• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.897-904
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• 2007

The aim of this paper is to discuss the methodology of our investigation of the dynamics of protein degradation and the total in situ protealytic activity in meso/eutrophic, eutrophic, and hypereutrophic freshwater environments. Analysis of the kinetics and rates of enzymatic release of amino acids in water samples preserved with sodium azide allows determination of the concentrations of labile proteins $(C_{LAB})$, and their half-life time $(T_{1/2})$. Moreover, it gives more realistic information on resultant activity in situ $(V_{T1/2})$ of ecto- and extracellular proteases that are responsible for the biological degradation of these compounds. Although the results provided by the proposed method are general y well correlated with those obtained by classical procedures, they better characterize the dynamics of protein degradation processes, especially in eutrophic or hypereutrophic lakes. In these environments, processes of protein decomposition occur mainly on the particles and depend primarily on a metabolic activity of seston-attached bacteria. The method was tested in three lakes. The different degree of eutrophication of these lakes was clearly demonstrated by the measured real proteolytic pattern and confirmed by conventional trophic state determinants.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.742-749
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• 2009

To examine the characteristics of the nutrient release from the sediments in two reservoirs, Lake Paldang and Lake Cheungpyeung, we analyzed physical and chemical properties of the sediments and calculated the nutrient release rates from the sediments. The particle properties of sediments in Lake Paldang changed from silt to sand after summer rainy season, especially in the water area of the Kyeungan River where the water depth was shallow and the width of river was narrow. The sediments in Lake Cheungpyeung had higher contents of silt and clay than in Lake Paldang, and the particle size was not much different before and after rainfall. The release rates of nutrients in two lakes varied with the kind of nutrients and the season. The release rates of DTN and ${NH_4}^+-N$ in Lake Paldang were faster in spring than autumn. But the Lake Cheungpyeung showed similar values of release rates before and after summer rainy season. ${NO_3}^--N$ and phosphorous were not released from sediments or were absorbed into sediments all the time in two lakes. Compared with other lakes, the sediments of two lakes consisted of bigger particles and had a lower organic matters content than other lake-type reservoirs. Due to the short hydraulic retention time and no stratification throughout the year in Lake Paldang and Lake Cheungpyeung, the release rates of nutrients from sediment in these reservoirs were lower than other lakes and this seems to be a typical characteristic of river-type reservoirs.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.294-300
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• 2008

The stable isotopes ratios ($\delta^{13}C\;and\;\delta^{15}N$) of two coexisting species of zooplankton (Daphnia longispina and Acanthodiaptomus pacificus) and POM were determined in two alpine lakes in Japan. The difference of $\delta^{13}C$ between A. pacificus and D. longispina was 4.1$\pm$0.9‰ in Lake Shirakoma, which was larger than in Lake Panke. Whereas the difference of $\delta^{15}N$ between A. pacificus and D. longispina (2.6$\pm$0.8‰) was larger in Lake Panke than in Lake Shirakoma. $\delta^{13}C$ of POM (-26.6$\pm$1.2‰) in Lake Shirakoma was different from those of zooplankton; it was heavier than those of D. longispina and A. pacificus by 3.7$\pm$1.6‰ and 7.8$\pm$1.0‰, respectively. Whereas $\delta^{15}N$ of POM (2.0$\pm$0.8‰) was similar with those of both A. pacificus and D. longispina. This implies that the two lakes may have different trophic structure and food sources for zooplankton, and each species are grazing on selectively different components of POM. The temporal variation of $\delta^{13}C$ for each zooplankton species was associated with lipid contents of zooplankton in both lakes. The results showed that stable isotope composition of zooplankton can be an useful information for understanding energy pathways and trophic structures in lakes.

• Journal of Microbiology and Biotechnology
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• v.23 no.6
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• pp.739-749
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• 2013

The seasonal and spatial diversity of picocyanobacteria (Pcy) in lakes of the Great Mazurian Lakes (GLM) system was examined by DGGE analysis of molecular markers derived from the 16S-23S internal transcribed spacer (ITS) of the ribosomal operon and the phycocyanin operon (cpcBA-IGS). The study of nine lakes, ranging from mesotrophy to hypereutrophy, demonstrated seasonal variance of Pcy. The richness and Shannon diversity index calculated on the basis of both markers were higher in spring and lower in early and late summer. No statistically significant relationships were found between the markers and trophic status of the studied lakes or Pcy abundance. There were, however, statistically significant relationships between the diversity indices and sampling time. The analysis pointed to a different distribution of the two markers. The ITS marker exhibited more unique sequences in time and space, whereas a greater role for common and ubiquitous sequences was indicated by the cpcBA-IGS data. Examination of the Pcy community structure demonstrated that communities were grouped in highly similar clusters according to sampling season/time rather than to the trophic status of the lake. Our results suggest that time is more important than trophic status in shaping the diversity and structure of Pcy communities. The seasonal changes in picocyanobacteria and differences in diversity and community structures are discussed in the context of well-established ecological hypotheses: the PEG model, intermediate disturbance hypothesis (IDH), and horizontal gene transfer (HGT).

• Advances in environmental research
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• v.2 no.2
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• pp.81-98
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• 2013

Mercury (Hg) dynamics in the boreal environment have been a subject of concern in recent decades, due to the exposure of local populations to the contaminant. Land use, because of its impact on mercury inputs, has been highlighted as a key player in the sources and eventual concentrations of the heavy metal. In order to evaluate the impact of watershed disturbances on Hg dynamics in frequently fished, large boreal lakes, we studied sediment cores retrieved at the focal point of eight large lakes of Qu$\acute{e}$bec (Canada), six with watersheds affected by land uses such as logging and/or mining, and two with pristine watersheds, considered as reference lakes. Using a Geographical Information System (GIS), we correlated the recent evolution of land uses (e.g., logging and mining activities) and morphological characteristics of the watershed (e.g., mean slope of the drainage area, vegetation cover) to total Hg concentrations (THg) in sedimentary records. In each core, THg gradually increased over recent years with maximum values between 70 and 370 ng/g, the lowest mercury concentrations corresponding to the pristine lake cores. The Hg Anthropogenic Sedimentary Enrichment Factor (ASEF) values range from 2 to 15. Surprisingly, we noticed that the presence of intense land uses in the watershed does not necessarily correspond to noticeable increases of THg in lake sediments, beyond the normal increment that can be attributed to Hg atmospheric deposition since the beginning of the industrial era. Rather, the terrestrial Hg inputs of boreal lakes appear to be influenced by watershed characteristics such as mean slopes and vegetation cover.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.215-220
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• 2003

Three lakes (lake Homanpo, Hyunkum and Daein) were revealed to be brackish by the results of zooplankton fauna and salinities (2.8 ppt and 0.8 at lake Hyunkum in May and October 2002, and 1.5 and 0.5 at the Daein) in Shinpo district, North Korea. Among 34 taxa of zooplankton occurred, copepods and rotifers showed the prosperity in species number with 15 species and 7 species, respectively. Twenty four taxa of freshwater animals, six brackish ones and four marine ones were found, Brackish copepods, Pseudodiaptomus inopinus and Sinocalanus tenellus, were found in all lakes. More than 90% of zooplankton abundances consisted of brackish and marine species in three lakes. The outburst of S. tenellus was observed (59,000 indiv./$m^3$) at lake Hyunkum in May, when the proportion of brackish and marine zooplankton exceeded 99% of total zooplankton abundance. Long-term monitoring appears to be needed to provide basic data to protect brackish lakes in the study area.

• Environmental Mutagens and Carcinogens
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• v.23 no.2
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• pp.51-55
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• 2003

Benzo(a)pyrene and bisphenol A have been classified as endocrine disrupting chemicals (EDCs), which have been of concern in toxicology and environmental sciences. Benzo(a)pyrene and bisphenol A were monitored by HPLC or GC-MS in Baekwoon and Ilwirl lakes of Kyonggi-Do province to investigate contamination levels of EDCs. During the period between June, 2000 and August, 2000, water samples were collected from four different sites of each lake once per month. Contamination levels of benzo(a)pyrene were 3.27~4.25 ppb in Ilwirl lake and 2.00~2.33 ppb in Baekwoon lake, respectively. Bisphenol A levels were detected with the range of 0.33~7.94 and 0.43~4.71 for Baekwoon lake and Ilwirl lake, respectively. pH levels were higher in Ilwirl lake than in Baekwoon lake, where the contamination was relatively lower. These data suggest that lakes in Kyonggi-Do province could be contaminated with EDCs and be subjected to the routine monitoring and water quality control.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.418-421
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• 2005

In this study, we analyzed surface temperature of lakes in the Han River system, using Landsat-5 and -7 time-series images. Surface temperature was extracted using NASA equation and compared with in situ 10m-depth temperature in Lake Soyang and surface temperature on five other dam lakes downstream. The 24 images out of 29 showed standard deviation of temperature difference less than $2^{\circ}C$, to which a novel statistical atmospheric correction could be applied. The correlation coefficients were 0.950 at Lake Soyang and 0.979-0.997 at the other lakes after atmospheric correction.

• Journal of Wetlands Research
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• v.5 no.1
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• pp.1-13
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• 2003

Conservation of wetlands are important because wetlands are hatcheries for fishes and habitat for migratory birds and mammals. Wetlands also function as a filter for polluted water and material and transition zone for harboring numerous species of plants and animals. This paper reviewed the importance of wetland conservation and policy on management of wetlands in Korea. Wetland Conservation Act(1999) and Maritime Management Act(1999) are two legislation for conservation of wetlands. Wetland Conservation Act is issued by both Ministry of Environment and Ministry of Maritime Affairs and Fisheries. The definition of wetlands are so diverse, but this paper categorized wetlands as both natural and man-made lakes, mud flat areas and inland wetlands. Management application was considered for each wetland categories.

• Journal of Environmental Health Sciences
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• v.44 no.4
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• pp.315-322
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• 2018

Objectives: A lake is a place used by many people, and compared to rivers it is easy for them to become polluted. The water quality in lakes and reservoirs has been worsening recently. The purpose of this study is to evaluate the water pollution characteristics of major lakes in northern Gyeonggi-do Province. Methods: Six lakes were selected as major lakes and were evaluated in terms of water pollution characteristics and eutrophication (as defined by results for $COD_{Mn}$, TOC, SS, Chl-a, T-N and T-P) over one year (from December 2016 through November 2017) in northern Gyeonggi-do Province. Results: The annual average $COD_{Mn}$ was found to be 3.1 mg/L in Onam, 3.6 mg/L in Sanjeong, 4.7 mg/L in Gisan, 4.8 mg/L in Ilsan, and 6.1 mg/L in Jangja. The results of the Korean trophic state index ($TSI_{KO}$ ) value indicated a eutrophic state ($TSI_{KO}$ 59.0) in Jangja lake. The other lakes were classified as being in a mesotrophic state ($TSI_{KO}$ of 38.1 in Sanjeong, 40.2 in Ilsan, 41.9 in Onam, 46.1 in Gisan, and 47.8 in Gomo). Conclusions: Ilsan Lake's water quality is being well maintained. Sanjeong, Onam, and Gisan are appropriate for use as agricultural water. Jangja lake requires efforts for water quality improvement and to prevent the inflow of non-point pollutant sources.