Factors Controlling the Spatial and Temporal Variability in Groundwater 222Rn and U Levels

Abstract

Radon (222Rn) and uranium (U) measurements were conducted in 98 groundwater samples in Yongin area, Korea to identify the factors controlling their levels and spatial distributions. Groundwater samples were obtained from the different depth of wells used for drinking water and irrigation. 222Rn and U concentrations were measured using a liquid scintillation counter (LSC) equipped with a pulse-shape analyzer and inductively coupled plasma mass spectrometers (ICP-MS), respectively. Large variations were observed in groundwater concentrations of 222Rn and U, ranging between 0.6 ± 0.1–673.7 ± 8.7 Bq L−1 and 0.02–117.00 µg L−1, respectively. Correlation analysis revealed no significant relationship between field parameters (temperature, electrical conductivity, pH, and dissolved oxygen) and 222Rn or U concentrations. The fact that 222Rn and U concentrations were higher in granite areas than gneiss areas suggests that lithology plays a significant role in controlling the levels and spatial distributions of the two radionuclides. Furthermore, groundwater 222Rn and U behaviors have been affected by the existence of fault and well depth. Especially, the temporal monitoring of 222Rn suggests that 222Rn concentrations in the shallow groundwater may be controlled by variation in rainfall and artificial effects such as water curtain cultivation conducted in the winter season in this study area.

A Case Study of the Radon Hazard at the Boundary of a Coal Minefield

“…Additionally, the unusual concentration of soil radon within the zone of disturbance and its crushing area is more extensive [16,38]. Furthermore, it is plausible that the augmented release of radon through faults stems from the concentration of radioactive substances within the fault [39,40].…”

Radon Hazard of the Zhurinsky Fault for the Population in the Kuznetsk Coal Basin: Primary Results

“…The predominance of the clay fraction in some observation points may lead to the growth of adsorbed uranium and radium in its particles. Fault zones may also act as collectors for uranium and radium in the process of their migration with groundwater [71,72].…”

Geospatial Assessment of Karst Spring Water Quality in Northeast Tennessee, USA

“…A recent study of radon in Tennessee well water [25] reported high radon concentrations in wells underlain by older Precambrian rocks on the Tennessee-North Carolina border. Aside from the effect of bedrock geology, karst, well depth, and faulting also influence the concentration of radon in groundwater [25,34,[39][40][41]. Moreover, radon concentration in springs may be influenced by the flow rate, such that low discharge volume springs (with less flushing potential) tend to have elevated levels of radon [47].…”

“…Elevated radon concentration in groundwater has been associated with karst landscapes [39], faults [25,40,41], and well depth [40]. This is not unique to karst landscapes alone, as elevated radon has been reported in groundwater wells of the Piedmont region of North Carolina (USA), which is underlain by fractured crystalline rocks [42], and in East Tennessee, with terrigenous clastic aquifers of the Ocoee Supergroup (pCo), Snowbird (pCs), and Great Smoky Groups (pCg), as well as the argillaceous and conglomerate aquifers of the Walden Creek Group (pCw) [25,29,43].…”