• Journal of Environmental Impact Assessment
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• v.27 no.2
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• pp.170-180
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• 2018

Highland fields are concentrated in the Jaun area of Hongcheong-gun, a large amount of sediments are discharged from the highland fields. The sediment runoff affect the turbidity and water quality of the Soyang Lake, furthermore adversely affect water supply source of the capital region. There are several kinds of BMPs(Best management practices) to decrease the sedimentrunoff from the highland fields. Although construction cost of multistage sedimentation basins is very high, there is no actual survey data for the removal efficiency of suspended sediments and water quality in our country. In this study, stormwaterinflow and outflow of the multistage sedimentation basins were surveyed, and the removal efficiency of nonpoint source pollutants were analyzed. The stormwater survey results fortwo rainfall events show thatremoval efficiencies of SS, BOD and TP loads in the multistage sedimentation basins are 35%~62%, 24%~55%, 35%~58%, respectively. Although the measured efficiencies of the basins were lower than the theoretical efficiency, the proper operation and management can improve the removal rate of the basins. Turbid water problem in the upper parts of the Soyang River can be managed effectively through the additional installation of multistage sedimentation basins.

• Korean Journal of Ecology and Environment
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• v.51 no.2
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• pp.160-167
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• 2018

The role played by reservoirs in the biogeochemical cycles of elements is a subject of ongoing debate. Recent research has revealed that reservoirs emit significant levels of greenhouse gases. To assess the importance of reservoirs in monsoon climate areas as a source of methane gas into the atmosphere, we investigated variations in organic carbon (OC) input into the reservoir, oxic state changes, and finally the amount of methane emitted (focusing on the ebullition pathway) in Lake Soyang, which is the largest reservoir in South Korea. Total organic carbon (TOC) concentrations were higher during summer after two years of heavy rainfall. The sedimentation rates of particulate organic carbon (POC) and particulate organic nitrogen (PON) were higher in the epilimnion and hypolimnion than the metalimnioin, indicating that autochthonous and allochthonous carbon made separate contributions to the TOC. During stratification, oxygen depletion occurred in the hypolimnion due to the decomposition of organic matter. Under these conditions, $H_2S$ and $CH_4$ can be released from sediment. The methane emissions from the reservoir were much higher than from other natural lakes. However, the temporal and spatial variations of methane ebullition were huge, and were clearly dependent on many factors. Therefore, more research via a well-organized field campaign is needed to investigate methane emissions.

• 한국해양학회지
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• v.26 no.1
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• pp.24-37
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• 1991

Marine benthic diatoms and environmental factors were studied at 60 sites on the Mangyung-Dongjin tidal flat of the west coast of Korea. Sediment samples were taken quantitatively from the upper 5 mm layer to obtain a representative estimate of the epipelic and epipsammic cell concentration. Surface sediments taken simultaneously with the quantitative diatom samples were analysed for the grain size. Exposure duration of study sites were calculated by the tide data recorded at Kunsan Outer-Harbour. Coarse sediments dominated mainly on the offshore coastal and lower tidal flat, whereas fine sediments occurred on inner and higher tidal flat. Total 371 diatom taxa were collected and the genera represented by a great number were Navicula and Nizschia. The 16 abundant species occupying more than 1% of total cell number are of the following: Paralia sulcata, Navicula sp. 1, Navicula arenaria, Cymatosira belgica, Amplora holsatica, Amphora coffeaeformis, Achnanthes hauckiana, Rhaphoneis amphiceros, Thalassionema nitzschioides. Navicula sp. 2, Dimeregramma minor, Amphora sp. 1, Cyclotella atomus, C, striata, Nitzschia kuetzingiana, Stephanodiscus sp. 1. The distribution pattern of these dominant species are described in relation to the habitat condition. Most of these species showed high densities in fine sediments. However, they occurred even silty sand and sandy sediments in low abundance. The epipsammic forms belonging to the Araphidineae and Monoraphidineae were restricted on the lower tidal flat. The typical species found in coarse sediments were: Cocconeis sp. 1, Opephora martyi, Amphora sabyii, Dimeregramma minor var. nana, Fragilaria virescens var. oblongella, F. virescens, Cocconeis grata. The higher tidal flat consisting of fine sediments showed relatively higher cell numbers than the lower tidal flat. River mouth region was the highest in abundance.

• Korean Journal of Environmental Biology
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• v.22
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• pp.30-37
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• 2004

Peysistent oyganochlorine compounds (OCs) weve determined in sediments and bivalves from Gwangyang Bay. The concentrations of ∑PCB, ∑DDT, ∑HCH and ∑CHL in sediments were in the range of f 2.25∼11.4 ng g$\^$-1/, 0.16∼1.16 ng g$\^$-1/, nd∼0.51 ng g$\^$-1/, and 0.05∼0.79 ng g$\^$-1/, respectively. The overall OCs concentrations in sediments were below the effect range -median (ER-M) values toy benthic organisms suggested by NOAA (1991). Levels of PCB compounds a re relatively lower than other industrialized bays (Pusan Bay, Ulsan Bay, and Youngil Bay). OCs accumulated in bivalves were higher than those in sediments. In bivalves, the concentration ranges of ∑PCB, ∑DDT, ∑HCH and ∑CHL were 9.97∼31.7 ng g$\^$-1/, 7.54∼22.6 ng g$\^$-1/, 0.49∼2.0 ng g$\^$-1/, and 0.82∼7.32 ng g$\^$-1/, respectively. Relatively high PCB concentrations in both environmental matrices are found at the inner bay than the outer part, indicating that the sources of PCBs were located inside the bay. DDT compound showed relatively high concentrations in the vicinity of the mouth of river and urban area, whereas other organochlorine pesticides show homogeneous distributions over the bay. Homologue profile of PCB compounds shows that low-chlorinated congeners (especially, di-, tyi- and tetra-) are abundant in Gwangynng Bay, which is diferent from other areas in Korea.

• Journal of the Korean earth science society
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• v.34 no.4
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• pp.289-302
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• 2013

In order to determine the provenance of the Huksan Mud Belt sediments in the southeastern Yellow Sea, the major and rare earth elements of the same sediments were analyzed. The surface sediments were sampled from top of piston-cores and box-cores taken at 51 sites within the Huksan Mud Belt. With the mean grain size of $5-6{\phi}$, the sediments of the study area are mud-dominated. The spatial distribution patterns show that silt content is high in the northern Mud Belt, whereas clay content increases as it moves toward the southern Mud Belt. Interestingly, the geochemical compositions both of major and rare earth elements have resulted in differences of sediment provenance. Among the major elements, plots of Fe/Al vs. Mg/Al ratios, $Al_2O_3$ vs. MgO ratios, and $Al_2O_3$ vs. $K_2O$ reveal that the Huksan Mud Belt sediments are dominated by the Korean river-derived sediments. However, the characteristics of rare earth elements infer sediments originating from the Chinese rivers. This discrepancy between the above provenances is attributed to the different contributory factors in the content of chemical elements. Considering strong correlation between major elements with grain sizes, the contents of the major elements are thought to be influenced by the grain size. However, there is a weak correlation between rare earth elements and grain sizes. The behaviour of rare earth elements may be controlled by heavy minerals, rather than grain sizes. Further study requires to solve the discrepancy arose from the difference in applied chemical tracers.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.565-572
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• 2004

Residual current plays more important role than the tidal current for long-term material transport in coastal areas. The main component of residual current is tide-induced residual current. Otherwise, wind driven current and buoyancy-driven current are important components which change the residual current. To clarify the characteristic of coastal current, application of a three -dimensional model is necessary. This study focuses on clarifying the stratified systems of coastal water affected by freshwater runoff from a river and analyzes the structure of current at Ulsan bay by applying a three-dimensional buoyancy-driven current model. According to the result of “Ulsan bay” study, it shows that the surface layer in semi-enclosed estuaries, which affected by freshwater runoff. has flows going out, and the bottom layer has flows coming in. Besides when the wind blows toward inside of the bay, the surface layer has flows coming in and the bottom layer has flows going out as compensation flows for the surface circulation. The results of simulation could be applicable to examine vertical upwelling, which might be caused by construction of artificial fishing reef to build aqua farm, submerged breakwater to control coastal sediment, and the formulation of oceanic ridge, or a basic study on application to the usage of deep water.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.14-21
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• 1993

N-Heterocyclic aromatics (NHA) are widely occurring environmental pollutants formed during the pyrolysis of nitrogen-containing organic chemicals. NAH are found in significant amounts in tobacco condensates, synthetic fuels, polluted river sediment, and effluents from the heating of coal. Following topical application 7H-dibenzo[c, g]carbazole (DBC) induces cancer in liver as well as skin, indicating that dermal exposure can lead to systemic effect. DBC and dibenz[a,j]acridine (DBA) are examples of NHA. The potency of many carcinogenic compounds is related, at least in part, to the efficiency of their biological activation. We undertook studies to determine which initial metabolites lead to the formation of high levels of carcinogen-DNA adducts in vivo. DBC and DBA's, DBA, trans-DBA-1,2-dihydrodiol (DBA-1,2-DHD), trans-DBA-3,4-dihydrodiol (DBA-3,4-DHD), and trans-DBA-5,6-dihydrodiol (DBA-5,6-DHD), were applied to the skin of mice. There were six adducts that were related to DBC application. These addusts were seen in the target organ, liver at high levels, but at very low levels in non-target organs, skin, lung and kidney. In skin, DBA produced two distinct adducts. The same two adducts were seen when DBA-3,4-DHD was applied. In addition the total adduct level elicited by DBA-3,4-DHD higher than that of parent compound. Two adducts were seen when DBA-5,6-DHD was applied, but these were very different from adducts seen with DBA. These results suggested that activation of DBA to DNA-binding compounds in skin includes initial formation of DBA-3,4-DHD.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.882-889
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• 2012

This study was surveyed that water physiochemical characteristics and phytoplankton incidence of main stream and Lake Doam near to Daegwallyeong agricultural area. Based on above results, it was conducted to get information overall water characteristics in south Han upstream river. COD value of Lake Doam was $6.1mg\;L^{-1}$ and T-P (Total phosphorous) from there was $0.26mg\;L^{-1}$ which was higher than the value of grade VI based on lake water living environment standard. Suspended solid was an average of 9.77 NTU which was higher than value of lake living standard. Concentration of phytoplankton was over $2.0{\times}10^3Cell\;mL^{-1}$ from July to September. It was considered that cyanobacteria were occurred due to massive influx of nutrient material by high temperature and rainfall during this season. Compare to Ontario's sediment quality guidelines, T-N and T-P was middle value between LEL and SEL in Lake Doam. This value means that contamination in water is serious. Therefore, it is considered that systematic management was needed to reduce and block contamination source.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.681-688
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• 2020

Approximately 6,000 chemicals are transported through the sea, including hazardous and noxious substances (HNS), which cause marine pollution and are harmful to marine life. The HNS discharged into the sea during the maritime transportation process undergoes physical and chemical changes on the sea surface and in seawater, and some types of HNS sink and are deposited on the seabed. The HNS deposited on the seabed adversely affects the benthic ecosystem, and hence, it is desirable to detect, treat, and recover the HNS on the seabed. Therefore, this study was conducted to analyze the performance requirements that should be considered as the top priority when developing a mechanical system for recovering the HNS deposited on the seabed. Various types of existing dredging devices used for collecting and recovering pollutants from river beds and seabeds were investigated, and 10 performance indices for the mechanical devices were selected. The new performance requirements for the development of the seabed-deposited HNS recovery system were proposed using performance indices. By considering the depth of water in domestic seaports, some of the performance requirements of the mechanical system for recovering deposited HNS from the seabed were obtained as follows: production rate (50-300 ㎥/hr), maximum operation depth (50 m), sediment type (most forms), percentage of solids (10 % or higher), horizontal operating accuracy (±10 cm), limiting currents (3-5 knots). These performance requirements are expected to be useful in the conceptual and basic design of mechanical systems for recovering seabed-deposited HNS.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.167-168
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• 2003

The Upo wetland, the largest natural wetland in Korea, is located in Changnyeong-gun, Gyeongsannam Province ($35^{\circ}33'$ N, $128^{\circ}25'$ E), and 70 km upstream from the Nakdong River estuary. Unlike most other Korean wetlands that have been destroyed under the name of economic development, the Upo wetland has been able to preserve its precious ecosystem throughout the years. Thanks to increased public awareness about natural wetlands and environmental conservation, the Korean Ministry of Environment designated the Upo wetland an 'Ecological Conservation Area' on July 26th, 1997. On March 2nd of the following year, the Upo wetland (8.54 $\textrm{km}^2$) was designated a 'Protected Wetland' in accordance with the international Ramsar Treaty. A 4.49m long (from 9.73 to 5.24 m in altitude) UP-1 core ($35^{\circ}33'05"N$, $128^{\circ}25'17"E$), recovered in the marginal part of the Upo wetland, is divided into eight buried paleosol units of different ages on the basis of the abundance of color mottles and vertical color variations (Aslan et al., 1998). Radiocarbon datings suggested that the paleosol profile represent the last 5700 years. The entire section of the core was more or less subjected to pedogenetic processes, and shows very weak to moderate soil profile development. These Holocene paleosols are therefore regarded as synsedimentary soils of deluvium (deposits formed by floods) origin (Sycheva et al., 2003). Unit 1 to 5 paleosols are generally silt-rich and exhibit moderate profile development. The boundaries between the units are somewhat distinguishable, but not so clear cut. This is due to variable repeated combination of accumulation, denudation and soil forming processes within various periods. Mottle textures gradually decrease in abundance with increasing clay content in Unit 6, which results in weak profile development. The lower boundary of Unit 6 lies around about 2000 yrBP, the beginning of Subatlantic in Korea (Kim et al., 2001). Abrupt sediment textural change is detected in Unit 7, which is interpreted to indicate the human activities on the Upo wetland. Unit 8 represents the recent soil forming processes. The preliminary results of this ongoing study imply the primary factor for pedogenetic processes is the water table fluctuations related to the sedimentary textures like grain size distributions, and the geomorphological stability of the Upo wetland.o wetland.