• 한국물환경학회지
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• 제31권2호
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• pp.110-119
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• 2015

The construction of the eight large weirs in the Nakdong River, the second largest river in Korea, caused big changes in the physical environment of the water system. Algal communities and their correlations with environmental factors, mainly nutrients were studied at five weir areas in the Nakdong River from 2010 to 2013. Water quality, hydrodynamics and algal composition were investigated. Results showed that flow velocities were reduced compared with that before weir construction near the areas where are located in the mid and upstreams of the Nakdong River. A seasonal algal community succession was observed and it was mainly correlated with temperature and phosphorus. Diatoms were dominated from winter to spring months and massive diatomic blooms of Stephanodiscus sp. occurred early in March during survey period. Cyanobacterial blooms of Microcystis sp. occurred from July to September 2013 and was preceded by the lower total phosphorus concentration of $0.05mg\;L^{-1}$. The correlations between total phosphorus concentrations and algal abundances were not significant during the survey periods. However, significant correlation with cyanobacteria was found in the period of weir construction after only at the GG survey site and blooms periods of 7 times in the survey sites, and its correlation coefficients were 0.53 (p<0.001) and 0.42 (p<0.01) respectively. When algal bloom was observed, partially low nutrient concentration was observed in the Nakdong River. In conclusion, partially low nutrient concentration which may result from algal bloom was observed, and we presume it caused the reduction of algal abundunces.

• ALGAE
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• 제22권4호
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• pp.297-304
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• 2007

This study is intended to clarify the effects of heated effluents on intertidal benthic marine algal community in Korea. The species composition and biomass of marine algae at the discharge canal of Gori nuclear power plant on the southeastern coast of Korea were investigated seasonally from February 2001 to October 2006. As a result, 54 species (7 blue-green, 12 green, 9 brown and 26 red algae) of marine algae were found at the discharge canal during the past six years. In general, the number of species observed was abundant during winter to spring and less in autumn. Enteromorpha compressa, E. intestinalis, E. prolifera and Caulacanthus ustulatus were common species found more than 80% frequency during the study period. Seasonal fluctuations of mean biomass were 1-440 g dry wt m–2 and dominant species in biomass were Enteromorpha spp. (contribution to a total biomass proportion 28%), Sargassum horneri (14%) and Amphiroa beauvoisii (14%). It is evident from the floristic composition and biomass data that unique micro-environment of the discharge canal support different communities from those on the intake or control area. Results from the large numbers of surveys before and during plant operation showed that, in the regions influenced by thermal effluents such as the discharge canal of power plants, the process of ecological succession has been proceeded. It is assumed that the uni-directional water flow and the time of overhaul largely affect the development and succession of benthic marine algal communities of the discharge canal.

• 한국환경과학회지
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• 제10권4호
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• pp.259-267
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• 2001

Investigations were carried out to observe the seasonal succession of phytoplankton, and viable counts of bacteria from the mid to lower reaches of Nakdong Fiver. An intensive monitoring was conducted from May to December 1999 biweekly at 6 sites in a main channel and 3 tributaries. Although there are several sites with high nutrient loading from the basin, all of study sites showed mesotrophic states owing to high discharge(June~September). Relatively low algal biomass and CFUs(mean of chi. a, $12.3{\pm}$11.5 $\mu\textrm{g}${\el}l$, CFUs : 1.8${\times}10^7$) were observed during the rainy season. The diatom population was dominant(over 85% of total community) year-long with peaks(Stephanodiscus hantzchii) in the fall and winter. Dominance of blue-green algal groups during the summer was not observed in the summer. Microorganisms peaked in the summer and fall(June~September), affected mainly by the inputs of phytoplankton and nutrients. Biomass of phytoplankton and CFU counts were higher in the Kumho River than other tributaries and main channel.

• 환경생물
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• 제28권1호
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• pp.20-29
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• 2010

Cochlodinium polykrikoides has occurs regularly during the summer in the South Sea of Korea. To investigate photosynthetic pigments concerned with phytoplankton community structure as bloom of Cochlodinium polykrikoides, the experiment was sampled at 20 stations three times between July and September 2002 in the Southern Sea of Korea. The distribution of peridinin, the biomarker of dinoflagellate, was higher at the blooming time than it was before and it disappeared after bloom. The correlative coefficients between Chl. a and peridinin at the blooming time and out of bloom were 0.9253 and 0.1613, respectively. This result indicated that the bloom was caused by dinoflagellate. The correlative coefficients between Chl. a and fucoxanthin were 0.3282 and 0.9759, respectively, and the correlative coefficients showed the succession from dinoflagellate to diatom. This result means that the bloom of Cochlodinium polykrikoides can be detected by Chl. a information from satellite remote sensing. Therefore, if the algorithm to detect peridinin in addition to Chl. a were to be developed, dinoflagellate red tide could be monitored more effectively.

• 한국물환경학회지
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• 제27권4호
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• pp.413-424
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• 2011

The study was aimed to evaluate the applicability of a three-dimensional (3D) hydrodynamic and water quality model, ELCOM-CAEDYM for Yongdam Reservoir, Korea. The model was applied for the simulations of hydrodynamics, thermal stratification processes, stream density flow propagation, and water quality parameters including dissolved oxygen, nutrients, organic materials, and algal biomass (chl-a) for the period of June to December, 2006. The field data observed at four monitoring stations (ST1~ST4) within the reservoir were used to validate the models performance. The model showed reasonable performance nevertheless low frequency boundary forcing data were provided, and well replicated the physical, chemical, and biological processes of the system. Simulated spatial and temporal variations of water temperature, nutrients, and chl-a concentrations were moderately consistent with the field observations. In particular, the model rationally reproduced the succession of different algal species; i.e., diatom dominant during spring and early summer, after then cyanobacteria dominant under warm and stratified conditions. ELCOM-CAEDYM is recommendable as a suitable coupled 3D hydrodynamic and water quality model that can be effectively used for the advanced water quality management of large stratified reservoirs in Korea.

• 한국환경보건학회지
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• 제24권3호
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• pp.131-136
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• 1998

Attached algal community and several physico-chemicai characters were investigated at Seokjong hot spring in Chollabukdo in February and in April, 1997. The results of physico-chemicai factors are as follows : water temperatures were varied from 6.5$^{\circ}$C to 32.0$^{\circ}$C; pH range was 6.9 to 7.7; The levels of electric conductivity were 105 $\mu$mhos/cm to 477 $\mu$mhos/cm; chemical oxygen demand(COD) range was 1.5 mg/l to 21.2 mg/l; ammonia concentration was 0.20 mg/l to 8.74 mg/l; nitrate concentrations were 0.36 mg/l to 2.43 mg/l; phosphate concentration was N.D. to 0.52 mg/l; sulfur concentration was 14.6 mg/l to 66.1 mg/l. Attacched algal species were identified. Totally, 63 taxa were classified and composed of 4 phylum, 4 class, 10 order, 17 family and 31 genera. The total biomass of attacched algae was $1.036 \times 10^{7}$ cells/l that composed of $5.39 \times 10^{6}$ cells/l of blue-green algae, $4.05 \times 10^{6}$ cells/l of diatom and $0.93 \times 10^{6}$ cells/l of green algae. The succession of dominant species was Synechocystis thermalis. This could be due to the thermal wastewaters. in biotic indices tests, the values of dominance index(DI) were 0.33 to 0.67 in winter, 0.18 to 0.68 in spring. The values of diversity index(H') were 1.44 to 2.69 in winter, 1.62 to 2.89 in spring. And the values of eveness index (J) were 0.31 to 0.61 in winter, 0.37 to 0.65 in spring.

• 생태와환경
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• 제38권2호통권112호
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• pp.181-187
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• 2005

한강 중하류의 남조류 및 환경요인의 연간변화 (2000 ${\sim}$ 2003)를 파악하기 위하여, 2000년 4월부터 2003년 10월까지 4년간 성수대교에서 성산대교까지 총 5개 지점을 선정하여, 수계의 기초환경요인 및 식물플랑크톤 현존량 변화를 조사하였다. 조사기간 동안, 남조류의 현존량은 점차적으로 감소하여 장기간 강우가 가장 많았던 2003년에는 거의 관찰되지 않았으며, 총 식물플랑크톤 현존량에 대한 남조류의 기여도는 약 10%범위내였다. 이러한 현상은 매년 강우집중기 동안 팔당댐으로부터 많은 방류수가 유입됨으로서 수온감소는 물론 광량감소, 영양염류 희석 등에 의한 남조류의 성장이 제한된 것으로판단되며, 동일시기에 다른 조류 (녹조, 규조 등)의 높은 성장으로 엽록소 a와 식물플랑크톤 현존량이 뚜렷하게 증가하였다. 따라서 한강 하류의 고온기 동안 남조류 성장은 잦은 강우와 방류에 의해 제한을 받지만 규조나 녹조와 같은 다른 조류들의 높은 성장으로 대치되는 천이현상을 보였으며, 기후영향을 크게 받는 전형적인 하천생태계의 특성을 나타냈다.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2001년도 Proceedings of the 3rd Annual Meeting of Yellow Sea Environment
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• pp.19-29
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• 2001

Nutrients are key environmental factors in marine ecosystem. They limit algal growth when at low concentrations and cause algal bloom when at high contents. They also control the growth and succession of many other biota including bacteria and zooplankton, either directly or indirectly. Nutrient contents therefore affect both the structure and functions of marine ecosystem. To study the contents and distribution of nutrients in Chinese Bohai Sea, two cruise surveys were undertaken in August 2000 (summer) and January 2001 (winter), respectively. A total of 595 water samples were collected from 91 sites. After collection the samples were transported to the laboratory and five nutrients, i.e., nitrate, nitrite, ammonia, phosphate and silicate, were analyzed. The results showed that tile average concentration of total inorganic nitrogen (TIN) in Bohai Sea in winter (6.5293.717 ${\mu}$mol$.$l$\^$-1/) was significantly higher than that in summer (3.717 ${\mu}$mol$.$l$\^$-1/). The phosphorus concentration in winter (0.660 ${\mu}$mol$.$l$\^$-1/) was also significantly higher than that in summer (0.329 ${\mu}$mol$.$l$\^$-1/). Mean silicate concentration in winter (7.858 ${\mu}$mol$.$l$\^$-1/) was not significantly different from that in summer (7.200 ${\mu}$mol$.$l$\^$-1/). Nutrients also varied considerable among different areas within Bohai Sea. TIN concentration in Laizhou Bay (4.444 ${\mu}$mol$.$l$\^$-1/), for example, was significantly higher than those in Bohai Bay (2.270 ${\mu}$mol$.$l$\^$-1/) and Bohai Straight (2.431 ${\mu}$mol$.$l$\^$-1/), which probably reflects tile discharge of large amounts of nitrogen into Laizhou Bay via Yellow River. The nutrients also showed vertical distribution pattern. In summer, nutrients in bottom layer were generally higher than those in surface and medium layers. In winter, however. nutrients in different layers were not significantly different Compared with historic data, TIN contents increased continuously since early 1980s, phosphorus arid silicone contents, nevertheless, fell down to some degree. Based on atomic ratios of different nutrients, nitrogen is still the main limiting factor for algal growth in Bohai Sea.

• 생태와환경
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• 제40권1호
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• pp.121-129
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• 2007

본 연구는 부영양 저수지에서 남조류의 발달과 천이에 영향을 미치는 요인들과 그 결과를 평가하기 위하여, 2003년 3월부터 2004년 2월까지 현장 조사를 통하여 남조류 종조성과 밀도변화, 침전특성, 퇴적물 특성을 분석하였다. 또한 인, 수온, 광도를 달리한 조건에서의 남조류 성장률을 비교하였다. 식물플랑크톤은 봄철(3${\sim}$4월)에 규조류와 편모조류가 우점한 시기를 제외하고는 연중 남조류가 우점하였고, 7월과 11월에 높은 밀도 증가가 관찰되었다. 남조류 우점기간 중 5월에는 Oscillatoria spp., 6월에는 Aphanizomenon sp.이 우점하였고, 7월부터 11월까지는 Microcystis spp.가 우점종으로 나타났다. Oscillatoria spp.가 우점하고 침강율이 높았던 5월에는 수온, 광도 그리고 TN/TP비가 높았던 반면, Microcystis spp.가 우점한 7월부터 11월까지의 TN/TP비는 상대적으로 낮은 범위 (평균 27)를 보였다. 침강속도는 규조류가 우점한 3월 가장 높았고, 남조류의 우점종 기간 중에서는 5월과 10월이 다른 시기와 비교할 때 빨랐다. 퇴적물의 C/N비는 $6{\sim}8$의 범위였고, 간극수내 무기인의 농도는 심층에 산소농도가 희박(<2mg $O_2$ $L^{-1}$)하였던 시기에 감소하였다. 남조류의 성장률은 영양염 농도와 수온에 크게 의존하였고, 특히 높은 인 농도는 낮은 수온에서도 남조류가 발달하는 원인으로 나타났다. 본 연구의 결과는, 인이 충분하게 공급되는 국내의 많은 소형 부영양 저수지에서 연중 남조류의 발달과 지속가능성을 시사하며, 수질개선과 조류제어를 위해 인의 저감(특히, 퇴적층 관리)을 매우 중요하게 고려해야 함을 강조한다.

• 한국환경과학회지
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• 제19권11호
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• pp.1407-1421
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• 2010

This study was carried out to elucidate the relation between water quality and structure of the aquatic ecosystem in the agriculture reservoir Otae-ji from January to December in 2009. The proportion of forest was 46.98%, which means that non-point sources are major contributor of water pollution in this area. The annual mean COD(Chemical Oxygen Demand) in Otae-ji was $3.6mgL^{-1}$, indicating, level II of environmental standards and the trophic state was mesotrophic. Although total phosporus concentration in the reservoir was high in August due to large inflow of nutrients from outside the reservoir during monsoon season, there was no break out of significant algal bloom in the summer. The seasonal succession of phytoplankton showed that the dinophyta dominated in the the spring, chlorophyta in the summer, chrysophyta and chlorophyta in the autumn and chrysophyta in the winter. In case of zooplankton, rotifers dominated in the most seasons, but cladoceran(Bosmina longirostris) dominated in June and copepod(Nauplii) in August. The macrophyte plants showed diverse species compositon consisted of 3 varieties, 24 species, 23 genera, 15 families and 14 orders. The macroinvertebrates also showed various FFG(Functional Feeding Groups) such as GC(Gathering-Collector), P(Predator), SH(Shedder), FC(Filter-Collector) and PP(Plant-Piercer). Ecosystem stability analysis using aquatic insects was classified as Group I, which has high resilience and resistance indices. A total of 14 species of fish was collected but exotic species such as Lepomis macrochirus and Micropterus salmoides were not found in Otae-ji. In conclusion, the preservation of healthy food wed in the reservoir ecosystem is closely related to water quality management as well as effective prevention of algal bloom by helping good material circulation in aquatic ecosystems.