• 환경영향평가
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• 제14권5호
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• pp.255-262
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• 2005

In summer and early autumn, eutrophication occurs occasionally in many reservoirs. Lakeside macrophyte which is one of internal pollutants effects on water quality when it is submerged during water surface is rising after rainy season. This study include examination of pollutant load, species of plant, community structure and productivity of macrophyte in unit area at lakeside. The result of this research will be used as a guideline of water quality management on reservoir through assessing water quality effect of submerged plant. The areal distribution, composition of species and submerged area of macrophyte changes according to rainfall pattern every year, so it is difficult to calculate nutrient load annually from submerged macrophyte. In this study, the nutrient load from submerged macrophyte assess from Daecheong and Juam reservoir in 2001. TN and TP load of submerged macrophyte shows 0.043% and 0.069%, respectively, of annual discharge load on Daecheong watershed. At lake Juam, TN and TP shows 0.64% and 1.28% load, respectively. The reason that nutrient load of lake Juam is greater than that of lake Daecheong is that macrophyte distribution area of lake Juam is 5 times greater than that of lake Daecheong. Total nutrient load of lake Daecheong is 3 times greater than that of lake Juam.

• 환경위생공학
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• 제15권1호
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• pp.1-6
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• 2000

A milky gray scum was observed at some water area of the lake Daecheong in the summer of 1997 and 1998. To identify a causing organism of scum and affecting factors, we observed the scum material by a phase contrast microscope and surveyed the phsico-chemical water quality during the outbreak of scum. The scum was found out to be clogging cysts of amoeboid protozoan, Asterocaelum sp.(Protozoea Sarcodina Aconchulinida), grazer of filamentous cyanobacteria, Anabaena genus. The protozoan scum appeared during Anabaena bloom period, which continued for a while. This protozoan was presumed acting as a regulator of Anabaena bloom in the lake Daecheong during the summer season. Moreover this is the first report on Asterocaelum sp. a grazing filamentous cyanobacteria occurred in Korean freshwater.

• ALGAE
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• 제20권3호
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• pp.197-205
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• 2005

Temporal variability in lake phytoplankton is controlled by a complex between hydrological and chemical factors, and biological interactions. We explored annual change of phytoplankton in Lake Daecheong, using phytoplankton analysis data from 1997 to 2002 (except 2000). The standing crop of phytoplankton was ranged from 3.5 x 10 to 1.5 x 106 cells mL$^{-1}$ and the highest mean value was at site 1. The class composition ratios of phytoplankton standing crop were divided into three classes. From January to March, diatoms showed a dominance (68.1-77.7%). From April to June, diatoms were mixed with cryptomonad etc. or blue-green algae. From July to October, blue-green algae showed a dominance (54.7-84.0%). In the case of green algae, the class composition ratios were below 10%. But green algae appeared all the year round.

• 상하수도학회지
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• 제29권2호
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• pp.211-222
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• 2015

This study focused on evaluating the efficiency of the removal of non-point source pollution by Daecheong Lake Juwon Stream constructed wetlands. The constructed wetland system is a surface flow type designed in the year 2007 for purifying eutrophic water of Daecheong Lake Juwon Stream. The value of conductivity, suspended solids(SS), chemical oxygen demand using a potassium permanganate($COD_{Mn}$), five-day biochemical oxygen demand($BOD_5$), total nitrogen(T-N), total phosphorous(T-P), and pH in inflow averaged 220.2, 2.46, 3.33, 1.34, 2.00, 0.04 mg/L and 7.24, respectively and in outflow averaged 227.9, 1.12, 3.34, 0.87, 1.16, 0.02 mg/L and 7.45, respectively. The average removal efficiency of constructed wetlands was 30 % for SS, 22 % for $BOD_5$, 45 % for T-N and 31 % for T-P. The removal rates of SS, $BOD_5$ and T-N in the spring, summer and autumn were higher than those in winter. The removal rate of T-P was not significant different in all seasons. The amounts of pollutants removal in the constructed wetlands were higher in the order of $3^{rd}$ < $2^{nd}$ < $1^{st}$ wetland for SS and T-P, $2^{nd}$ < $3^{rd}$ < $1^{st}$ wetland for $BOD_5$ and T-N. Therefore, our findings suggest that the constructed wetlands could well treat the eutrophic Daecheong Lake Juwon Stream waters.

• 한국물환경학회지
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• 제22권2호
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• pp.342-348
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• 2006

Changes in water quality and algal growth according to the differences in the inflow volume were investigated in the Daecheong Lake from 1998 to 2001. Until year 2000, inflow volume considerably depended on the rainfall throughout the basin. However, the correlation was low since 2001 when water storage in the upstream Yongdam Lake was started. According to inflow volume-TP relationship analyses, significant correlation was found at up- and middle-stream sites, excluding down-stream site of the Daechong Lake. For chlorophyll-a, correlation was found with flow volume at all sites except for Choo-So. In a dry year, although nutrients loads were relatively lower than those in rainy years, there were higher concentrations of chlorophyll-a and massive bloom of Microcystis. Limiting factors for algal growth seems to be not the volume of nutrients load but retention time and physical disturbance of the water body influenced by inflow volume. Thus, in the Daecheong lake, it would be more important to focus on the management of eutrophication in dry years than in rainy ones.

• 한국습지학회지
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• 제22권1호
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• pp.49-58
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• 2020

경작지의 과다 비료와 퇴비의 사용은 토양내 양분 축적을 증가시키며 잉여 양분은 지표유출 및 지하유출 과정을 통해 수질 오염과 녹조발생 등을 유발시킨다. 또한 토양내 과다 양분축적과 함께 지속적 작물 재배는 토양의 산성화를 초래하여 토양의 물리적 구조를 변화시켜 양분의 침출을 더욱 증가시킨다. 대청호 저수구역 내 경작은 대청호의 수질에 직접적 영향을 주기도 하며, 대청댐 수위상승시 침수되어 토양 내 양분이 용출되기도 한다. 본 연구는 대청댐 저수구역 내 경작지의 물리화학적 성상을 분석하여 대청호 수질관리 대책수립에 활용가능한 기초자료를 제공하고자 수행되었다. 대청호 저수구역 경작지 토양은 잉여양분이 이동 가능한 Sandy Loam 토양으로 분류되었다. 작물별 토양내 화학적 성상은 작물별 서로 다른 시비량에 크게 영향을 받는 것으로 나타났다. 그러나 농민의 경작방식과 미기후 변화 등도 경작지 토양의 화학적 성상변화에 영향을 주는 것으로 평가되었다. 경작지 토양내 양분양은 지하수 및 인근 하천의 수질 및 대청호 주요 녹조발생에 영향을 주는 것으로 나타났다. 논에서의 양분유출은 봄철 강우시 집중되었으며, 밭에서의 양분유출은 여름에서 가을까지의 기저유출 및 멀칭으로 인한 지표유출 등이 영향을 주는 것으로 나타났다. 하천내부의 과다한 식생과 경작지의 유기성 농업잔재물도 하천의 유기물 및 영양염류 증가에 기여하는 것으로 평가되었다. 본 연구결과는 대청호 녹조발생 저감을 위한 저수구역내 경작지 관리를 위한 우선 관리지역 지정 및 관리기법 선정에 활용될 수 있다.

• ALGAE
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• 제21권1호
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• pp.75-82
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• 2006

Cyanobacteria regulate their buoyancy in response to changing environmental conditions. This process is essential for cyanobacterial development and can account for their dominance in eutrophic waters in summer. The present investigation was conducted to understand the 24-hour vertical distribution of cyanobacteria and water quality characteristics in Lake Daecheong. Water samples were collected and analyzed at depth intervals of 2 or 3 m and at an interval of three hours for a day on August 28, 2001 and September 24, 2002. In 2001 the accumulated standing crop of Microcystis spp. from surface to a depth of 6 m was 94.9%. Microcystis spp. showed no vertical migration below the thermocline. Microcystis spp. had maximum density near the surface, but shifted to 2 m depth at 2 p.m. A dense population of Anabaena spp. accumulated near the surface from 2 to 5 p.m. in 2002.

• 한국물환경학회지
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• 제34권6호
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• pp.579-590
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• 2018

The lakes' metabolism bears important information for the assessment of the carbon budget due to the accumulation or loss of carbon in the lake as well as the dynamics of the food webs through primary production. A lake-scale metabolism is evaluated by Gross Primary Production (GPP), Ecosystem Respiration (R), and Net Ecosystem Production (NEP), which is the difference between the first two values. Methods for estimating GPP and R are based on the levels carbon and oxygen. Estimation of carbon is expensive because of the use of radioactive materials which requires a high degree of proficiency. The purpose of this study was to estimate Lake Daecheong ecosystem metabolism using high frequency water temperature data and DO measurement sensor, widely utilized in the field of water quality monitoring, and to evaluate the possibility of using the application method. High frequency data was collected at intervals of 10 minutes from September to December 2017 by installing a thermistor chain and a DO sensor in downstream of Daechung Dam. The data was then used to estimate GPP, R and NEP using the R public program LakeMetabolizer, and other metabolism models (mle, ols, kalman, bookkeep). Calculations of gas exchange coefficient methods (cole, crusius, heiskanen, macIntyre, read, soloviev, vachon) were compared. According to the result, Lake Daecheong has some deviation based on the application method, but it was generally estimated that the NEP value is negative and acts as a source of atmospheric carbon in a heterotrophic system. Although the high frequency sensor data used in this study had negative and positive GPP and R values during the physical mixing process, they can be used to monitor real-time metabolic changes in the ecosystem if these problems are solved.

• 한국토양비료학회지
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• 제27권2호
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• pp.111-116
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• 1994

댐 저위층에 축전된 저니와 수강조류를 규조토드럼에 흡착시킨 물질에 대한 농업적 활용 가능성을 검토하기 위하여 Windrow method를 이용한 저니의 부숙퇴비화를 시도하였으며, 저니자체 및 저니함유 부숙퇴비에 대하여 토마토를 공시하여 식물영양적 효과를 포트실험으로 조사한 결과는 다음과 같다. 1. 생계분과 톱밥을 부재료로 한 저니의 부숙방법은 Windrow method를 이용하였다. 부숙과정중 50일 경과후 최종 대(對) 초기 탄질율의 비율은 0.69 수준으로 감소하였고, 양이온치환용량은 약 66%가 증가하였으며, 온도변화는 15일째 $52^{\circ}C$까지 상승하였다가 50일 경과후 $30^{\circ}C$를 유지하여 이 지점을 부숙완료점으로 판정하였다. 2. 미부숙 저니의 토마토에 대한 건물중, 초장 및 엽록소함량에 미치는 효과를 검토한 결과, 대조구에 비해 미부숙 저니 시용구의 효과가 현저하였으며, 시용 수준의 증가와 더불어 건물중 및 초장이 증가하는 경향이었다. 저니 부숙퇴비의 시용 역시, 대조구에 비하여 생체중, 건물중 및 초장의 현저한 증가효과를 나타내었으며, 미부숙 저니에 비해 저니부숙퇴비의 생육효과가 우수하였다. 3. 미부숙 저니 및 저니부숙퇴비를 시용하여 작물재배 후 토양의 물리화학성질을 조사한 결과, pH, T-N, O.M. 및 CEC 면에서 다소 개선효과가 나타났다. 그러므로 저니 및 조류를 직접 토양에 이용하기는 곤란하나 퇴비제조시 충진제로 사용했을 때 부숙화된 저니 퇴비는 토양개량제 및 퇴비자원으로 활용할 수 있는 가능성이 있다고 판단된다.

• 생태와환경
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• 제38권3호통권113호
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• pp.382-392
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• 2005

대청호 연중 수질 환경요인의 변화를 해석하고 영양단계를 평가하고자, 1997년부터 2002년까지 수질 환경요인과 수문학적 특성을 조사하였다. 대청호의 표층 수온은 3.2\;{\sim}\;33.1^{\circ}C$로 2월 중순에 가장 낮았다. 탁도는 $0.1\;{\sim}203.5\;NTU$이었지만, 정점 1에서만 30 NTU의 이상이었다. COD의 평균은 $3.6{\pm}1.4\;mg\;O_2\;L^{-1}$이었고, Chl a의 평균 농도는 $9.3{\pm}12.8\;{\mu}g\;L^{-1}$이었다. 총질소는 0.14 ${\sim}$ 5.09 mg N $L^{-1}$ 범위로 4월과 6월부터 8월에 다른 시기보다 높았다, 총인은 $1\;{\sim}\;247\;{\mu}g\;P\;L^{-1}$로, 11월부터 4월까지$10.6\;{\sim}\;18.1\;{\mu}g\;P\;L^{-1}$로 상대적으로 낮다가 5월부터 8월까지 평균 30.0 P $L^{-1}$ 이상으로 증가하였다. TN/TP비의평균은 $98.7{\pm}56.2$이었다. 대청호의 수질은 적용한 지수와 시기별로 영양단계평가 등급이 중영양단계 또는 부영양단계로 판정되었다.