• 해양환경안전학회지
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• 제26권3호
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• pp.242-253
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• 2020

This study examined the ef ects of freshwater discharge by artificial dikes from the Kanwol and Bunam lakes on the dynamics in the Chunsu Bay, Yellow Sea, Korea, during the summer season based on three-dimensional numerical modeling experiments. Model performances were evaluated in terms of skill scores for tidal elevation, velocity, temperature, and salinity and these scores mostly exceeded 90 %. The variability in residual currents before and after the freshwater discharge was examined. The large amount of lake water discharge through artificial dikes may result in a dramatically changed density field in the Chunsu Bay, leading to an estuarine circulation system. The density-driven current formed as a result of the freshwater inflow through the artificial dikes (Kanwol/Bunam) caused a partial change in the tidal circulation and a change in the scale and location of paired residual eddies. The stratification formed by strengthened static stability following the freshwater discharge led to a dramatic increase in the Richardson number and lasted for a few weeks. The strong stratification suppressed the vertical flux and inhibited surface aerated water mixing with bottom water. This phenomenon would have direct and indirect impacts on the marine environment such as hypoxia/anoxia formation at the bottom.

• 해양환경안전학회지
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• 제17권4호
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• pp.339-343
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• 2011

본 연구에서는 EFDC모델과 입자추적모델을 이용하여 마산만의 담수유입에 의한 폐쇄성 내만의 물질체류시간을 산정하였다. 마산만의 해수유동을 재현하고 이를 바탕으로 평균체류시간을 계산하였다. 마산만의 조석에 의한 평균물질체류시간은 만 북측과 돝섬 부근까지가 약 110일이내, 모도 주변 해역이 약 40일, 부도에서 외해까지 약 20일 정도로 산정되었다. 담수유입에 따른 마산만의 4개 소해역별 평균물질체류시간은 I과 II영역에서 약 81일로 감소하였으나, 마산만의 외해측에 위치한 III과 IV영역은 각각 58일과 17일로 증가하였다.

• 한국균학회지
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• 제46권3호
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• pp.213-225
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• 2018

Trichoderma (Hypocreaceae) is one of the most ubiquitous genera worldwide. This genus has an excellent ability to adapt to diverse environments, even under poor nutritional conditions, such as in freshwater. However, little is known about the diversity of Trichoderma species in freshwater environments. In this study, we isolated diverse fungal strains from algae, plant litter, and soil sediment in streams in Korea. The strains were identified based on molecular phylogenetic analyses of internal transcribed spacer (ITS) rDNA and translation elongation factor 1 ($TEF1{\alpha}$) sequences. We also investigated their morphological characteristics by microscopic observation and determination of cultural features on different media. As a result, six Trichoderma species were found in Korea: T. afroharzianum, T. capillare, T. guizhouense, T. paraviridescens, T. reesei, and T. saturnisporum. Interestingly, T. paraviridescens showed both cellulose activity and hypoxia stress tolerance phenotypes, indicating its role as a decomposer in freshwater ecosystems. Our study revealed that freshwater environment could be a good candidate for investigating the species diversity of Trichoderma.

• 한국물환경학회지
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• 제25권1호
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• pp.136-141
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• 2009

Inactivation rates between enterococci and total coliforms were compared in order to find the suitability of enterococci as an indicator microorganism under various experiment conditions - freshwater and/or seawater, indoor and/or outdoor conditions. In case of indoor laboratory experiments, inactivation rates of enterococci ($k_D$: 0.050~0.082) were faster than those of total coliforms ($k_D$: 0.034~0.045) in freshwater matrix. In seawater matrix, however, survival rate of enterococci was longer than that of total coliforms at two out of three experiments in indoor condition. When incubated in outdoor conditions, enterococci were inactivated significantly more rapidly than total coliforms both in freshwater and seawater matrices. With these results, enterococci appear to be less suitable than total coliforms in terms of inactivation rates.

• 한국환경생태학회지
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• 제10권1호
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• pp.140-150
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• 1996

국립공원에서 자연보존의 일환으로 기초자료를 축적하고자 1994년 6월부터 12월까지 3회에걸쳐 주왕산 국립공원 일대의 10개 지소에서 담수어류상을 조사한 결과 한국고유종 및 아종인 긴몰개, 점몰개, 왕종개, 수수미꾸리, 미유기, 자가사리 그리고 동사리를 포함한 6개과 17종의 담수어류를 확인하였다. 낙동강 수계에서는 14종이, 영덕 오십천 수계에서는 10종이 분포하였으며 공통적으로 분포하는 어종은 붕어, 버들치, 피라미, 갈겨니, 미꾸리, 자가사리 및 동사리로서 7종이었고 우세종은 버들치, 갈겨니 그리고 동사리였다.

• 한국환경생태학회지
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• 제6권2호
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• pp.193-200
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• 1993

국립공원에서 자연보존의 일환으로 기초자료를 축적하기 위하여 1992년 5월부터 1992년 10월까지 소백산국립 공원 일대의 9개 지소에서 담수어류상을 조사하였다. 이 지역에는 13종의 한국고유종을 포함하여 9개 과에 속하는 27종의 담수어류가 분포하였다. 한강수계에서는 15종이 낙동강 수계에서는 17종이 분포하였고 공통적으로 분포하는 종은 6종뿐이었다. 이 지역의 우세종은 갈겨니, 피라미, 버들치 그리고 동사리였다. 갈겨니. 피라미, 버들치를 포함한 11종에서 형태적 이상을 나타낸 개체가 출현하였다, 따라서 이와 같은 양상에 대하여 구체적인 조사와 사려 깊은 대책이 절실히 요망된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.90-102
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• 2015

To understand the hyrogeochemical variation of bedrock aquifer during underground space construction, various graphical methods including multiple-component plots and chemical trends were used to estimate the mixing rate between seawater and freshwater and to investigate the evolution of water quality. The water chemistry and mixing rate between fresh and sea waters, which are generally localized in the construction area (MW-7, in land), shows typical characteristics of freshwater that doesn’t affect its validity as seawater intrusion. Especially, the water chemistry of a MW-4 (coastline) was classified as Na-Cl type, Na-HCO₃ type, and Ca-Cl type due to the influence of the seawater intrusion. And hydrogeochemical and isotopic data show that local freshwater is subjected to geochemical processes, such as reverse ion-exchange. Throughout the Chadha’s diagrams, four different case histories with the temporal and spatial variation of groundwaters in the study area were proposed, which is recommended to interpret the hydrogeochemical reactions effectively.

• Journal of Ecology and Environment
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• 제40권1호
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• pp.45-54
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• 2016

Background: Macrophytes are commonly utilised as habitat by epiphytic species; thus, complex macrophyte structures can support high diversities and abundances of epiphytic species. We tested the hypothesis that the presence of aquatic macrophytes is an important factor determining Sida crystallina (O.F. Muller, 1776) distribution. Results: An ecological survey was conducted in 147 lentic freshwater bodies. S. crystallina was frequently observed, and its density was strongly associated with macrophyte abundance. S. crystallina was found on emergent plant species such as Phragmites australis and Paspalum distichum, attached to the stem surfaces by adhesive substances secreted by the nuchal organ. Thus, S. crystallina was more strongly attached to macrophytes than to other epiphytic cladoceran species. We found higher densities of S. crystallina in filtered water with increased macrophyte shaking effort (i.e. 10, 20, 40, or 80 times). S. crystallina attachment was not related to fish predation. Stable isotope analysis showed that S. crystallina utilises epiphytic organic matter (EOM) on macrophytes as a food source. Conclusions: Consequently, S. crystallina seems to have a strong association with species-specific macrophyte biomass than with other cladoceran species, which may contribute to this species' predominance in various freshwater ecosystems where macrophytes are abundant.

• 한국물환경학회지
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• 제23권1호
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• pp.12-18
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• 2007

Difference of total coliforms (TC) survival time of mixed samples (effluent were mixed by seawater or freshwater) were examined in various conditions. The time taken to achieve a 90% reduction in the TC concentration ($T_{90}$) of effluent, high initial TC concentration and low initial TC concentration samples indicated 143.9, 121.9 and 89.6 hours at $25^{\circ}C$, respectively. At $4^{\circ}C$, log removal rate after 336 hours were 0.96, 1.04, and 1.30. TC survival time of effluent-inoculated seawater sample was longer than that of effluent-inoculated freshwater sample in laboratory. At outdoor condition, TC inactivation curves of effluent-inoculated seawater or freshwater samples showed similar patterns. And both of them were greatly influenced by climate condition. There was not enough evidence that TC survived longer in freshwater than sea water. It was unlikely that the salinity of sea water contributed to the inactivation process of TC.

• 한국균학회지
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• 제51권4호
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• pp.265-276
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• 2023

본 연구는 담수 환경에서 분리한 곰팡이의 특성을 알아보기 위해 효소 활성을 평가하였다. 40개의 곰팡이들은 다양한 담수 시료로부터 분리되었으며, 계통분석을 통해 동정하였다. 실험에 사용된 균주들은 최근에 국내에 보고되었거나, 아직 보고되지 않은 종으로서 이에 대한 특성 정보가 거의 알려지지 않았다. 본연구에서는 40개 균주를 대상으로 protease, amylase, lipase, cellulase, laccase, chitinase의 효소에 대해서 활성을 검정하였다. 대부분의 균주가 laccase 활성을 보였으며, protease, amylase 순으로 높게 나타났다. 담수 환경에서의 효소 활성 정보는 이들의 생태적 역할을 이해하고 산업적으로 활용하는데 기여할 수 있을 것이다.