• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.320-331
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• 2012

A combination system of catch canal and constructed wetland was designed and suggested to improve water quality in gagricultural region of lower Dong-jin river basin. In order to evaluate an water quality improvement efficiency of the designed combination system, the NPS-WET model was applied in this study. Simulation result of the NPS-WET shown that the nutrient load removal rate of constructed wetland was BOD, T-N, T-P and SS was 30.7~39.0%, 46~60%, 40.7~57.0% and 68.2~74.7%, respectively. Nutrients reduction of constructed wetland was higher in growing season than winter season because vital activity of microorganism, macrophyte and algae was augmented with high air and water temperature. Effluents from constructed wetland can affect water-quality of catch canal drains, especially, water-quality on junction point to Dong-jin river. Water-quality improvement in low-flowed catch canal (Un-san) was more significant than in high-flowed catch canal (Won-pyeong). In conclusion, a feasible design of constructed wetland is necessary to treat large quantity of receiving water. The NPS-WET is useful tool for assessing water-quality improvement efficiency using constructed wetland.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.3-6
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• 2001

Various Parameters such as stream velocities, discharges, and dispersion coefficients of dissolved solutes were estimated by fitting 1-D nonreactive solute transport model to the time-series chemistry data. This study was done for the reaches of Mankyung River lower than the Jeonju Wastewater Treatment Plant (Jeonju WTP). Korea. Concentrations of inorganic chemicals in the stream waters are strongly influenced by mixing with the chemically distinct effluent from Jeonju WTP. Sulfate, EC. and the total major cation were proved to be nearly conservative in the study area front their relationships with chloride, the conservative chemical species. The solute transport model was constrained to the time-series concentrations for these 4 conservative species. The variations of concentration and discharge of Jeonju WTP were used as input parameters, and the stream velocities, dispersion coefficients, and concentrations and discharges of some inflows were optimized. The differences between the observed arid simulated values for alkalinities and nitrates are inversely correlated and show diurnal fluctuations, indicating the photosynthesis. The parameters obtained front this mode] range from 550 to 774 kcmd (stream discharge at the outlet of the study area), from 0.06 to 0.10 m/sec (flow velocity), and from 0.7 to 6.4 m$^2$/sec (dispersion coefficient). The history of Jeonju WTP discharge was well predicted when optimized, indicating the validity of the model results.

• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.859-877
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• 2012

In this study, Echo-sounder($E_s$) monitoring methodology was applied to test environmental impacts of artificial weirs(SCW and JSW) in the Yeongsan River on fish community and habitat structures at first time, and was compared with conventional fish sampling methodologies($C_s$). For the Es monitoring in the fields, parallel transect methods was employed in determining the survey distance interval with every 125 m within the upper-lower 2 km of the weirs. Four different fish sampling gears such as casting nets, kick nets, fyke nets, and gill nets were used for applications of $C_s$ monitoring methodology. According to the Echo-sounder monitoring, fish density, expressed as a number of individuals per square meter, along the longitudinal axis of the weir was significantly greater(JSW, t = 3.506, n = 30, p < 0.001) in the down-river reach of the weir than in the up-river reach. Also, fish density along the vertical water column was highest at mid-depths of Seungchon weir, which has simple habitat substrates, while fish density was highest at hypolimnetic depth of Juksan weir. According to fish sampling by the $C_s$ methodology, the fish compositions decreased as the river goes upward, and significant differences(JSW, t = 0.248, n = 30, p < 0.05) in the compositions of fish species occurred between up-reach and down-reach of the weirs. The dominant species near the two weirs were Opsarichthys uncirostris amurensis, Hemiculter eigenmanni and Coilia nasus. Overall, our fish and habitat data, based on $E_s$ and $C_s$ monitoring methodologies, suggest that the weirs disturbed the rivers due to initial habitat disturbances by the weir constructions as well as the barrier roles of weirs on fish passage and migrations. More long-term scientific and systematic fish impact monitoring and assessments($E_s$ and $C_s$) are required in the future to predict changes of ecological structures and functions on the constructions of the weirs.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.110-115
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• 2000

This study was conducted to monitor the irrigation water qualities along Dong-Jin river watershed. The water quality was surveyed at 6 sites from April to september during $1994{\sim}1998$. And the results were as follows : In July and August, water quality was better than that of any other months due to dilution with rainwater. Whereas, it became worse in April but it involved lower contents than limitted contents affected to the crop damage. Content of inorganic components was higher at Jeong-up and Won-pyeong stream. The reason for it that Jeong-up stream was deteriorated with sewage water from Jeong-up city, and Won-pyeong stream has narrow width. Water quality in upstream of Dong-Jin river, was evaluated best conditions in all sampling sites. For investigated period, water quality got worse from 1994 to 1995 but it was getting better to 1998 after 1995, especially at Jeong-up stream. The total equivalent of cation and anion was the highest at April through all months and at Jeong-up stream in sampling sites. Equivalent ratio of cation to $anions({\Sigma}C/{\Sigma}A)$ was higher at May than any other months and lower at Won-pyeong streams than any other sites. The value of most inorganic components was highly correlated with those of other components. But the value of $NO_3\;^--N$ was not correlated with that of most components, and $PO_4\;^{3-}-P$ was not correlated with COD, $NH_4\;^+-N$, $NO_3\;^--N$, $SO_4\;^{2-}$.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.322-327
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• 2007

This study was conducted to analysis the chemical properties of Peunggang river and investigate the effect of irrigation sources on the growth of tomato and cucumber. The salt concentration in Peunggang river was high by $3.22{\sim}3.62dS{\cdot}m^{-1}s$ from March to May and lower gradually from April to February of next year, which was also lower in upper stream than in middle or low stream of Peunggang river. The growth such as plant height, fresh weight and dry weight in tomato and cucumber was better in drain water and tap water irrigation than in PR water (Peunggang river) irrigation. Mean fruit weight was highest in the tap water, and that of cucumber was no significance in the treatments. The number of setting fruit was lower in the PR water than in the treatments, and which was no significance between rain water and tap water. The yield of tomato and cucumber was found to be highest by 10,594 and 11,826 kg/10a in tap water, respectively and also lowest in the PR water among the three treatments. The fruit quality, soluble solids of tomato shows a tendency to increase in the PR water as compared with the other treatment, and the rate of blossom-end rote was higher by 13.6% in the PR water. T-N and P content of tomato and cucumber were no significance in the treatments. Ca content was lowest, but Na content highest in the PR water. It was thought that a rain water and tap water as alternative irrigation source of a PR water were proper.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.338-351
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• 2019

BACKGROUND: To investigate distribution and seasonal variation of concentration and flux of pesticides in Han river basin, water samples were examined at 24 sites in 2012 and 2014. METHODS AND RESULTS: Water samples were collected four times per year and subjected to liquid-liquid partition extraction followed by GC-ECD/NPD analysis. Of fifteen pesticides detected, iprobenfos, diazinon, isoprothiolane, endosulfan sulfate and oxadiazon were detected in a higher frequency, while fenoxanil, carbofuran, fenitrothion, butachlor and metolachlor were only detected in a sample. Pesticides with high occurrences, iprobenfos, diazinon, isoprothiolane, endosulfan sulfate and oxadiazon were detected in residue level of 0.01-0.46, 0.01-0.24, 0.03-0.85, 0.02-0.06 and 0.05-0.24 ㎍/L, respectively. Carbofuran and acetanilide herbicides were found at lower frequencies, but their concentrations were one order of magnitude higher than those of the others. CONCLUSION: Discharge of pesticides in downstream area were mainly contributed from rice farming and suburban horticulture, while pesticide occurrences in upstream area, such as Donggang river basin were caused by highland agriculture for cabbage and potato production. Despite the influx of pesticides from tributaries through intensive agriculture areas, pesticide concentration in the main stream water was low due to the dilution effect from the upstream. Therefore, the water quality was considered to be good at the most downstream, the effluent of Paldang dam.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.85-92
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• 2006

To evaluate the primary production and nutrient uptake of macrophytes in Lake Paldang, this study investigate the vegetation areas of six dominant aquatic plants including Typha angustifolia, Zizania latifolia, Phragmites australis, Trapa japonica, Nelumbo nucifera and Savinia natans, and contents of carbon, nitrogen and phosphorus of each macrophyte. Total vegetation area of six dominant aquatic plants was 1.37 $km^2$. Among them, Typha angustifolia was the most wide-distributed species which occupied the 46.7% of total vegetation area. Littoral zone of South Han river had the largest vegetation area with 0.458 $km^2$, and North Han river, Kyungan river and confluence area in the order named. The results of the contents of carbon, nitrogen and phosphorus of macrophytes showed that the carbon contents of emergent macrophytes was higher than that of other life-forms. The nitrogen content of Salvinia natans, free-floating macrophyte was highest and that of Typha angustifolia, emergent macrophyte was lowest. The phosphorus content of Trapa japonica showed the highest content of phosphorus among six macrophytes and emergent macrophytes such as Zizania latifolia and Phragmites australis showed lower contents of phosphorus than other life-forms. The annual net primary production of macrophytes in Lake Paldang, 2004, was calculated as 758.4 ton C $yr^{-1}$ and the annual net nitrogen and phosphorus uptake of macrophyte was 16,921 kg $yr^{-1}$ and 1,841.0 kg P $yr^{-1}$ respectively. Comparing the total budget of organic carbon, nitrogen and phosphorus in Lake Paldang, the amount of primary production and nutrient uptake by macrophytes take a small portion in total budget implying macrophytes do not play an important role in budget of matters in river-type lake, Lake Paldang.

• Journal of environmental and Sanitary engineering
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• v.19 no.3 s.53
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• pp.1-12
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• 2004

This study was conducted to evaluate the variation characteristics of influent and effluent quality from sewage treatment facilities using activated sludge processes and to assess the impact caused by discharge of treated sewage on the receiving water Monthly data of five water quality items (BOD, COD, SS, T-N, T-P) were used to understand the water quality at three sewage treatment plants in Seoul for five years from 1999 to 2003. Concentration differences of water quality parameters were observed between upstream and downstream site at the sewage treatment plant outfall to investigate the impact of discharge in Tan stream and Han river basin. 1. Due to the effect of continuous improvement in sewer system, the concentrations of influent went on increasing generally. 2. Effluent concentrations of BOD, COD and SS showed the trend of a little decreasing, but the trend of increasing in T-N and T-P. 3. In Tan stream basin, the impact of sewage treatment plant discharge was not observed directly, because concentration of discharge was lower than stream water's. But discharges from sewage treatment plants affected water quality at downstream site in Han river, concentration of T-P especially.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.159-165
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• 2023

This study was limited to the underwater search part among water accidents on the inland water surface, and analyzed five underwater search methods and lifesaving time at 5m underwater. The subjects of the experiment were 10 people. The semi-circle search took the longest with 259 seconds, and the modified round-trip search took 78.60 seconds, showing a significant difference with an average of 180.04 seconds. Subjects B and D showed similar values, with average underwater search times of 199 seconds and 202 seconds, respectively. Subject C showed a significantly higher average underwater search time of 209 seconds. The reason seems to be from increased anxiety and excessive tension due to poor underwater watch. Subject A showed a significantly lower underwater search time of 187 seconds. The reason seems to be the result of E's experience being the most among the test subjects and his rich diving experience in the Han River with poor visibility. As for convenience, semicircle search showed a low score of 6~7, and modified reciprocal search showed a high score of 8~9. The most suitable rescue method as an underwater search method in the Han River where visibility is poor is determined to be a modified round-trip search method.

• Ocean and Polar Research
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• v.30 no.4
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.