• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.292-303
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• 2016

This study described the spatial distributions of marine environmental factors such as water temperature, salinity, chlorophyll a concentration and turbidity, and characteristics of phytoplankton community such as species composition, standing crops and dominant species at 19 fishing ports around Jeju Island during the early summer of 2016. I analyzed bio-oceanographical characteristics using principal component analysis (PCA) of the environmental factors and biological parameters. Water temperature, salinity, chlorophyll a and turbidity ranged from 17.6 to $20.7^{\circ}C$, from 26.19 to 32.33 psu, from 0.76 to $7.13{\mu}g\;L^{-1}$, and from 0.51 to 14.49 FTU, respectively. A total of 51 species of phytoplankton belonging to 35 genera were identified. In particular, diatoms and dinoflagellates accounted for more than 56.8% and 27.4% of all the species, respectively. Moreover, the number of phytoplankton species was controlled by salinity. Phytoplankton cell density ranged from $2.9cells\;mL^{-1}$ to $185.9cells\;mL^{-1}$. The dominant species were Navicula spp. Stephanopyxis turris, Eutreptiella gymnastica and Mesodinium rubrum. Environmental factors and the phytoplankton community varied greatly between sampling sites. According to PCA, the biological oceanographic characteristics of the around Jeju Island were characterized by meteorological factors such as air temperature, precipitation and discharge of ground water during early summer.

• Journal of the korean society of oceanography
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• v.39 no.2
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• pp.119-135
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• 2004

A three-dimensional numerical model using POM (the Princeton Ocean Model) is established in order to understand the dispersion processes of the Yangtze River water in the Yellow and East China Seas. The circulation experiments for the seas are conducted first, and then on the bases of the results the dispersion experiments for the river water are executed. For the experiments, we focus on the tide effects and wind effects on the processes. Four cases of systematic experiments are conducted. They comprise the followings: a reference case with no tide and no wind, of tide only, of wind only, and of both tide and wind. Throughout this study, monthly mean values are used for the Kuroshio Current input in the southern boundary of the model domain, for the transport through the Korea Strait, for the river discharge, for the sea surface wind, and for the heat exchange rate across the air-sea interface. From the experiments, we obtained the following results. The circulation of the seas in winter is dependent on the very strong monsoon wind as several previous studies reported. The wintertime dispersion of the Yangtze River water follows the circulation pattern flowing southward along the east coast of China due to the strong monsoon wind. Some observed salinity distributions support these calculation results. In summertime, generally, low-salinity water from the river tends to spread southward and eastward as a result of energetic vertical mixing processes due to the strong tidal current, and to spread more eastward due to the southerly wind. The tide effect for the circulation and dispersion of the river water near the river mouth is a dominant factor, but the southerly wind is still also a considerable factor. Due to both effects, two major flow directions appear near the river mouth. One of them is a northern branch flow in the northeast area of the river mouth moving eastward mainly due to the weakened southerly wind. The other is a southern branch flow directed toward the southeastern area off the river mouth mostly caused by tide and wind effects. In this case, however, the tide effect is more dominant than the wind effect. The distribution of the low salinity water follows the circulation pattern fairly well.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.4
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• pp.452-468
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• 2012

Marine organisms were collected by the stow nets and the stow net on boat fisheries from April 2010 to November 2011 in the Han River Estuary and categorized as 126 species, 61 families, and 5 taxa. The species were consisted with 34 in Crustacea, 5 in Cephalopoda, 79 in Pisces, unidentified jellyfishes in Cnidaria, and Finless porpoise in Mammals. The major species were composed of fish and crustaceans in the Han River Estuary. The dominant species in Crustacea were Chinese ditch prawn (Palaemon gravieri), blue crab (Portunus trituberculatus), Ridgetail prawn (Exopalaemon carinicauda), and mantis crab (Oratosquilla oratoria), and those in Pisces were Korean anchovy (Coilia nasus), and Japanese grenadier anchovy (Coilia mystus). The length structures of the six dominant species have more than one mode in the Han River Estuary. It reflects that the species inhibit during a part of and/or whole lifetime in the Han River Estuary where they utilize as spawning and/or nursery grounds. Freshwater fishes were collected from station D where is the closest location to the Han River stream, and their appearances were well matched with the large amount of freshwater discharge due to flood periods. Principal components analysis (PCA) was carried out with species compositions and showed temporal and spatial differences by the variations of species.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3345-3350
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• 2014

We investigated to assess the relationships between the major nutrients and phytoplankton dynamics during the spring season in 2010 and 2011 at 23 stations in Jinhae Bay, Korea. The bay is divided into four different zones based on pollutant sources and geographical characteristics. Nutrient limitation (>80%) was significant in Zone II, which is located in central bay and is influenced by the water well mixed from outer bay. The limited nutrient was followed in Zone III and IV that was occupying between 17% and 83%. However, the low levels are being kept below 35% in Zone I, which is characterized by the semi-enclosed eutrophic area of Masan and Haegam bays. Based on the PCA (principle component analysis) analysis, the nitrogen (N) sources in 2010 were particularly dominant and it may be due to the water mixing and wastewater formed from bottom layers and sewage. In 2011, major nutrients including nitrogen, silicon and phosphorus were dominant in the bay and are supplied by the river discharge after rainfalls with low salinity conditions. In particular, the N nutrients being supplied in 2010 are correlated with pennate diatoms Pseudo-nitzchia spp. and is not related to the phytoplankton population densities in 2011. The present study suggests that N sources play an important role in the proliferation of diatom, and the rapid nutrient uptakes by them are potential nutrient limitation factors in the bay.

• Korean Journal of Environment and Ecology
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• v.22 no.6
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• pp.658-665
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• 2008

One of the characteristics of fluvial river channel with sand bed-material is the existence of movable sand bars not occupied with vegetation. However, sand bars at the Hahoe's reach of the Nakdong River showing a double-meandering channel has been changed into expanding vegetation area. Moreover, sand material, in recent years, has stopped moving to downstream in channel and the number and area of bare bars which did not occupied by vegetation have been decreased. In order to find out the mechanism, we carried out the channel characteristics surveys such as hydro-geomorphologic, soil physio-chemical and vegetation surveys were conducted twice on autumn season in 2005,2006. The results so far achieved showed that the reduced discharge of transported sediment and duration of dry season might be critical factors for the spread of luxuriant vegetation. The vegetation area was significantly expanded by floods exceeding the subsequent dominant flow discharge. Furthermore, the expansion of vegetation area was highly correlated with the supply of organic matter, nutrients and alteration of soil texture by sediment deposition during the flooding event.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.567-579
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• 2011

Scirpus planiculmis is one of the most dominant species found in the Nakdong River estuary. In order to understand the recent changes in S. planiculmis and the environmental characteristics of the estuary, from 2005 to 2010, an analysis of the density, total dry biomass, tuber biomass, and distribution pattern of S. planiculmis as well as an analysis of the temperature, salinity, precipitation, barrage discharge, and soil texture of the estuary were conducted. In 2006, the density ranged from 10.1 to $87.6no./m^2$, but in 2009, it ranged from 0.4 to $2.2no./m^2$ in 2009 and drastic reductions were observed throughout the sampled areas in the Nakdong river estuary. In 2010, S. planiculmis was observed on the tidal flats of Myungji and Mangummerydeung, at a density of $18.3{\pm}7.7no./m^2$ and $17.5{\pm}20.7no./m^2$, respectively. Hence, S. planiculmis is considered to be in a recovery phase. The aboveground/belowground ratio reduced from $4.54{\pm}0.70$ in 2005 to $1.91{\pm}0.35$ in 2009, clearly showing a large decrease in the biomass amount of the aboveground than of the belowground. Tubers were distributed in the soil, with only 36.0% at the 0~15 cm depth but 64.0% at the 15~30 cm depth. Apparently, tubers were more likely to be found at 15~30 cm below the soil in the Nakdong River estuary. A drastic reduction in the S. planiculmis biomass in 2009 is possibly due to the high salinity in S. planiculmis habitats.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.52-61
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• 2006

The aim of this study was to analyze the seasonal patterns of zooplankton community dynamics in the lower Nakdong River (Mulgum, RK; river kilometer; 27 km from the estuarine barrage), with a Self-Organizing Map (SOM) based on weekly sampled data collected over ten years(1994 ${\sim}$ 2003). It is well known that zooplankton groups had important role in the food web of freshwater ecosystems, however, less attention has been paid to this group compared with other community constituents. A non-linear patterning algorithm of the SOM was applied to discover the relationship among river environments and zooplankton community dynamics. Limnological variables (water temperature, dissolved oxygen, pH , Secchi transparency, turbidity, chlorophyll a, discharge, etc.) were taken into account to implement patterning seasonal changes of zooplankton community structures (consisting of rotifers, cladocerans and copepods). The trained SOM model allocated zooplankton on the map plane with limnological parameters. Three zooplankton groups had high similarities to one another in their changing seasonal patterns, Among the limnological variables, water temporature was highly related to the zooplankton community dynamics (especially for cladocerans). The SOM model illustrated the suppression of zooplankton due to the increased river discharge, particularly in summer. Chlorophyll a concentrations were separated from zooplankton data set on the map plane, which would intimate the herbivorous activity of dominant grazers. This study introduces the zooplankton dynamics associated with limnological parameters using a nonlinear method, and the information will be useful for managing the river ecosystem, with respect to the food web interactions.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.58-67
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• 2016

This study was performed to investigate the long-term changes in water quality and benthic ecology around the Nakdong River Estuary. The effect of the estuarine barrage on the ecosystem was also evaluated. The water quality was interpreted using the field survey (2013 and 2014) and monitoring data (MOE, 1989~2013) and the macrobenthic-fauna was investigated through analysis of the field survey data (2014) and literatures review (1985~2013). The long-term variation of water quality of Nakdong River generally showed increased nutrient concentration with decreased discharge, while abrupt influence of the barrage construction was not observed. However, the nutrient and organic matter concentration inside the barrage distinctly was higher than the concentration outside the barrage because the mixing of fresh and seawater was limited by the barrage. Especially, in the period of low discharge during winter, the Chlorophyll-a concentration clearly increased more in the downstream inside the barrage, showing the barrage effect. In other words, stagnant effect caused by barrage construction had an effect on the water quality degradation in dry seasons. As for the benthic ecology inside barrage after barrage construction, molluscans and brackish-water crustaceans disappeared. Outside the barrage, benthic ecosystem has deteriorated and the small-sized organic indicative species like Prionospio membranacea, Pseudopolydora kempi, Sinocorophium sinensis became dominant due to several construction such as Myeong-Gi Bridge, Airport construction, industrial complex after the Nakdong barrage construction.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.2
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• pp.25-33
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• 2002

We were trying to understand indirectly the range of the discharge from the Nakdong with the dispersion of suspended solid(SS) related to the amount of discharge from river in this study. The range of dispersion of SS from the Nakdong was estimated using satellite remote sensing and numerical modeling. The stream field with two dimensional and numerical model using the condition of integrated depth was calculated. According to the results, the streamline flowed from Busan to the Jinhae Bay and Geojae Island. at the flood. The situation at the ebb was totally changed. The streamline flowed out Busan from the Bay. The velocity in offshore was faster than one at coastal water of the Nackdong. Residual current which was averaged during 12hours dominantly appeared the dominant direction from the southwestern part of the Nackdong to the northeastern part of it. The eastward current appeared at the eastern coast of Gaduck Is. Base on the results of the velocity field, the quantifying of the dispersion of SS was estimated by the method of numerical tracer related to the Lagrangian method. The significant range of the dispersion of the SS from the Nackdong was from the eastern coast of Gaduck Is, to the coastal areas of Busan, Korea. The estimated range of the dispersion of the SS using the SeaWiFS and Landsat satellite data was similar to the estimated results using the numerical model.

• Journal of Trauma and Injury
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• v.19 no.1
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• pp.47-53
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• 2006

Purpose: Recently, the American Heart Association recommended that routine cervical spine protection in submerged patients was not necessary, except in high-energy injury situations. However, until now, this recommendation has few supportive studies and literatures. This retrospective study was performed to demonstrate the risk of cervical spine injury in patients who had been submerged in a river. Methods: Seventy-nine submerged patients who visited St. Mary's Hospital between January 2000 and December 2005 were included in this retrospective study. We investigated and analyzed the victim's age, sex, activity on submersion, mental status and level of severity at admission, prognosis at discharge, associated injuries, and risk group by using the medical records and cervical spine lateral images. According to the activity on submersion, victims were classified into three groups: high risk, low risk, and unknown risk. The reports of radiologic studies were classified into unstable fracture, stable fracture, sprain, degenerative change, and normal. Results: The patients' mean age was 36.8 yrs, and 54% were males. Of the 79 patients, adult and adolescent populations (80%) were dominant. Jumping from a high bridge (48%) was the most common activity on submersion and accounted for 52% of the high-risk group. The Glasgow coma scale at admission and the cerebral performance scale at discharge showed bimodal patterns. The results of the radiologic studies showed one stable fracture, one suspicious stable fracture, and 18 sprains. The incidence of cervical spine fracture in submerged patients was 2.5% in our study. The incidence of cervical spine injury was higher in the high-risk group than it was in the low-risk group, especially in the jumping-from-high-bridge subgroup; however this observation was not statistically significant. No other factors had any significant effect on the incidence of cervical spine injury. Conclusion: Our study showed that even submerged patients in the high risk group had a low incidence of cervical spine fracture and that the prognosis of a patient did not seem to be influenced by the cervical spine fracture itself.