국내 변성암 지역 음용지하수 중 자연방사성물질(238U,222Rn)의 환경 특성 연구

Abstract

This study has investigated naturally occurring radioactive materials (N.O.R.M; <TEX>$^{238}U$</TEX>, <TEX>$^{222}Rn$</TEX>) for 353 drinking groundwater wells in metamorphic rock areas in Korea. Uranium concentrations ranged from N.D (not detected) to 563.56 <TEX>${\mu}g/L$</TEX> (median value, 0.68 <TEX>${\mu}g/L$</TEX>) and radon concentrations ranged from 108 to 11,612 pCi/L (median value, 1,400 pCi/L). Uranium and radon concentrations in the groundwater generally are similar to USA with similar geological setting. Uranium concentrations in 9 wells (2.6%) exceeded 30 <TEX>${\mu}g/L$</TEX>, which is the maximum contaminant level (MCL) by the US environmental protection agency (EPA), radon concentrations in 46 wells (13%) exceeded 4,000 pCi/L, which is the Alternative MCL (AMCL) by the US.EPA. The log-log correlation coefficient between uranium and radon was 0.32. The correlation coefficient between uranium and pH was 0.12 and the correlation coefficient between radon and temperature was -0.01. The correlation coefficient between uranium and <TEX>$HCO_3$</TEX> was 0.09 and the correlation coefficient between uranium and Ca was 0.11. The median value of uranium was high Chung-Buk (1.78 <TEX>${\mu}g</TEX><TEX>/L$</TEX>), Gyeong-Buk (1.37 <TEX>${\mu}g/L$</TEX>), In-Cheon (1.06 <TEX>${\mu}g/L$</TEX>) for each province. On the other hand, the median value of radon was high In-Cheon (2,962 pCi/L), Chung-Buk (2,339 pCi/L), Jeon-Buk (2,165 pCi/L) for each province. Jeon-Buk for log-log correlation coefficient is the highest (0.63) among provinces.