• Journal of Plant Biology
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• v.29 no.2
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• pp.117-127
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• 1986

Phytoplankton community was investigated at the Paldang Dam Reservoir in the Mid-Han River by it's depth, in spring and summer known as the period of phytoplankton's blooming. It was only in summer that phytoplankton bloomed at the investigated area. 128 kinds of phytoplankton were identified and of them, diatoms were abundunt in spring but cyanophyta and chlorophyta were in summer. Because some species with high pollution index were observed in summer, it could be proved that the investigated area was polluted especially in summer. In spring shown the circulation period by vertical distribution pattern of chlorophyll-a and isothermal distribution pattern of water temperature, maximum value of phytoplankton standing crops appeared at the upper layer, except for surface layer. In summer shown the circulation period after the stagnation period by vertical distribution pattern of chlorophyll-a and immediate destruction after stratification of water temperature, maximum value of phytoplankton standing crops appeared at the lower layer. the layer at which the maximum value of chlorophyll-a appeared also accorded with that of phytoplankton standing crops. So, it could be approved that there existed a close relationship among phytoplankton standing crops, chlorophyll-a, and water temperature.

• Journal of Life Science
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• v.21 no.8
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• pp.1183-1189
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• 2011

The present study is aimed at examining the effects of the physico-chemical environmental factors of water systems on water bloom at Homin and Gagok reservoirs in Pungcheon-Myeon, Andong, Gyeongsangbuk-do. The mean water temperature and the contents of chlorophyll-a, total-nitrogen, total-phosphorus and phosphate-phosphorus were higher at the Gagok reservoir. On the other hand, the pH mean value was higher at the Homin reservoir. The mean value of microelements (Na, K, Mg, Fe, Si) was higher at the Gagok reservoir. The cyanobacteria which was considered to be the cause of water bloom at the two reservoirs was Microcystis aeruginosa. It started to grow in May and showed the highest standing crop in August. Between the increase of standing crop of M. aeruginosa and the water quality, correlation values of $Na^+$ (r=-0.910, p<0.05), $Fe^{2+}$ (r=-0.855, p<0.05) and $Si^{4+}$ (r=0.989, p<0.01) at the Homin reservoir increased amount of standing crop. Meanwhile, at the Gagok reservoir, the contents of $Na^+$ (r=-0.776, p<0.05), $Si^{4+}$ (r=0.899, p<0.05) were highly related to the increase of standing crop. Interestingly, Si, which is the limiting factor for diatoms, has a high correlation with standing crop of cyanobacteria. In conclusion, the water blooming is caused not by a simple factor but a synergistic effect due to complex actions including high concentrations of nitrogen and phosphorus ions and many other environmental factors.

• Korean Journal of Ecology and Environment
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• v.56 no.2
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• pp.127-139
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• 2023

Daechung Reservoir has been suffering from severe cyanobacterial blooming periodically due to the water pollutants from the watershed, especially nutrients from nonpoint sources. As a countermeasure, an artificial wetland was constructed to mitigate the pollutant load from the watershed by utilizing the vegetation. We investigated the water quality of the influent and outflow of the wetland during years 2014~2020 to evaluate the performance of pollutant removal through the wetland. Major pollutants (e.g. BOD, COD, SS, T-N, and T-P) were largely reduced during the retention in the wetland while nutrients removal was more efficient than that of organic matters. Pollutant removal efficiency for different inflow concentrations was also investigated to estimate the wetland's capability as a way of managing nonpoint sources. The efficiency of water treatment was significantly higher when inflow concentrations were above 75^th percentile for all pollutant, implying the wetland can be applied to the pre-treatment of high pollution load including initial rainfall runoff. Furthermore, the yearly variation of removal efficiency for seven years was analyzed to better understand long-term trends in water treatment of the wetland. The annual treatment efficiency of T-P was very high in the early stages of vegetation growth with high concentration of inflow water. However, it was confirmed that the concentration of inflow water decreased, vegetation stabilized, and the treatment efficiency gradually decreased as the soil was saturated. The findings of the study suggest that artificial wetlands can be an effective method for controlling harmful algal blooms by alleviating pollutant load from the tributaries of Daechung Reservoir.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.503-509
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• 2005

The growth characteristic of a predominant planktonic blooming species, Mallomonas elongata in a small shallow eutrophic pond was investigated In the field (from October 2004 to September 2005) and laboratory, Dense blooming (max. 17,600 cells $mL^{-1}$) of this silica-scaled chrysophytes was observed for a short time period in early spring (water temperature 12-$18^{\circ}C$ and pH 8.4-9.5), The growth characteristics of M. elongata isolated from this pond was investigated at various temperatures and pH under batch culture. The unialgal culture of M. elongata showed maximum growth rate (${\mu}max$) at $15^{\circ}C$ similar to the natural conditions. However, the optimal pH of the isolated batch culture was lower than the pond water pH at which M. elongata appeared in large population density.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.231-233
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• 2002

The potential of calcium peroxide to act as an agent for waterblooming control was In-vestigated by examining the growth inhibition of Microcystis aerusinosa. Due to the chemical nature of calcium peroxide, it can remove dissolved phosphate by forming an Insoluble precipitate, generating radicals, coagulant, and oxygen as byproducts as it dissolves in water. The growth of M. aerusinosa was severely inhibited and the chlorophyll-n concentration was drastically decreased in the presence of calcium peroxide. With 200 ppm of calcium peroxide dosage, a chlorophyll-a concentration of 1,700 mg/m$^3$ was lowered to below 10% of its initial concentration after 4 days. One possible explanation for this growth Inhibition is the removal of the available phosphate by calcium peroxide.

• Environmental Engineering Research
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• v.22 no.1
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• pp.1-11
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• 2017

One of the most threatening consequences of eutrophic freshwater reservoirs is algal blooming which typically occur after the long a mega drought or/and irregular rainfall under influence of climate change. The long-term experiences of chemical treatment are known as a most practical effort to reduce health concerns from human exposure of harmful cyanobacteria as well as to preserve ultimate freshwater resources. Even though these conventional chemical treatment methods do not completely solve the algal residue problem in water treatment plant or directly in the water bodies, they still have big advantages as fast and efficient removal process of cyanobacteria due to cheaper, easier to manage. This review summarizes their chemical treatment scenarios of the representative coagulants, pre-oxidants and algaecides composed to chemical compounds which immediately may help to manage severe cyanobacteria blooms in the summer seasons.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.95-95
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• 1995

This study was carried out to evaluate the variations of headloss rate and of specific deposit to depths with effective size of media and configuration of filter layer during algae blooming period. 0.51mm size media was disqualified because most of headloss occurred rapidly below 5cm from surface layer however 0.91mm size media acted deep filtration more than 20cm from top, as result 0.91mm sixte media filter had 2∼3 times longer filtration time than 0.51mm sixte media filter, but 0.91mm size media have break-through potentiality. multi-layer filter with 1.02mm anthracite and 0.51mm sand had large deposit volume in upper layer that could longer filtration time, moreover smaller media in lower layer that could protect break-through.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.299-307
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• 2000

To understand the mechanism of phytoplankton succession in the Nakdong River, the resource availability (silica) and grazing effect on the phytoplankton community were investigated in an enclosure experiment at Mulgum in March 1995. In all enclosures, Stephanodiscus hantzchii was dominant during the first week. Two weeks later, the diatom community in the A (river water only) and B (filtered river water) enclosures was shifted to colonial green algae (Actinastrum sp., Pediastrum spp. and Scenedesmus spp.) and nanoplankton (2~3 ${\mu}$m of diameter) due to the silica depletion. In the C (silica addition in river water, 3 mg 1$^{-1}$ week$^{-1}$) and D (silica addition in filtered water) enclosures, Fragilaria crotonensis and Synedra acus increased as the silica addition was continued. The percentage of small phytoplankton (size, 10~13 ${\mu}$m) in the filtered enclosures (B and D) was much higher than that of A and C enclosures. A laboratory bottle experiment conducted in the fall of 1994 also showed similar results. Therefore, it is concluded that silica and zooplankton are important regulators in phytoplankton succession during the diatom blooming season in the Nakdong River.

• Journal of Plant Biology
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• v.34 no.2
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• pp.165-173
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• 1991

Subtidal algal communities of lnchon Dock, an enclosed artificial dock in the western coast of Korea, were investigated qualitatively and quntitatively. Assessments of species composition, biomass rlominant species, and vertical distribution were conducted from January to December, 1990. Duf"16 the study, benthic marine algal community was disturbed completely by water blooming in June, and was recolonized from July. Forty-five species of marine algae, 18 blue green. 13 green. 6 brown, and 8 red algae, were identified as results. Mean biomass was in ranges of $53.50-118.00\;g-dry\;wt/m^2$ in community before disturbance and $0.57-2.62\;g-dry\;wt/m^2$ after it. Dominant species determined by biomass and frequency were Polysiphonia m0\ulcorner7owii and Ceramium fastigiramosum before disturbance, while Lyngbya semiplena, Lyngbya lutea and Lyngbya rivulariarum after disturbance as pioneer colonizers.nizers.

• Journal of Plant Biology
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• v.17 no.2
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• pp.53-62
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• 1974

A study was made on the primary production of Lake Changjamot during the spring season of 1973 by menas of the oxygen method. The stratification of temperature and dissolved oxygen were formed in May with the stratified structure of phytoplankton. The range of Secchi disc transparency was from 0.8m to 2.3m during the nine months of this investigation, which was begun in January, 1973. The value was lowest in early June when the phytoplankton blooming reached the peak. The concentration of PO4-P, NH3-N, NO3-N and NO3-N was reduced at the beginning of the phytoplankton blooming and increased again after May except PO4-P. It might have been caused by the inflow of the nitogenous fertilizer from the surrounding agricultural area since May when farming was started. The total amount of chlorophyll-a in the entire water column varied from 25mg/$m^2$ to 277mg/$m^2$ from January till September with the maximum value occurring in early June. These values show a considerable eutrophication of the in comparison with the data obtained in 1969. The daily gross production in the lake varied from a low of 655mgC/$m^2$ to a high of 2,859 mgC/$m^2$ during the spring season and this corresponds to the variation of the amount of chlorophyll. The total amount of daily respiration varied from 650mg C/$m^2$ in winter to 2,307 mg C/$m^2$ in late spring and exceeds gross primary production especially in late May showing the negative balance of daily production and consumption of organic material at that time. In conclusion, Lake Changjamot is a fairly productive and a moderately autotrophic lake and has been eutrophicated much during the past four years.