• Korean Journal of Microbiology
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• v.42 no.2
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• pp.95-102
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• 2006

To evaluate bacteriological water quality of groundwater in Yeungnam Province, samples were taken from 123 locations during summer and 117 locations during winter. The medians of heterotrophic plate counts.(HPCs) were 30 CFU/mL for the summer samples and 40 CFU/ml for the winter, and more than 25% showed HPCs higher than 100 CFU/ml. Coliform bacteria were detected from 46% of the summer samples and 30% of the winter. In these coliform-positive samples, the medians of coliform counts were 20 CFU/ml for the summer samples and 4 CFU/ml for the winter. Genera such as Citrobacter, Enterobacter, Escherichia, Klebsielia, Pantoea, Rahnellia, and Serratia were identified from the coliform isolates; among them, 48% were members of the genus Enterobacter. While E. cloacae, E. amnigenus, and K. pneumoniae were the most frequently isolated species, E. coli was isolated only from 1 location. The coliform counts were positively correlated with the HPCs, which also positively correlated with water temperature. The results of present study provide further insight on the extent of groundwater contamination with coliform bacteria.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.533-545
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• 2015

Spatial and seasonal variations in hydrogeochemical characteristics and the factors affecting the deterioration in quality of shallow portable groundwater in an agricultural area are examined. The aquifer consists of (from the surface to depth) agricultural soil, weathered soil, weathered rock, and bedrock. The geochemical signatures of the shallow groundwater are mostly affected by the NO₃⁻ and Cl⁻ contaminants that show a gradual downward increase in concentration from the upper area, due to the irregular distribution of contamination sources. The concentrations of the major cations do not varied with the elapsed time and the NO₃⁻ and Cl⁻ ions, when compared with concentrations in background groundwater, increase gradually with the distance from the upper area. This result suggests that the water quality in shallow groundwater deteriorates due to contaminant sources at the surface. The contaminations of the major contaminants in groundwater show a positive linear relationship with electrical conductivity, indicating the deterioration in water quality is related to the effects of the contaminants. The relationships between contaminant concentrations, as inferred from the ternary plots, show the contaminant concentrations in organic fertilizer are positively related to concentrations of NO₃⁻, Cl⁻, and SO₄²⁻ ions in the shallow portable groundwaters, which means the fertilizer is the main contaminant source. The results also show that the deterioration in shallow groundwater quality is caused mainly by NO₃⁻ and Cl⁻ derived from organic fertilizer with additional SO₄²⁻ contaminant from livestock wastes. Even though the concentrations of the contaminants within the shallow groundwaters and the contaminant sources are largely variable, it is useful to consider the ratio of contaminant concentrations and the relationship between contaminants in groundwater samples and in the contaminant source when analyzing deterioration in water quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.597-601
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• 2007

1990년대 정부는 비점오염원 부하의 심각성을 인식하여 1995년부터 한강, 낙동강, 금강 그리고 영산강 이른바 4대강 유역에 대한 비점오염원의 조사연구사업을 실시하였다. 그러나 비점오염원의 경우 처리시설만으로는 처리하는데 한계가 있다는 특성 때문에 도시지역과 비도시지역에 대한 비점오염원을 관리하기 위한 대책 마련과 제도적 관리방안의 수립이 시급한 실정이었다. 따라서 본 연구는 토지매수가 상수원 수질개선에 미치는 영향 및 효과분석을 하고, 토지매수를 통한 비점오염물질 저감효과 분석을 위해 토지매수에 따른 비점오염원에 의한 오염물질 변화 해석 및 토지매수에 따른 최적 수변녹지대 조성을 위한 식생 효과를 분석 하였다. 수변구역 내의 비점오염물질의 공공수역 유입을 억제하기 위한 방법들 중에서 보편적이고 자연친화적인 방법이 수변구역(riparian buffer strip), 또는 수변완충구역(riparian buffer zone)을 조성하여 관리하는 것이다. 수변구역은 하천유역의 토양, 식물, 동물을 포함하는 시스템으로서 하천흐름을 조절하고, 물을 저장하며, 물에서 유해한 물질을 제거할 뿐만 아니라, 수중 및 육상의 식물과 동물을 위한 서식처를 제공하는 등 수질과 수량 그리고 생태계 측면에서 중요한 지역이라고 할 수 있다. 따라서 현재 낙동강 수계에 수변구역 조성시의 수질개선효과 연구를 수행하였다. 토지매수가 상수원 수질개선에 미치는 영향 및 효과분석을 위해서 SWAT 모형을 적용하여 유량 및 수질모의를 실시하였다. 유역내 수변구역을 조성시 수변구역의 범위가 증가함에 따라 비점오염원의 감소가 크게 나타나고 있었다.로 대부분의 가정(家庭)은 아침 식사로 밥을 좋아하였다. (8) 편식을 고치는 것이 어렵다고 하였으며, 어린이 간식에 대하여는 깊은 관심을 나타냈다. 2. 영양교육(營養敎育) 현황실태(現況實態) (1)식생활(食生活)에 필요한 지식(知識)은 신문이나 잡지, 라디오와 텔레비젼을 통해서 대체로 얻고 있다. (2) 음식과 영양섭취와의 관계성이 있다고 답한 주부(主婦)는 70.8% 이었으며, 가족(家族)의 영양(營養)에 대하여 늘 생각하는 주부는 60% 이었다. 3. 식품섭취 빈도 거의 먹지 않는 식품(食品)으로 버터가 43.%로 가장 높았고, 육류의 섭취율이 낮았다. 반면, 김치와 채소류의 섭취율은 높았다. 집단간의 상관도를 보면 교육별로 김치, 장아찌, 콩이 각각 p>0.5 수준에서 유의한 차가 없었고, 나머지는 유의한 차가 있었다. 연령별로는 멸치가 유의한 차가 없었고(p>0.5), 수입별로는 콩이 유의한 차가 없었다(p>0.5). 4. 영양지식(營養知識) 검토 가정생활(家庭生活)에 필요(必要)한 일반적(一般的)인 영양지식(營養知識)은 대체적으로 낮은 편이었다. 어린이 영양, 편식의 해로움, 비만증의 해로움, 임신부 그리고 수유부 영양에 대하여는 일반적으로 알고 있다고 하였으며, 그다음으로 이유기 영양, 어린이 발육에 필요한 식품, 식품과 영양소와의 관계, 우유의 성분, 노인영양에 대하여 잘 알고 있는 비율이 낮았으며, 인체의 영양소, 식단작성여부, 간식의 이론, 식품감별법에 대하여는 가장 낮은 비율을 나타냈다. 각 영양지식은 교육정도가 높을수록 영양지식이 높았고, 교육별 집단간의 유의한 차가 나타났다. (0.001

• Journal of Korean Society of Environmental Engineers
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• v.38 no.2
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• pp.63-70
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• 2016

The distributed systems managed by K-water were surveyed to study the characteristic of disinfection-by-product (Trihalomethans & Haloacetic acids) formation and the correlations between the concentrations of disinfection-by-product and physico-chemical parameters. Five distribted system were selected according to their water ages and the degree of deterioration of their pipelines. Total seven items including Trihalomethans (THMs), Haloacetic acids (HAAs), BDOC, DOC, pH, chlorine residual, and temperature were analysed in monthly basis. The concentration of organic matter were increased according to water age and pipeline deterioration in this study. The coefficient of determination between the decline of residual chlorine and the increase of water age was revealed as high. Also, the coefficient of determination between the decline rate of residual chlorine and the increase of the Trihalomethans concentration were studied as high. Furthermore the longer water age is the bigger the effect on Trihalomethans formation and temperature. However, the coefficient of determination between the concentraion of Haloacetic acid and water age, residual chlorine, and temperature were revealed as low in this study.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.2
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• pp.124-134
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• 2021

Water in the Mulgol pond on Dokdo (island), Korea, was historically used for drinking water, but now it has been no longer used for this purpose due to regionally low water quality. Since 2007, this pond has been covered with a metal lid to protect from pollutants of seabirds, indicating limited light penetration into the Mulgol pond. Here, we investigated water quality in the pond and potential relationships of nitrogen components and microbes in May, June, August, and November 2020. The source salinity ranged from 1.39 to 1.57 psu. Suspended solids (0.8~5.1 mg L^-1) and chlorophyll-a (<0.01~0.49 ㎍ L^-1) remained low. The concentration of dissolved inorganic nitrogen (DIN) was between 35.9 and 47.2 mg L^-1. Thus, water in the Mulgol pond proves to be brackish water with low chlorophyll-a and high nutrients. This unique environment may be established by limited light intensity, sea fog (or seawater), and fecal pellets from many seabirds. Although the light source (800~8000 lux) was exposed to the four subsamples, chlorophyll-a concentrations were below <0.5 ㎍ L^-1 during the incubation periods. This result suggests that the biomass of phytoplankton does not increase along with an increase in light intensity. Furthermore, the content of nitrate constituted more than 90% of DIN, and a significant negative correlation between nitrate concentration and bacterial abundance was shown in May and June 2020 during the light exposure experiments (R=-0.762, p<0.05). Thus, it is possible that bacteria may be a significant agent to reduce nitrate concentration in the Mulgol pond, the relationship between nitrate concentration and bacterial abundance may vary seasonally.

• Journal of Korea Water Resources Association
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• v.57 no.2
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• pp.111-125
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• 2024

The study has examined alterations in groundwater quality by investigating the influence of rainfall on electrical conductivity (EC) and nitrate concentration in the groundwater of the Geum River Basin in South Korea. Mann Kendall and Sen's Slope estimator were employed to analyze the trends and estimate the trend's magnitude. The administrative map of the study area was utilized to assess the trends of these parameters within each administrative region. Seventeen years (from 2005 to 2021) of data on EC, groundwater levels (GWL), precipitation, and six years (from 2015 to 2020) of nitrate concentration data were utilized for this analysis. The results indicate that, in most administrative regions, there has been an increase in nitrate concentration, and EC, whereas precipitation has seen a slight decrease in a downstream and an increasing trend in upstream. The correlation coefficients calculated between these parameters reveal that there is no direct impact of precipitation on nitrate and EC, but a negative correlation was observed between GWL and EC. The most significant increasing trend in nitrate concentration was observed in two districts (Iksan and Gunsan ), which correspond to regions with significant agricultural activity; about 50% of these districts area are used for agricultural activities.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.197-206
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• 2010

To provide baseline information essential for assessing environmental impacts of monsoon rainfalls in a mountainous watershed under mixed land use, we investigated spatiotemporal variations in water quality using a combined approach of seasonal water quality survey and intensive storm samplings. Biannual water sampling at nine locations encompassing major land use types showed generally lower electrical conductivity and Cl- concentrations during the typical wet period compared to the dry period, indicating rainfall-induced dilution of dissolved ions. Total metal concentrations, however, were significantly higher during the monsoon period, probably associated with rainfall-induced increases in suspended sediments. Intensive storm sampling during a small monsoon rainfall event (18 mm) and an extreme event (452 mm) showed rapid changes in both suspended sediments and dissolved solutes in an agricultural stream draining the Haean Basin where arable lands have expanded rapidly over the recent decades. By contrast, a nearby forest stream derived from North Korea showed little responses to the small event compared to larges changes during the extreme event. In the agricultural stream total Pb concentrations showed significant positive relationships with suspended sediments. Although limited sampling frequency and locations require a cautious interpretation, the overall results suggest that expansion of agricultural fields in steep mountainous watersheds can increase the susceptibility of soil erosion and its off-site environmental impacts under increasing rainfall variability and extremes.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.419-424
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• 2006

대청호로 유입하는 탁수의 감시와 저수지내의 시공간분포를 예측할 수 있는 실시간 탁수감시 및 예측시스템(RTMMS)을 개발하였다. RTMMS는 탁도와 수온 등 실시간 계측자료를 데이터베이스에 저장.조회하는 실시간 감시(Realtime Monitoring), 2차원 탁수예측 수치모델의 입력자료 생성(Input Data), 탁수예측 수치모델의 수행 (W2 Run), 모의결과의 조회 및 저수지 운영 시나리오별 탁수조절 효과분석을 위한 후처리 (Post-Process) 기능을 제공한다. 시스템의 GUI 화면은 개별 기능을 탭 형식으로 제공하여 사용자가 순차적으로 자료조회와 모델수행 그리고 결과분석을 쉽게 수행할 수 있도록 설계하였다. RTMMS는 강우사상 동안 유입하천의 수온예측을 위해 대기기온, 이슬점온도, 하천유량자료를 독립변수로 이용하는 다중회귀모델(DMR)을 사용하며, 탁도 예측은 유량과 SS 부하량의 상관관계를 이용하는 탁도예측모델(QLM)을 사용한다. 저수지로 유입한 탁수의 밀도류 거동과 시공간적인 탁도분포 예측은 2차원 횡방향 평균 수리 수질해석 모형인 CE-QUAL-W2를 채택하였다. 개발된 시스템은 2004년 홍수기를 대상으로 시범적용 하였으며, 그 결과를 실측자료와 비교하여 제시하였다. RTMMS는 저수지 탁수발생 현황조회, 취수원 도달시간 및 지속기간, 밀도류와 전도현상을 고려한 시공간 분포 예측, 발전 및 수문방류, 선택취수 등 다양한 저수지운영 시나리오에 따른 상.하류 영향 분석, 용수 이용자에게 탁도 예측정보의 제공 등 탁수를 고려한 저수지운영 의사결정지원 도구로써 매우 유용하게 활용 될 것으로 기대된다.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.198-212
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• 2002

A numerical variation and abnormalities were studied on egg bags and embryos of Korean salamander, Hynobius leechii from agricultural habitat. The teratogenic and toxic effects of fungicide benomyl were also investigated with early embryos from non-agricultural habitat. We collected 144 egg bags from agricultural region, and 3418 of early embryos were contained. The lengths of egg bags were varied from 10 to 23 cm and the most frequent length was 19 cm. The number of embryos was varied from 7 to 43, and the most frequent range was 22 to 26. Spontaneous abnormalities were occurred in 406 embryos among 116 egg bags, and 24 kinds of external abnormalities were found. Individuals showing severe external defect were histologically studied and they showed optic dyspalsia, thyroid carcinoma, somatic muscular dysplasia, partial biaxial structure, decrease of red blood cells in the heart, cephalic degeneration and intestinal dysplasia. 385 embryos from non-agricultural region were exposed to 200 nM${\sim}$ 1 ${\mu}$M of benomyl at blastula or gastrula for 12 days. All embryo were dead in the concentration of 1 ${\mu}$M (LD$_{100}$) and 75% of embryos were dead in 800nM of benomyl. Speciflc effect due to benomyl was acrania or cephalic dysplasia and this restult suggests that the benomyl inhibit stongly to the development of neural tissue. These abnormal developments may be caused by antimitotic action, inhibition of tubulin complex, destruction of microtubule, inhibitions of neurulation and closing of neural fold, and by the inhibition of the movement of neural crest cells.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.173-180
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• 2018

The utilization of TOC(Total organic carbon), a new environmental standard, was evaluated for 30 lakes in the Nakdong River Basin, which is used for drinking and agricultural usage. The active use of water resources begins with securing satisfactory water quality. Since this allows people and nature to maintain stability of quality, water quality standards are being tightened to ensure good water quality. In order to improve the pollution level of organic matter in lakes in the living environment, it is important to use the appropriate organic substance index. The relationship between the newly introduced TOC and the existing COD(Chemical oxygen demand) in the targeted lake was positively correlated with the possibility of replacing the TOC with COD. However, the environmental grade standard using TOC is better than the environmental grade standard using COD, so it has the same effect as that of the grade of water quality using TOC as an organic substance factor. This indicates the limitation of TOC to directly replace existing COD when trying to determine or improve the quality level using organic indicators of lakes. Therefore, in order to secure the qualitative safety of the lake, it is required to strengthen environmental standards of TOC in terms of water quality grade. In addition, the correlation between TOC and COD shows a great difference depending on the utilization characteristics of the lake. This requires clear scientific identification, and it requires continuous monitoring of COD that has been used to accumulate indicators of lake organic matter.