• Journal of Aquaculture
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• v.10 no.2
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• pp.105-112
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• 1997

For improvement of fishermen's income by oyster cultivation in eastern coast of Korea, the spats of oyster (Crassostrea gigas) collected from Hadong in southern coast of Korea were transplanted to Chumunjin and cultured by hanging long line method from August 1994 to July 1995 for examination of their growth and ground environmental conditions. The environmental conditions show the annual range of water temperature as 8.33~$25.62^{\circ}C$, salinity as 32.84~$34.28\textperthousand$, PO4-P as 0.09~0.40$\mu$g-at/1, dissolived inorganic nitrogen (DIN) as 0.32~3.21$\mu$g-at/1. The growth of oyster in hanging culture was as follows : 88.7mm (shell hight) in upper layer (7m), 84.9mm in middle layer (10m) and 78.0mm in lower layer (13m) after one-year cultivation. Thus, the oysters in upper layer had grown relatively faster than those in lower layer. The relationships between shell hight (SH) and shell length (SL) in each culturing depth as follows : SL=0.5403 SH+8.5486 (r=0.9959) in upper layer, SL=0.5813 SH+3.7775 (r=0.9869) in middle layer, and SL=0.5159 SH+6.8736 (r=0.9961) in lower layer. The meat weight of oyster was the highest value as 13.24g in upper layer, and 12.68g in middle layer, and lowest as 10.96g in lower layer. The relationships between total wight (TW) and meat weight (MW) with culturing water layer were as follows : MW=0.1933 TW+0.1051 (r=0.0073) in upper layer, MW=0.1915 TW+0.1894 (r=0.9984) in middle layer, and MW=0.1650 TW+0.0558 (r=0.9983) in lower layer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.506-510
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• 2013

This study aimed to understand relationship between potential risky species and environmental factors at ports in Korea. During the study periods, 25 potential risky species (red tide and toxic species) representing 20 red-tide species, 5 toxic species were observed in the all ports. Skeletonema costatum (red-tide species) was predominated in all study area. This species showed positive correlation with pH, while negative correlation with dissolved oxygen (p<0.05) at Busan port. Also, this species showed positive correlation with total suspended solids and pH (p<0.05) at Ulsan port. However, Sk. costatum showed positive correlation with nitrate at Incheon port (p<0.01). Pseudo-nitzschia spp. producing amnesic shellfish poison (domoic acid) showed positive correlation with nitrate and silicate in all study areas (p<0.05). Alexandrium spp. (paralytic shellfish poison) and Dinophysis acuminata (diarrhetic shellfish poison) were affected by chemical oxygen demand (p<0.01). Our results indicated that red-tide species were affected by physical factors, while chemical factors affected toxic species.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.19-25
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• 2008

To evaluate the functions of vegetation mat of artificial floating island (AFI) installed in Lake Paldang, nutrients, such as total phosphorus (TP), dissolved inorganic phosphorus (DIP), total nitrogen (TN) and nitrate $(NO_3)$ and microbial factors such as total bacterial numbers, active bacterial numbers and exoenzymatic activities of $\beta$-glucosidase and phosphatase in pore water of medium and bulk lake water were analyzed. The concentration of TN and $NO_3$ in pore water ranged from 4.4 to 7.5mg $L^{-1}$ from 1.2 to 3.8mg $L^{-1}$ respectively, which were ca. 2 times higher than those of lake water. The ranges of TP and DIP of were $1.4\sim4.1mg\;L^{-1}$ and $0.003\sim0.137mg\;L^{-1}$ in pore water of media which were $4\sim25$ and 5 times higher than those of lake water, respectively. The numbers of total bacteria and active bacteria in pore waterwere about 10 times higher than those of laker water. Also, both phosphatase and $\beta$-glucosidase activities of pore water were on an average 10 times higher than those of lake water. These results suggest that the bacteria were playing important role for nutrients concentrating and cycling in media of artificial floating island. And the medium of artificial floating island contained newly created microbial ecosystem, which is responsible for sustaining the growth of macrophytes and the creation of new aquatic ecosystem.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.476-476
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• 2022

농업용수는 전통적 기능으로 농업용수 그 자체로서의 기능과 시대적 요구에 따른 지역용수로서의 기능을 가진다. 농업용수 그 자체의 기능으로 가장 중요한 것은 관개용수이며, 논, 밭관개, 하우스 시설농업에의 용수공급이다. 농업용수의 실 수요량 측면에서는 논용수가 전체용수 수요량의 60.1%로 가장 많은 양을 차지하고 있으며, 다음으로는 밭용수가 18.6%, 그 외 생활용수, 공업용수, 환경용수, 축산용수 등으로 이용되고 있다. 농업용수 수요 측면에서 논용수의 비중이 가장 높게 나타나기 때문에 본 연구에서는 농업용수 공급에 따라 농업용저수지-관개수로-논에 이르는 공급단계별 수질변화를 분석하였다. 본 연구는 경기, 충남 권역의 오염도가 높은 3개 농업용저수지를 대상으로 하였으며, 농업용수를 본격적으로 공급하는 5월부터 관개가 종료되는 10월까지 농업용저수지와 관개수로, 논을 대상으로 수온, TOC, Chl-a 등 10개 항목을 분석하여 나타내었다. 연구기간동안 수온의 변화는 18.6~34.6 ℃로서 관개수로에 가장 낮고, 논에서 가장 높은 값을 보여 주었으며, 공급단계별 평균 수온은 저수지(R) 27.6 ℃, 관개수로(C) 26.4 ℃, 논(P) 28.4 ℃로 논에서 수온증가가 나타났다. pH는 7.4~9.7의 범위로 저수지에서 최고값, 논에서 최저값을 보였으며, 공급단계별 평균값은 R 9.1, C 8.3, P 8.0으로 저수지, 수로, 논으로 이동하면서 감소하였다. 전기전도도(EC)는 저수지 수질오염도에 따라 다양하게 나타났으며, 공급단계별 평균값은 R 706.3 uS/cm, C 585.5 uS/cm, P 771.2 uS/cm로 논에서 가장 높은 값으로 보였으며, 이는 논에서 추가적인 영양분 공급에 의한 것으로 보였다. 평균 용존산소량(DO)은 R 6.3, C 4.0, P 4.5로 저수지에서 가장 높고, 수로에서 가장 낮게 나타났다. 유기물 지표인 COD와 TOC의 변화를 보면 평균 COD R 21.7 mg/L, C 14.5 mg/L, P 22.7 mg/L, 평균 TOC R 11.2 mg/L, C 8.5 mg/L, P 12.3 mg/L로 두 항목 모두 논에서 가장 높은 값을, 수로에서 가장 낮은 값을 나타내었다. 반면 엽록소 a 평균 농도는 R 128.4 mg/m³, C 54.3 mg/m³, P 31.7 mg/m³로 저수지의 내부생산으로 다량 발생한 조류가 수로와 논으로 이동하면서 급격하게 감소하여 나타났다. 이는 저수지와 논의 유기물 성상이 다름을 보여준다. 영양염류인 총인(TP)의 평균값 변화를 보면 R 0.302 mg/L, C 0.374 mg/L, P 0.384 mg/L로, 저수지에서 수로, 논으로 이동하면서 점차 증가하여 나타났다. 이는 농업용저수지에서 수로, 논으로 관개용수가 이동하면서 오염수 유입 또는 비료 등의 투입이 이루어진 결과로 판단된다. 이와 같이, 농업용저수지의 수질이 논에 그대로 유지되어 유입되지 않고 공급단계에 따라 변화하고 있으므로 항목별 수질 변화 특성을 이해한 후 농업용수 수질관리가 이루어 져야 할 것이다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.192-202
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• 2010

Submarine groundwater discharge (SGD) has been recognized as a provider for freshwater, nutrients, and dissolved constituents from continents to the oceans and paid more attention with regard to the mass balance of water or dissolved constituents on local and global scales. The submarine discharge of fresh groundwater (fresh SGD) through seepage or springs in coastal ocean may be especially important in aspects of water resource and marine environment managements in the future. Based on the worldwide compilations of observed fresh SGD, our review reveals that fresh SGD occurs in various marine environments along most shoreline of the world and the global estimates of fresh SGD were approximately 0.01-17% of surface runoff. In addition, the input of fresh SGD calculated and investigated in this study were about 50%, 57%, 89%, and 420% of total river discharge in Jeju Island, Yeongil Bay, Masan Bay, and Yeoja Bay, respectively. These inputs from fresh SGD along the shoreline of Korea Peninsula are much higher than those of the whole world, greatly vary with the region. However, since these estimates are based on the water balance method mainly used in coastal ocean, we have to perform continuous monitoring of various parameters, such as precipitation, tide, evapotanspiration and water residence time, which have an impact on the water balance in a lot of areas for evaluating the precise input of fresh SGD. In addition, since the method estimating the input of fresh SGD has brought up many problems, it is required to make an intercomparison between various methods such as hydrogeological assumption, numerical modeling, and seepage meter.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.73-84
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• 2006

The objective of this study was to analyze long-term temporal trends of water chemistry and spatial heterogeneity for 10 sampling sites of the Yeongsan River watershed using water quality dataset during 1995 to 2004 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (Do), total phosphorus (TP), total nitrogen (TN) and total suspended solids (TSS), largely varied depending on the sampling sites, seasons and years. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summmer monsoon rain. Conductivity, used as a key indicator for a ionic dilution during rainy season, and nutrients of TN and TP had an inverse function of precipitation (absolute r values> 0.32, P< 0.01, n= 119), whereas BOD and COD had no significant relations(P> 0.05, n= 119) with rainfall. Minimum values in conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of total suspended solids (TSS) occurred during the period of summer monsoon. BOD values varied with seasons and the values was closely associated (r=0.592: P< 0.01) with COD, while variations of TN were had high correlations (r=0.529 : P< 0.01) with TP. Seasonal fluctuations of DO showed that maximum values were in the cold winter season and minimum values were in the summer seasons, indicating an inverse relation with water temperature. The spatial trend analyses of TP, TN, BOD, COD and TSS, except for conductivity, showed that the values were greater in the mid-river reach than in the headwater and down-river reaches. Conductivity was greater in the down-river sites than any other sites. Overall data of BOD, COD, and nutrients (TN, TP) showed that water quality was worst in the Site 4, compared to those of others sites. This was due to continuous effluents from the wastewater treatment plants within the urban area of Gwangju city. Based on the overall dataset, efficient water quality management is required in the urban area for better water quality.

• Journal of Aquaculture
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• v.15 no.3
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• pp.145-155
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• 2002

Effect of density (30, 40, 65, 90 or 120/cage) of lantern and bottom cages on growth of the ark shell, Scapharca satowi was studied in the Korean west coast from April 2000 to October 2001, when the following range of environmental conditions prevailed : temperature : 4.2 -25.5 $^{\circ}C, salinity : 30.23-32.$15\textperthousand, dissolved oxygen : 5.12-7.16 $ml$/l, pH : 7.84-8.17, phosphate : 0.22-0.56 $\mu $M, dissolved inorganic nitrogen : 3.16-9.10 $\mu $M, suspended solid : 7.6-17.9 mg/l, chemical oxygen demand: 0.46-1.61 mg/l and chlorophyll-a : 0.92-5.93 $\mug/l. Daily growth rate of shell length ranged from 0.066 to 0.071 mm/day for the lantern net cages, and from 0.079 to 0.082 mm/day for the bottom cages. Total weight also ranged from 0.067 to 0.082 g/day in the lantern net cages, as against 0.099 to 0.114 g/day in the bottom cages. Hemoglobin content of S. satowi (55 mm shell length), which was about 3.9 g/dl during february, 2001, increased to 6.0 and 7.0 g/dl during October, 2001 in animals culture in the lantern and bottom cages, respectively. ANOVA test of the growth rate showed that the growth rate of S. satowi, was significantly dependent on rearing density and the tested culture methods (P < 0.0001). The daily growth rate of the shell length was more significantly correlated with water temperature; the growth rate of shell length and total weight showed a tendency decrease with decreasing temperature. In cages suspended at the bottom, not only the increase shell weight but also the meat obtainable from comparable sized S. satowi was greater. Survival decreased with increasing density and was optimal at the density of 30 individual/cage.

• Journal of Aquaculture
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• v.15 no.2
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• pp.95-101
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• 2002

During the periods from lily to October, 2000 in Hongseong and lucy to October, 2001 in Taean in the west coast of Korea, the following environmental conditions prevailed : water temperature : 22.0~26.817, salinity 27.23 ~30.80%, dissolved oxygen 4.12 ~6.26 ml/l, pH 7.89 ~8.09, phosphate 0.39 ~0.65 $\mu m$ , inorganic nitrogen 5.05~9.26 $\mu m$, suspended solid 5.4~20.8 mg/l and chemical oxygen demand 1.12~1.87 mg/l. The B-shaped veliger larvae of the Ark shell occurred in maximum number at $25^{\circ}C$ prevailing from mid-August at Hongseong and Taean. Full grown larvae reached maximum abundance from late August. To identify the effectiveness of the substratum for spat collection, raschel net were tested to Larval settlement. The most effective depth to collect the larvae in natural environment was the collectors suspended at 7~8 m depth. At these depths, about 49 to 94 spats were found on the collector (40$\times$50 cm), The growth of shell height (Y) to shell length (X), and total weight (W) to shell length (L) could be formulated as follows respectively: Hongseong: SH = 0.7168 SL -0.6466 ( $r^2$ = 0.9839), TW = $0.0001SL^{3.1705}$ ($r^2$ = 0.9882) Taean: SH = 0.736 SL -0.8824 ($r^2$ : 0.9899), TW : 0.00005 $SL^{3.3731}$ ($r^2$ : 0.9899)

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.257-262
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• 2012

This study was conducted to verify the performance of the solar water circulation apparatus that was installed in a semi-closed sea area of Tongyeong to improve the water quality through removing thermocline and oxygen depleted water mass, and to prevent the occurrence of red tides caused by eutrophication. From 8 weeks of experiments, we found that the thermocline in the semi-closed sea area has been removed gradually after installation of the apparatus. The initial temperature of surface and bottom was $27.9^{\circ}C$ and $23.8^{\circ}C$, respectively and it was changed to $22.1^{\circ}C$ in both depth. In case of DO concentration, there was a big gap between surface (5.49 mg/L) and bottom (2.61 mg/L) and was an oxygen depleted water mass in the bottom area at initial. However DO concentration in bottom layer has increased gradually after operation (6.19 mg/L) and the oxygen depleted water mass has removed. Due to the effects of seasonal variation and the operation of the solar water circulation apparatus for 8 weeks, COD concentration decreased from 5.61 mg/L to 2.36 mg/L in surface area, and from 6.08 mg/L to 1.73 mg/L in bottom area. Dissolved inorganic nitrogen concentration also decreased from 0.135 mg/L to 0.050 mg/L in surface area, and from 0.076 mg/L to 0.051 mg/L in bottom area. This research was conducted from July to September, and it might be possible that the variation of water quality was affected by both seasonal variation and the operation of the water circulation apparatus. Hence a further research is required to verify the performance of the water circulation apparatus itself and to monitor dissolved inorganic nitrogen and phosphorous concentrations as well as Chl-a.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.3
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• pp.28-37
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• 2016

Through the research and analysis on the hydrological environment and soil environment of habitats through documentary and field studies over 14 habitats of Euryale ferox Salisb. within Jeollabukdo, with the objective of acquiring the basic data for forming an environment based on plantation of reservoirs that are composed with Euryale ferox, the following results were obtained. As a result of analyzing the construction period of the habitats of Euryale ferox from a total of 14 places, the average period of duration after construction of all subject reservoirs appeared to be 71.8 years. Moreover, when examining the relationship between the age of reservoirs and eutrophication, it could be judged that at least the eutrophication of subsoil and water environment is not an obstacle to the growth of Euryale ferox grows in habitats that have a reservoir age of approximately 70 years or more. As a result of analyzing the gardening of soil sediment of the Euryale ferox habitats, the component ingredients appeared to be composed of 80.2% of clay, 16.7% of silt and 3.1% of sand, and the soil class pursuant to such was classified as 'heavy clay'. The organic matter contents of soil sediment appeared to be an average of 36g/kg, and there appeared to be no noticeable difference between the habitats and non-habitats of Euryale ferox. The water quality environment of Euryale ferox habitat appeared to be pH 6.5~7.9, concentration of dissolved oxygen to be $1.8{\sim}8.8mg/{\ell}$, concentration of COD to be $6.8{\sim}74mg/{\ell}$, floating materials to be $2.0{\sim}213mg/{\ell}$, total nitrogen to be $0.422{\sim}10.723mg/{\ell}$, and phosphate to be $0.003{\sim}0.126mg/{\ell}$. The average DO concentration of Aedang Reservoir at Jeongeup, Daejeong Reservoir at Imsil, and Myeongdeokji at Gimje with high vitality and green coverage ratio of Euryale ferox appeared to be $3.5mg/{\ell}$, total nitrogen to be $1.33mg/{\ell}$, and concentration of phosphorus-phosphate to be $0.061mg/{\ell}$. When comparing such with the entire average value, the DO and total nitrogen concentration appeared to be rather low, and the phosphorus-phosphate concentration appeared to be higher by two times or more, thus, an in-depth study on the correlation of the vitality of Euryale ferox Salisb. and concentration of phosphorate-phosphorus will be needed in the future.