• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.591-602
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• 2018

Clithon retropictus has been designated as an endangered wildlife Class II due to its high value as a biological indicator species capable of judging environmental quality such as salinity, water flow, and ground conditions. However, basic research on its physiological and ecological characteristics is still lacking. As such, this study intended to examine the impact of environmental conditions such as salinity and soil particle size on the size and density of Clithon retropictus at the Yeoncho river estuary. The investigation of the salinity, which is a key variable that affects the distribution of organisms in the estuary, showed that Clithon retropictus could grow at a salinity ranging from 0#x2030; (freshwater) to 25‰ (brackish water). The coarse gravel (19-75mm) tended to increase nearer the upper stream (under the Yeoncho weir), while the proportion of particles smaller than sand (less than 19mm) increased toward the downstream. The population and the size of the individuals decreased rapidly in the downstream where water stagnated near the Yeoncho weir, and the salt water joined. The results indicated that Clithon retropictus had a high tolerance to salinity, but the adaptability was weaker toward the extremes since the population, and the size tended to decrease as the salinity increased. The correlation analysis revealed that both salinity and soil particle size affected the population and individual size. The correlation between the individual size and salinity was -0.242 (P <0.01), indicating that the size decreased with increasing salinity. The correlation between individual size and coarse gravel having a particle size of 19mm or more was 0.420 (P <0.01), indicating that the size increased with increasing the particle size.

• Microbiology and Biotechnology Letters
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• v.31 no.3
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• pp.264-270
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• 2003

A quantitative survey of the protozoa microfauna at bioreactor of advanced sewage treatment plant was carried out during a period of 11 months. In this study, 32 genera were identified, including 17 ciliates. The abundance of the important protozoa were compared with the operating parameters and water quality of the effluent of the plant using statistical procedure. Statistical analysis revealed a relationship between the abundance of some genera and removal rate. In particular, correlation analysis on the quality of effluent and protozoa indicated that Lepadella may be used as the bioindicator of TP removal and Trochilia, Entosiphon, Colepus may be used as the bioindicator of TN removal when water temperature was below $20^{\circ}C$.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.407-410
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• 2004

우리나라 연근해 해역에서 발생하는 적조 현상은 매년 특정 시기에 끊임없이 나타나고, 그 피해액은 해를 거듭해갈 수록 증가하고 있다. 이러한 적조 발생을 조기에 탐지할 수 있는 것만으로도 그 피해는 상당히 줄어들 것이라고 여겨진다. 본 논문에서는 우리나라 연근해 해역에서 발생하는 적조의 우점종 플랑크톤인 Cochlodinium polykrikoides를 탐지하기 위한 방법으로 C. polykrikoides 의 개체수 변화에 따른 후방산란신호를 획득하여 그 상관관계에 관한 실험을 실시하였다. 실험에 사용된 주파수는 5MHz, 10MHz 이고, 적조 주의보와 적조 경보에 해당하는 개체수인 300cell/mL, 1000cell/mL 을 중심으로 개체수를 변화하였다. 필터링 후의 해수와 Cochlodinium 이 있는 해수의 체적산란 패턴 변화뿐만 아니라 Cochlodinium 의 개체수 변화에 따른 산란 패턴의 변화를 볼 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.378-385
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• 2014

The chlorophyll-a concentration in algae bloom warning system of Hangang basin did not predict the cyanobacteria dominance. In this study, suggest the predicting indicator of cyanobacteria dominance through analyzing the environmental factors affecting on the cell count of cyanobacteria. Firstly, the dominance of algae was analyzed with seasonal variation during Jan. 2012~Sep. 2013. The diatom dominated phytoplankton communities during the period of January~April. In the May~June, the green algae dominated. And, the dominance of algae was changed to cyanobacteria in the July~August. Also, the environmental factors affecting to cyanobacteria blooms ; nutrients (TN, TP), temperature, precipitation, dam-discharge were evaluated during the study period. Rather than temperature factor, relatively low dam discharge causes cyanobacteria to grow rapidly and create a blooms. The low dam-discharge may increase the water retention time. Finally, it is proved that a low ratio of TN to TP (<29:1) can favour the development of cyanobacteria blooms. Thus, the predicting indicator (TN:TP) have need to apply to the alarm bloom warning system of Hangang basin.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.240-247
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• 2006

The dynamic of zooplankton community and its relationship with dissolved oxygen were studied at the Soho area of Gamak Bay from 22 August to 15 September in summer. We found that zooplankton were in low abundance or absent from bottom waters when oxygen concentrations were <3 mg $L^{-1}$. The relationship between summer low-oxygen in bottom-layer and zooplankton community structure was discussed at vertical abundance in Soho area of Gamak Bay. To examine effects of bottom-layer low-oxygen on abundance and vertical distributions in the stratified Soho area, zooplankton was surveyed near-surface, within the near-bottom in the study area under a range of near-bottom dissolved oxygen conditions. There were vertical variation in total zooplankton abundance in the study area (ANOVA, P<0.05). Overall abundance of zooplankton: copepod nauplii, Oithona sp. and tintinnids were lower throughout the water column when bottom-layer DO was low (${\leq}3mg\;L^{-1}$). In this context it was postulated that zooplankton distribution in the Soho area of Gamak Bay might be controlled by dissolved oxygen condition.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.199-199
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• 2019

친환경적인 산업기술인 초미세기포(Ultra Fine Bubble, 이하 UFB) 제조 기술은 농업, 수처리, 그리고 환경재생 등 다양한 분야에서 적용되고 있다. UFB는 1,000nm 이하의 크기를 가진 기포로서 용존산소를 통한 농작물 성장 촉진 및 수중의 대장균 및 세균제거 등 다양한 성질을 지니고 있다. 본 연구는 기존의 방식과는 다르게 자왜현상을 메카니즘으로 갖는 타격식으로 제조된 UFB 생성장치를 통해 생성된 200nm이하의 크기를 가진 UFB를 실제 딸기 농장에 적용하여 딸기의 성장을 모니터링하고 살균 성능을 가진 화학제품과 UFB를 대장균에 적용하여 대장균 제거효율을 비교하였다. 딸기농장에 기존에 사용되던 지하수 대신 UFB를 주입하여 딸기성장 초기단계의 DO농도를 측정하고 딸기 생식단계에 산소포화도에 대한 질산염의 농도를 측정하여 상관관계를 분석하였으며 각각의 딸기 열매를 수확하여 무게를 비교하였다. 또한 대장균이 함유되어있는 대변을 채취하여 살균 성능을 가진 화학제품과 UFB수를 각각 대장균이 포함된 실험원수와 반응시켜 배양하고 검출된 대장균 개체 수에 확인하여 제거효율을 비교분석 하였다. 딸기성장 초기단계의 DO농도 측정결과 DO농도가 6~9ml/L로 높게 유지되고 있음을 확인하였고 딸기 생식단계에서 산소포화도가 일정하게 유지되고 있음에 따라 질산염의 농도가 점차 감소하는 것을 확인하였다. 또한 수확한 열매의 무게는 각각 37g, 19g으로 UFB수를 통해 재배된 딸기가 약 2배 이상 높은 것으로 나타났다. 이와 같은 결과는 수중의 용존산소가 딸기 성장 초기에 뿌리의 발육에 긍정적인 영향을 미치고 질산염을 원활하게 섭취하게 하여 딸기의 성장이 촉진되었고 열매의 무게가 증가하였다고 판단된다. 또한 대장균이 함유된 원수, 원수+화학제품, 원수+UFB를 접종하여 대장균과 반응시켜 배양하여 대장균 개체 수를 확인한 결과, 원수의 경우 약 600개의 대장균의 개체수가 나타났고, 원수+화학제품의 경우 검출된 대장균의 개체 수는 약 300개 정도로 나타났다. 이를 희석한 비율을 계산하여 대장균 개체 수를 나타내면 원수 약 6000개/ml, 원수+화학제품 약 6000개/ml로 비슷하게 나타난다. 반면, 원수+UFB 경우 검출된 대장균의 개체 수는 1개로 희석한 비율을 계산하여 대장균 개체 수를 나타내면 약 20개/ml로 나타난다. 이와 같은 결과를 통해 UFB는 99.9%의 대장균 제거효율을 보였으며, 화학제품은 대장균 제거효율을 보이지 않았다. 따라서 화학제품은 항균기능은 작용하지만 살균기능은 거의 없다고 판단하였고, UFB의 경우 기포가 소멸하면서 발생되는 초고온, 초고압을 형성하여 주변에 존재하는 대장균을 제거하였거나, 기포가 소멸할 때 발생되는 OH 라디칼을 통해 대장균의 세포를 화학적으로 분해시켜 대장균을 제거하였다고 보인다.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.317-324
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• 2001

We have previously developed three stage methane fermentation system capable of digesting food wastes effectively and then releasing high organic wastewater as a final product. In this study, we tried to devise an ecological water treatment system, which can efficiently remove the nitrogen and phosphorus contained in the organic wastewater. The system was made of microbiological filters, algae, and waterfleas. Of two species of alga tested, Selenastrum capricornutum showed higher growth rate and more efficiently removed the nitrogen from the wastewater than by Chlorella sp. In addition, the highest growth rate and the nitrogen removal efficiency could be obtained when high concentrations of $Mg^{2+}\; and\; Ca^{2+}$ were added to the diluted wastewater and the molar ratio of nitrogen to phosphorus was adjusted to 10 : 1. In this study the population relationship between alga and water flea was also examined in a test tube. The initial number of algal cells decreased as the waterflea population increased. However, the number of algal cells gradually increased again when waterflea population decreased partly due to the environmental resistance. From these results, it was believed that the ecological water treatment system could be used for removing the nitrogen and phosphorus from organic wastewater very effectively. Moreover, the waterflea cultured by this system as a final predator could be used as a good foodstuff for fishes.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.312-320
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• 2011

In order to estimate a better methodological factor to understand phytoplankton ecology between abundance and bio-volume of phytoplankton, each 1,160 phytoplankton data, including abundance, classification and chlorophyll $a$ concentration were collected in Korean coastal waters of Incheon (Yellow sea), Tongyeong (South sea), and Ulsan (East sea). Based on these data, phytoplankton bio-volume can be calculated through a geometric model. The correlation coefficient between abundance and chlorophyll $a$ concentration was higher than the coefficient between biovolume and chlorophyll $a$ concentration, because a small size phytoplankton has relatively dense chlorophyll contents compared with the proportion of chlorophyll in a large size phytoplankton. Thus, the interpretation using abundance to understand phytoplankton ecology in Korean coastal waters may be more effective than that using bio-volume.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.573-580
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• 2017

The oxicity assesment of Phenanthrene (PHE) has been investigated by using the rate (r) of survival and population growth in rotifer Brachionus plicatilis. The survival rate was determined after 24 h of exposure to PHE. The survival rate of PHE had no effect at a maximum of $300mg\;L^{-1}$. The r was determined after 72 h of exposure to PHE. It was observed that r in the controls (absence PHE) was greater than 0.5, but that it suddenly decreased with an increased concentration of PHE. PHE reduced r in a dose-dependent manner and a significant reduction occurred at a concentration of greater than $37.5mg\;L^{-1}$. The $EC_{50}$ value of r in PHE exposure was $63.7mg\;L^{-1}$. The no-observed-effect-concentration (NOEC) of r in PHE exposure was $18.8mg\;L^{-1}$. The lowest-observed-effect-concentration (LOEC) of r in the PHE exposure was $37.5mg\;L^{-1}$. From the results, the concentration of PHE (greater than $37.5mg\;L^{-1}$) has a toxic effect on the r of B. plicatilis in natural ecosystems. These results(including NOEC, LOEC and $EC_{50}$) might be useful for the Polycyclic aromatic hydrocarbons(PAHs) toxicity assessment in marine ecosystems.

• Korean Journal of Environment and Ecology
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• v.15 no.2
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• pp.153-158
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• 2001

영산강 수계의 습지생태계 모니터링의 일환으로 4개 지역을 선정하여 황소개구리 205개체를 채집하여 이들의 외부기형 출현율 및 양상을 조사하고 그들의 체내 조직에 축적된 중금속 농도를 분석하였다. 황소개구리의 기형 출현율은 6.8%로 다른 척추동물에서의 자연발생률 3%보다 높았으며, 기형은 모두 앞 또는 뒷발갉에서 나타났다. 유형별로 보면 결손(Ectrodactyly)이 64.3%로 가장 많았고 다음으로 확장(Dilation)이 28.6%, 절단(Truncation) 7.1%의 순이었다. 정상과 기형 개체간에 중금속의 농도를 조직별로 비교해 본 결과 기형개체의 신장에서 Mn은 4배, Zn 은 1.5배, Cu은 7배, Pb는 8배, Cd는 7배 정도 높았다. 또한 기형 개체에서는 이들 원소의 조직분포 패턴도 변화한 것으로 나타났다. 이러한 결과들로부터 황소개구리는 습지생태계의 모니터링 시료로서 유용하게 이용될 수 있음을 알 수 있었다.