• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.148.3-148
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• 2003

No Abstract, See Full Text

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.309-317
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• 2009

This study analyzed a hydrodynamic behavior using the EFDC model (Environmental Fluid Dynamics Code) in the downstream of the Nakdong River in the case of a storm surge and a localized torrential rainfall caused by a major typhoon, and the sea level rise caused by global warming. The study area is selected Gaduk island with the lower boundary and Jindong with the upper boundary, to investigate the total river hydrodynamic behavior including the estuary. In order to verify this numerical model, the calculated results was compared with the observed stage at each gauging point in case of the storm rainfall in 2003 and 2006. From the results, it was shown that the numerical model(EFDC) has high accuracy and is useful in simulating more various cases.

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.461-468
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• 2019

Background: This study aimed to identify NO₃^--N sources using the stable isotope δ¹⁵N in Chydorus sphaericus (OF Müller), to investigate hydrological characteristics and nutrient states in artificial wetlands near the Nakdong River. Chydorus sphaericus is dominant in wetlands where aquatic plants are abundant, occurring in high density, and is sensitive to wetland water pollution, making it suitable for identification of NO₃^--N sources. Results: NO₃^--N sources for each wetland were strongly dependent on hydrological characteristics. Wetlands with sewage or rainfall/groundwater as their main sources had high levels of NO₃^--N, whereas wetlands with surface water as their main input had comparatively lower levels. Since wetlands with sewage and rainfall/groundwater as their main water sources were mostly detention ponds, their inputs from tributaries or the main river stream were limited and nutrients such as NO₃^--N easily become concentrated. Changes in NO₃^--N levels at each wetland were closely associated with δ¹⁵N of C. sphaericus. Interestingly, regression analysis also showed positive correlation between δ¹⁵N of C. sphaericus and NO₃^--N level. Conclusions: We conclude that the nitrate stable isotope (δ¹⁵N) of C. sphaericus can be used to elucidate the hydrological characteristics of riverine wetlands. This information is important for maintenance and conservation of artificial wetlands at the Nakdong River.

• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.75-83
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• 1998

The purpose of this survey was to investigate the regional and seasonal characteristics of a water system and to obtain basic information of a water system at Andong bridge, Nakdan bridge, Kangjung, Waekwan bridge and Koryung bridge along Nakdong River. We surveyed the water quality in the Nakdong River for 2 years from Jan. 1996 to Dec. 1997. The results summarized were follows; 1) The pH in the Nakdong River on the basic of 2 years average were 6.5-8.6. 2) The DO, the COD and the BOD were low level in summer and high level in winter, respectively. 3) The suspended solids(SS) contents was high especially in summer. 4) The T-P and the T-N contents were higher than the lower level of nitrogen and phosphorous for algae growth and the contents were high especially in winter. 5) The $NH_4{^+}$-N and $NO_3{^-}$-N were also observed to be quite high.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.882-887
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• 2006

Sedimentological, geochemical, geophysical and micropaleontological analyses of 10 borehole cores were carried out to understand depositional environment and sequence stratigraphy of late Quaternary sedimentation in the estuary of the Nakdong River. Holocene Formation in study area is classified into five sedimentary units. Early Holocene freshwater lower pebbly sandy deposit(Unit I), lower muddy deposit(Unit II), middle thin sandy deposit(Unit III), upper muddy deposit(Unit VI), and upper sandy deposit(Unit V), in ascending order contolled by global sea-level change since interglacial period(about 15,000 yrs B.P.). Unit I deposited in erosional environments before marine trangression. Unit II and Unit VI composed of clay were deposited in cold and worm currents for marine trangression., respectively.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.807-813
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• 2007

Settling velocity is one of major parameters determining algal biomass in water quality modeling. In this study, the settling velocity of phytoplankton was measured in reservoir and stream sites of the Nakdong River, Korea. Settling velocities of various phytoplankton species were determined by measuring algal cell biomass settled in a sedimentation cylinder. Mean settling velocities were $0.22m\;day^{-1}$ in reservoir sites and $0.33m\;day^{-1}$ in stream sites, which were relatively higher compared with other default values suggested by water quality models (e.g. $0.1m\;day^{-1}$ in CE-QUAL-W2). The lower settling velocity in reservoirs than in stream implies the adaptation of phytoplakton to low turbulence in lentic environments. Cyanobacteria showed lower settling velocity ($0.2m\;day^{-1}$) than diatoms ($0.3m\;day^{-1}$), and this phenomenon may have resulted from buoyancy mechanisms of cyanobacteria. Cell volume did not show a significant correlation with settling velocity in this study, implying that conformation factors of colonies or other factors had large effects on settling velocity of algal cells as well as cell size. The result of this study may suggest proper coefficients of settling velocity of phytoplankton in the calibration of water quality model.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.3
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• pp.160-180
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• 2012

We have studied the eukaryotic plankton species diversity to compare the community structure of fresh and brackish waters in the lower reaches of the Nakdong River using metagenomic methods. We constructed 18S rDNA clone libraries of total DNAs extracted from environmental water samples collected at Mulgeum (MG100929, fresh) and Eulsukdo bridge (ES, brackish). Through the steps of colony PCR, PCR-RFLP, sequencing and similarity analysis, we discovered the diverse species composition of eukaryotic plankton. Total 338 clones (170 at MG100929 and 168 at ES) were analyzed, and then we found 74 phylotypes (49 for MG100929 and 25 for ES). From the phylogenetic analysis, we confirmed various eukaryotic plankton of broad range of taxonomic groups, including Stramenopiles, Cryptophyta, Viridiplantae, Alveolata, Rhizaria, Metazoa, and Fungi. We also found several unreported species in Korea and candidates of new taxonomic entities at levels higher than genus. Especially, the cryptic species diversity including unreported phylotypes of Pirsonia (Stramenopiles) and Perkinsea (Alveolata) suggests that the molecular monitoring method can produce new informative biological data in monitoring the changes in the Nakdong River Mouth ecosystem.

• Journal of Environmental Science International
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• v.14 no.10
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• pp.905-910
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• 2005

The purpose of this study is the comparative analysis of Susan citizens' images of Eulsook-do as a coastal tourism destination before and after the construction of a road bridge across the Nakdong estuary in order to analyze local people's changes in leisure patterns. Analysis of the images of a pre-construction Eulsook-do that people aged both 40 and less and 50 and more had on five dimensions showed values higher than zero(0) that suggests neutral image, while their images of a post-construction Eulsook-do showed the shrinking size of pentagon on all five dimensions: ET(Entertainment), CA(Culture & Art), EE(Environment & Ecology), RC(Recreation) and LP(Leports) dimensions. Its pre- and post- construction image analysis conducted 20 years after it came to be built finds that the road bridge construction has led to the ecological, environmental disruption of the coast and the lower Nakdong river, having negative influence on the images of Eulsook-so.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.183-189
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• 2002

Investigation was carried out to observe the dominant bacteria and the effect of metals(Cd ＆ Zn) and its nitrate compound on growth of bacteria isolated from the three tributaries and lower reach of the Nakdong River. Mean CFU(log$_{10}$) level was highest in Kumho River(8.30 CFU), Nam River, Hwang River, and Mulgum followed. Staphylococcus xylosus, Staph. lentus, Pasteurella pneumotropica, Aeromonas hydrophilla were dominant species in each study site. Cadmium powder and Zinc powder showed strong effect to inhibit the growth of Micrococcus spp., Pasteurella pneumotropica, Aeromonas hydrophilla. But, nitrate compounds of Cd and Zn(Cd(NO$_3$)$_2$4$H_2O$, Zn(NO$_3$)$_2$6$H_2O$) did not clearly show the strong effect to inhibit the growth of dominants.s.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.160-180
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• 2005

Long-term data (Ministry of Environment Water Quality Monitoring data) of phytoplankton biomass (chlorophyll a) and water quality were analyzed to investigate trends in biomass of the primary producers and water quality for the estuarine systems in Korea: Sumjin River, Han River, Asan Lake- Bay, Youngsan River, Keum River and Nakdong River. The literatures were also reviewed to examine the characteristics of phytoplankton biomass and water quality in the estuarine systems. The Sumjin River estuary, the single estuary without a dike in Korea showed the characteristics similar to other typical estuarine systems. Phytoplankton biomass was high during the fall at transitional regions (5 ${\sim}$ 15 psu) after riverine freshwater inputs were increased in summer. Concentrations of the nitrate and silicate were increased with the high river discharge rates. Phytoplankton biomass and nutrient concentrations were high during spring at the lower regions in the Han River whereas phytoplankton biomass and nutrient concentrations were high during spring at the upper regions in the Youngsan River. Phytoplankton biomass was the highest in the Asan Lake and nutrient concentrations were high at the upper region of the lake. In Nakdong River, phytoplankton biomass was high during winter and the biomass was slightly higher at upper region than at lower region. Long-term trends showed that total nitrogen and total phosphorus were mostly increased in the river systems. Implications of these results relevant to the water quality management for the river systems were also discussed.