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Dataset related to the paper: Can rock deformation control radon emission? data fotmat is a structured .mat data are listed by experiment name mechanical data start with "s" and contain: Time_new (time in day hh:mm), shear1 (shear stress MPa), normal (normal load MPa), short (axial shortening (mm + shortening - dilation), slipF (slip, m ), velF (slip rate m/s) slip and slip rate are filtered using an acausal filter with butter windows. shortening data are smoothed of 200 points acquisition rate was 200 Hz radon data start with "r" and contain: t (time in day hh:mm), time (time in s), countesec (counts for seconds), cumcounts (cumulative counts) mm# (counts averaged every 1, 5, 10 15, 30, 60 minute)

Il "progetto Michelangelo" è nato dall'esigenza di rallentare la diffusione dei contagi da SARS-CoV-2 e alleggerire il carico a livello ospedaliero. Inizialmente, la maggior parte degli ospiti dell'hotel Michelangelo di Milano erano pazienti dimessi dagli ospedali con test molecolare ancora positivo che non avevano la possibilità di restare in isolamento domiciliare. Ben presto, però, il progetto è stato esteso e circa un ospite su quattro era un adulto/nucleo familiare in condizioni di grave disagio economico o sociale o una persona senza fissa dimora. Inoltre, la maggior parte degli ospiti era di nazionalità non italiana: persone che, a causa di barriere linguistiche, legali, culturali e sociali, hanno trovato maggiore difficoltà ad avere un rapido accesso ai servizi sanitari. Il "progetto Michelangelo" non ha solo contribuito a ridurre il sovraffollamento degli ospedali, ma è stato di supporto ai servizi rivolti al contrasto della grave marginalità.

This contribution illustrates the state of the art on the development of the multiparametric network in Sicily in the last three years. This region is wellknown for the strong earthquakes (M>6.5) which struck in historic time. However, the coverage of the seismic network developed in the last decades was not fully optimized to the need of the seismic surveillance. Since 2017, the group belonging to the National Earthquake Observatory (ONT) which operates in Sicily launched a developing plan of the preexisting seismic network in the framework of the project FISR “Sale Operative Integrate e Reti di Monitoraggio del futuro: l’INGV 2.0 (S.O.I.R.)”. Such update will end by the next years thanks to the project “GRINT Italian Research Infrastructure for Geosciences” in the framework of the “Programma Operativo Nazionale” (PON) of the Italian Ministry for the University and Research. This plan envisages both the upgrade of monitoring systems in the already existing nodes, and the integration of new nodes. The main objective is to build a multiparametric network which integrates the main seismic network, with the monitoring of other geophysical signals through the implementation of other sensors: accelerometers, geodetic GPS, radon detectors, and corner reflectors. We also illustrate the plan for the realization of a redundant network which could support the tasks of the main infrastructure in case of failure of the latter. Finally, we present some experimental urbanscale networks which in the future could support the main infrastructure., In questo contributo viene illustrato lo stato dell’arte sullo sviluppo della rete multiparametrica in Sicilia in riferimento all’ultimo triennio. Questa regione è storicamente nota per i suoi forti terremoti (M>6.5), ma la copertura della Rete Sismica Nazionale (RSN) sviluppata nel corso degli anni dall’INGV non risultava ancora ottimale in funzione delle esigenze di monitoraggio e sorveglianza sismica. A partire dal 2017, il personale dell’Osservatorio Nazionale Terremoti (ONT) operativo in Sicilia, ha dato il via ad un programma di sviluppo e implementazione della rete sismica preesistente (RSN) nell’ambito del Progetto FISR “Sale Operative Integrate e Reti di Monitoraggio del futuro: l’INGV 2.0 (S.O.I.R.)”; tale programma si concluderà nei prossimi anni, grazie anche al Progetto “GRINT Infrastruttura di Ricerca Italiana per le Geoscienze” nell’ambito del Programma Operativo Nazionale (PON) del Ministero dell’Istruzione, dell’Università e della Ricerca. Questo progetto consiste sia nell’upgrade dei sistemi di monitoraggio in alcuni dei siti di stazione già esistenti, sia nell’aggiunta di nuovi nodi alla rete. L’obiettivo è quello di realizzare una rete multiparametrica che, parallelamente alla preesistente RSN che rappresenta l’infrastruttura principale, preveda il monitoraggio anche di altri segnali e parametri geofisici mediante apposita sensoristica: accelerometri, GPS geodetici, rilevatori di gas radon e riflettori radar (Corner Reflector). Viene inoltre illustrato il programma di realizzazione di una rete fiduciaria ridondante rispetto alla rete esistente, che possa garantire la sorveglianza sismica in caso di crisi dell’infrastruttura primaria. Vengono infine presentate le potenzialità di reti sperimentali a scala urbana, che in futuro potranno essere integrate all’infrastruttura principale.

Il monitoraggio sismico del territorio nazionale e dell’area Euro-Mediterranea si avvale dei dati velocimetricie accelerometrici acquisiti dalle stazioni della Rete Sismica Nazionale (RSN [INGV Seismological Data Centre; 2006; Michelini et al., 2016]) e della Rete MedNet [Pondrelli et al., 2020] e dei dati geodetici della Rete Integrata Nazionale GNSS (RING [Avallone et al., 2010; INGV RING Working Group, 2016]). Nell’ambito del WP2 del progetto “S.O.I.R. monitoraggio futuro” [Rao et al., 2018; 2020] si stanno integrando sensori in grado di rilevare contemporaneamente parametri geofisici e geochimici. In questo rapporto tecnico viene descritta l’integrazione di un sensore di radon. Nel corso degli ultimi decenni il radon ha trovato una varietà di applicazioni di Scienza della Terra, che vanno dal suo utilizzo come potenziale precursore di terremoti ed indicatore di stress tettonico al suo ruolo specifico negli ambienti vulcanici, dove variazioni significative di concentrazione precedenti o concomitanti a crisi eruttive sono anche indotte da gas vulcanici, CO2 ad esempio, che agiscono da carrier accelerando la migrazione del radon attraverso la crosta terrestre e quindi la sua rivelabilità. Al fine di esplorare la possibilità di un legame tra processi sismogenici e variabilità temporale delle emissioni di radon è stata creata una rete permanente a livello nazionale, Italian Radon mOnitoring Network (IRON [Cannelli et al., 2017; 2018; 2020]), che impiega sia strumenti radon commerciali dotati di un sistema di memorizzazione, trasmissione e consultazione dati proprietario, sia sensori INGV che necessitano di un’interfaccia per acquisire e rendere disponibili i dati da remoto. È stata pertanto progettata, realizzata e testata un’interfaccia HW/SW in grado di: i) contare e memorizzare gli impulsi in formato Transistor-Transistor Logic (TTL) generati dallo strumento per la misura della concentrazione di radon in aria, ii) essere collegata ad un router per l’invio ad un server dei dati acquisiti. È stato inoltre creato un servizio (syncproc) in PHP per interrogare, ad intervalli regolari, le stazioni remote e raccogliere i dati acquisiti destinati a popolare un database, creato con MariaDB. “Clarice”, un sito web raggiungibile esclusivamente dalla rete interna INGV e appositamente realizzato, consente di estrarre dal database i dati memorizzati e configurare ogni sensore installato. I vari elementi software sono stati progettati utilizzando risorse open source.

Nell’ambito del progetto “S.O.I.R. monitoraggio futuro”, la sezione INGV dell’Osservatorio Nazionale Terremoti (ONT), ha rivolto l’attenzione principalmente nel centro Italia e nelle aree non vulcaniche della Sicilia. La scelta di convogliare le attività di potenziamento in queste due aree è stata attentamente ponderata: da un lato la necessità di ottimizzare e irrobustire la rete di monitoraggio in centro Italia, un’area ad elevatissimo rischio interessata negli ultimi anni da importanti sequenze sismiche, dall’altro quello di avviare lo sviluppo della rete multiparametrica in Sicilia, un territorio che offre una innumerevole varietà di ambienti e sotto-sistemi, che rendono tale regione un laboratorio naturale unico al mondo. Gli interventi ONT possono essere essenzialmente raggruppati in due categorie: quelli finalizzati all’aumento del grado di multiparametricità del sito e quelli mirati all’aumento del livello di affidabilità e robustezza del servizio. La presenza simultanea di molteplici sensori permette infatti di migliorare la comprensione del fenomeno sismico e dei fenomeni ad esso associati, di aprire nuove prospettive per la valutazione della pericolosità sismica, per la previsione probabilistica dei terremoti, per la prevenzione e l’aumento di resilienza, e più in generale per la mitigazione del rischio sismico. Mentre sistemi di back-up dell’alimentazione e la ridondanza di trasmissione, garantiscono una maggiore continuità soprattutto per le stazioni considerate strategiche per il servizio di monitoraggio e di sorveglianza sismica.

IRON (Italian Radon mOnitoring Network) rappresenta il primo esempio in Italia, ed uno dei primi in assoluto al mondo, di network denso su scala regionale di stazioni permanenti per il monitoraggio in (quasi) real time di concentrazione radon [Cannelli et al., 2018; Soldati et al., 2019a]. Sviluppato ed implementato negli ultimi 11 anni, comprende attualmente circa 60 stazioni, la maggior parte delle quali è concentrata lungo la catena appenninica centro-meridionale (Figura 1). Allo stato attuale, la maggior parte delle stazioni IRON registra serie storiche del radon da più di 4-5 anni. Le varietà e diversità in termini di strumenti, tipologia di installazione e soprattutto il grande numero di dati di concentrazione acquisiti, sono supportate da un database relazionale [Cannelli, 2017] in continuo sviluppo e costante implementazione, che permette, attraverso un’interfaccia WEB dedicata, la visualizzazione di tutte le serie temporali, il loro download e la consultazione delle caratteristiche associate ad ogni stazione/strumento. Gli obiettivi di IRON, oltre al continuo potenziamento della rete di monitoraggio in sé, sono rappresentati dallo sviluppo tecnologico della strumentazione [Galli et al., 2019], in particolare l’implementazione di protocolli di trasmissione remota dei dati il più possibile versatili ed efficienti e il miglioramento delle prestazioni strumentali in condizioni di alta umidità ed in ambienti aggressivi e dallo sviluppo scientifico delle tecniche di monitoraggio e dei protocolli di analisi numerica [Piersanti et al., 2015; Cannelli et al., 2016; Piersanti et al., 2016; Siino et al., 2019; Soldati et al., 2019b]. Con il progetto “S.O.I.R. Monitoraggio futuro” è stata avviata l’integrazione di IRON all’interno di un network di monitoraggio multiparametrico, che prevede la realizzazione di una rete a scala nazionale di siti omogenei nei quali siano presenti velocimetri, accelerometri, sensori GPS, apparati per il monitoraggio elettromagnetico e misuratori radon [Rao et al., 2018; 2020]. In questa ottica sono stati acquisiti ed installati sensori radon relativamente economici e originariamente progettati per uso in ambiente indoor, che permettono sia un monitoraggio intensivo del radon su scala regionale che l’acquisizione remota dei dati in tempo reale in modalità autonoma, garantendo una maggiore autonomia di funzionamento grazie ai consumi elettrici estremamente ridotti. Tuttavia, alcune limitazioni connesse all'adozione di questi dispositivi permangono soprattutto per quanto riguarda i protocolli di trasmissione dei dati. Al fine di superare le limitazioni di tali protocolli e di migliorare la loro versatilità in vista di una futura compatibilità con i protocolli di trasmissione della Rete Sismica Nazionale (RSN), sono state apportate una serie di modifiche ad-hoc sui dispositivi acquistati. Sono contestualmente in atto esperimenti pilota per monitorare congiuntamente al radon i segnali VLF-EM (Very Low Frequency-Electromagnetic Measurements) attraverso la rete prototipale Cassandra già implementata in Italia per il monitoraggio continuo di VLF. Dal 2019 è stata attivata, a seguito di bando pubblico, una convenzione con il sito iLMeteo per la fornitura di dati atmosferici rilevati al suolo, in ambiente aperto e in prossimità delle stazioni IRON, per il filtraggio delle serie storiche e il miglioramento del rapporto segnale-rumore.

The seismic monitoring of the national territory and of the Euro­Mediterranean area makes use of the velocimetric, accelerometric and GPS (geodetic) data acquired by the stations of the National Seismic Network, by the RING Network and by the MedNet Network. As part of the FISR 2017 project “Integrated operating rooms and monitoring networks for the future: INGV 2.0” (2017), sensors capable of detecting both geophysical and geochemical parameters at the same time are being integrated. This technical report describes the integration of a Rn­222 sensor (radon hereafter). Over the past few decades radon has found a variety of Earth Science applications, ranging from its use as a potential earthquake precursor and tectonic stress indicator to its specific role in volcanic environments, where significant changes in concentration previous or concomitant to eruptive crises are also induced by volcanic gases, CO2 for example, which act as carriers accelerating the migration of radon through the earth’s crust and therefore its detection. In order to explore the possibility of a link between seismogenic processes and temporal variability of radon emissions, a permanent national network has been created, IRON (Italian Radon mOnitoring Network), which uses both commercial radon instruments, equipped with a proprietary system for data storage, transmission and consultation, and INGV sensors that need an interface to acquire and make data available remotely. A hardware and software interface has therefore been designed, built and tested capable of i) counting and storing the pulses in TTL format generated by the instrument which measures the radon concentration in air, ii) being connected to a router for sending the acquired data to a server. A service (syncproc) was also created in PHP to query remote stations at regular intervals and collect the acquired data intended to populate a database created with MariaDB. An expressly created website allows to extract the stored data from the database and configure each installed sensor. The various software elements have been designed using open source resources., Il monitoraggio sismico del territorio nazionale e dell’area Euro­Mediterranea si avvale dei dati velocimetrici, accelerometrici e GPS (geodetici) acquisiti dalle stazioni della Rete Sismica Nazionale, dalla Rete RING e dalla Rete MedNet. Nell’ambito del progetto FISR 2017 “Sale operative integrate e reti di monitoraggio per il futuro: l’INGV 2.0” (2017) si stanno integrando sensori in grado di rilevare contemporaneamente parametri geofisici e geochimici. In questo rapporto tecnico viene descritta l’integrazione di un sensore di Rn­222 (radon da qui in avanti). Nel corso degli ultimi decenni il radon ha trovato una varietà di applicazioni di Scienza della Terra, che vanno dal suo utilizzo come potenziale precursore di terremoti ed indicatore di stress tettonico al suo ruolo specifico negli ambienti vulcanici, dove variazioni significative di concentrazione precedenti o concomitanti a crisi eruttive sono anche indotte da gas vulcanici, CO2 ad esempio, che agiscono da carrier accelerando la migrazione del radon attraverso la crosta terrestre e quindi la sua rivelabilità. Al fine di esplorare la possibilità di un legame tra processi sismogenici e variabilità temporale delle emissioni di radon è stata creata una rete permanente a livello nazionale, IRON (Italian Radon mOnitoring Network), che impiega sia strumenti radon commerciali dotati di un sistema di memorizzazione, trasmissione e consultazione dati proprietario sia sensori INGV che necessitano di un’interfaccia per acquisire e rendere disponibili i dati da remoto. È stata pertanto progettata, realizzata e testata un’interfaccia hardware e software in grado di i) contare e memorizzare gli impulsi in formato TTL generati dallo strumento per la misura della concentrazione di radon in aria, ii) essere collegata ad un router per l’invio ad un server dei dati acquisiti. È stato inoltre creato un servizio (syncproc) in PHP per interrogare, ad intervalli regolari, le stazioni remote e raccogliere i dati acquisiti destinati a popolare un database, creato con MariaDB. Un sito web appositamente realizzato consente di estrarre dal database i dati memorizzati e configurare ogni sensore installato. I vari elementi software sono stati progettati utilizzando risorse open source.

Within the training courses of Alternanza Scuola­Lavoro (a governative project for the introduction of work themes to the undergraduate students), a group of researchers from the Istituto Nazionale di Geofisica e Vulcanologia proposed and developed a project to a third class of the Liceo Scientifico Cavour in Rome. The idea was to introduce the students to the world of scientific research, allowing them to be faced in all their phases. The work was envisaged through the use of measuring instruments, data analysis, graph production, the construction of thematic maps and finally the writing in English of a scientific article (essential part of the researcher’s work) with the description of the research carried out and the results obtained. The research involved the distribution of radon indoor in some districts of Rome. The students had the opportunity to measure radon indoor through specific instruments in their houses and in their school, looking for possible spatial and temporal distribution between different data type and to isolate particularly anomalous cases. The aim was to investigate links between the measured values, the area’s geology and the housing typologies, to build thematic maps able to highlight the results achieved and finally to write a scientific article. This technical report has been introduced by the researchers and developed by the students., All’interno dei percorsi formativi di Alternanza Scuola­Lavoro un gruppo di ricercatori dell’Istituto Nazionale di Geofisica e Vulcanologia ha proposto e sviluppato con una terza classe del Liceo Scientifico Cavour di Roma un progetto riguardante l’avvicinamento degli studenti al mondo della ricerca scientifica, allo scopo di affrontarla e svilupparla in tutte le sue fasi. Dopo aver spiegato e condiviso l’obiettivo della ricerca con gli alunni, la prima fase del progetto ha riguardato la raccolta dei dati tramite l’utilizzo di strumenti di misura; si è in seguito proceduto all’analisi dei dati ottenuti, attraverso un foglio elettronico di calcolo, la produzione di grafici e mappe tematiche e infine la scrittura di un articolo scientifico (parte essenziale del lavoro del ricercatore) con la descrizione della ricerca svolta e dei risultati ottenuti. La ricerca ha riguardato la distribuzione del radon indoor in alcuni rioni di Roma. Gli studenti hanno avuto la possibilità di misurare il radon indoor tramite strumenti specifici nelle loro abitazioni e nella loro scuola, di analizzarne la distribuzione spaziale e temporale e di individuare dei casi particolarmente anomali. Sono stati quindi evidenziati i legami tra i valori misurati, la geologia del sottosuolo e le tipologie abitative, illustrati per mezzo di mappe tematiche, facendo confluire il tutto nella scrittura di un articolo scientifico. Il presente rapporto tecnico è stato introdotto dai ricercatori e sviluppato dagli studenti.

Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose. This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations. This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: • familiarize itself with natural radioactivity; • be informed about the levels of natural radioactivity caused by different sources; • have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor; • and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter. Additional information at: https://remon.jrc.ec.europa.eu/About/Atlas-of-Natural-Radiation, JRC.G.10-Knowledge for Nuclear Security and Safety

Naturally occurring 222Rn is increasingly recognized as a powerful environmental tracer in hydrology. Radon-in-water concentrations can be measured in the field by stripping radon from a water sample into a gas volume and measuring the respective radon-in-gas concentration using a portable radon-in-gas monitor. Alternatively, radon is firstly extracted from the water body by diffusion through a radon exchanger such as polypropylene (PP) tubing and then is measured using a radon-in-gas monitor, connected in closed-loop to the PP membrane. The paper discusses results of field experiments in which the Radon-in-Water Probe (Durridge co.), a 2.2 m long PP tubing, connected to a RAD7 monitor (method A), is used to determine dissolved radon concentration in four water bodies characterised by different water flow velocity and radon concentration. The efficiency of this method is validated by comparison with two established methods, gamma-ray spectrometer + charcoal canister (method B) and RAD7 monitor + Big Bottle RAD H20 accessory (method C). Relative efficiency of method A is directly proportional to water flow velocity, ranging from about 0.50 ± 0.05 at 0.01 m/s to about 0.92 ± 0.08 at 0.57 m/s. A minimum of 2–3 h are needed to collect enough records to asymptotically fit radon-in-gas data and obtain equilibrium radon concentration, which is then converted into radon-in water concentration, considering the temperature-dependency of radon partition coefficient between water and air. Equilibrium condition is reached after about 6–8 h. No correlation was found between relative efficiency and radon concentration. An equation is proposed to correct radon data as a function of water flow velocity, even for poorly moving water bodies. The DURRIDGE Water Probe is useful to monitor radon-in-water levels, without the potential risk of radon loss during water sampling and sample handling. However, it must be pointed out that duplicate or triplicate sampling using other methods similarly permit to evaluate whether radon loss is an issue.

Estimating the quantity of CO2 diffusively emitted from the Earth’s surface has important implications for volcanic surveillance and global atmospheric CO2 budgets. However, the identification and quantification of non-hydrothermal contributions to CO2 release can be ambiguous. Here, we describe a multi-parametric approach employed at the Nisyros caldera, Aegean Arc, Greece, to assess the relative influence of deep and shallow gases released from the soil. In April 2019, we measured diffuse soil surface CO2 fluxes, together with their carbon isotope compositions, and at a depth of 80 cm, the CO2 concentration, soil temperature, and the activities of radon and thoron. The contributions of deep CO2 and biogenic CO2 fluxes were distinguished on the basis of their carbon isotope compositions. A Principal Component Analysis (PCA), performed on the measured parameters, effectively discriminates between a deep- and a shallow degassing component. The total CO2 output estimated from a relatively small testing area was two times higher with respect to that observed in a previous survey (October 2018). The difference is ascribed to variation in the soil biogenic CO2 production, that was high in April 2019 (a wet period) and low or absent in October 2018 (a dry period). Accounting for seasonal biogenic activity is therefore critical in monitoring and quantifying CO2 emissions in volcanic areas, because they can partially- or completely overwhelm the volcanic-hydrothermal signal., Scientific Reports, 10 (1), ISSN:2045-2322

Indoor radon is the second cause of lung cancer. Mitigation strategies are based on (i) building protection with radon barrier materials, (ii) increasing home ventilation or (iii) room pressurization. A scale model room created with a porous ignimbrite rich in radon precursors was used as an analogue to test the indoor radon reduction ability of various radon barrier materials in a real room. The properties of these materials were tested with and without room pressurization by introducing outdoor air at different flow rates. The best materials reduced indoor radon up to 80% and, when the highest pressurization was applied, to 93%.

Estimating the quantity of CO2 diffusively emitted from the Earth’s surface has important implications for volcanic surveillance and global atmospheric CO2 budgets. However, the identification and quantification of non-hydrothermal contributions to CO2 release can be ambiguous. Here, we describe a multi-parametric approach employed at the Nisyros caldera, Aegean Arc, Greece, to assess the relative influence of deep and shallow gases released from the soil. In April 2019, we measured diffuse soil surface CO2 fluxes, together with their carbon isotope compositions, and at a depth of 80 cm, the CO2 concentration, soil temperature, and the activities of radon and thoron. The contributions of deep CO2 and biogenic CO2 fluxes were distinguished on the basis of their carbon isotope compositions. A Principal Component Analysis (PCA), performed on the measured parameters, effectively discriminates between a deep- and a shallow degassing component. The total CO2 output estimated from a relatively small testing area was two times higher with respect to that observed in a previous survey (October 2018). The difference is ascribed to variation in the soil biogenic CO2 production, that was high in April 2019 (a wet period) and low or absent in October 2018 (a dry period). Accounting for seasonal biogenic activity is therefore critical in monitoring and quantifying CO2 emissions in volcanic areas, because they can partially- or completely overwhelm the volcanic-hydrothermal signal.

Thermal gradients due to magma dynamics in active volcanic areas may affect the emanating power of the substrate and the background level of radon signal. This is particularly effective in subvolcanic substrates where intense hydrothermal alteration and/or weathering processes generally form hydrous minerals, such as zeolites able to store and release great amounts of H2O (up to ~25 wt.%) at relative low temperatures. To better understand the role played by thermally induced devolatilization reactions on the radon signal, a new experimental setup has been developed for measuring in real time the radon emission from a zeolitized volcanic tuff. Progressive dehydration phenomena with increasing temperature produce radon emissions two orders of magnitude higher than those measured during rock deformation, microfracturing and failure. In this framework, mineral devolatilization reactions can contribute significantly to produce radon emissions spatially heterogeneous and non-stationary in time, resulting in a transient state dictated by temperature gradients and the carrier effects of subsurface gases. Results from these experiments can be extrapolated to the temporal and spatial scales of magmatic processes, where the ascent of small magma batches from depth causes volatile release due to dehydration phenomena that increase the radon signal from the degassing host rock material.

A soil radon-deficit survey was carried out in a site polluted with kerosene (Rome, Italy) in winter 2016 to assess the contamination due to the NAPL residual component in the vadose zone and to investigate the role of the vapor plume. Radon is indeed more soluble in the residual NAPL than in air or water, but laboratory experiments demonstrated that it is also preferentially partitioned in the NAPL vapors that transport it and may influence soil radon distribution patterns. Specific experimental configurations were designed and applied to a 31-station grid to test this hypothesis; two RAD7 radon monitors were placed in-series and connected to the top of a hollow probe driven up to 80-cm depth; the first instrument was directly attached to the probe and received humid soil gas, which was counted and then conveyed to the second monitor through a desiccant (drierite) cylinder capturing moisture and eventually the NAPL volatile component plus the radon dissolved in vapors. The values from the two instruments were cross-calibrated through specifically designed laboratory experiments and compared. The results are in agreement within the error range, so the presence of significant NAPL vapors, eventually absorbed by drierite, was ruled out. This is in agreement with low concentrations of soil VOCs. Accordingly, the radon-deficit is ascribed to the residual NAPL in the soil pores, as shown very well also by the obtained maps. Preferential areas of radon-deficit were recognised, as in previous surveys. An average estimate of 21 L (17 Kg) of residual NAPL per cubic meter of terrain is provided on the basis of original calculations, developed from published equations. A comparison with direct determination of total hydrocarbon concentration (23 kg per cubic meter of terrain) is provided.

An integration of laboratory radon and thoron exhalation data with gamma radiation mapping is applied to assess the geogenic radon and the exposure of people to natural radiation in a highly-urbanized city (Roma, Italy). The study area is a protected territory where ignimbrites from Colli Albani volcano and alluvial sediments largely crop out. A map of total gamma radiation, a gamma transect across Caffarella valley and 9 vertical gamma profiles have been carried out, showing that the main control of gamma levels is, of course, the lithological nature, without neglecting the simultaneous effect of other parameters such as slope morphology, erosion/weathering processes, occurrence of sinkholes or underground tunnels. The surveys allowed to distinguish the medians of ignimbrites (from 816 ± 16 cps to 936 ± 19 cps) from that of alluvial materials (611 ± 14) cps), but showed also that alluvial sediments with anomalously high radioactivity (769 ± 14 cps) can be locally recognized, providing valuable information on the interaction between sedimentation and erosion in fluvial valleys. Total gamma activity was converted into absorbed gamma dose rate ranging from 0.33 to 0.38 μSv/hr. Outdoor Annual Effective Dose Equivalents were also estimated between 0.58 and 0.67 mSv y−1. Laboratory radon and thoron exhalation rates of collected material are positively correlated with gamma radiation. Volcanic and alluvial sediments are well-discriminated. The correlation between the two variables is evident, but not robust because of the variable concentration of 40 K, which is not contributing to radon and thoron exhalation rates. Anomalous data of soil samples located at the foot of a slope can be interpreted as due to reworking and accumulation processes. Similar gamma radiation data documents analogous concentration of radon and thoron parent-nuclides, but coexisting different radon and thoron exhalation rates provides an additional information on different grain size distributions which can be considered as a proxy for soil gas permeability. The integration of gamma mapping and radon and thoron exhalation measurements is a very useful tool to assess people exposure to natural radiation, in terms of dose rates and potential indoor radon. Gamma mapping, which provides data on the radiation source (the bedrock) is fast and not expensive. It allows to obtain very detailed pictures of a study area, but it needs to be combined with laboratory determination of radon and thoron release in order to definitely and correctly interpret variations of gamma signal. Furthermore, laboratory determination of soil radon exhalation gives information on the release of radon and is a good proxy for soil gas permeability. It has the great advantage over in-situ measurements of gas flow not to be influenced by seasonal pedoclimatic parameters and is affected by lower analytical uncertainties. These data are thus reproducible and precise and can be used to estimate potential radon hazard, which is the main source of exposure and thus the most important parameter for human protection from environmental radioactivity.

RAD7 and BigBottle system has been developed, using large glass bottles, but these are fragile and awkward to carry around. In searching for a better solution, we tested polyethylene terephthalate (PET) bottles for water samples storage to estimate radon loss over time. Two sets of experiments with 0.355 and 1.75 L bottles demonstrated that PET is a suitable material for storage. If correction for 226Ra content in water is applied, we can also calculate the rate of radon loss (0.03 ± 0.08 % day−1).

Radon concentration in soil gas can be employed to trace the presence of gasolinecontamination because it is very soluble in hydrocarbons. Radon available in the soil pores accumulates in the contaminated volume, producing a local deficit at shallow depth that can be easily mapped. The suitability of this method is here checked by field simulation of a gasoline spill and by laboratory experiments where known amounts of a volcanic tuff contaminated with increasing gasoline show proportional drops of radon exhalation rates.

Geochemical and geophysical surveys employing radon deficit, resistivity, and induced polarization (IP) measurements were undertaken on soil contaminated with non-aqueous phase liquids (NAPLs) in two different sites in India and in Italy. Radon deficit, validated through the comparison with average soil radon in reference unpolluted areas, shows the extension of contamination in the upper part of the unsaturated aquifers. In site 1 (Italy), the spill is not recent. A residual film of kerosene covers soil grains, inhibiting their chargeability and reducing electrical resistivity difference with background unpolluted areas. No correlation between the two parameters is observed. Soil volatile organic compounds (VOCs) concentration is not linked with radon deficit, supporting the old age of the spillage. NAPL pollution in sites 2a and 2b (India) is more recent and probably still active, as demonstrated by higher values of electrical resistivity. A good correlation with IP values suggests that NAPL is still distributed as droplets or as a continuous phase in the pores, strengthening the scenario of a fresh spill or leakage. Residual fraction of gasoline in the pore space of sites 2a and 2b is respectively 1.5 and 11.8 kg per cubic meter of terrain. This estimation is referred to the shallower portion of the unsaturated aquifer. Electrical resistivity is still very high indicating that the gasoline has not been strongly degraded yet. Temperature and soil water content influence differently radon deficit in the three areas, reducing soil radon concentration and partly masking the deficit in sites 2a and 2b.

Soil radon is employed to trace residual NAPL (Non-Aqueous Phase Liquid) contamination because it is very soluble in these substances and is strongly depleted over polluted volumes of the subsoil. The solubility of radon into NAPL vapors, generally poorly considered, is investigated here, either as growth of radon exhalation from a material contaminated with increasing volumes of kerosene, or as radon partition between liquid kerosene, water and total air, considered ad the sum of kerosene vapors plus air.

Polyethylene terephthalate (PET) and polylactic acid (PLA) bottles were tested to evaluate radon loss from water during 15 days of storage. PET bottles (lower surface/volume-ratio vials) lost 0.4–7.1% of initial radon, whereas PLA bottles lost 3.7% of it. PET bottles with volume of 0.5 L, lower surface/weight ratio, and hence higher thickness display proportionally reduced radon loss. Corrections for dissolved radium are needed during analyses. Formulas for calculating degassing efficiency and water interference on electrostatic collections are developed.