Controls on groundwater Rn‐222 concentrations in fractured rock

Abstract

Approximately 150 Rn‐222 analyses from groundwater wells in fractured lithologies of eastern Connecticut were made to evaluate the intralithologic and interlithologic variability. Although there is a control of Rn‐222 activity in porefluids by uranium (radium) concentration in the host rock, the variability of local Rn‐222 is dominated by site‐specific rock properties. These are (with their contribution to the variability); (i) the specific fracture surface area (>103x), which is functionally dependent on crack width, (ii) the emission efficiency (>102x) which is functionally related to the fracture spacing and (iii) the enrichment of uranium (Ra‐226) on the fracture surface (>102x). Thus, the activity of radon in fractured lithologies is difficult to predict and the measurement of radon activity does not uniquely constrain the geometry of the rock or the chemical inhomogeneity.

Uranium groundwater anomalies and L'Aquila earthquake, 6th April 2009 (Italy)

“…The geodynamic processes induced by earthquakes can modify radon migration patterns in groundwater as a potential indicator of strain. However, to predict the activity of radon in fractured lithologies is difficult and the measurement of radon concentration does not uniquely characterize the rock deformation or the chemical inhomogeneity (Torgersen et al, 1990), as well as its relationship with the transient crustal strain signals from 'aseismic' fault slip near the earthquake's nucleation point (Roeloffs, 1999). Moreover, nontectonic factors related to variations of chemical and physical groundwater parameters may be of importance (Shapiro et al, 1985;Plastino, 2006), requiring proper geological, hydrological and hydrogeological settings (Trique et al, 1999), so only the variations induced by stress-strain processes should be considered in evaluations.…”

Characterising the distribution of near-shore submarine groundwater discharge along a coastline using222Rn and electrical conductivity

“…238 U and 226 Ra concentration; Chouby & Ramola 1997) and hydraulic properties (e.g. porosity, fracture size and hydraulic conductivity; Torgersen et al 1990;Folger et al 1996), which are all known to be variable within the Willunga Basin (Cooper 1979;Watkins & Telfer 1995). The observation of elevated radon activity within regional groundwater suggests that radon is likely to be a useful tracer of SGD in this region.…”

Groundwater, Radon Continuous Monitoring System ( α -scintillation Counting) for Natural Hazard Surveillance

“…At the same time, extensive knowledge that could be applied to earthquake prediction research was accumulated regarding the basic behaviour of radon gas in natural environments (SCHROEDER et al, 1965;SOONAWALA and TELFORD, 1980;HOLUB and BRADY, 1981;KRISTIANSSON and MALMQUIS, 1982;MEGUMI and MAMURO, 1987;TORGERSEN et al, 1990;VARHEGYI et al, 1992;ZHANG et al, 1994).…”