• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.64-69
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• 2004

Growth inhibition of Microcystis aeruginosa was examined with single-or mixed treatment of algicidal bacterium Streptomyces neyagawensis and heterotrich ciliate Stentor roeseli, which isolated from natural freshwater. The harmful Cyanobac-terium, Microcystis aeruginosa density was effectively suppressed by the algicidal bacterium Streptomyces neyagawensis, and the bacterial biomass was few changed. The heterotrich ciliate S, roegeji isolated from the eutrophic Pal'tang riverine, Korea suppressed the algal biomass effectively. But mixed-treatment of both bio-agents was less effective, leading to an increase in algal density.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.512-517
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• 2007

The limiting nutrient of eutrophication in freshwater bodies in Korea was examined and the phosphorus concentration standard for sewage treatment effluent was discussed. The weight ratio of N/P in 13 major reservoirs showed the range of 18 to 163, which implies phosphorus is more limited than nitrogen for algal growth. In the correlation analysis phosphorus showed higher correlation with chlorophyll-a concentration than with nitrogen. In the algal bioassay phosphorus spike test enhanced algal growth in all 25 samples of five reservoirs, while nitrogen was found to co-limit only in four samples. It confirms that phosphorus is the only limiting nutrient for eutrophication in Korean reservoirs. As many reservoirs are eutrophic in Korea, phosphorus control is critical for the management of water quality. The phosphorus standard of sewage treatment effluent in Korea was compared with other countries, and it can be concluded that phosphorus standard is too high to be effective in eutrophication control and a lower phosphorus standard is essential for the water quality improvement.

• ALGAE
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• v.29 no.4
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• pp.311-319
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• 2014

The biocide sodium hypochlorite (NaOCl) is widely used for controlling algal growth, and this application can be extended to marine environments as well. This study evaluates the biocidal efficiency and cellular toxicity of NaOCl on the harmful dinoflagellate Cochlodinium polykrikoides, with emphasis on pigment production and antioxidant enzyme activity. The test organism showed dose-dependent decrease in growth rate on exposure to NaOCl, and the 72 h $EC_{50}$ was measured to be $0.584mg\;L^{-1}$. NaOCl significantly decreased pigment levels and chlorophyll autofluorescence intensity, indicating possible detrimental effects on the photosystem of C. polykrikoides. Moreover, it significantly increased the activities of antioxidant enzymes, suggesting the production of reactive oxygen species in the cells. These data indicate that NaOCl exerted deleterious effects on the photosynthetic machinery and induced oxidative damage in the dinoflagellate and this biocide could be effectively used for the control of algal blooms.

• KCID journal
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• v.18 no.1
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• pp.33-43
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• 2011

Jundae reservoir has basin area of 234ha, average depth of 3.77m and total storage of $619{\times}10^3m^3$, and is located in Dangin-gun, Chungcheongnam-do. The water quality of Jundae reservoir exceeded the IV grade of water quality standard as available for irrigation water in COD, TN, TP, Chl-a. COD and Chl-a were higher in spring season, because the algal bloom by phytoplankton increased. And the algal blooms in October by inflow non-point pollution during summer rainy season. The most dominant zooplankton was rotifers during study period at all stations. Dominant species were Keratella cochlearis, Polyarthra spp., and Trichocerca spp. We successfully established 2 isolated clone cultures as predator. One is Rotifer, Euchlanis sp. and another is cladocerans, Bosmina sp. To test the removal rate of 2 cultures against Microcystis aeruginosa, we inoculated Euchlanis sp. and Bosmina sp. separately when the abundance reached at $1.0{\times}10^6$cells/ml. Euchlanis sp. removed M. aeruginosa around 98.9% and Bosmina sp. removed it around 98.4%. They are useful grazers for controling algae blooms, Euchlanis sp. and Bosmina sp. feeding on M. aeruginosa highly.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.558-566
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• 2018

The objective of the study was to determine nutrition regime and limitation in the Boryeng Reservoir where there's a water tunnel between Geum River and the reservoir. Evaluation was conducted through in situ algal bioassay experiments (in situ ABEs) using the cubitainer setting in the reservoirs. For in situ ABEs, we compared and analyzed variations in chlorophyll-a (CHL-a) and phosphorus concentrations in Boryeong Reservoir before and after the water tunnel construction. We then analyzed the nutrient effects on the reservoir. Analysis for nitrogen and phosphorus was done in the three locations of the reservoir and two locations of the ABEs. The in situ ABEs results showed that phosphorous and Nitrogen, the primary limiting nutrient regulating the algal biomass was not limited in the system. The treatments of phosphorus or simultaneous treatments of N+P showed greater algal growth than in the control of nitrate-treatments, indicating a phosphorus deficiency on the phytoplankton growth in the system. The water from the Geum River had 5 times higher total phosphorus (TP) than the water in the reservoir. Efficient management is required as pumping of the river water from Geum River may accelerate the eutrophication of the reservoir.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.431-438
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• 2007

This study was to test algal removal efficiency by top-down fish biomanipulation experiments in the laboratory during Agust${\sim}$September 2000. We selected eight candidate fishes for the biomanipulation. We set up the experiments of eight fish-treatment tanks (3${\sim}$6 fishes) with initial chlorophyll-${\alpha}$ concentrations (CHL-${\alpha}$) of $100{\sim}120{\mu}g\;L^{-1}$ and one control tank including no fish with the same initial CHL-${\alpha}$. All tanks were maintained water quality of dissolved oxygen $(5.3{\sim}8.2mg\;L^{-1})$ and pH $(7.4{\sim}8.1)$ in the tests. During the biomanipulation, DO and pH in the treatments were lower than those of the control, while conductivity increased gradually in the treatments. Biomanipulation experiments showed that CHL-${\alpha}$ increased 13% and 0% (mean values of 8 fishes) in the controls and treatments, respectively. These results indicate that algal growth was maintained in the control and fish treatments, but the rate of CHL-${\alpha}$ in the treatments was lower than that of the control. The removal rates of bluegreens algae decreased 32% in the control, and 20% in treatments (mean values of 8 fishes) respectively, In other words, bluegreen algae showed greater growth rate in the fish treatments than the control and this was due to higher nutrients supplied from fish excretions. Overall, simple fish biomanipulation on algal control was not effective at all in these laboratory tests.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.267-274
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• 2022

This paper is a result of research conducted on the 800,000 m³/d capacity of A Water Treatment Plant (WTP) and 400,000 m³/d capacity of B WTP plant in operation in the Nakdong River region. We evaluated the effect of algae broom on the WTP operation based on the running data of both WTP and the data on the pre-oxidation process field test for algae control using sodium permanganate (SPM) at the B WTP. The study results showed that during the algal bloom period, the coagulant dose increased by 102% in A WTP and 58% in B WTP, respectively, and the chlorine dose also increased by 38% and 29%, respectively, which may affect Total trihalomethane (THM) production. Data such as algal populations and Chl-a, residual chlorine and THM, algal populations, and ozone dose appeared also highly correlated, confirming that algal broom affects WTP operations, including water quality and chemical dosage. As a result of the field test of B WTP, THMs appeared lower than that of the control, suggesting the possibility of the SPM pre-oxidation process as an alternative to algae-related water quality management. Furthermore, in terms of GHG emissions due to energy consumption, it was observed that the pre-oxidation process using SPM was approximately 10.8%, which is a very low ratio compared to the pre-ozonation process. Therefore, these results suggest that the SPM pre-oxidation process can be recommended as an alternative to low-carbon water purification technology.

• Journal of Korean Society on Water Environment
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• v.33 no.4
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• pp.441-448
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• 2017

Microcystis aeruginosa (M. aeruginosa) is a cyanobacterium species that can form harmful algal blooms in freshwater bodies worldwide. The use of Artemisia asiatica extracts to control M. aeruginosa inhibition will be environmentally friendly and promising. Artemisia asiatica extracts removed successfully upto 88% of M. aeruginosa pH 8 at $25^{\circ}C$ of temperature. These results was indicated that the amount of 2.24 g/L Artemisia asiatica extracts was removed 1g dryweight/L of M. aeruginosa. The kinetic data showed substrate inhibition kinetics and maximum growth rate was obtained when the M. aeruginosa was grown in medium containing 2.5 g/L of initial concentration of Artemisia asiatica extracts. In the various growth control models, Luong model showed the highest correlation coefficient of 0.9916. Therefore, the Luong model was the most suitable control model for the growth control of M. aruginosa using Artemisia asiatica extracts. In conclusion, the growth control of M. aruginosa using Artemisia asiatica extracts can be applied in the field without controlling the temperature and pH of rivers and streams, and it is possible to control the growth of M. aruginosa efficiently in a short time. The natural extract, Artemisia asiatica extracts, can be a promising inhibition due to its high efficiency and low dose requirements.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.7
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• pp.1047-1053
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• 2006

The current study was designed to determine the effects of dietary docosahexaenoic acid (DHA) on fatty acid deposition in egg yolk and various tissues of laying Tsaiya ducks, and on the mRNA concentrations of hepatic lipogenesis-related transcription factors. Thirty laying ducks were randomly assigned to three treatments with diets based on corn-soybean meal (ME: 2803 kcal/kg; CP: 17.1%; Ca: 3.4%) supplemented with 0% (control diet), 0.5% or 2% algal DHA oil. The DHA content in egg yolks of the ducks was elevated significantly (p<0.01) with the supplementation of dietary DHA. The DHA percentage of the total fatty acids in the egg yolk of laying ducks was 0.5%, 1.3% and 3.4% for 0%, 0.5% and 2% algal DHA oil treatments, respectively, for the $1^{st}$ week, and 0.5%, 1.5% and 3.3% for the $2^{nd}$ week. Therefore, algal DHA oil can be utilized by laying Tsaiya ducks to enhance the egg-yolk DHA content. The concentrations of triacylglycerol (TG) and cholesterol in plasma of laying Tsaiya ducks were not affected by dietary DHA treatments (p>0.05). The DHA concentration in plasma, liver, and skeletal muscle was increased with the addition of dietary algal DHA oil (p<0.05). The mRNA abundance of sterol regulatory element binding protein 1 (SREBP1) and SREBP2 in the livers of laying Tsaiya ducks was not affected by dietary DHA, suggesting that the expression of these transcription factors is tightly controlled and not sensitive to DHA treatments.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2003.06a
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• pp.135-136
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• 2003