• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.392-401
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• 2008

The vertical changes (upper layer: 0$\sim$0.5 m, middle layer: 4$\sim$5 m and lower layer: 8$\sim$10 m) of the limnological variables, zooplankton dynamics and community filtration rate on the phytoplankton were evaluated monthly intervals from November 2004 to June 2007 at the artificiallake (Okjeong Lake). During the study, the annual mean of water temperatures were 15.2$\pm$7.8$^{\circ}C$ (upper layer), 14.5$\pm$7.4$^{\circ}C$ (middle layer) and 13.0$\pm$6.2$^{\circ}C$ (lower layer), respectively (n=30). The vertical variations of most limnological parameters (DO, pH, conductivity and turbidity) were fairly similar, except for chl.-${\alpha}$ concentration. Annual mean of chl.-${\alpha}$ concentration was highest at the upper layer (21.4 ${\mu}g$ L$^{-1}$), while annual means of concentrations were low at the middle layer and lower layer (4.3 ${\mu}g$ L$^{-1}$ and 3.5 ${\mu}g$ L$^{-1}$, respectively). Annual mean of Secchi depth was 261 cm (n=30). A total 45 species of zooplankton were identified (28 rotifers, 12 cladocerans and 5 copepods) during the study. The mean abundance of rotifers was highest (124$\pm$232 ind. L$^{-1}$, n =90) and that of cladocerans and copepods were relatively low (22$\pm$56 ind. L$^{-1}$ and 13$\pm$30 ind. L$^{-1}$) in the whole layer. Total zooplankton abundance increased from late spring to summer, and then declined and remained low throughout the winter. The annual mean of total zooplankton filtration rate for phytoplankton at the lower layer was much higher than that of both layers (upper layer: 44.4$\pm$107.8, middle layer: 95.1$\pm$436.4 and lower layer: 158.2$\pm$436.4 mL L$^{-1}$ day$^{-1}$). Among the major zooplankton community, relative community filtration rate (RCFR, %) of copepods for phytoplankton (50.2$\sim$54.8%) was much higher than that of cladocerans (27.7$\sim$36.3%) and rotifers (8$\sim$17.6%). The seasonal variation of RCFRs of major zooplankton community was observed. The RCFRs of rotifers were high in winter (44.6%, n=9), while the RCFRs of cladocerans were high in summer (58.0%, n=7). In spring and fall, the RCFRs of copepods were high in the whole layer (spring: 67.4%, n=9; fall: 74.4%, n=5).

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.1-11
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• 2004

The limnological characteristics of a coastal lagoon were studied in Lake Hyangho, one of a series of brackish lagoons along the eastern coast of Korea. Phytoplankton community structure, physical factors, and chemical factors were surveyed from May 1998 through November 2002 on a two-month interval basis. Temperature, salinity, Secchi disc transparency, TN, TP, organic matter content of sediment, chlorophyll a concentration, dominant phytoplankton species, and phytoplankton cell density were measured. Salinity gradient was formed between the overlying freshwater stream water and the permeated seawater at the bottom. The chemocline was persistent at the depth of 2 ${\sim}$ 5 m that caused discontinuities of salinity, DO, and temperature profiles. The inversion of vertical temperature profiles with higher temperature in deeper layer was observed in early winter. Secchi disc transparency was very low with the range of 0.1 to 1.1m. TP, TN, and Chl. a concentration in the epilimnion was 0.011 ${\sim}$ 0.238 mgP $L^{-l}$, 0.423 ${\sim}$ 2.443 mgN $L^{-l}$, and 0.7 ${\sim}$ 145.2 mg $m^{-3}$, respectively. Sediment was composed of silt and coarse silt. COD, TP, and TN content of dry sediment were 19.7 ${\sim}$ 73.3 mg$O_2\;g^{-1}$, 0.61 ${\sim}$ 1.32 mgP $g^{-l}$ and 0.64 ${\sim}$ 0.88 mgN $g^{-l}$, respectively. Dominant phytoplankton species were chlorophytes (Ankistrodesmus falcatus) and cyanobacteria (Oscillatoria sp. and Merismopedia tennuissima). The total cell density was in the range of 560 ${\sim}$ 35,255 cells $mL^{-l}$.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.317-324
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• 2012

To reduce non-point source pollutants in Juam Lake eco-wetlands, purification efficiencies of pollutants were investigated at three different systems. The constructed wetlands (CWs) consisted of A system, B system and C system. A system consisted of $1^{st}$ free water surface (FWS) CW, $2^{nd}$ FWS CW, $3^{rd}$ FWS CW, $4^{th}$ subsurface flow (SSF) CW and $5^{th}$ SSF CW. B system consisted of $1^{st}$ FWS CW, $2^{nd}$ FWS CW, $3^{rd}$ FWS CW, $4^{th}$ FWS CW and $5^{th}$ SSF CW. C system consisted of $1^{st}$ FWS CW, $2^{nd}$ FWS CW, $3^{rd}$ FWS CW, $4^{th}$ FWS CW and $5^{th}$ SSF CW. The concentrations of BOD, COD, SS, T-N and T-P in inflow ranged 0.20 ~ 0.91, 1.24 ~ 8.00, 0.60 ~ 8.60, 0.04 ~ 2.50 and $0.001{\sim}0.685mg\;L^{-1}$ from March to October in 2011, respectively. Removal rates of BOD, SS, T-N and T-P were high in Autumn, Spring, Spring and Summer, respectively. In A system, $1^{st}$ FWS CW, $2^{nd}$ FWS CW and $3^{rd}$ FWS CW were dominated by Leersia oryzoides. In B system, $1^{st}$ FWS CW, $3^{rd}$ FWS CW and $4^{th}$ FWS CW were dominated by Leersia oryzoides. In C system, $2^{nd}$ FWS CW and $3^{rd}$ FWS CW were dominated by Nymphaea teragona.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.923-931
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• 2005

A study was carried out to identify the major causes of sediments pollution in the Paldang Lake in the vicinity of Gyeongan river. Samples from 40 sites were collected and analyzed to characterize the regional distributions of grain size, organic matter contents, and concentrations of T-N, T-P and heavy metals. contaminations. The mean grain size(Mz) ranged from sand type(Mz, $1{\sim}3\;{\phi}$) where Bukhan River and Namhan River converges at a high flow rate to silt type(Mz, $5{\sim}10\;{\phi}$) at the downstream of Gyeongancheon and Paldang lake, reflecting the water circulation in the area. Except sampling point St. 36 near the wetland, the determination coefficient($r^2$) of Mz and organic matter(LOI) was 0.88, showing that more organic matters are concentrated inside finer sediments. The concentrations of T-N and T-P in sediments were higher in the area at which Mz and organic matters are also higher. High concentrations of T-P analyzed in the sediments, ranging from $216{\sim}1,623\;{\mu}g/g$ (Avg. $769\;{\mu}g/g$) could be considered as a critical level. Adsorbed-P and NAI-P, which are easily released to the surrounding environments when physico-chemical characteristics of sediments are changed, was found to be around 20%, which was showed by the result of fractionated-P. Moreover, Principle Component Analysis(PCA), showed that high concentrations of T-N, T-P, organophilic metals (Cd, Cu, Pb, Zn) are distributed in the areas where high organic matter contents and fine grain-sized sediments are found. However, results of $I'_{geo}$ (Geoaccumulation Index) that considers the grain size of sediments showed that heavy metal concentrations in the lake was low enough to be considered as Class 1 indicating the relative degree of pollution was less than zero.

• Korean Journal of Remote Sensing
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• v.39 no.5_1
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• pp.589-597
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• 2023

Floating debris in large quantities from land during heavy rainfall has adverse social, economic, and environmental impacts, but the monitoring system for the concentration area and amount is insufficient. In this study, we proposed an efficient monitoring method for floating debris entering the river during heavy rainfall in Daecheong Lake, the largest water supply source in the central region, and applied remote sensing techniques to estimate the standing-stock of floating debris. To investigate the status of floating debris in the upper of Daecheong Lake, we used a tracking buoy equipped with a low-orbit satellite communication terminal to identify the movement route and behavior characteristics, and used a drone to estimate the potential concentration area and standing-stock of floating debris. The location tracking buoys moved rapidly during the period when the cumulative rainfall for 3 days increased by more than 200 to 300 mm. In the case of Hotan Bridge, which showed the longest distance, it moved about 72.8 km for one day, and the maximum moving speed at this time was 5.71 km/h. As a result of calculating the standing-stock of floating debris using a drone after heavy rainfall, it was found to be 658.8 to 9,165.4 tons, with the largest amount occurring in the Seokhori area. In this study, we were able to identify the main concentrations of floating debris by using location-tracking buoys and drones. It is believed that remote sensing-based monitoring methods, which are more mobile and quicker than traditional monitoring methods, can contribute to reducing the cost of collecting and processing large amounts of floating debris that flows in during heavy rain periods in the future.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.755-764
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• 2009

To estimate the pollutant removal efficiency by surface sediment, matter content within surface sediment and its release from the sediment were investigated at 12 sites in the Sihwa constructed wetland. The content of COD, TOC, IL, TN, and TP within sediment varied temporally and spacially, showing ranges of 4.1~7.7 mg/g, 0.29~2.81%, 1.88~8.15%, 0.03~0.35%, 362~1,150 ${\mu}g$/g, respectively. The contents of organic matter and TN were significantly highest in March and decreased towards fall (March${\geq}$May${\geq}$July${\geq}$September, p=0.003 for COD, p=0.001 for TOC, p=0.017 for IL, p=0.015 for TN), whereas TP content was not significant statistically in difference between sampling times. The contents of heavy metals also varied largely with sampling sites and times (As:3.5~3.9 ${\mu}g$/g, Cd:0.08~0.38 ${\mu}g$/g, Cr:51.8~107.0 ${\mu}g$/g, Cu:16.4~81.8 ${\mu}g$/g, Pb:26.~81.8 ${\mu}g$/g, Zn:85~559 ${\mu}g$/g). As compared with sediment quality guideline, the content of organic matter within surface sediment of the Sihwa constructed wetland was classified as unpolluted level. In contrast, the contents of TN, TP and heavy metals were classified as medium or severe pollution state, except some heavy metals (Cu and Pb). From the results of release experiment, TN, Pb, and Zn tend to be removed by surface sediment, but TP, Cd, and Cu have a tendency to released from sediment. Therefore, a relevant plan to improve the removal efficiency of pollutant (especially phosphorus) by surface sediment in the Sihwa constructed wetland is needed.

• Geophysics and Geophysical Exploration
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• v.5 no.4
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• pp.223-235
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• 2002

Since weak Bones or geological lineaments are likely to be eroded, there may develop weak Bones beneath rivers, and a careful evaluation of ground condition is important to construct structures passing through a river. DC resistivity method, however, has seldomly applied to the investigation of water-covered area, possibly because of difficulties in data aquisition and interpretation. The data aquisition having high quality may be the most important factor, and is more difficult than that in land survey, due to the water layer overlying the underground structure to be imaged. Through the numerical modeling and the analysis of a case history, we studied the method of resistivity survey at the water-covered area, starting from the characteristics of measured data, via data acquisition method, to the interpretation method. We unfolded our discussion according to the installed locations of electrodes, ie., floating them on the water surface, and installing them at the water bottom, because the methods of data acquisition and interpretation vary depending on the electrode location. Through this study, we could confirm that the DC resistivity method can provide fairly reasonable subsurface images. It was also shown that installing electrodes at the water bottom can give the subsurface image with much higher resolution than floating them on the water surface. Since the data acquired at the water-covered area have much lower sensitivity to the underground structure than those at the land, and can be contaminated by the higher noise, such as streaming potential, it would be very important to select the acquisition method and electrode array being able to provide the higher signal-to-noise ratio (S/N ratio) data as well as the high resolving power. Some of the modified electrode arrays can provide the data having reasonably high S/N ratio and need not to install remote electrode(s), and thus, they may be suitable to the resistivity survey at the water-covered area.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.657-664
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• 2011

The plant community of water`s edge was investigated using the methodology of the Z-M school of phytosociology, from March to October, 2008, 2011. The results were obtained as follow ; hygrophyte hydrophye of 2008 year of this area consist of 38 taxa : 1 varieties, 37 species, 31 genera, 21 families and 14 orders, hygrophyte hydrophye of 2011 year of this area consist of hygrophyte 15 species, 13 species were reduced by approximately 13.33%. And emerged hydrophyres did not show a change. 9 species, 4 species of Floating-Leaved hydrophyres 55.56%, Submerged hydrophyres of the 4 species, 1 species, 75%, Free-Floating hydrophyres remarkable I the 3 species was reduced to 33.33%, respectively. Plants Community of the water's edge was classified into 16 communities as follows; (Leersia japonica community, Spirodela polyrhiza community, Miscanthus sacchariflorus community, Hydrocharis dubia community, Zizania latifolia community, Paspalum distichum var. indutum community, Leersia japonica-Hydrocharis dubia community, Salix glandulosa community, Trapa japonica community, Humulus japonicus community, Nelumbo nucifera community, Carex dimorpholepis community, Salix koreensis community, Trapa japonica-Spirodela polyrhiza community, Persicaria thunbergii). Higher in 2011 than in 2008, the ratio was reduced to Leersia japonica community. Between July-August by a sudden change in the rate of water storage changes in vegetation are thought to have appeared.

• Journal of Wetlands Research
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• v.10 no.1
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• pp.59-68
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• 2008

Three phases of development in construction projects (i.e. pre-development, construction and post construction) diversely effect the environment, hydraulics and ecosystem. Currently, the domestic environmental policy is in control of the various environmental hazards produced after completion of development operations. Nevertheless, with the enforcement of water pollution total amount management system, improving the water quality; also the water and ecosystem preservation law recommends enforcing the sediment management for development operations in order to lessen the negative impacts to the environment. Recently, the country is experiencing difficulties in various development project locations due to insufficiency of interpreting the fundamental data for sediment loss and miscalculation of soil loss unit loads of sediment. This research utilizes data from 2000 to 2005 discussing a total of 1,036 environment impact assessment projects gathered from various ministries and offices namely Ministry of Environment (MOE), Ministry of Agriculture, the Office of Forestry, and Ministry of Construction and Transportation. Moreover, quantity of sediment from high land agriculture reports involving contaminant discharge characteristic investigation previously did concerning old land agriculture and So-Yang lake non-point pollution source management area as well as management measured data from MOE. The findings of this study reveal that the highest soil loss rate occurred from mountain district for pre-development and post construction and sports facility during construction.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2009-2013
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• 2009

일반적으로 비닐하우스내의 농작물 경작은 자연환경과 차단된 조건에서 작물을 집약적으로 재배하므로 비료의 사용량이 많아 오염원으로 작용하고, 휴작기에 비닐을 제거 방치하므로 비닐 표면에 집적된 오염물은 강우 시 유출되어 이들로 인한 주변 하천수 및 지하수 오염을 가중시킨다. 따라서 팔당호 유역내 하천 부지에서 비닐하우스 등이 집단화 되어 있어 이로 인해 팔당호 유역내 수질에 영향을 미칠 것으로 판단된다. 또한 팔당호 유역내 하천부지에서 대단위 비닐농가가 집단적으로 조성되어 있는 것으로 조사되었으며, 팔당호 유역내 산발적으로 비닐하우스 농가가 형성되어 있는 것으로 조사되었다. 이들 비닐하우스로부터 비강우시에는 유출 오염수는 없는 것으로 파악되었으나, 강우 시 강우유출수가 표면 유출되는 과정에서 오염수가 팔당호로 직접 유입되어 팔당호 수질에 영향을 미치는 것으로 파악되었다. 팔당호 유역의 비닐하우스 경작에 의한 수질특성 조사 결과, SS 농도는 북한강 $372{\sim}446$ $mg/{\ell}$, 남한강 $488{\sim}547$ $mg/{\ell}$, 경안천 $345{\sim}415$ $mg/{\ell}$로 조사되었으며, BOD 농도는 북한강 $12.2{\sim}15.3$ $mg/{\ell}$, 남한강 $13.3{\sim}16.8$ $mg/{\ell}$, 경안천 $15.6{\sim}18.8$ $mg/{\ell}$으로 조사되었고, COD 농도는 북한강 $23.9{\sim}26.8$ $mg/{\ell}$, 남한강 $25.2{\sim}26.0$ $mg/{\ell}$, 경안천 $26.4{\sim}32.9$ $mg/{\ell}$로 조사되었다. 또한 T-N 농도는 북한강 $17.39{\sim}23.64$ $mg/{\ell}$, 남한강 $17.87{\sim}22.09$ $mg/{\ell}$, 경안천 $18.34{\sim}19.55$ $mg/{\ell}$으로 조사되었으며, T-P 농도는 북한강 $1.425{\sim}1.795$ $mg/{\ell}$, 남한강 $1.519{\sim}1.767$ $mg/{\ell}$, 경안천 $1.727{\sim}1.827$ $mg/{\ell}$로 조사되었다. 또한, 오염부하량으로부터 산정된 비닐하우스의 하천에 미치는 오염부하기여율은 SS의 경우 17.3%, BOD 4.5%, COD 5.2%, T-N 11.0%, T-P 7.4%로 조사되었다. 이는 비닐하우스 농가에서 유출되는 SS 및 T-N, T-P 오염부하량이 하천에 미치는 영향이 상대적으로 높다는 것을 의미하며, 이는 비닐하우스 주변이 주로 나대지로 되어 있고 비료 또는 영양물질이 많기 때문인 것으로 판단된다. 그러나 탄소성 유기물질을 나타내는 BOD 및 COD의 오염부하기여율은 주변 토양과 큰 차이를 보이지 않았다. 결국 비닐하우스의 재배는 토양 표면피복의 효과적인 관리 및 영양물질에 대한 관리가 이루어지지 않을 경우 팔당호에 영향을 미칠 수 있을 것으로 판단된다.