222Rn Flux Research Articles

Measurement of indoor radioactivity and dose derived from 222Rn, 220Rn and EECs by using SSNTD based technique.

Alpha flux radiated from 222Rn, 220Rn and progeny is the primary contributor of natural radioactivity to the inhabitants in the ambient atmosphere. The annual indoor 222Rn and 220Rn concentrations were found to be 85±43 and 84±36Bq m-3, respectively. The estimated annual indoor 222Rn and 220Rn concentration is below to reference value of 100Bq m-3 suggested by WHO. The calculated annual inhalation dose due to exposure to the alpha flux of 222Rn, 220Rn and their progeny is well below the recommended reference level given by UNSCEAR and ICRP. The data were further checked for normalisation and found that 222Rn and Effective Equilibrium Radon Concentration (EERC) data are not normally distributed.

Geochemical characterization and implications of soil gas and geothermal fluids in the fault zone of Xiongan new area

This study investigates the geochemical characteristics and implications of soil gas and geothermal fluids in the fault zone of Xiongan New Area (XNA). Spatial distribution analysis reveals high soil gas concentrations along the fault zone, prompting the establishment of measurement lines along specific fault segments, such as Niudong fault, with a vertical burial trend. The measured average Rn flux ranges from 71.44 to 335.35 mBq m−2s−1, while CO2 flux ranges from 25.96 to 78.23 g m−2d−1. Furthermore, the average Rn and CO2 concentration intensities range from 0.91 to 2.30 and 1.13 to 2.61, respectively, indicating significant degassing in the fault zone.Geothermal well samples are collected from the deep reservoir in XNA, displaying a predominance of Cl–Na composition. Analysis of the Na–K–Mg equilibrium diagram suggests that the chemical characteristics of deep geothermal water are a result of interactions with rocks and mixing with shallow cold water in XNA. Isotopic analysis indicates the atmospheric precipitation origin of the deep geothermal water with extensive lateral recharge from underground runoff, emphasizing strong water-rock interactions. Comparison with other tectonic units in the region reveals that the Niudong Fault Zone serves as a regional geothermal control structure, facilitating deep fluid convection.In the eastern part of XNA, the geochemical analysis reveals concentrated degassing and a relatively high proportion of mantle-derived sources near the Niudong Fault Zone. This observation suggests the fault zone serves as a primary conduit for deep gases and geothermal fluids. The findings of this research provide valuable scientific references for future urban planning, energy utilization, and geologic hazard monitoring in XNA. Continued monitoring efforts are crucial for understanding the nature of fault activity and resource distribution in the region.

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

Abstract. 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 ∼ 1800 mBq m−2 s−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.

Groundwater as a source of phosphorus and silicate in an estuarine zone: results from continuous monitoring of nutrients and 222Rn

The concentrations of 222Rn and dissolved inorganic nutrients in river water at a fixed station of the Nakdong River estuary which has an artificial barrage were continuously measured from October 2014 to May 2015. Monthly benthic 222Rn flux from the river bottom was estimated using a simple mass balance model, taking into account 222Rn sources and sinks. The estimated benthic 222Rn flux shows a significant correlation with groundwater level, suggesting that groundwater level can be used as a representative of the groundwater input. Based on correlation analyses, the concentration of dissolved inorganic nitrogen (DIN) was found to be dependent primarily on river water input. In contrast, the concentrations of dissolved inorganic phosphorus (DIP) and dissolved inorganic silicate (DSi) were predominantly controlled by groundwater input. Our results suggest that groundwater input may be an important source of DIP, especially under P-limited condition, which can affect marine primary production and ecological problems such as eutrophication and algal blooms in the coastal zones.

Exploration of Deep Ocean Ferromanganese Nodule Fields Using Radon as a Tracer

AbstractFerromanganese nodules (Fe‐Mn nodules) are considered as potential sources of in‐demand metals (such as manganese, cobalt, nickel, copper, and rare‐earth elements) that are used in high‐technology industries. The resource potential of Mn nodules in the world ocean remains uncertain due to technological and financial challenges. Here we propose an effective tracer: the natural radioactive radon isotope (222Rn) to assess the abundance of Fe‐Mn nodules on the sea floor. Significant linear relationships were observed between benthic excess 222Rn fluxes and concentrations with Fe‐Mn nodule occurrence and coverage on the global seafloor. Benthic excess 222Rn flux >107 dpm/m2/yr or bottom water 222Rn concentrations >2,000 dpm/m3 indicate the possibility of Fe‐Mn nodules occurrence at >80% and seabed coverage of >25%. Our results indicate radon, relatively easy to measure, could serve as a novel and efficient tool for targeting Fe‐Mn nodule resources in the global abyssal ocean.

Environmental impacts of 222Rn, Hg and CO2 emissions from the fault zones in the western margin of the Ordos block, China.

Investigating the emissions of soil gas including radon, mercury and carbon dioxide (222Rn, Hg and CO2) from the solid earth to the atmosphere through active fault zones is of great significance for accession of atmospheric environment. In this study, the concentrations and fluxes of 222Rn, Hg and CO2 were measured at the main active fault zones at the western margin of the Ordos block, China. The concentrations of 222Rn, Hg and CO2 were in the range of 0-60.1kBq m-3, 3-81ng m-3 and 0.04-9.23%, respectively, while the fluxes of 222Rn, Hg and CO2 are in the range of 1.99-306.99mBq m-2s-1, 0-15.12ng m-2h-1 and 0-37.91g m-2d-1, respectively. Most of the major fault zones at the study area are CO2 risk-free regions (CO2 concentration in soil gas < 5%). However, the extend of 222Rn pollution at the fault zones of F1, F4, F5 and F9 (the fault number) and that of Hg pollution at the fault zones of F2, F4, F5 and F7 were higher than the pollution level of 1. The annual emission of Hg and CO2 from the western margin of the Ordos block was estimated to be 2.03kg and 0.70 Mt, respectively. Comprehensive analyses indicated that the higher emission rates of soil gases from the active fault zones were related to the seismic activities. The results suggest that the earthquake activity is a dominant factor enhancing the emission of 222Rn, Hg and CO2 from the solid earth through active fault zones and, furthermore, resulting great impact on the atmospheric environment.

Evaluation of the Terrestrial 222Rn Flux from 210Pb Deposition Measurements

The study of the 222Rn terrestrial flux (Bq/(m2·s) or Bq/(m2·h)) is a complex issue involving both radiation-protection and environmental aspects. While the radiation-protection aspects are quite obvious—it has been well known for several decades that soil is the major source of indoor radon—environmental issues such as the correlation with conventional pollutants (PM2.5, PM10, NOX, etc.) and the use of radon for the esmation of the natural component of GHG (CO2) emissions are relatively less discussed in spite of their growing relevance. In this work we present a method for the estimation of the average value of 222Rn flux from HPGe γ-spectrometry 210Pb measurements performed on wet and dry deposition samples gathered monthly in the period 2006–2020. The results obtained with this technique give an average radon flux in the period Φ = 57 ± 27 Bq/(m2·h), the value of which is comparable with those coming from other methods and direct radon flux measurements as well. The method can thus be used to obtain a worldwide map of the radon flux.

Limitations of the radon tracer method (RTM) to estimate regional greenhouse gas (GHG) emissions – a case study for methane in Heidelberg

Abstract. Correlations of nighttime atmospheric methane (CH4) and 222radon (222Rn) observations in Heidelberg, Germany, were evaluated with the radon tracer method (RTM) to estimate the trend of annual nocturnal CH4 emissions from 1996–2020 in the footprint of the station. After an initial 30 % decrease in emissions from 1996 to 2004, there was no further systematic trend but small inter-annual variations were observed thereafter. This is in accordance with the trend of total emissions until 2010 reported by the EDGARv6.0 inventory for the surroundings of Heidelberg and provides a fully independent top-down verification of the bottom-up inventory changes. We show that the reliability of total nocturnal CH4 emission estimates with the RTM critically depends on the accuracy and representativeness of the 222Rn exhalation rates estimated from soils in the footprint of the site. Simply using 222Rn fluxes as estimated by Karstens et al. (2015) could lead to biases in the estimated greenhouse gas (GHG) fluxes as large as a factor of 2. RTM-based GHG flux estimates also depend on the parameters chosen for the nighttime correlations of CH4 and 222Rn, such as the nighttime period for regressions and the R2 cut-off value for the goodness of the fit. Quantitative comparison of total RTM-based top-down flux estimates with bottom-up emission inventories requires representative high-resolution footprint modelling, particularly in polluted areas where CH4 emissions show large heterogeneity. Even then, RTM-based estimates are likely biased low if point sources play a significant role in the station footprint as their emissions may not be fully captured by the RTM method, for example, if stack emissions are injected above the top of the nocturnal inversion layer or if point-source emissions from the surface are not well mixed into the footprint of the measurement site. Long-term representative 222Rn flux observations in the footprint of a station are indispensable in order to apply the RTM method for reliable quantitative flux estimations of GHG emissions from atmospheric observations.

Radon flux estimates, from both gamma radiation and geochemical data, to determine sources, migration pathways, and related health risk: The Campania region (Italy) case study

An empirical method was applied to estimate the 222Rn fluxes distribution across the Campania region (Italy) by using both gamma-rays and U, Th, K concentrations in soils. As a first step, K, Th and U soil concentrations and 4 K, 238U and 232Th activity have been converted into their own specific activity to calculate the Terrestrial Gamma Dose Rate (TGDR). This latter has been then used to determine the 222Rn fluxes across the region. Regardless of the radiometric or geochemical origin, 222Rn fluxes reached, as expected, their maximum values in correspondence with the volcanic centres of Campania (Mt. Somma-Vesuvius, Phlegrean Fields, Mt. Roccamonfina). However, comparing the results obtained from the two different datasets, it was also possible to infer the existence of contributions to surficial 222Rn fluxes proceeding from both some underlying geological bodies and active seismogenic sources.In line with some national regulations, the 222Rn flux esteemed from gamma radiations was also used to assess the possible regional distribution of risk deriving from the indoor environmental exposure to 222Rn; results were compared with standardized incidence rates (SIRs) of lung cancer for an area on the south-western sector of Mt. Somma-Vesuvius showing a potential spatial relationship among flux data and SIRs.

Radon fluxes at four uranium mill tailings disposal sites after about 20 years of service

To evaluate the properties of earthen covers over uranium mill tailings disposal cells after about 20 years of service, we measured Rn-222 fluxes and radon barrier properties at the Falls City, TX, Bluewater, NM, Shirley Basin South, WY, and Lakeview, OR disposal sites in western USA. A total of 115 in-service Rn fluxes were obtained at 26 test pit locations from the top surface of the exposed Rn barrier (i.e., after protective layers were removed by excavation) and 24 measurements were obtained from the surface of the underlying waste after excavation through the Rn barrier layer. Rn-222 concentrations were determined in accumulation chambers using a continuously monitoring electronic radon monitor (ERM) equipped with a solid-state alpha particle detector. Effects of surface features on Rn flux including vegetation, seasonal ponding, and animal burrowing were quantified. Comparison of measured fluxes with values that were measured shortly after the Rn barriers were completed (as-built) show that most measurements fell within the range of the as-built fluxes, generally at very low fluxes. At two sites fluxes were measured that were greater than the highest as-built flux. High fluxes are typically caused by a combination of enhanced moisture removal and preferential pathways for Rn transport, often caused by deep-rooted plants. Such localized features result in a spatially heterogeneous distribution of fluxes that can vary substantially over only a meter or two.

Integrated approach into the characterization of the fracture network of a geothermal reservoir

As an inert gas 222Rn can be employed as a natural radiotracer for the characterization of hydrogeological properties of geothermal systems. In fractured reservoirs, diffusion through non-conductive rock matrices allows recoiled 222Rn to enter larger, hydraulically conductive fractures. In this study, we examine the possibility of assessing fracture dimensions from 222Rn activity in geothermal brines. 222Rn activity in the geothermal fluid is mainly controlled by the 222Rn flux from fracture surfaces and the fracture geometry (aperture, length, degree of connectivity, etc.).Estimates of site-specific fracture length and width were derived by a 222Rn mass balance approach for the geothermal reservoir at Bruchsal (Germany). Integral hydraulic parameters of the Bruchsal reservoir were obtained from classical hydraulic tests. The results show a 222Rn diffusion flux of 4.2 × 10−3 atoms s−1 cm−2 resulting in an equivalent fracture width of 10 mm. The equivalent fracture length varies between a few hundred meters as a function of the flow velocity where about 250 m correspond to a mean flow velocity of 2.0 × 10−6 m s−1.Since the specific surface area of the fracture is inversely proportional to the fracture width, the fracture surface area depends on (1) the type of fracture system, i.e. whether the estimated equivalent fracture width represents a single large fracture or a fracture network of a large number of small aperture fractures and (2) the extent of the variance from the averaged equivalent fracture width. The joint inversion of the radon diffusion model with the pumping test results and a heat transport model is expected to considerably reduce interpretative hydraulic parameter ambiguity.

Radon R222 flux associations with standardized mortality rates of lung cancer in men and women in Spain

Background/Aim: López-Abente et al. (2017) found a linear significant relationship between residential concentration of radon and mortality for lung, stomach and brain cancer in women in Galicia (Spain). Karsten et al. (2015) presented a method applied for developing a high-resolution 222Rn flux map for Europe, based on a parameterization of gas production depending on soil properties, uranium content, moisture and transport in the soil. Aim of our exploratory study was to check association between 222Rn flux values and standartised mortality rates (SMR) of lung cancer in men and women in 48 regions of Spain. Methods: 222Rn flux data were calculated as per Karsten et al. (2015) methods. The epidemiological data on lung cancer mortality in men and women by region were taken from free available source (Carlos III Institute). Paired t-differences were used to observe the statistically significant differences in seasonal variations of 222Rn flux. Regression analysis was performed to observe the relationship of epidemiological data with 222Rn flux. Results: Statistically significant differences were found between seasonal variations: winter / spring vs. summer / autumn (but not between winter and spring or summer and autumn) in 222Rn flux parameters. The higher values were related to summer and autumn period (by a factor 1.4 in average). Regression analyses reveled statistically significant associations between SMR of lung cancer in men and Rn flux in summer/autumn: R2=0.15, p=0.007), winter/spring: R2=0.10, p=0.002). No any significant relationship was found for women in this study. Conclusions: In spite of study limitations (not availability of epidemiological data for the periods posteriors to measurements to perform time series analyses with associations related on time lags); 222Rn flux data could be used as proxies comparable to 222Rn concentrations. Further comparative studies with similar data on indoor concentration vs. flux are to be performed and analyses with corresponding epidemiological data.

A seasonal 222Rn mass-balance of Lake Burullus, Egypt: Indications for higher pore water exchange rates during the dry season

Radon mass balances in lakes can be used to trace transport processes along the sediment-water interface, such as groundwater discharge or pore water exchange. Understanding these transport processes is important, as they can affect the lake water budget, or biogeochemical cycles in lakes due to nutrient inputs. We present here a seasonal 222Rn mass balance of Lake Burullus (Northern Egypt), the second largest lake of Egypt. The Lake receives 222Rn from drainage water and the decay of 226Ra, and loses 222Rn via decay of 222Rn, atmospheric evasion and water discharge into the Mediterranean Sea. However, the mass balance reveals a significant surplus of 222Rn, which cannot be explained by the previously mentioned processes. The 222Rn surplus is especially high during the dry season, and might be explained by groundwater discharge and pore water exchange which transports 222Rn into the lake. Higher 222Rn fluxes into the lake during dry season might be explained by higher bioirrigation rates due to warmer temperatures, or higher groundwater discharge rates due to a higher hydraulic head on land caused by excessive irrigation in adjacent fields. Groundwater discharge and pore water exchange should be investigated in further detail in order to understand if they have effects on water budgets and biogeochemical cycles of Lake Burullus.

Multi-channel singular spectrum analysis of underground Rn concentration at Asahi station, Boso Peninsula, Japan: Preliminary report on relation between the variation of underground Rn flux and the local seismic activity

Multi-channel singular spectrum analysis of underground Rn concentration at Asahi station, Boso Peninsula, Japan: Preliminary report on relation between the variation of underground Rn flux and the local seismic activity

Exploration of geothermal activity using time series analysis of subsurface gases data from Bakreswar hot springs area, eastern India

Geothermal power seems to be a potential source of green energy in India. But these renewable energy resources are still ignored in India even after having a lot of potential sources as seen in more than 300 hot springs scattered throughout different geothermal areas of the country. Many of them could be utilized for power generation using the earth’s internal heat. More hours are needed to explore these geothermal areas using geochemical, geophysical techniques, and statistical analysis to qualitatively estimate power harnessing capabilities and sustainability of the areas for generation of geothermal power. In the present paper, attention has been focused to investigate Bakreswar geothermal field of India by continuous (24*7) and online monitoring of terrestrial gases such as He and radioactive gases (222Rn) in hot spring emanations of the geothermal area for more than 5 years along with discrete measurement of some other geochemical and geophysical parameters. The discrete measures imply that the seven hot spring vents at the study area are linked to the aquifer through different ways covering non-uniform rock assemblies and ascertain the presence of high amount of radioactive minerals at the underneath terrains. Stable activities with a high-out flux of 222Rn and He for a prolonged time period is expected within the reservoir present at the study area as consequence of analysis of the temporal variations and statistical measures of the continuous data sets. Seasonal variation of time series data also recommends that the high amount of radioactive sources present at the crust of the reservoir is able to produce enough quantity of heat irrespective of meteorological effects. The investigation on the power spectra interferes that the geothermal system is still in quite active phase on the influence of tectonic activities. Therefore, the geothermal reservoir present at the Bakreswar geothermal area may be utilized as a constant and continuous heat source for a long time period to run a geothermal power plant.

Deciphering and Predicting Microscale Controls on Radon Production in Soils, Sediments and Rock

Soils, sediments and rock are natural sources of radon (Rn), which poses an ongoing threat to human health. Numerous studies have measured Rn release from bulk earth materials, yet few have examined microscale controls on Rn flux from solids (emanation), which is required to develop a process-based framework for predicting the rate and extent of production. Here, we use a novel closed loop flow-through system to measure Rn emanation from two crushed rock types with disparate physical and geochemical characteristics, shale and granitic pegmatite. We relate the extent of Rn emanation from each sample to microscale characteristics examined using conventional and synchrotron-based techniques, such as Rn parent radionuclide distribution within mineral grains, porosity, and surface area. Our results illustrate that the extent of Rn release from solids is primarily dependent on the position of parent radionuclides within host mineral grains relative to the “recoil range”—the maximum distance a daughter product (such as Rn) may traverse within a solid and into an adjacent pore owing to alpha-recoil—and is less dependent on the bulk parent radionuclide (e.g., radium) activity. We also present a simple model for predicting the emanation coefficient for pure solids based on mineralogical and physical parameters, which is an initial step toward developing a framework for predicting Rn efflux (exhalation) from soils.

Study of the daily and seasonal atmospheric CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; mixing ratio variability in a rural Spanish region using &amp;lt;sup&amp;gt;222&amp;lt;/sup&amp;gt;Rn tracer

Abstract. The ClimaDat station at Gredos (GIC3) has been continuously measuring atmospheric (dry air) mixing ratios of carbon dioxide (CO2) and methane (CH4), as well as meteorological parameters, since November 2012. In this study we investigate the atmospheric variability of CH4 mixing ratios between 2013 and 2015 at GIC3 with the help of co-located observations of 222Rn concentrations, modelled 222Rn fluxes and modelled planetary boundary layer heights (PBLHs). Both daily and seasonal changes in atmospheric CH4 can be better understood with the help of atmospheric concentrations of 222Rn (and the corresponding fluxes). On a daily timescale, the variation in the PBLH is the main driver for 222Rn and CH4 variability while, on monthly timescales, their atmospheric variability seems to depend on emission changes. To understand (changing) CH4 emissions, nocturnal fluxes of CH4 were estimated using two methods: the radon tracer method (RTM) and a method based on the EDGARv4.2 bottom-up emission inventory, both using FLEXPARTv9.0.2 footprints. The mean value of RTM-based methane fluxes (FR_CH4) is 0.11 mg CH4 m−2 h−1 with a standard deviation of 0.09 or 0.29 mg CH4 m−2 h−1 with a standard deviation of 0.23 mg CH4 m−2 h−1 when using a rescaled 222Rn map (FR_CH4_rescale). For our observational period, the mean value of methane fluxes based on the bottom-up inventory (FE_CH4) is 0.33 mg CH4 m−2 h−1 with a standard deviation of 0.08 mg CH4 m−2 h−1. Monthly CH4 fluxes based on RTM (both FR_CH4 and FR_CH4_rescale) show a seasonality which is not observed for monthly FE_CH4 fluxes. During January–May, RTM-based CH4 fluxes present mean values 25 % lower than during June–December. This seasonal increase in methane fluxes calculated by RTM for the GIC3 area appears to coincide with the arrival of transhumant livestock at GIC3 in the second half of the year.

SEARCH AND MAPPING OF THE OLD BURIED TAILINGS WITH RADIOACTIVE WASTES AT THE URBAN TERRITORY.

The article presents results of investigation on search and mapping of the old buried tailings with radioactive wastes on the territory of Kamianske City. For solving the problem used complex of methods. These methods are as follows: soil-gas 222Rn measurement and measurement of 222Rn flux density from the ground surface, gamma-radiation survey, prospecting drilling, gamma-ray logging and laboratory analysis of radionuclides. The leading method in this complex was the method of soil-gas 222Rn measurement. Using this method location of the tailings has been precisely defined. The tailings boundaries have been contoured in the plan. Other methods permitted to define such parameters as thickness of the wastes, their volume (~330 000 m3), radionuclide and chemical composition. It was found that radioactive residues occur at a depth from 2 to 11 m and contain in its composition 226Ra, 210Pb and 210Po in the range from 8370 to 37 270 Bq kg-1.

Submarine groundwater discharge driven nitrogen fluxes to Long Island Sound, NY: Terrestrial vs. marine sources

Bottom-waters in Smithtown Bay (Long Island Sound, NY) are subject to hypoxic conditions every summer despite limited nutrient inputs from waste-water and riverine sources, while modeling estimates of groundwater inputs are thought to be insignificant. Terrestrial and marine fluxes of submarine groundwater discharge (SGD) were quantified to Smithtown Bay using mass balances of 222Rn, 224Ra, 226Ra and 228Ra during the spring and summer of 2014/2015, in order to track this seasonal transition period. Intertidal pore waters from a coastal bluff (terrestrial SGD) and from a barrier beach (marine SGD) displayed substantial differences in N concentrations and sources, traced using a multi-isotope approach (222Rn, Ra, δ15N-NO3−, δ18O-NO3−). NO3− in terrestrial SGD did not display any seasonality and was derived from residential septic systems and fertilizer. Marine SGD N concentrations varied month-to-month because of mixing between oxic seawater and hypoxic saline pore waters; N concentrations were greatest during the summer, when NO3− was derived from the remineralization of organic matter. Short-lived 222Rn and 224Ra SGD fluxes were used to determine remineralized N loads along tidal recirculation flow paths, while long-lived 228Ra was used to trace inputs of anthropogenic N in terrestrial SGD. 228Ra-derived terrestrial N load estimates were between 20 and 55% lower than 224Ra-derived estimates (excluding spring 2014); 228Ra may be a more appropriate tracer of terrestrial SGD N loads. Terrestrial SGD NO3− (derived from 228Ra) to Smithtown Bay varied from (1.40–12.8)∗106 molN y−1, with comparable marine SGD NO3− fluxes of (1.70–6.79)∗106 molN y−1 derived from 222Rn and 224Ra. Remineralized N loads were greater during the summer compared with spring, and these may be an important driver toward the onset of seasonal hypoxic conditions in Smithtown Bay and western Long Island Sound. Seawater recirculation through the coastal aquifer can rival the N load from terrestrial SGD from a heavily polluted aquifer.

What happens to in‐soil Radon activity during a long‐lasting eruption? Insights from Etna by multidisciplinary data analysis

AbstractWe analyze short‐ to long‐term changes (from days to months) in Radon (Rn) activity measured nearby (&lt;2 km) the eruptive fractures that fed a lava effusion at Mt. Etna, Italy, between 13 May 2008 and 6 July 2009. The N120‐140°E eruptive fractures opened between 3050 and 2620 m above sea level before a dike‐forming intrusion fed the ∼14 month‐long lava emission. Our high‐rate data streams include: Rn, ambient parameters (barometric pressure and soil temperature), and seismic data (earthquakes and volcanic tremor) recorded from January 2008 to July 2009. The analysis highlights repeated episodes of rock‐fracturing related to seismic swarms, and vigorous gas pulses and peak values in Rn emissions (maximum ∼4.1×105 Bq/m3 on 16 November 2008), which we interpreted in a conceptual model as the response to inputs from the magmatic system during the eruption. This multidisciplinary study: (i) provides evidence of a close relationship between Rn emission at a fumarole near the summit active craters and local earthquakes, and (ii) enables exploring the important role of the volcanic source on the temporal development of the Rn flux, which may account for the much higher (≫94 m/d) ascent speed of the Rn carrier (vapor) than diffusion. The close location of Rn probes to the active conduits, along with the application of our multidisciplinary approach, may shed new light on the internal dynamics of other active volcanoes worldwide.