• 생태와환경
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• 제38권3호통권113호
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• pp.304-312
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• 2005

내분비계 장애물질이 식물플랑크톤의 개체군 성장에 미치는 영향을 이해하고자 부영양 호수 및 하천에서 우점하는 남조 M. aeruginosa와 규조 S. hantzschii를 성장시기에 따라 자연수 농도의 10 ${\sim}$ l,000배까지 다양한 농도로 투여하고 현존량 및 형태적 변화를 조사하였다. Nonylphenol (NP)을 조류세포 배양초기나 대수성장기에 처리하였을 경우 농도 0.01 ppm이상에서 곧바로 성장억제 현상을 보였으며, 남조 M. aeruginosa가 규조 S. hantzschii보다 더 심한 억제현상을 보였다. 이에 반해 diethyhexyl phthalate(DEHP)의 경우에는 조류세포 성장시기나 처리농도에 상관없이 성장 억제 현상은 관찰되지 않았고, 실험 중 가장 높은 처리농도인 3.00 ppm 처리군에서는 오히려 대조군보다 10% 이상의 높은 성장을 나타냈다. 조류세포의 형태적 변화는 NP를 처리한 모든 실험군에서 조류세포의 색소체 변화가 뚜렷하였으며, M. aeruginosa 세포의 경우, 크기가 점차 작아지는 특징을 보였다. 결국 DEHP의 자연계로의 유출은 식물플랑크톤을 섭식하는 섬모충이나 동물플랑크톤의 성장을 억제하거나 M. aeruginosa 및 S. hantzschii와 같은 유해조류의 성장을 촉진함으로써 부영양수역 조류대발생의 중요한 요인으로 작용될 수 있음을 시사해주고 있다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.233-233
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• 2017

Algal communities are important to maintain the aquatic ecosystems function. Algae have short life cycles, they respond quickly to environmental change and their diversity and density can indicate and the quality of their habitat. The bloom forms before the rice seedings have emerged, it may present a physical barrier that prevents the seedlings from penetrating the floodwater. Wind may also move the algal bloom, pushing the young plants beneath the surface. Another harmful action develops when the water dries up and the algae form a layer at the bottom of the field. The layer envelops the seedlings, which are not yet deeply rooted, and drag them to the surface when the water is let in again. Soil utilization pattern can be the mail facter affecting soil physico-chemical properties, especially in soil phosphorus (P). Solid content of the algae culture solution increased with the increase in the nitrogen rather the phosphors concentration. Phosphoric acid was treated with conventional treatments (100-0%, before transplanting time-tillering stage), 50-50%, 0-100%, and un-treated. The herbicide was treated on the 7 DAT (day after transplanting). Green algae samples were collected 20 DAT. Total phosphoric acid was the highest at 0.06 in 50-50% treatment in 20 DAT. The amount of green algae was about twice (9.8 mg/20ml) that of un-treated. Total number of green algae was 54 species(Green algae 35 species, Euglena 9 species, Stone wheel 10 species). Among the phosphoric acid treatment methods, the number of occurrences of green algae were the highest with 39 species in 0-100%, followed by 50-50%, 28 species, conventional treatments, 22 species, non-treatment, 18 species, respectively. Rice Yield was not significantly different by phosphoric treatment time, but slightly higher than un-treated. The maximal algal biomass was observed about 2weeks or 1 month after transplanting; the subsequent decrease of the biomass was related to the consumption by grazers and to a deficient light under the rice canopy. Maximal algal growth was observed just before tillering. To estimate the suitable method of phosphorus application in puddled-soil drill seeding of rice, available phosphorus appearance of algal water bloom, and rice yield were investigated in paddy soil of rice-barley double cropping system.

• 한국양식학회지
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• 제19권1호
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• pp.33-39
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• 2006

Anticoagulant activities of a fermented edible brown alga, Laminaria ochotensis was investigated. L. ochotensis was fermented with 15% sugar (w/v) at $25^{\circ}C$ for 10 weeks. Anticoagulant activity was measured from the supernatant of algal mixture at biweekly intervals up to $10^{th}$ week by activated partial thromboplastin (APTT), prothrombin time (PT) and thrombin time (TT) assay using citrated human plasma. Sample having high APTT activity $(6^{th}\;week)$ was filtered, ethanol precipitated and freeze-dried. The polysaccharide compound having anticoagulant activity was purified by DEAE ion exchange chromatography followed by Sepharose-4B gel filtration chromatography. Anticoagulant activity, polysaccharide concentration, and heparin like activity were determined for the collected fractions by APTT, $phenol-H_2SO_4$, and glycosaminoglycan assay, respectively. The anticoagulant activity assay showed that the activity was increased up to $6^{th}$ week, and decreased thereafter. The concentration of our purified compound was $31.0{\mu}g/ml$ and showed higher APTT activity than commercial heparin. At the same concentration of $31.0{\mu}g/ml$, the heparin showed 186.5 sec activity while our purified compound showed an activity of 386 sec. Single spot on agarose gel electrophoresis showed that the compound was purified and polyacrylamide gel electrophoresis (PAGE) results revealed that the molecular mass of the purified polysaccharide compound was between 60 and 500 kDa. Therapeutic interest of the algal polysaccharide as an anticoagulant has recently been in highlighted. This purified anticoagulant compound from fermented L. ochotensis can be used as a model for anticoagulant agent or could be developed as an anticoagulant agent. This study can be extended to identify the structure and chemical composition of the purified polysaccharide, and to establish a relationship between structure and the function of the identified anticoagulant compounds.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.432-438
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• 2018

Microalgae hold promise as a renewable energy source for the production of biofuel, as they can convert light energy into chemical energy through photosynthesis. However, cost-efficient harvest of microalgae remains a major challenge to commercial-scale algal biofuel production. We first investigated the potential of electrolytic water as a flocculant for harvesting Tetraselmis sp. Alkaline electrolyzed water (AEW) is produced at the cathode through water electrolysis. It contains mineral ions such as $Na^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ that can act as flocculants. The flocculation activity with AEW was evaluated via culture density, AEW concentration, medium pH, settling time, and ionic strength analyses. The flocculation efficiency was 88.7% at 20% AEW (pH 8, 10 min) with a biomass concentration of 2 g/l. The initial biomass concentration and medium pH had significant influences on the flocculation activity of AEW. A viability test of flocculated microalgal cells was conducted using Evans blue stain, and the cells appeared intact. Furthermore, the growth rate of Tetraselmis sp. in recycled flocculation medium was similar to the growth rate in fresh F/2 medium. Our results suggested that AEW flocculation could be a very useful and affordable methodology for fresh biomass harvesting with environmentally friendly easy operation in part of the algal biofuel production process.

• 환경위생공학
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• 제24권2호
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• pp.40-48
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• 2009

Unusual bloom of toxic cyanobacteria in water bodies have drawn attention of environmentalists world over. Major bloom of Anabaena, Microcystis in water storage reservoir, rivers and lake leading to adverse health effects have been reported from Australia, England and many part of the world. These cyanobacterial cells can release intercellular matter like toxin in water and these intercellular matter can increase the concentration of organic matter. Cellysis can occur when algal cells meet the disinfectants like chlorine in water treatment plant and the resultant rising up of DOC(Dissolved Organic Carbon) or TOC(Total Organic Carbon) can increase the formation of disinfection by products. Disinfectants that kill microorganisms react with the organic or inorganic matter in raw water. In general disinfectants oxidize the matter in raw water and the resultant products can be harmful to human. There are always conflict about which is more important, disinfection or minimizing disinfection by products. The best treatment process for raw water is the process of the lowest disinfection by products and also the the lowest microorganism. In this study the cultured cells, Microcytis Aeruginosa(MA), Anabaena Flos-aquae(AF), Anabaena Cylindrica(AC), and the cells obtained in Daechung Dam(DC) whose dominant species was Anabaena Cylindrica were subjected to chlorination. Chlorination oxidizes inorganic and organic compounds and destruct live cells in raw water. Chloroform was analyzed for the cultured cells which were treated with $20mg/\ell$ dose of chlorine. In general chloroform is easily formed when dissolved organic matter react with chlorine. The cultured cells contributes the concentration of dissolved organic carbon and also that of total organic carbon which might be potent precusors of chloroform formed. The correlations of the concentration of chloroform, DOC and TOC were investigate in this study.

• 한국물환경학회지
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• 제31권3호
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• pp.286-294
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• 2015

Temporal and spatial characteristics of cyanobacterial communities at the monitoring stations for Harmful Algal Bloom Alert System (HABAS) in Nakdong River and Lake Dukdong were investigated for two years (2013 to 2014). A total of 30 cyanobacterial species from 14 genera were found at the survey stations. Microcystis sp. showed maximum cell density in the total cyanobacterial community in August, 2014 at ND-2 and in September, 2013 at ND-3 station. Lynbya limnetica and Geitlerinema sp., non-target species for alert criteria showed maximum cell density at ND-1 (August, 2013) and Dam station of Lake Dukdong (September, 2014), respectively. Total cyanobacterial cell density and the relative abundance of four target genera (Microcystis, Anabaena, Aphanizomenon and Oscillatoria spp.) for alert criteria was relatively lower in the mesotrophic Lake Dukdong than at the eutrophic riverine stations of Nakdong River, indicating cyanobacterial density and the RA of target genera is affected by the trophic state of the monitoring stations. Simulating the alert system using phycocyanin concentration as an alert criterion resulted in the longer period of alert issued compared to the period of alert issued using the current criterion of harmful cyanobacterial cell density due to the influence of phycocyanin concentration from non-target cyanobacterial species.

• 생태와환경
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• 제35권2호통권98호
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• pp.133-140
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• 2002

본 연구는 실험실규모의 산화지 공법을 적용하였다. 체류시간 변화 및 산화지 형태가 처리율에 미치는 영향을 조사하였다. 조류의 광합성에 대한 유기물 제거율과 용존산소와의 상관관계는 야간에 비해 주간의 상관성이 더 높은 것으로 나타났고, 단일지의 경우는 체류시간 15일의 경우가 5일에 비해 상관성이 더 높은 것으로 조사되었다. 시간대별 DO변화는 체류시간 5일의 경우 다단산화지 내의 DO농포는 $42{\sim}19.8\;mg/l$를 나타내었고, 첫번째 조에 비해 후단으로 갈수록 높아졌다. 유기물 처리효율은 체류시간 5일이고, 4단 직렬식 다단 산화지 시설에서 제거효율이 더 높았다. 유기물 제거효율로 $TBOD_5$ 평균 제거율은 $49{\sim}83%$를 나타내었고, $SBOD_5$의 경우는 $87{\sim}92%$의 높은 처리율을 나타내었다. 또한 산화지내 조류생성량을 일정 농도로 유지시켜 주는 것이 산화지 공법의 처리율을 높일 수 있는 것으로 나타났다.

• 한국물환경학회지
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• 제38권6호
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• pp.292-305
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• 2022

The Yeongsan River, one of the four largest rivers in South Korea, has been facing difficulties with water quality management with respect to algal bloom. The algal bloom menace has become bigger, especially after the construction of two weirs in the mainstream of the Yeongsan River. Therefore, the prediction and factor analysis of Chlorophyll-a (Chl-a) concentration is needed for effective water quality management. In this study, Chl-a prediction model was developed, and the performance evaluated using machine and deep learning methods, such as Deep Neural Network (DNN), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost). Moreover, the correlation analysis and the feature importance results were compared to identify the major factors affecting the concentration of Chl-a. All models showed high prediction performance with an R² value of 0.9 or higher. In particular, XGBoost showed the highest prediction accuracy of 0.95 in the test data.The results of feature importance suggested that Ammonia (NH₃-N) and Phosphate (PO₄-P) were common major factors for the three models to manage Chl-a concentration. From the results, it was confirmed that three machine learning methods, DNN, RF, and XGBoost are powerful methods for predicting water quality parameters. Also, the comparison between feature importance and correlation analysis would present a more accurate assessment of the important major factors.

• 한국수산과학회지
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• 제42권3호
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• pp.276-283
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• 2009

Enrichment in nutrients coming from urban sewage outfalls can lead to eutrophication in coastal areas, which can also change the species composition and community structure of macro algal communities. We investigated the structure of the macro algal community within three rocky shores in order to assess any possible differences in their characteristics. Site 1 was located near Tongyeong city's sewage outfall, Site 2 was located near a public beach area, and Site 3 faced open channel of the Ocean. All three sites were located within the same stretch of the coast, where Site 2 was located between sites 1 and 3. We measured the nutrient concentration in water and the tissue nitrogen content in macro algae samples. Nutrients in the water column surrounding site 1 were high in ammonium ($30.2\pm1.8{\mu}M$), nitrate ($26.2{\pm}0.1{\mu}M$), and phosphate ($2.7{\pm}0.1{\mu}M$) content, and were characterized by low numbers of macroalgal species and species and a low species diversity index. In contrast, site 3 exhibited relatively low nutrient concentration levels and a high number of macroalgal species and a high species diversity index. Comparative analysis showed that the tissue nitrogen content of macroalgae were significantly (P<0.05) affected by the nutrient concentration in the water column. The tissue nitrogen content of green algae within site 1 was higher than the others sites. However, the tissue nitrogen content of brown algae was similar at all three sites. Thus, the tissue nitrogen content of macro algae and the macro algal community structure of intertidal rocky shores were dependent on location and the performance of macroalgal communities was dependent on water quality.

• 생태와환경
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• 제34권3호통권95호
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• pp.192-198
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• 2001

경안천과 팔당호 유입부는 하수처리장 배출수와 미처리된 생하수의 영향이 큰 곳이다. 자연조류 개체군을 이용한 희석법(bioassay)으로 배출농도 및 수질의 fertility를 평가하였다. $NH_4$, SRP 및 SRSi의 농도와 조류 생물량은 정상관 관계로서 특히 P에 대한 상관성에 대해 유의포가 높았다(r=0.959, p<0.001).배양 초기 농도에 비해 하수처리장과 생하수의 $NH_4$는 96%, 7%, SRP는 78%, 66% 및 SRSi는 97%, 60% 감소하였으나 NO3는 변화가 없거나 오히려 증가한 경향을 보였고, chl-a범위는 $20{\sim}125\;{\mu}g/l$로서 최대 89배 증가하였다. Chl-a와SRP의 관계로부터 조류 생물량을 중영양 기준(<25\;{mu}g$\;chl-a/l$) 이하로 유지할 경우 배출 P농도는 $83\;{mu}g\; P/l$에 해당하였다. 또한 이 기준을 고려하여 하천 유량의 희석에 의존할 경우 현재 유량보다 $16{\sim}25$배의 수량이 요구되었다. 수량 확보는 현실적으로 매우 어렵기 때문에 조류 생장을 촉진하는 $NH_4$, SRP의 저감을 위한 고도하수처리는 필수적이다.