대청호와 소양호에서 질화작용에 관한 연구

이옥재 단국대학교 1994 국내석사

본 연구의 대상수역인 대청호와 소양호에서 물리-화학적 환경요인과 생물학적 인자 그리고 질화작용능이 조사되었다. 대청호의 경우 4개 정점에서 1992년 3월부터 1994년 1월까지 총 12회를, 소양호의 경우 2개 정점에서 1992년 8월 부터 1993년 10월 까지 총 10회에 걸쳐 조사 하였다. 또한 이들 수계 생태계로 부터 환경인자의 영향은 단순회귀, 중회귀 분석 및 요인분석과 같은 통계적 방법으로 분석 하였다. 질화작용능은 질화작용의 저해제인 N-serve를 사용한 14C-dark incorporation 방법으로 측정하였으며, 질화세균의 수의 측정은 Most-Probable Number(MPN)방법을 사용하였다. 암모니아 산화세균은 대청호에서 0.5∼220 MPN/mL(평균 17.39 MPN/mL)로 분포하였으며, 소양호의 경우는 0.5∼220 MPN/mL(평균 10.88 MPN/mL) 로 분포하였다. 아질산 산화세균은 대청호에서 nd∼220 MPN/mL(평균 12.67 MPN/mL)의 범위로, 소양호에서는 0.5∼92 MPN/mL(평균 8.46 MPN/mL)의 범위로 분포하였다. 질화작용능은 대청호에서 0.O1∼7.15 ug/L/day(평균 0.57 ug/L/day)의 범위로 조사되었으며, 소양호에서는 0.O1∼2.25 ug/L/day(평균 0.28 ug/L/day)의 범위로 조사 되었으며, 대청호의 경우, 소양호보다 질화작용능이 높게 나타났다. 위의 결과로서, 대청호가 소양호보다 더 많이 오염되었던 것으로 생각된다. 단순회귀의 결과로 부터, 대청호의 질화작용능은 수온(0.485), pH(0.391), 용존산소량(-0.485), 부유물질량(0.472), 엽록소-a(0.294), 암모니아염 질소(0.600)와 상관관계를 나타내었고, 소양호에서의 질화작용능은 수온(0.632), pH(0.494), 부유물질량(0.294), 페오파이틴-a(0.355)와 상관관계를 나타냈다. 그러나 3차례의 단기연속 관측 결과, 빛은 일일 주기에서 질화작용을 조절하는 가장 중요한 인자로 나타났다. 중회귀 분석 결과, 대청호에서의 질화작용은 암모니아염 질소(38%), 부유물질(21%), 질산염 질소(8%), 아질산염 질소(3%) 등에 매우 의존하였으나, 소양호의 경우는 수온(40%)에 의해 지배되어 졌다. 이러한 사실은 대청호와 소양호의 환경이 각기 다르기 때문으로 보여진다. 그러나, 질화작용능은 이 두 곳 수계 환경에서 질화세균 군집의 크기에 영향을 받지 않았다. 요인 분석 결과, 대청호 생태계 상태의 23.7%는 요인 1에 의해 지배되는 데, 이것은 계절에 따른 영양염류의 유입으로 생각되어 진다. 반면에 소양호의 생태계는 계절적 영향(23.8%)을 가장 많이 받는 것으로 생각된다. The Phisico-chemical environmental factors, biological parameters and nitrification rate were investigated 12 times at 4 stations in Daechung Reservoir from Mar. 1992 to Jan. 1994 and 10 times at 2 stations in Lake Soyang from Aug. 1992 to Oct. 1993. And the influences of environmental factors were analyzed by statistical method, such as simple regression, multiple regression and factor analysis. Nitrification activity was detected by ^14 C-dark incorporation method using the N-serve, nitrification inhibitor. And the number of nitrifying barteria were detected by Most-Probable Number(MPN) method. The distribution of ammonia-oxidizing bacteria was from 0.5 to 220 MPN/mL(mean 17.39 MPN/mL) in Dechung Reservoir and from 0.5 to 220MPN/mL(mean 10.88 MPN/mL) in Lake Soyang. The distribution of nitrite-oxidizing bacteria ranged nd∼220 MPN/mL(mean 12.67 MPN/mL) and 0.5∼92 MPN/mL(mean 8.46 MPN/mL) in Lake Soyang. The range of nitrification activity was 0.01∼7.15 ug/L/day(mean 0.57 ug/L/day) in Daechung Reservoir and 0.O1∼2.25 ug/L/day(mean 0.28 ug/L/day) in Lake Soyang. In the case of Daechung Reservoir, nitrification activity showed higher than that in Lake Soyang. The above result showed that pollution of Daechung Reservoir would be higher than that of Lake Soyang. From the result of simple regression, nitrification activity showed correlation with water-temperature(0.485), pH(0.391), dissolved oxygen(-0.485), seston(0.472), Chl-a(0.294), ammonium-N(0.600) in Daechung Reservoir and water-temperature(0.632), pH(0.494), seston(0.294), pheophytin-a(0.355) in Lake Soyang. But the results from the three short-term surveys indicated that the light should be the most important factor in the control of nitrification activity in one day. In multiple regression, nitrification in Daechung Reservoir is much more dependent on ammonium-N(38%), seston(21%), nitrate-N(8%), nitrite-N(3%), whereas nitrification in Lake Soyang was controlled by temperature(40%). This facts showed a distinct difference of environment between Daechung Reservoir and Lake Soyang. However, nitrifying activity was not affected by population size of nitrifying bacteria in both ecosystem. By factor analysis, it was shown that 23.7% of the status of Daechung Reservoir ecosystem was controlled by factor 1, which was supposed to be the seasonal influx of nutrient salt, while factor 1(23.8%) of Lake Soyang was supposed to be the seasonal effect.

소양호 유역으로부터의 총인과 총질소의 유입특성

정창수 江原大學校 大學院 1996 국내석사

Watershed characteristics of population, hydrology, land use, industry, sightseeing, livestock and others were investigated using existing data and through experiments. Water quality data measured at the major inlet of the Lake Soyang between 1990 and 1994 were analyzed with the watershed characteristics to describe total phosphorus(TP) and total nitrogen(TN) loading characteristics from the Lake Soyang watershed. The following results were obtained from the study. 1. Population of the watershed has gradually decreased while campers and tourists rapidly increased during the study period, Untreated city sewage and storm runoff from scattered small cities has burdened a large pollutant load to the Lake Soyang. Numbers of cow and swine have been gradually decreased while poultry and others rapidly increased. Land uses were forests 88.9%, cultivated land 5.3%, building site 0.2% and roads and others 5.6%. 2. TP concentration in inflow was high when the inflow was high in general. TP load, average annual TP concentration, and unit discharge of TP from the Lake Soyang watershed ranged from 104.3 to 108.4 ton/year, 0.031 to 0.050 ㎎/I, and 0.475 to 0.494 ㎏/ha, respectively. 3. TN concentration and inflow did not show a significant correlation. It is shown a trend that TN concentration in inflow was low in the spring and gradually increased to its peak in the late winter. Total TN load, average annual TN concentration, and unit discharge of TN from the _aLake Soyang watershed ranged from 3,894 to 4,313 ton/year, 1.292 to 1.771 ㎎/I, and 17.763 to 19.637 ㎏/ha, respectively. 4. Rational and effective reduction of TP and TN loads from the Lake Soyang watershed are required to improve the lake's water quality. The reduction method must be developed based on the data of water quality and land use, collected from major river branches inflowing to the Lake Soyang for a long time. Once the reduction method was developed, it can be applied to other watersheds to improve respective lake's water quality.

소양호와 대청호에서의 종속영양세균에 의한 질소고정능

이일규 檀國大學校 大學院 1994 국내석사

소양호와 대청호에서 종속영양세균에 의한 질소고정능을 측정하였다. 소양호에서는 1992년 8월부터 1993년 8월까지 2개의 정점에서 총 8 회에 걸쳐 조사하였고 대청호에서는 1992년 8월부터 1993년 5월까지 총 6회에 걸쳐 5개의 정점에서 종속영양세균에 의한 질소고정능을 조사하였다. 소양호의 경우 0 ∼ 520.6μM-ethylene/L/day, 대청호는 0 ∼ 615.2μM-ethylene/L/day 로 측정되었다. 두 호수 모두 겨울철에는 질소고정능이 없는 것으로 나타났다. 이는 통계학적인 분석에서도 온도와 가장 밀접한 관계를 갖는다는 결과와 일치하는 것이다. 소양호에서는 수심이 낮고 조류대발생이 자주 발생하는 상걸리 유역의 정점 2가 소양호의 본류 유역에 해당하는 정점 5보다 높은 질소고정능을 보이고 있으며 정점 5의 하층수는 여름철에도 깊은 수심에의해 수온이 10℃ 정도로 조사되어진 기간 중에 질소고정능이 한번도 측정되지 않았다. 대청호의 경우에는 거의 모든 정점이 비슷한 양상을 보이며 여름철과 봄철에는 표층수가, 가을철에는 하층수가 더 높은 고정능을 나타내는 것으로 관찰되어졌다. 소양호에서 분리되어진 4가지의 균주는 주로 glucose를 탄소원으로 이용할 때 높은 고정능을 보이고 있다. 이들 4가지의 균주들 중 SY-4 균주가 lactose를 이용할 때 432.22±3.11 nM-ethylene/hour/mg-protein으로 가장 높았다. SY-1 균주는 암모늄 이온, 질산 이온, 그리고 glutamine에 의해서 nitrogenase가 switch-off 되어졌다. 그러나 glutamate, threonine, methionine은 switch-off 시키지 못하였다. In situ의 질소 고정능에 대한 암모늄 이온의 영향은 그 농도가 500μM 까지는 큰 영향이 없으나 1mM 부터는 급격하게 억제되었다. 또 더해지는 기질 중 탄소원과 인이 첨가되어지지 않을 때는 질소고정능이 관찰되지 않았고 이온이 제거되었을 때는 대조군에 비하여 약 절반의 고정능이 측정되었다. 따라서 종속영양세균에 의한 질소고정능의 제한 인자는 탄소와 인을 포함하는 유기물일 것이다. The nitrogen fixation potentials by heterotrophic bacteria were investigated 8 times from August 1992 to August 1993 in Lake Soyang and 6 times from the August 1992 to May 1993 in Daechung Reservoir. The potentials ranged 0 ∼ 520.6μM-ethylene/L/d in Lake Soyang and 0 ∼ 615.3 μM-ethylene/L/d in Daechung Reservoir. No nitrogen fixation potentials were measured during winter, which matches the results of the statistical simple regression that they correlate quite positively with temperature. The potential of site 2 located in Sangul-ri was higher than that of site 5 located in the middle of main stream. No potential, however, was detected in hypolimnetic water at site 5 which is thought to be due to the low temperature maintaining 10℃ even in summer season. In case of Daechung Reservoir, there was not large variation among the potentials of various sites. But, epilimnetic water showed higher potential in spring and summer and so hypolimnetic water did in autumn and winter. Four strains of microbe isolated showed high nitrogen fixation potential by using glucose as carbon source. Among those, SY-4 strain showed the highest potential when using lactose. Nitrogenase switch-off phenomenon was occured when SY-2 strain was treated with NH_4, NO_3 or glutamine, but not by glutamine, threonine or methionine. The effect of NH_4 on nitrogen fixation potential was not estimated to be serious with the addition of 500μM of NH_4 but was serious with increasing concentrations of added NH_4 above 1mM. Without carbon or phosphorus source the potential was not detectable and when ions were eliminated it was measured as about half as control. Thus, limiting factors for the nitrogen fixation potential by heterotrophic bacteria are thought to be some organic materials containing carbon and phosphorus.

昭陽湖의 窒化作用과 環境要因에 관하여

강은숙 檀國大學校 大學院 1992 국내석사

소양호의 질화작용과 환경요인에 관하여 미생물학과 강 은 숙 지도교수 안 태 영 1991년 8월부터 1992년 6월까지 7회에 걸쳐 소양호에서 질화작용 및 이에 영향을 미치는 여러 환경요인에 대하여 조사하였다. 질화작용능은 dark incorporation 방법으로 구하였으며, 0.1 - 92.6 ug-N/l/day 의 범위에서 변화하였다. 질화작용능에 영향을 미치는 환경요인을 알아보기 위한 중회귀 분석의 결과는 다음과 같다. 정점 1에서는 질화작용능이 온도, 용존산소에 의해 98%가 설명되고, 정점 2는 chlorophyll-a에 의하여 81%가 설명되었다. 질화작용능이 최고치를 나타낸 정점 3은 상층이 온도에 의해 53%, 암모니아에 의해 28%, 하층은 온도에 의해 80% 설명된다. 정점 4의 상층은 N/P 비와 아질산에 의해 79%가 설명되고, 정점 4의 하층은 온도와 용존산소, 인산염인에 의해 100%가 설명된다. 정점 5의 상층은 N/P 비와 pH, 온도, 암모니아에 의하여 100%가 설명되며, 정점 6의 하층은 인산염 인, pH, 아질산, 암모니아에 의하여 100%가 설명된다. From August 1991 to June 1992, Nitrification Activity and the influences of Environmental Factors on the nitrification activity were investigated for 7 times in the water column of 6 stations in Lake Soyang. Nitrification Activity was detected by dark incorporation method. The range of nitrification activity was 0.1 - 92.6 ug-N/l/day and its average was 18.1 ug-N/l/day. Nitrification activity was strongly affected by temperature than other environmental factors. Influences of envirobmental factors to nitrification activity were analyzed by step-wise regression. Nitrification activity at station 1 could be explained 98% by temperature and dissolved oxygen, suface water of station 2 was explained 81% by chlorophyll-a. Nitrification activity was the highest activity at station 3. Surface and bottom water of station 3 was explained by temperature. Surface water of station 4 was explained 79% by N/P ratio and nitrite-N, bottom water of station 4 was explained 100% by temperature and dissolved oxygen, phosphate-p. Station 5 could be explained 10% by N/P ratio and pH, temperature, ammonia-N and bottom water of station 6 could be explained 100% by phosphate-p, pH, nitrite-N, ammonia-N. Key words : Nitrification Activity Nitrifying bacteria Ammonia-oxidizing bacteria Nitrite-oxidizing bacteria Simple regression Step-wise regression

昭陽湖의 制限水位에 關한 硏究

박종운 忠南大學校 1987 국내석사

本 論文은 域上寫眞測賃에서 撮影基綿長의 變化가 誤差傳播에 미치는 影響을 규명하여 보다 이상적인 影據條件을 제시하기 위한 것이다. P3l測定用 사진기에 依해 얻은 陰晝로 부터 機械座標를 求하고 affine 변환에 의해 寫眞座標를 구해 collinearity condition에 의한 bundle ad-justment로 標定點의 3차원좌표와 標準誤差를 比較 分析함으로써 握影距離에 따른 기선변화가 誤差傳播에 미치는 영향을 直角水平 및 偏心의 경우로 分類하여 考奈하였다. 重複度가 80%에서 70%로 변화할 때 X,Y,2의 標準誤差는 各各 約 9.8%, 24.4%, 30.7%로 감소되며, 70%에서 60%로 변화할 때 X.Y,2의 標準誤差는 5.6 %, 14.8 %, 21.9 %의 감소현상을 나타내므로 기선변화는 淸度解析에 중요한 의미를 가진다. 또 直角水平인 경우 실제 data에 의한 標準誤差는 simulation標準誤差보다 정도가 양호하나 偏心의 경우는 정도가 낮으므로 攝影方法도 정도에 큰 영향을 미친다. 雌上寫眞에서 解情的 方法은 標定에 의한 方法보하 높은 精度의 解析이 能하므로 精密測定을 要하는 各種 構造物의 位置解析에 널리 이용될 것으로 기대된다. This thesis proposed a new restricted water Level for flood season, based on statistical analysis and operation study for the Soyang lake in the Han river . This reservoir has been operated with a joint-use capacity for water conservation, which ranges from EL . 190.3m to EL . 193.5m. The higher level is the top of the conservation pool during the non-flood season, while the Lower is that during the flood season of 3 months from 21s1 June to 20th september. However, this restricted water Level for flood season was not determined by a detailed hydrological analysis, but by rather political judgement. The restricted water Level should be technically adjusted md justified in order to increase the water supply, electric power ·generation, and flood control effects . The rationality of the restricted water Level should be sub=j act o Long-term operation study . An the operation study can be done n the monthly time-horizon, because the data size of short term such as daily flows is not Large enough to provide the consistency f the study. The restricted water Level was identified by monthly operation under the optimal control Law, which was derived in the previous study. And gamma function was accepted as the best fitted distribution f probability density function of flows under the significance Level of 0.05. The difference of variance of flows between the monthly and daily probability density function was evaluated by statistical moment. The corresponding stage difference was read out based on the storage difference between two types of p.d.f. and the restricted later Level for the daily operation was concluded higher than that for the monthly operation at 0.7-0.9 meter. * A thesis sumbmitted to the committee of the Graduate School of Chng-nam National Universtty in partial fulfillment of the requirements he degree of Master of Sctence in Civil Engineering in August,1987.

昭陽湖의 富營養化의 藍藻類 bloom에 관한 硏究

허우명 江原大學校 大學院 1993 국내박사

1. hosphorus loading into Lake Soyang was estimated by determining phosphorus input via runoff of drainage basin and the phosphorus discharge from floating-net fishfarms within the lake. The loading from drainage basin was determined by measuring total phosphorus concentration in the main inflowing stream, Soyang River, from July 1990 to May 1992, Because the total phosphorus concentration and the flow rate of Soyang River was high in flood period, most of phosphorus loading was concentrated in rainy season. Phosphorus discharge of fishfarms was estimated from the amount of fishfeeds applied annually and the unit rate of phosphorus excretion per feed weight. The loading from the watershed and fishfarms were calculated to be 104 and 48 tp/yr, respectively. Both combined, the phosphorus loading of Lake Soyang far exceeded the critical loading for eutrophication. The amount of phosphorus discharge through outflowing water was 62 tP/yr. Thus the retention rate of phosphorus was 0.59. 2. The amount of phosphorus discharge per kg feed from the aquaculture of Israeli carp(Cyprinus carpio) was determined by monitoring the phosphorus discharge in the effluent of culture tanks. 10 brands of the commercial fishfeeds were used in order to examine the relationship between dicharge rate of phosphorus from flsh culture and the phosphorus content of feeds ranging from 1.1% to 2.3%. Phosphorus discharge was higher for feeds of higher P-content and also increased with the feed conversion ratio. The higher phosphorus discharge for feeds of higher P-content was mostly contributed by the increase of particulate phosphorus excretion, whereas dissolved P excretions were at the similar level regardless of P-content. The total phosphorus discharge per kg feed was 8.4 gP for the feed of P-content 1.5% which was the average of the tested commercial carp feeds. 3. To elucidate the mechanism of algal dominance in aquatic system, the effect of algal extracellular excretion upon algal growth was assessed. The filtrates of algal culture were added into medium and the algal growth was compared. Some cyanobacteria showed allelopathy suppressing photosynthesis or growth of orther algae. The filtrate of a cyanobacteria(Anabaena flos-aquae) culture inhibited the growth of two green algae ( Selenastrum capricornutum and Scenedesmus brasiliensis) while the filtrate of Selenastrum capricornutum and Scenedesmus brasiliensis did not inhibit the growth of Anabaena flos-aquae. 4. The trend of eutrophication in Lake Soyang from 1985 to 1990 was studied by the measurement of chlorophyll a concentration, total phosphorus, nitrate-nitrogen. And the cause of the cyanobacterial blooms was studied by fncscenα cell density, frequancy of heterocyst, and NO_(3)-N/TP. After the first advent in 1986 Anαbaenα sp. showed increasing dominancy year by year, which is thought to be enhanced by the increase of phosphorus concentration and the decrease of N/P ratio caused mainly by the phosphorus discharge from fishfarms within the lake. The cyanobacteria blooms in a water without nitrogen depletion is the unique feature of Lake Soyang. Nitrate-nitrogen was maintained always above 0.5 mgN/l throughout the year, though the NO_(3)-N/TP ratio decreased from 100 in 1985 to 50 in 1990 due to the increase of phosphorus concentration, Heterocyst of Anabαenα trichome was not observed from 1985 to 1988 when NO_(3)-N/TP ratios were high. Heterocysts appeared first in 1989 and increased much in 1990. The increase in the heterocyst cell density of Anabaenα was matched with the decrease in NO_(3)-N/TP ratios.

昭陽湖에서 無菌純粹分離된 單細胞 綠藻 Scenedesmus quadricauda의 電子顯微鏡的 微細構造

장정경 이화여자대학교 교육대학원 1982 국내석사

소양호에서 질소동화와 광물화에 영향을 미치는 환경요인에 대하여

전은형 檀國大學校 大學院 1994 국내석사

본 조사 수역인 소양호에서 1992년 9월 부터 1993년 8월 까지 총 9회에 걸쳐 2개 정점에서 물리 화학적 환경 요인과 미생물의 분포 및 활성도에 관하여 조사하고, 이들 요인간의 상관 관계를 분석하기 위하여 회귀 분석을 실시 하였다. 또한 질소 동화능과 광물화능을 장기 연속 관측하여 위와 같이 비교 분석 하였다. 물리 화학적 환경 요인은 계절적으로, 지역적으로 매우 다양 하게 나타 났으며, 미생물 분포 및 활성도의 영향을 미치는 것으로 분석 되었다. 종속 영양 세균의 분포는 2.0 × 10^2 ∼ 1.5 × 10^4 CFU/mL으로 관찰 되었으며, 또한 질소의 동화능의 범위는 0 ∼ 100.55 ㎍-N/L/day에서 변화하였고 광물화능은 0 ∼ 130.29 ㎍-N/L/day의 범위에서 변화하였다. 중회귀 분석에 결과에 의하면 질소 동화능은 상충수의 경우에는 모든 정점에서 온도의 영향을 가장 많이 받는 것으로 나타났으며 하층수의 경우에는 무기 이온과의 상관관계를 나타내고 있다. 광물화능은 전체적으로 수온과 pH에 높은 의존도를 나타내고 있다. 일반적으로 이전의 연구는 암모니아 염의 동화율이 높은 것으로 나타났으나 본 실험에서 소양호의 질소원의 이용도를 관찰한 결과 질산염 질소의 동화율이 높은 것으로 나타났다. From September 1992 to August 1993, boilogical and physico-chemical environmental factors were investigated 9 times at 2 sites in the surface and bottom area of Lake Soyang. In order to understand the correlation between these factors, we executed simple and multiple regression with investigated data. Also by calculationg the rate of nitrogen assimilation and mineralization in Lake soyang, we have compared these values with the environmental capacity of Lake Soyang. Seaeonal variation of physico-chemical environmental parameters had influenced bacterial activity. Heterotrophic bactera ranged from 2.0×10^2 to 1.5×10^4 CFU/ml, ammonia assinmilation rate 0 to 100.55 ㎍ -N/L/day, mineralization rate 0 to 130.29 ㎍-N/L/day. In multiple regression, the results suggest that the ammonia assimilation rates depended on temperature at surface of all sites while bottom sites are strongly affected by inorganic ion. Influences of temperature and pH to mineralization rate were analyzed by step-wise regression. Generaly, ammonia mitrogen uptake is higher than nitrate nitrogen according toseveral investigators, but this stydy indicates that the uptake of nitrate nitrogen was higher than the uptake of ammonia nitrogen.

昭陽湖의 富營養化와 藍藻類 Bloom에 관한 硏究

허우명 江原大學校 1993 국내박사

昭陽湖에서의 藻類의 季節的 遷移와 制御方法

이창호 建國大學校 産業大學院 1992 국내석사

This is a study on the seasonal succession of algae specles and control technology in lake Soyang, KanywonDo, Korea. The survey was performed by the physico-chemical, microbiological analysis and biological experimentation for fifty days from May16, 1990 to may 25, 1991. The results obtained from the study are as follows. 1) This diatoms were replaced by dinoflagelfates (Peridinium sp) in late spring and blue-green algae (Anabaena planktonica) succeeded the dinoflagelfates in summer. The diatoms that dominated in spring reduced in automn. 2) Yearly variations of algal biomass at bay of lake Soyang (KangwonDo Yanggugun Seokhunri) showed high growth ammount up to 103 mg/㎥ as chlorophyll .a concentration from may to August when peridinium and Anabaena grew abundant tv and low growth ammount from autumn to next spring when diatoms dominated. 3) On the occurrence of a red tide by peridlnium in Soyang Lake the relation in quantity of TN/TP shows high from 13 to 42 when the average quantity of chlorophyll.a is 50 mg/㎥ or more. 4) In Sovang Lake, on the occurrence of a water blooms by Anabaena planktonica the relat iou in quant ity of TN/TP is that the average Quantity of chlorophyll.a is under 50 mg/㎥ and the ratio of TN/TP varies from 10 to 50. 5) The format ion of strat ificat ion in Soyang Lake is made up in the depth of 50M below the surface of water body. therefore, in the depths of that and downward, it seems that circulation of water is not real iged and overturning in the depths is considered being carried out slowly over a long period of time. 6) The method of getting rid of peridinium which is the cause algae of a red tide in Soyang Lake is taking advantage of phototaxis which is the special character of this algae. We remove it by pilling up peridinium to the surface by means of driving light into the upper part of a water tank in the process of making use of water or can think over the method of repressing generation of algae by shading the light.