Geochemical Behavior of Uranium and Radon in Groundwater of Jurassic Granite Area, Icheon, Middle Korea

Byong Wook Cho,Chang Oh Choo

doi:10.3390/w11061278

Abstract

Uranium concentrations (a total of 82 samples) in groundwater in Icheon, middle Korea, showed a wide range from 0.02 to 1640 μg/L with a mean of 56.77 μg/L, a median of 3.03 μg/L, and a standard deviation of 228.63 μg/L. Most groundwater samples had quite low concentrations: 32.9% were below 1 μg/L, while 15.9% exceeded 30 μg/L, the maximum contaminant level (MCL) of the US EPA (Environmental Protection Agency). Radon concentrations also ranged widely from 1.48 to 865.8 Bq/L. Although the standard deviation of radon was large (151.8 Bq/L), the mean was 211.29 Bq/L and the median was 176.86 Bq/L. Overall, 64.6% of the samples exceeded the alternative maximum contaminant level (AMCL) of the US EPA (148 Bq/L). According to statistical analyses, there was no close correlations between uranium and radon, but there were correlations between uranium and redox potential (Eh) (−0.54), dissolved oxygen (DO) (−0.50), HCO3− (0.45), Sr (0.65), and SiO2 (−0.44). Radon showed independent behavior with respect to most components in groundwater. Uranium concentrations in groundwater increased with increasing water–rock interactions. Anomalously high uranium and radon concentrations in groundwater are preferentially localized in granite areas and spatial distributions are remarkably heterogeneous.

Highlights

Radionuclides such as uranium and radon naturally occur in groundwater around the world.at high concentrations, they can be harmful to public health and their mobility is sensitive to aqueous geochemical conditions
Uranium concentrations in groundwater increased with increasing water–rock interactions
High uranium and radon concentrations in groundwater are preferentially localized in granite areas and spatial distributions are remarkably heterogeneous

Summary

Introduction

Radionuclides such as uranium and radon naturally occur in groundwater around the world.at high concentrations, they can be harmful to public health and their mobility is sensitive to aqueous geochemical conditions. Radionuclides such as uranium and radon naturally occur in groundwater around the world. Many studies have reported higher uranium and radon concentrations in groundwater in granitic terrains [3,4,5,6,7,8,9,10]. Higher radon concentrations are commonly detected in areas underlain by granites that usually contain more uranium than other rock types [8,9,10]. The radon concentration in groundwater generally increases with an increase in the uranium content of the soil and bedrock [11,12], but is highly variable, depending on aquifer characteristics, bedrock geology, water chemistry, and good conditions [4,13,14]

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