology for low-cost CO2 sensors applications: the case of a steady-state through-flow (SS-TF) chamber for CO2 fluxes observations

Soil CO2 emissions are one of the largest contributions to the global carbon cycle, and a full understanding of processes generating them and how climate change may modify them is needed and still uncertain. Thus, a dense spatial and temporal network of CO2 flux measurements from soil could help reduce uncertainty in the global carbon budgets. In the present study, the design, assembly, and calibration of low-cost air enquirer kits, including CO2 and environmental parameters sensors, is presented. Different types of calibrations for the CO2 sensors and their associated errors are calculated. In addition, for the first time, this type of sensor has been applied to design, develop, and test a new steady-state through-flow (SS-TF) chamber for simultaneous measurements of CO2 fluxes in soil and CO2 concentrations in air. The sensors’ responses were corrected for temperature, relative humidity, and pressure conditions in order to reduce the uncertainty in the measured CO2 values and of the following calculated CO2 fluxes based on SS-TF. CO2 soil fluxes measured by the proposed SS-TF and by a standard closed non-steady-state non-through-flow (NSS-NTF) chamber were briefly compared to ensure the reliability of the results. The use of a multiparametric fitting reduced the total uncertainty of the CO2 concentration measurements by 62 %, compared with the uncertainty that occurred when a simple CO2 calibration was applied, and by 90 %, when compared to the uncertainty declared by the manufacturer. The new SSTF system allows the continuous measurement of CO2 fluxes and CO2 ambient air with low cost (EUR ~ 1200), low energy demand (< 5 W), and low maintenance (twice per year due to sensor calibration requirements).Peer ReviewedPostprint (published version

Characterizing the automatic radon flux transfer standard system autoflux: laboratory calibration and field experiments

High-quality, long-term measurements of terrestrial trace gas emissions are important for investigations of atmospheric, geophysical and biological processes to help mitigate climate change and protect the environment and the health of citizens. High-frequency terrestrial fluxes of the radioactive noble gas 222Rn, in particular, are useful for validating radon flux maps and used to evaluate the performance of regional atmospheric models, to improve greenhouse gas emission inventories (by the radon tracer method) and to determine radon priority areas for radiation protection goals. A new automatic radon flux system (Autoflux) was developed as a transfer standard (TS) to assist with establishing a traceability chain for field-based radon flux measurements. The operational characteristics and features of the system were optimized based on a literature review of existing flux measurement systems. To characterize and calibrate Autoflux, a bespoke radon exhalation bed (EB) facility was also constructed with the intended purpose of providing a constant radon exhalation under a specific set of controlled laboratory conditions. The calibrated Autoflux was then used to transfer the derived calibration to a second continuous radon flux system under laboratory conditions; both instruments were then tested in the field and compared with modeled fluxes. This paper presents (i) a literature review of state-of-the-art radon flux systems and EB facilities; (ii) the design, characterization and calibration of a reference radon EB facility; (iii) the design, characterization and calibration of the Autoflux system; (iv) the calibration of a second radon flux system (INTE_Flux) using the EB and Autoflux, with a total uncertainty of 9% (k=1) for an average radon flux of ~1800mBqm-2s-1 under controlled laboratory conditions; and (v) an example application of the calibrated TS and INTE_Flux systems for in situ radon flux measurements, which are then compared with simulated radon fluxes. Calibration of the TS under different environmental conditions and at lower reference fluxes will be the subject of a separate future investigation.Peer ReviewedPostprint (published version

Atmospheric Carbon Dioxide variability at Aigüestortes, Central Pyrenees, Spain

Unidad de excelencia María de Maeztu MdM-2015-0552In order to improve the understanding of the carbon cycle in the Pyrenean region, two atmospheric monitoring mountain stations were set up within the Long-Term Ecological Research node of Aigüestortes i Estany de Sant Maurici at Central Pyrenees, Spain. The atmospheric concentration of carbon dioxide (CO2) was measured over 2008-2014 and 2010-2014 at Estany Llong (ELL) site and Centre de Recerca d'Alta Muntanya (CRAM), respectively. Measurements were carried out fortnightly off-line with high precision instrumentation at ELL and every minute online with a lower precision sensor at CRAM in conjunction with meteorological variables. The two datasets were analyzed in this study, quantifying whenever possible annual growth rates (AGR), seasonal variability, and diurnal amplitudes. Results were also compared with the NOAA Marine Boundary Layer (MBL) reference product and CO2 data from other background monitoring stations. Four-harmonics adjusted CO2 data from ELL showed a high correlation with the NOAA MBL reference product for the same latitude (Spearman's rho ρ = 0.96). In addition, AGRs of CO2 at ELL correlated well with those observed at Mace Head (MHD) station (ρ = 0.94), suggesting that ELL can be considered a background station. Winter CRAM CO2 data was not statistically different from ELL data, while in summer, it was 5.5 ppm lower on average, suggesting a higher photosynthesis uptake. The amplitude of the CO2 diurnal cycle at CRAM was found to be exponentially related to the local mean daily temperature and dependent on forthcoming wind sector (N-NW or E-SE-S-SW). An increase in CRAM CO2 concentrations was observed under N-NW winds during daytime, which could be related to traffic emissions. This study demonstrates that the use of CO2 sensors with low precision but continuously corrected and periodically calibrated can be used for the study of local and regional CO2 sources and sinks