• 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.

• 대한토목학회논문집
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• 제26권1B호
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• pp.1-6
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• 2006

낙동강, 섬진강, 영산강, 그리고 금강 권역의 충적 대수층에서 해안선을 통하여 바다로 유출되는 지하수 해안유출량이 평가되었다. 증반산, 하천 유출과 같은 수문학적 주요 인자와 양적으로 비교하면 지하수 해안유출량은 상대적으로 많은 양이 아니다. 하지만 수문순환 과정에서 최하류라는 특징에 의하여 지하수 해안 유출의 개발은 환경적인 영향을 상대적으로 적게 받으며, 현재 물 부족으로 어려움을 겪고 있는 많은 해안지역에서 유용하게 사용될 수 있는 중요한 수자원이다. 유출량 평가를 위하여 기 조사된 지하수위 조사 자료와 Darcy의 법칙에 기반을 둔 평가방법을 이용하였다. 주요 변수의 산정에는 해안선의 복잡성과 해수쐐기의 영향을 고려할 수 있는 기술을 적용하였다. 연구결과 조사 대상 4개 하천 권역의 지하수 해안 유출량은 연간 18억$m^3$에 달하는 것으로 나타났다. 이는 권역별 강수총량의 2.3%에 이르는 수치이다. 지하수 개발 측면에서 는 낙동강 권역이 가장 유리한 것으로 나타났다.

• Ocean and Polar Research
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• 제26권1호
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• pp.33-42
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• 2004

Effect of freshwater discharge on the long-term salt balance in the Northern and Central Indian River Lagoon (IRL) is successfully simulated by a new analytical solution to a water balance-based one-dimensional salt conservation equation. Sensitivity tests show that the salinity levels drop abruptly even during the dry season (November to May) due to the high surface runoff discharge caused by tropical storms, depressions, and passage of cold fronts. Increasing surface runoff and direct precipitation has risen by ten times, lowering the salinity level down to 12psu in the Northern Central zone, and to 17 psu in the Northern zone. However, the salinity level in the Southern Central zone has decreased to 25 psu. High sensitivity of the Northern Central zone to freshwater discharge can be partially explained by a rapid urbanization in this zone. During the dry season, less sensitivity of the Southern Central zone to the increased surface runoff is attributed to the proximity of the zone to the Sebastian Inlet and a strong diffusion condition possibly resulting from the seawater intrusion to the surficial aquifer at the Vero Beach. During the wet season, however, the whole study area is highly sensitive to freshwater discharge due to the weak diffusion conditions. High sensitivity of the IRL to the given diffusion conditions guarantees that the fresh-water release occurs during strong wind conditions, achieving both flood control in the drainage basin and a proper salinity regime in the IRL.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.121-121
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• 2004

The groundwater in the Pocheon area occurs from both a fractured bedrock aquifer in igneous and metamorphic rocks and an alluvial aquifer with a thickness of <50 m, and forms a major source of domestic and agricultural water supply. In this study, we performed a hydrogeochemical study in order to identify the control of geochemical processes on groundwater quality. For this study, groundwater level and physicochemical parameters (EC, Eh, pH, alkalinity) were monitored once a month from a total of 150 groundwater wells between June 2003 to August 2004. A total of 153 water samples (13 surface water, 66 alluvial groundwater, 74 bedrock groundwater) were also collected and analyzed in February 2004. Groundwater chemistry in the study area is very complex, depending on a number of major factors such as geology, degree of chemical weathering, and quality of recharge water. Hydrochemical reactions such as the leaching of surficial and near-solace soil salts, dissolution of calcite, cation exchange, and weathering of silicate minerals are proposed to explain the chemistry of natural groundwater. Alluvial groundwaters locally have very high TDS concentrations, which are characterized by their chloride(nitrate)-sulfate-bicabonate facies and low Na/Cl ratio. Their grondwater levels are highly fluctuated according to rainfall event. We suggest that high nitrate content and salinity in such alluvial groundwaters originates from the local recharge of sewage effluents and/or fertilizers. Likewise, high concentrations of nitrate were also locally observed in some bedrock groundwaters, suggesting their effect of anthropogenic contamination. This is possibly due to the bypass flow taking place through macropores. Tile degree of the weathering of silicate minerals seems to be a major control of the distribution of major cations (sodium, calcium, magnesium, potassium) in bedrock groundwaters, which show a general increase with increasing depth of wells. Thermodynamic interpretation of groundwater chemistry shows that the groundwater in the study area is in chemical equilibrium with kaolinite and Na-montmorillonite, which indicates that weathering of plagioclase to those minerals is a major control of hydrochemistry of bedrock groundwater. The interpretation of the molar ratios among major ions, as well as the mass balance calculation, also indicates the role of both dissolution/precipitation of calcite and Ca-Na cationic exchange as bedrock groundwaters evolves progressively.

• 대한환경공학회지
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• 제27권2호
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• pp.158-162
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• 2005

이 연구에서는 대규모 나노여과 정수처리 시스템의 각 단계의 생물학적 안정성과 공정내의 AOC를 측정하고자 한다. 나노 여과 정수처리 시스템은 미 플로리다 주 남부의 Plantation 시의 $45,400\;m^3$/day (12 mgd) 규모의 연수화 시설에서 연구하였으며, 표면 대수층의 유기물이 많은 지하수를 원수로 이용하였다. 유입원수의 평균 AOC 농도는 158 g/L acetate-C이다. 전처리(산과 스케일 방지제첨가) 후 AOC농도는 12.7% 가량 증가하였는데, 이는 전처리 과정에서 투입된 화학물들이 생물학적 안정성을 저감시킬 수 있음을 의미한다. 전체적으로 나노여과공정은 63.4%와 94.8% 의 AOC 및 DOC 제거효율을 보였다. 특히 1단계에서의 AOC 제거율 (68%)이 2단계에서의 제거율 (58%)보다 다소 높았는데 이는 높은 회수율과 산 전처리과정이 있는 대규모 나노 공정 2단계에서 흔히 형성되는 낮은 pH 높은 이온강도 및 경도 등의 화학적 환경에 기인한다고 사료된다.