• Journal of the Korean Society of Environmental Restoration Technology
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• v.1 no.1
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• pp.3-17
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• 1998

The purposes of this study is to investigate the possibility of planting trees at space land in the riverside. The space land is for the green space. Calculating the plantable space in the representation section and the flood flowing stability of the existing banks based on the hydrological and meteorological data of the Kap-Chon riverbasin located in Tae-jon, the following results are drawn. (1) The flood discharges in each flow section are $698.7m^3/s$ in section 1, $654.6m^3/s$ in section 2, and $1353.3m^3/s$ in section 3 during 100 years recurrence interval. Because the designed-flood discharges in those sections are $1719.9m^3/s$, $2119.7m^3/s$, and $1512.8m^3/s$ respectively, safety for flood flowing is sufficient in existing banks. (2) The possible clearance for planting trees is 1.80m in section 1, 3.90m in section 2, and 0.01m in section 3. Planting clearance is enough in section 1 and 2. However, planting should be planned after estimating a rise-height due to the bridge piers, because many piers under riverine-highway are now on the construction in section 2. The section 3 does not have sufficient clearance for planting trees, but the planting is possible after getting enough flow area with slope by cutting the terrace land on the river artificially heightened. (3) In case of planting a tree 70cm diameter in $1m^2$ in section 1, the water level increases by 0.60m. Planting a tree in a $48m^2$ area increases the water level by 0.90m. Considering that plantable clearance is 1.8m in section 1, it is sufficient to flow safely. But if the trees are planted so compactly from the upper stream, expected heavy resistance is expected due to caught materials on the trees. So, trees have to be planted widely in upper streams but compactedly in lower streams. (4) The river width without changing, Kap-Chon's flow channel can be snaked in accordance with the nature law the wide terrace land in the riverside. Decreased flow area due to planting trees will be compensated by the inclination of terrace land. And, it is theoretically proved that the flood discharge is safe even though the terrace land on the river is parked similar to the nature. Planting trees in the terrace land of the Kap-chon river to the extent that flood flowing is not adversely affected, we can get the enjoyable park to citizens not spending expensive cost. It also contributes to the recovery of ecosystem, which gives the natural beauty of river and shade to citizens and becomes good natural-educational places for children.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.268-273
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• 2006

Soil loss induced by erosion has come to be a serious problem in Korea's sloped land since more than 70% of upland fields are located on the sloped land area. The purpose of this study was to investigate the phase of water flow in differently soil textured plot soil types by rainfall amount. Lysimeters with slope of 15%, 5 m in length, 2 m in width, and 1 m in depth were prepared and filled up with three different soil textures, such as sandy loam, loam, and clay loam, then relationships between seasonal rainfall and runoff, percolation were analyzed. Runoff and percolation rate were shown to increase linearly with increasing rainfall intensity in all the soil textures, but the starting threshold and increment rate in runoff and percolation occurrence were dependent differently upon soil textures. Percolation increment rate according to the increasing rainfall amount was 0.52, 0.36, and 0.57 for sandy loam, loam and clay loam soil respectively. The threshold rainfall amounts in which percolation occurs were 5.73 mm, 6.80 mm, and 12.86 mm for sandy loam, loam and clay loam respectively. Runoff increment rates were 0.42, 0.48 and 0.46 for sandy loam, loam and clay loam soil. The threshold rainfall amount in which runoff occurs was 10.50 mm in sandy loam, 7.76 mm in loam and 17.40 mm in clay loam. These different phases of water flow by soil texture could be used to suggest guidelines for the best management practice of the farming slope land.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.214-226
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• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.152-159
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• 2002

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chi-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of $0.8{\sim}1.5{\times}10^6\;cells/ml$ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only $1.0{\sim}7.4%$. The variations of ammonia-oxidizing bacteria ranged from $1.1{\times}10^4$ to $3.0{\times}10^4\;cells/ml$ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in $1.3{\sim}5.7{\times}10^4\;cells/ml$ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature (r = 0.355, p<0.05) and DOC (r = 0.58G, p<0.01) positively whereas nitrite-oxidizing bacteria correlated with temperature (r = -0.416, p<0.05) and pH (r = -0.568, p = 0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers (r = 0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.549-556
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• 2017

Rivers continuously transport terrestrial organic carbon matter to the estuary and the ocean, and they play a critical role in productivity and biodiversity in the marine ecosystem as well as the global carbon cycle. The amount of terrestrial organic carbon transporting from the rivers to ocean is an essential piece of information, not only for the marine ecosystem management but also the carbon budget within catchment. However, this phenomenon is still not well understood. Most large rivers in Korea have a well-established national monitoring system of the river flow and the TOC (Total Organic Carbon) concentration from the mountain to the river mouth, which are fundamental for estimating the amount of the TOC flux. We estimated the flux of the total terrestrial organic carbon of five large rivers which flow out to the Yellow Sea, using the data of the national monitoring system (the monthly mean TOC concentration and the monthly runoff of river flow). We quantified the annual TOC flux of the five rivers, showing their results in the following order: the Han River ($18.0{\times}10^9gC\;yr^{-1}$)>>Geum River ($5.9{\times}10^9gC\;yr^{-1}$)>Yeongsan River ($2.6{\times}10^9gC\;yr^{-1}$)>Sumjin River ($2.0{\times}10^9gC\;yr^{-1}$)>>Tamjin River ($0.2{\times}10^9gC\;yr^{-1}$). The amount of the Han River, which is the highest in the Korean rivers, corresponds to be 4% of the annual total TOC flux of in the Yellow River, and moreover, to be 0.6% of Yangtze River.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.193-204
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• 2000

In order to get some basic data on environmental friendly function by Korean organic farming, the chemical characteristics of soil were determined on 100 farm cultivating site in Paldang watershed area of Great Seoul. The EC and content of $NO_3-N$ and Av. $P_2O_5$ in topsoil(0~30cm) showed $2.30dS\;m^{-1}$, $82mg\;kg^{-1}$, $918mg\;kg^{-1}$ in the soil cultivated chinese cabbage. $2.29dS\;m^{-1}$, $86mg\;kg^{-1}$, $954mg\;kg^{-1}$ in the soil of lettuce, $1.83dS\;m^{-1}$, $66mg\;kg^{-1}$, $1114mg\;kg^{-1}$ in the soil of crown daisy. These salt accumulation(EC) and the high concentration of mineral content in topsoil such as nitrate and phosphate showed the soils of organic farming were contaminated by practice of organic farming for the maintenance strategy of soil fertility. The $NO_3-N$ and Av. $P_2O_5$ in the subsoil(30~60cm) showed $75mg\;kg^{-1}$ and $641mg\;kg^{-1}$, $72mg\;kg^{-1}$ and $466mg\;kg^{-1}$, $42mg\;kg^{-1}$ and $873mg\;kg^{-1}$ in soil cultivated chinese cabbage, lettuce and crown daisy respectively. It indicates eventually the high concentration of nitrate and phosphate in topsoil caused penetration to subsoil, and the high concentration of mineral contents in subsoil indicate the potential risk of leaching of ground water by Korean organic farming. The positive correlation at 1% between EC and $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N show the salt accumulation in the both soil depth of Korean organic farming were caused by minerals such as $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N by overuse of organic fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.18-24
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• 2007

Paddy fields are apparently nonpoint source pollution and influence water environment. In order to improve water quality in rivers or lakes, to low nutrient load from paddy fields are required. To establish comprehensive plan to control agricultural non-point source pollution, it is imperative to get a quantitative evaluation on pollutants and pollution load from paddy fields. A field monitoring study was carried out to investigate the water balance and losses of nutrients from fields in Sumjin river basin. The size of paddy fields was 115 ha and the fields were irrigated from a pumping station. The observed total nitrogen loads from paddy fields were larger than those of the unit loads determined by Ministry of Environment data (MOE). It is because the nitrogen fertilization level at the studied field was higher than the recommended rate and the high irrigation and subsequent drainage amount. On the contrary, total phosphorus loads were less than those addressed by MOE since phosphorus fertilization level was lower than that of standard level. Therefore, it was found that fertilization, irrigation, and drainage management are key factors to determine nutrient losses from paddy fields. When the runoff losses of nutrients were compared to applied chemical fertilizer, it was found that 42 to 60% of nitrogen lost via runoff while runoff losses of phosphorus account for 1.3 to 7.6% of the total applied amount during the entire year.

• Journal of Life Science
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• v.31 no.10
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• pp.905-912
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• 2021

In this study, four common food-borne bacteria, namely, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Bacillus subtilis, were targeted via irradiation with 270 nm UV C-LED, 365 nm UV A-LED, 465~475 and 620~630 nm visible-LED, and 850 and 5,000~7,000 nm infrared-LED light. The effect on the growth of each bacterial species was investigated. In the case of 270 nm UV C-LED, all four strains showed inhibitory effects compared with the control group when irradiated for 10 or 30 min. Furthermore, when irradiated with 365 nm UV A-LED for 1 or 3 hr, B. subtilis showed 100% growth inhibition. When irradiated with 465~475 nm visible-LED for 1 hr, all four strains showed no significant difference from the control group but showed significant growth inhibition when irradiated for 3 hr. S. aureus and B. subtilis treated with 620~630 nm visible-LED; S. typhimurium and S. aureus treated with 850 nm infrared-LED; and E. coli, S. typhimurium, and S. aureus treated with 5,000~7,000 nm infrared-LED were confirmed to significantly proliferate compared with the control group. The results of this experiment show the potential of the use of various LED light sources as a food preservation and application technology by examining their effect on the inhibition and growth of food-borne bacteria and by grasping the characteristics of each wavelength.

• Journal of Environmental Science International
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• v.28 no.1
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• pp.7-18
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• 2019

This study aimed to assess the impact of livestock excreta discharged from an Intensive Livestock Farming Area (ILFA) on river water quality during a rainfall event. The Bangcho River, which is one of the 7 tributaries in the Cheongmi River watershed, was the study site. The Cheongmi River watershed is the second largest area for livestock excreta discharge in Korea. Our results clearly showed that, during the rainfall event, the water quality of the Bangcho River was severely deteriorated due to the COD, $NH_4-N$, T-N, $PO_4-P$, T-P, and heavy metals (Cu, Zn, and Mn) in the run-off from nearby farmlands, where the soil comprised composted manure and unmanaged livestock excreta. In addition, stable isotope analysis revealed that most of nitrogen ($NH_4-N$ and $NO_3-N$) in the run-off was from the ammonium and nitrate in the livestock excreta. The values of ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ for the Bangcho River water sample, which was obtained from the downstream of mixing zone for run-off water, were lower than those for the run-off water. This indicates that there were other nitrogen sources upstream river in the river. It was assumed from ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ stable isotope analyses that these other nitrogen sources were naturally occurring soil nitrogen, nitrogen from chemical fertilizers, sewage, and livestock excreta. Therefore, the use of physicochemical characteristics and nitrogen stable isotopes in the water quality impact assessment enabled more effective analysis of nitrogen pollution from an ILFA during rainfall events.

• Journal of Korea Water Resources Association
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• v.51 no.spc
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• pp.1091-1103
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• 2018

Having knowledge regarding to which region is prone to drought or flood is a crucial issue in water resources planning and management. This could be more challenging when the occurrence of these hazards affected by climate change. In this study the future streamflow during the wet season (July to September) and dry season (October to March) for the twenty first century of South Korea was investigated. This study used the statistics of precipitation, maximum and minimum temperature of one global climate model (i.e., INMCM4) with 2 RCPs (RCP4.5 and RCP8.5) scenarios as inputs for The Precipitation-Runoff Modelling System (PRMS) model. The PRMS model was tested for the historical periods (1966-2016) and then the parameters of model were used to project the future changes of 5 large River basins in Korea for three future periods (2025s, 2055s, and 2085s) compared to the reference period (1976-2005). Then, the different responses in climate and streamflow projection during these two seasons (wet and dry) was investigated. The results showed that under INMCM4 scenario, the occurrence of drought in dry season is projected to be stronger in 2025s than 2055s from decreasing -7.23% (-7.06%) in 2025s to -3.81% (-0.71%) in 2055s for RCP4.5 (RCP8.5). Regarding to the far future (2085s), for RCP 4.5 is projected to increase streamflow in the northern part, and decrease streamflow in the southern part (-3.24%), however under RCP8.5 almost all basins are vulnerable to drought, especially in the southern part (-16.51%). Also, during the wet season both increasing (Almost in northern and western part) and decreasing (almost in the southern part) in streamflow relative to the reference period are projected for all periods and RCPs under INMCM4 scenario.