Radon-222 and radium-226 occurrence in water: a review

Abstract

A total of 2143 dissolved radon-222 and radium-226 activity concentrations measured together in water samples was compiled from the literature. To date, the use of such a large database is the first attempt to establish a relationship for the 226Ra–222Rn couple. Over the whole dataset, radon and radium concentrations range over more than nine and six orders of magnitude, respectively. Geometric means yield 9.82±0.73 Bq l−1 for radon and 54.6±2.7 mBq l−1 for radium. Only a few waters are in 226Ra–222Rn radioactive equilibrium, with most of them being far from equilibrium; the geometric mean of the radium concentration in water/radon concentration in water (CRa/CRn) ratio is estimated to be 0.0056±0.0004. Significant differences in radon and radium concentrations are observed between groundwaters and surface waters, on the one hand, and between hot springs and cold springs, on the other. Within water types, typical ranges of radon and radium concentrations can be associated with subgroups of waters. While the radium concentration characterizes the geochemistry of the groundwater–rock interaction, the radon concentration, in most cases, is a signal of non-mobile radium embedded in the encasing rocks. Thus, the 226Ra–222Rn couple can be a useful tool for the characterization of water and for the identification of water source rocks, shedding light on the various water–rock interaction processes taking place in the environment.

Persistent CO2 emissions and hydrothermal unrest following the 2015 earthquake in Nepal

“…Dissolved radon concentration in water was measured in the field by emanometry in air 54 . After air–water equilibrium is reached by manual shaking, radon concentration is inferred from scintillation flask sampling and photomultiplier counting, as described elsewhere 51 .…”

From Separated Laws and Directives to a Unique Regulatory Issue in Europe about the Synergic and Conflicting Use of Subsurface to Produce Low Carbon Energy

“…The main problems inherent in the storage of natural gas (mainly methane, CH4) analyzed to be included in the new "Unified European Directive for the use of subsurface and lands to produce energy/heat/resources" are: capacity (volumes), gas containment as main fair of the citizens also in prairies, where gas storage (CO2, CH4) or geothermal prone areas are located [8][9], mostly if associated to strong earthquakes [10][11][12][13][14][15][16][17] and shallow fluid preservation (safety), geomechanical-induced/triggered seismicity or weak caprock [18][19][20][21] safety and public awareness/public acceptance, by a correct and transparent communication. Induced hazards could be produced as CO2 degassing, radon indoor and enhanced radioactivity in aquifers, being 222 Rn a natural gas released from the rock matrix during stress-related episodes or activated faults over the CO2/CH4/radon natural background [22,23,24] We refer to the papers [2][3] mainly, which are also published to calculate the "energetic density" [MWh/hectars/year], normalized to the minimum GHGs emissions, for all technologies, among which is exploited / stored natural gas, located in the single-out studied regions.…”

222Rn Concentration in Groundwaters Circulating in Granitoid Massifs of Poland

“…The radon isotope 222 Rn, alongside radium isotopes 226 Ra and 228 Ra, is the most important natural component of groundwaters, giving them their radioactive properties [1,2]. 222 Rn is a natural radioactive isotope whose activity concentration in groundwaters varies in a very broad range-from 10 −4 Bq•L −1 to 102,000 Bq•L −1 , hence reaching 9 orders of magnitude [3]. Among the four natural isotopes of radon (with mass numbers 222, 220, 219 and 218), it is only 222 Rn that, owing to its half-life of slightly more than 3.82 days [4][5][6], can be transported with groundwater over distances of dozens or even hundreds of metres, and occasionally even further [2,7].…”

“…Among the four natural isotopes of radon (with mass numbers 222, 220, 219 and 218), it is only 222 Rn that, owing to its half-life of slightly more than 3.82 days [4][5][6], can be transported with groundwater over distances of dozens or even hundreds of metres, and occasionally even further [2,7]. This is the reason for common occurrence of 222 Rn in groundwater environment [3,8,9]. The activity concentration of this gas in groundwater is mainly due to the parent 226 Ra content in the reservoir rock and the emanation coefficient of this rock [2,10,11] enabling the 222 Rn formed in it to be released from the structures of rock minerals and grains containing 226 Ra, and then dissolved in water.…”