• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1616-1622
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• 2022

Selenium has been identified as an element of interest for the safety assessment of a deep geological repository (DGR) for used nuclear fuel. In Canada, groundwaters at DGR depths in sedimentary rocks have been observed to have a high ionic strength. This paper examines the sorption behavior of Se(-II) onto illite, MX-80 bentonite, Queenston shale, and argillaceous limestone in Na-Ca-Cl solutions of varying ionic strength (0.1-6 mol/kgw (m)) and across a pH range of 4-9. Little ionic strength dependence for Se(-II) sorption onto all solids was observed except that sorption at high ionic strength (6 m) was generally slightly lower than sorption at low ionic strength (0.1 m). Illite and MX-80 exhibited the expected results for anion sorption, while shale and limestone exhibited more constant sorption across the pH range tested. A non-electrostatic surface complexation model successfully predicted sorption of Se(-II) onto illite and MX-80 using the formation of an inner-sphere surface complex and an outer-sphere surface complex. Optimized values for the formation reactions of these surface species were proposed.

• 한국지하수토양환경학회지:지하수토양환경
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• 제13권2호
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• pp.36-43
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• 2008

Guelph 투수계를 이용한 현장 토양 불포화 수리전도도의 산정기법을 제시하고 이 기법을 활용하여 강변여과수 취수계획 지역인 김해시 낙동강 딴섬 일대의 지표 특성을 조사하였다. 조사된 지표 포화 및 불포화 수리전도도의 값은 대규모 강변여과 개발에 대한 지하수 모델링 평가시 중요한 경계조건인 지표 함양량과 하천 경계조건을 설정하는데 활용될 수 있다. 딴섬의 지표 수리전도도는 상류에 조립질 입자가, 하류에 상대적으로 세립질 입자가 퇴적되었음을 보여주었고, 이러한 현상은 강의 부유물이 퇴적되는 특성을 반영하고 있다. 이러한 결과는 상대적으로 딴섬의 남측지역(상류)이 북측 지역(하류)에 비해 강변여과 방식 취수에 유리한 조건을 가질 수 있음을 시사한다.

• 한국환경과학회지
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• 제21권8호
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• pp.989-996
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• 2012

Nitrate contamination of water environments can create serious problems such as eutrophication of rivers. Conventional biological processes for nitrate removal by heterotrophic denitrification often need additional organic substrates as carbon sources and electron donors. We tried to accelerate biological denitrification by using bioelectrochemical reactor (BER) in which electrode works as an electron donor. Denitrification activity of 8 environmental samples from various sediments, soils, groundwaters, and sludges were tested to establish an efficient enrichment culture for BER. The established enrichment culture from a soil sample showed stable denitrification activity without any nitrite accumulation. Microbial community analysis by using PCR-DGGE method revealed that dominant denitrifiers in the enrichment culture were Pantoea sp., Cronobacter sakazakii, and Castellaniella defragrans. Denitrification rate ($0.08kg/m^3{\cdot}day$) of the enrichment culture in BER with electrode poised at -0.5 V (vs Ag/AgCl) was higher than that ($2.1{\times}10^{-2}kg/m^3{\cdot}day$) of BER without any poised potential. This results suggested that biological denitrification would be improved by supplying potential throughout electrode in BER. Further research using BER without any organic substrate addition is needed to apply this system for bioremediation of water and wastewater contaminated by nitrate.

• 자원환경지질
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• 제37권6호
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• pp.657-667
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• 2004

울산광역시 46개 지하수 시료 중 29개 시료에서 비소가 검출되었고, 그 농도는 $<0.1-7.2{\mu}g/L$의 범위를 나타낸다. 그 중 3개의 지하수에서 국내음용수 기준치$(50{\mu}g/L)$를 초과하였고, 10째 시료에서는 세계보건기구 기준치인 $(10{\mu}g/L)$를 초과하고 있음이 이번 연구에서 밝혀졌다. 비소의 농도가 높은 곳은 지질구조선 부근 특히 과거 울산철광 부근인 달천리 일대와 정자역암이 분포하는 효문동 일대이다. 울산철광 부근은 주로 황철석이 산화된 형태로 산화환경을 보이나, 효문동 일대는 환원상태의 FeOOH의 산화에서 야기되는 것으로 해석된다. pH-Eh 도표에 따른 연구지역 지하수중 비소의 존재형태는 달천리 일대에서는 As(V)로 $H_2AsO_4^-,\;HAsO4_^{-2}$로 존재한다. 효문리등 구조선일대는 As(III)로 $H_3AsO_3$ 형태로 존재한다.

• 자원환경지질
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• 제33권6호
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• pp.469-489
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• 2000

The hydrogeochemical and isotopic studies on deep groundwater (below a 550 m depth from the ground surface) in the Munkyeong area, Kyeongbuk province were carried out. Two types of deep groundwater (${CO_2}$-rich groundwater and alkali groundwater) occur together in the Munkywong area. ${CO_2}$-rich groundwater (Ca-${HCO_3}$ type) is characterized by low pH (5.8~6.5) and high TDS (up to 2,682 mg/L.), while alkali groundwater (Na-${HCO_3}$ type) shows a high pH (9.1~10.4) and relatively low TDS (72~116 mg/L). ${CO_2}$-rich water may have evolved by ${CO_2}$ added at depth during groundwater circulation. This process leads to the dissolution of surrounding rocks and Ca, Na, Mg, K and ${HCO_3}$ concentrations are eniched. The low $Pco_2$ ($10^{-6.4}$atm) of alkali groundwaters seems to result from the dissolution of silicate minerals without a supply of ${CO_2}$. The ${\delta}^{18}O$ and ${\delta}^D$values and tritium data indicate that two types of deep groundwater were both derived from pre-thermonuclear meteoric water and have evolved through prolonged water-rock interaction. The carbon isotope data show that dissolved carbon in the ${CO_2}$-rich water was possibly derived from deep-seated ${CO_2}$ gas, although further studies are needed. The ${\delta}^{34}S$ values of dissolved sulfate show that sulfate reduction occurred at great depths. The application of various chemical geothermometers on ${CO_2}$-rich groundwater shows that the calculated deep reservoir temperature is about 130~$l75^{\circ}C$. Based on the geological setting, water chemistry and environmental isotope data, each of the two types of deep groundwater represent distinct hydrologic and hydrogeochemical evolution at depth and their movement is controlled by the local fracture system.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권2호
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• pp.22-27
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• 2012

$^{226}Ra$ in groundwater could be analyzed by various methods. LSC (liquid scintillation counter) is used to measure its activity of Ba co-precipitates with Hisafe III scintillation cocktail solution. Counting efficiency was obtained using NIST $^{226}Ra$ standard solution in triplicate and calculated $^{226}Ra$ concentration using the efficiency values. $^{226}Ra$ values of 19 groundwaters having Gross-${\alpha}$ concentrations of more than 5 pCi/L ranged from ND (${\leq}$ 0.1 pCi/L) to 1.18 pCi/L. Geologic settings of the 19 areas are composed of granitic rocks of Pre-Cambrian and Jurassic and Cretaceous, gneiss (schist) of Pre-Cambrian, and volcanic rocks of Cretaceous. No relationship was shown among $^{226}Ra$ a concentrations and in-situ water quality data, and Gross-${\alpha}$, uranium, radon concentrations.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권3호
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• pp.33-51
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• 2013

Spatial and temporal characteristics of nitrate contamination and hydrogeochemical parameters were investigated for springs and surficial and bedrock groundwaters in northeastern part of Hongseong. Two field investigations were conducted at dry and wet seasons in 2011 for 120 sites including measurement of field parameters with chemical analyses of major dissolved constituents. Nitrate concentrations were at background levels in springs while 45% of bedrock groundwater and 49% of surficial groundwater exceeded the drinking water standard of nitrate (10 mg/L as $NO_3$-N). The difference in nitrate concentrations between surficial and bedrock groundwater was statistically insignificant. Cumulative frequency distribution of nitrate concentrations revealed two inflection points of 2 and 16 mg/L as $NO_3$-N. Correlation analysis of hydrogeochemical parameters showed that nitrate had higher correlations with Sr, Mg, Cl, Na, and Ca, in surficial groundwater in both dry and wet season. In contrast, nitrate had much weaker correlations with other hydrogeochemical parameters in bedrock groundwater compared to surficial groundwater and had significant correlations only in wet season. Temporally, nitrate and chloride concentrations decreased and dissolved oxygen (DO) increased from dry season to wet season, which indicates that increased recharge during the wet season affected groundwater quality. Aerobic conditions were predominant for both surficial and bedrock groundwater indicating low natural attenuation potential of nitrate in the aquifers of the study area.

• 대한지하수환경학회지
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• 제4권4호
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• pp.175-184
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• 1997

부산 석대 생활폐기물 매립지는 1987년 6월부터 1993년 5월까지 만 6년간 사용된 중간규모의 매립장이다. 매립장에 분포하는 안산암질암과 유문암질암에는 절리와 단층이 발달되어 있다. 1996년 7월과 1997년 6월에 2차에 걸쳐 침출수, 하천수 및 지하수의 수질을 조사한 결과 침출수와 하천수의 수질은 농도가 약간 감소되었으나, 지하수 수질은 더 악화되었다. 석대매립지의 지하수 오염은 충적층에 개발된 천층지하수는 물론이고, 150m 심도의 암반지하수들도 오염이 심화되어 있다. 침출수에 의한 지하수 오염범위는 매립장 경계에서 서쪽으로 약 500 m 정도, 남쪽으로 약 1 km 정도 까지이다. 석대 매립지 주변 수질의 오염제어를 위해서는 매립지 일윈에 감시정 및 채수정의 개발, 침출수처리장 건설, 기존의 지하 차수벽시설 보완작업 등이 필요하다.

• 한국지구과학회지
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• 제31권3호
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• pp.205-213
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• 2010

옥천대 우라늄 광화대 부근 퇴적암 지하수에 대한 수리지화학적 연구를 수행하여 옥천대 우라늄 광화대와 대전지역 우라늄 지하수와의 성인적 관련성을 고찰하였다. 지하수의 pH는 6.4-8.1의 범위로 중성에서 약칼리성 특성을 보이며, Eh는 대체로 -50-225 mV의 범위로서 일부는 환원성 환경의 특성을 보인다. 지하수는 탄산염광물의 용해반응으로 $Ca^{2+}$ 및 $HCO_3^-$ 함량이 우세한 Ca-$HCO_3^$ 유형에 해당된다. 석탄광산 폐수에서는 $1165{\mu}g/L$의 우라늄이 검출되었으나 지하수내 우라늄 함량은 $3.2{\mu}g/L$ 이하로 매우 낮다. 우라늄 광화대 부근 지하수에서 낮은 우라늄 함량은 낮은 Eh를 보이는 수리지화학적 특성에 기인한다. 대전지역 지하수 내 우라늄은 옥천대 우라늄 광화대로부터 공급되지는 않은 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제34권5호
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• pp.517-531
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• 2002

The speciation and solubility of Am, Np, Pu and U have been analyzed by means of the geochemical code MUGREM, under the chemical conditions of domestic deep groundwater, in order to support the preliminary safety assessment for a Korean HLW disposal concept. Under the conditions of groundwaters studied, the stable solid phase is AmOHC $O_3$(s) or Am(OH)$_3$(s), soddyite((U $O_2$)$_2$ $SiO_2$.2$H_2O$) or N $a_2$ $U_2$ $O_{7}$ (c), Np(OH)$_4$(am), and Pu(OH)$_4$(am) for Am, U, Np, and Pu, respectively. The dominating aqueous species are as follows: the complexes of Am(III), Am(OH)$_2$$^{+}$ and Am(C $O_3$)$_2$$^{[-10]}$ , the complexes of U(VI), U $O_2$(OH)$_3$$^{[-10]}$ and U $O_2$(C $O_3$)$_3$$^{4-}$, the complexes of Np(IV), Np(OH)$_4$(aq) and Np(OH)$_3$C $O_3$, and the complexes of Pu(IV), Pu(OH)$_4$(aq) and Pu(OH)$_3$C $O_3$$^{[-10]}$ . The calculated solubilities exist between 1.9E-10 and 1.3E-9 mol/L for Am, between 5.6E-6 and 1.2E-4 mol/L for U, between 3.1E-9 and 1.3E-8 mol/L for Np, and between 6.6E-10 and 2.4E-10 mol/L for Pu, depending on groundwater conditions. The present solubilities of each actinide agree well with the results of other studies obtained under similar conditions.s.