• 한국물환경학회지
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• 제36권1호
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• pp.1-13
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• 2020

The purpose of this study was to investigate the thermal and chemical stratification in Lake Paldang 2013-2018 weekly using Schmidt's stability index (SSI) and the index of chemical stratification (IC-i). The annual average for SSI was 19.1 g cm/㎠ with the maximum value of 45.3 g cm/㎠ in the summer and the minimum value of 4.8 g cm/㎠ in fall-winter showing seasonal differences as well as increased vertical mixing in the summer. The lake stability increased higher in 2016 as compared with the other period. The most influential factors of thermal stratification were temperature and heavy rainfall. Especially, high water temperature and a prolonged residence duration caused by reduced rainfall and inflows could result in an increase of the stratification period. While decreasing inflow and outflow at the end of the rainfall, the thermal stratification was restrengthened within 7-14 days, and then stabilized rapidly before the rainfall. IC-DO increased with high air temperature in the spring and fall-winter. However increasing sunshine duration and residence time and decreasing rate of outflow caused an increase of IC-DO in the summer. Rainfall (less than 800 mm/year) and discharge (less than 200 CMS) significantly declined in 2015 resulting in IC-DO (0.77) increased more than three times over the other years and bottom water hypoxia occurred. The SSI and IC-i used in this study could be applied to other lakes to understand changes in stratification and mixing dynamics.

• 한국농공학회논문집
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• 제62권6호
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• pp.43-50
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• 2020

The Doam Lake watershed is one of the non-point source management areas announced by the Ministry of Environment, and is a constant problem for the stream ecosystem dut to Storm water. In this study, a total of 48(rainfall) and 47(non-rainfall) sites were investigated for the entire watershed (Samyangcheon, Chahangcheon, Hoenggyecheon, Yongpyeongcheon, Songcheon, Lake Doam) on August 15, 2019 and on October 18, 2019 to estimate the source of turbid water in the Doam Lake watershed. Subsequently, water quality analysis was performed on Suspended Soild (SS), Turbidity, Total Phosphorus (TP), Total Nitrogen (TN), and Biochemical Oxygen Demands (BOD) and correlation among water quality parameters was analyzed based on the analyzed samples. As a result, most of the turbid water generated during rainfall was in highland fields. During rainfall, Hoengyecheon had the highest average SS concentration among all streams, and during non-rainfall, the average SS concentration was highest in Yongpyeongcheon, so the two stream were selected as vulnerable areas. However, since Yongpyeongcheon may be a temporary phenomenon due to river construction, additional continuous monitoring is required. Therefore, in the Doam Lake watershed, intensive management is required for vulnerable areas.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권5호
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• pp.10-19
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• 2012

The aim of this study was to examine chemical and isotopic compositions of groundwater and lake water near an area contaminated by petroleum and to evaluate influence of petroleum on them during the period from March to August 2011. In dry season, $Ca^{2+}$ and $SO{_4}^{2-}$ were dominant in the groundwater and lake water and $Ca^{2+}$ and $HCO{_3}^-$ were significant in wet season. ${\delta}^{18}O$ and ${\delta}D$ of the groundwater and lake water were plotted near LMWL (${\delta}D=8.06{\delta}^{18}O+12.5$). ${\delta}^{18}O$ and ${\delta}D$ of the lake water did not show seasonal variation. However, ${\delta}^{18}O$ and ${\delta}D$ of the groundwater were enriched in wet season compared with those in dry season because of influence of small ponds around wells where evaporation losses were slightly experienced. Redox condition of most lake water was oxidation environment in contact with the atmosphere during the study period. However, redox condition of groundwater was transitional environment in dry season and oxidation environment in wet season because of influence of contaminant such as petroleum. In some groundwater, the concentrations of $NO{_3}^-$ in some groundwater were less than 1 mg/L because of denitrification. Also, $NO{_3}^-$ showed positive correlation with $SO{_4}^{2-}$ and weak negative correlation with $HCO{_3}^-$, because of influence of denitrification.

• 한국물환경학회지
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• 제35권1호
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• pp.28-34
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• 2019

This study analyzed the occurrence pattern of Dolichospermum (= Anabaena) in the Bukhan river from March 2012 to December 2014 in order to identify the genotypes of Dolichospermum. Furthermore, 16S rRNA were analyzed to identify the genotypes of Dolichospermum that occurred in 2015 which were then compared to the reference sequence deposited at NCBI. During this period, the occurrence of Dolichospermum was highly correlated to water temperature. In the year 2012 and 2013, Dolichospermum appeared in Lake Cheongpyeong (CP), Sambong (SB), and Lake Paldang (P2) between July and August. However, in 2014, it appeared in SB and P2, but not in CP. This reduction in appearance was attributed to the decreased inflow to Lake Uiam as a result of low rainfall in 2014 as compared to 2012. In July 2015, the Dolichospermum 16S rRNA genotype was confirmed in five locations; Lake Cheongpyeong (CP), Seojong (SJ), Songchon Sewage Treatment Plant (SC), Joan (P4), and Lake Paldang (PD). Anabaena crassa of spiral clone, A. planctonica of linear clone, and A. circinalis of spiral clone exhibited high genetic similarity with the reference sequence. The 16r RNA genotype showed approximately 3 % sequence variation between the locations and were more similar to each other in locations that were closer.

• 한국환경복원기술학회지
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• 제25권5호
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• pp.77-88
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• 2022

This study aims to understand the relationship between the distribution of fish species in the two water ecosystems and the habitat factors according to the survey period targeting Gwanggyo Lake Park in the city. There are studies on the appearance and distribution of species by applying eDNA to freshwater ecosystems. However, in the domestic, streams are the target, and studies on the relationship between species distribution and habitat environment in two water environments are lacking. We conducted to analyze the species list and relationship with habitat factors using eDNA research in May and October at 21 points in Gwanggyo Lake Park, Suwon City, which were connected to lakes and streams. As a result, there was no species difference in the water environment according to the survey period. However, the total number of reads during the spawning season(May) was 3,126,482, which was more than double that after the spawning season(October). Tolerant species appeared in Woncheon Lake with a slow or stagnant flow, but there was no significant correlation between species and habitat factors depending on the survey period. On the other hand, intermediate and sensitive species appeared in the Woncheon stream with high flow. There was a significant correlation between the low temperature during the spawning season and the high dissolved oxygen content after the spawning season(P<0.001, Tem.: 20.7±2.6℃, DO: 8.6±1.7). It is expected that environmental DNA will be used to survey species and suggest monitoring methods according to the survey period.

• 한국물환경학회지
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• 제39권1호
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• pp.20-29
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• 2023

This study analyzed the relationship between harmful cyanobacterial abundance and environmental factors in order to figure out the causes of the recent increase of cyanobacteria in Lake Dukdong from 2019 to 2021. Lake Dukdong, which is used as a drinking water source for Gyeongju City, has an algae alert system in place. Lake Dukdong has maintained good water quality, but algae alert level 1 (over 1,000 cells/mL) has been issued in recent years. As a result of Pearson correlation analysis (from May to Oct.), the cell density of Microcystis and Aphanizomenon, which form part of the most harmful cyanobacteria genus, were significantly positively correlated with the water temperature and water storage volume. T-test was performed to compare the data from 2016-2018 and 2019-2021 (from May to Oct.). The average density of harmful cyanobacteria cells increased about six-fold from 54 to 344 cells/mL. There were significant differences in water temperature, pH, total nitrogen (TN), total phosphorus (TP), TN/TP ratio, water storage volume, and cyanobacterial cell density. Water temperature increased from 19.2 to 22.8 ℃. TP concentration increased from 0.017 to 0.028 mg/L. The main cause of the recent increase of harmful cyanobacteria in Lake Dukdong is thought to be the increase in water temperature, TP concentration, and water storage volume from 2019 and 2021, resulting in more favorable conditions for cyanobacterial growth.

• 산업기술연구
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• 제29권B호
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• pp.215-219
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• 2009

Based on the data interpretation on an artificial marsh built in Chun-cheon Lake, the study analyzed flow characteristics and found that flow was unstable due to sediment of natural river but the effect of artificial marsh was similar with that of river improvement works. Flow velocity in the section of artificial marsh was found to be 1m/sec. Therefore flow velocity was stable, which could contribute to improving water quality. A flow velocity as well as stream vector was improved.

• 한국물환경학회지
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• 제20권6호
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• pp.698-702
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• 2004

At five stations in Gyeongan River, a tributary of Lake Paldang, physicochemical and biological environmental factors of water, particulate matters, and sediments were investigated biweekly from April 11 to December 22 in 2001. The studied area was characterized as a stream-lake system. The system is primarily referred to a place where the environmental factors had considerably changed depending on the amount of precipitation. As a result, the river turned out to be strongly eutrophicated. Also, some characteristics of the water and the particulate matters at midstream such as average concentrations of conductivity, nutrients, and chlorophyll $\alpha$ were higher than the characteristics of up and down-stream. However, the concentrations of organic matters and ratio of clay and silt of the midstream were determined to be higher than up and down-stream sediments. As the result of the factor analysis, 4 major different patterns for environmental factors are found from samples of water, particulate matters, and sediments.

• 환경위생공학
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• 제13권3호
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• pp.128-132
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• 1998

In this study, water quality characteristics of lakes in the Seosan area are analyzed. Components water quality were analysed at 10 sampled points in each lakes, and the results were evaluated for seasonal variation. It was found that water quality was over II~III class. Most of lakes in the Seosan area which implies that are suitable as the maintenance water. The concenturation of T-N, T-P was observed IV~V class during all seasons. Particularly, T-N concenturation peaks in spring, while was lowered in other seasons. In the lake, high concenturation of T-N, T-P bring about Eutrophication when algae was growth causing various physico-chemical changes in the water. It is suggested that the water quality management strategies need to be applied for each lake.

• 보존과학연구
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• 통권16호
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• pp.129-138
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• 1995

For the study of the pigments on lacquer with wooden for comparing a characteristics and chemical structures have been selected samples from tombs at Tanwol-dong, Ch′ungch′ong-do, Hwang-namtaech′ong, Anapchi Lake in Kyongju-shi and Miruksa Site. Analysis showed that red pigments on the lacquer with wooden from Anapchi Lake and Tomb at Tanwol-dong was found to Cinnabar, and those sample sexcavated from Hwang-namtaech′ong have been analyzed to calcite, maghematite and kornelite. In general, red pigments have two components like cinnabar and hematite. Hematite was found that red lacquer at Hwang-namtaech′ong was to beidentified Maghematite caused by their environment air pollution. Cinnabar was handled more valuable than hematite for unchanging characteristics for their colour under same condition since old times.