• 한국해양학회지
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• v.30 no.2
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• pp.77-90
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• 1995

The sedimentary environments and biostratigrapy of the tidal sediments off the Mankyung-Dongjin River estuary were studied based on sedimentary facies and diatom assemblage analysis. Sediment facies from the five vibracores are mainly clay, silt, and sand facies. The clay and silty sediment facies are more dominant than the sandy facies, and contain diatom frustules. The frequency of the diatom frustules are rate to common, but not found in sandy sediment facies. Bigeneric structures such as burrow and non-bigeneric primary sedimentary structures such as laminated sand and mud or silt and mud couplets, flaser bedding, ripple-cross lamination are found in several stratigraphic levels of the sedimentary sequences. A total of 219 species and varieties, belonging to 61 genera has been identified in the present study. Among them, paralia sulcata is the most abundant species about 30 to 50% of the total diatom frustules. Another predominant species are Cyclotella striata. Thalassionema nitzschioides. Actinoptychus undulatus. Delphineis surirella, Raphoneis amphiceros. Most of the diatoms occurred in this study area are marine, marine-brackish water, and brackish water species, and are benthic and tychopelagic or meroplanktonic species. Also, most of the species are coastal to littoral and littoral to inner neritic species. The occurrences of freshwater species, about 1 to 5% is higher than that of the Namyang Bay tidal sediments. The ecological properties of the diatoms occurred in the study area and primary sedimentary structure such as flaser bedding ripple cross bedding indicate that the deposits are formed under coastal or littoral to subeditorial environments such as tidal zone which was subjected to the influenced of stream water and was more strongly influenced by temperate to warm water than cold water. The sedimentary environments have not been changed distinctively during the time of deposition. The vertical distribution pattern of diatoms in the study area is studied by Q-mode cluster Analysis using spss/pc+ (ver.4.0). The results show that the three cores (GE-3, GE-11, GE-12) are divided into two diatom assemblages, respectively. Biostratigraphic correlation using the data of Q-mode Cluster Analysis are attempt in this study.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.403-411
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• 2012

Acoustic telemetry is used to obtain a relatively continuous record of fish movement. This method has several advantages for studying migrating fish populations that are moving from large rivers. The Nakdong River is the longest river in South Korea and the main stream has faced a change, which consists of the installation of the large weirs. In this study, we applied acoustic telemetry to monitor the movement pattern of Erythroculter erythropterus (family Cyprinidae) and identified home range and movement distance in the Nakdong River. A total of fourteen individuals were released at three different locations and around 80 km section from the estuary barrage was investigated. Eight individuals were tagged and released at estuary barrage (N02) utilized up to 15.9 km (home range) upstream from the release site as home range. Four individuals were tagged and released at Samrangjin (N07), most fish moved and stayed within 9.7 km (home range) downstream area, except E12, which did not show any movement. Two individuals were tagged and released at Changnyeong-Haman weir (N10), and all individuals migrated downstream from the release site. Especially, E14 recorded the longest accumulated detected distance, 36.7 km downstream during 32 days after release. There was no correlation identified between movement (accumulated detected distance and home range) and standard length (Spearman rank correlation, p>0.05). Although, this technique could be an available method to monitor behavior and ecology of freshwater fish effectively, increment of number of receivers and tags are required for more detailed results of fish migration.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.1
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• pp.44-55
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• 1998

Imgok creek is the most severly polluted one out of the streams which have been being polluted by acid drainages from the abandoned coal mines in the Gangdong-Myeon area, the central part of the so called Gangreung coal field. Imgok creek is being mainly polluted by the drainage from Youngdong coal mine, which supplies such pollutants as Mg, Fe, Al, Si, Ca, Mn, and SO$_4$as major dissolved components and Cr, Co, Ni, Cu, Zn, Rb, Sr, Cd, Pb, and U as minor dissolved components. After the influx, the pollutants migrate mainly as dissolved solid, rather than as suspended solids along Imgok creek. The suspended solids in Imgok creek are very rich in Fe and Al, indicating that they mainly consist of the precipitates of present and past from the polluted water. Most of the dissolved components in the stream waters of Imgok creek removed from the aqueous phase by precipitation and dilution before reaching the East Sea, so that water quality of the downstreams of Imgok creek is very similar to that of unpolluted tributaries. It suggests that Imgok creek itself is now being severly polluted by the acid drainages from the abandoned coal mines, but the East Sea is relatively safe from the same pollution. The estuary and sea waters around the Goonseon estuary, which accepts Imgok creek water, certainly show no significant difference in chemical compositions from the mean oceanic water. The bottom sediments at the sampling sites of the sea waters also show no significant trend of their component variation, especially the variations of Fe, SO$_4$ and Al concentrations. These facts again supper that the acid mine drainage is not considerablly polluting the East Sea. However, the tributaries supplying the fresh water to the Imgok creek will be certainly polluted by the acid mine drainage as time passes and pollutants will have more chance to migrate in significant amount to the downstream area, which all can be a real threats to the East Sea on the pollution possibility. Therefore, it is suggested that urgently required are not only water quality and environmental improvement of the severely polluted Imgok creek but also preparation of the measures on the possible future pollution of the East Sea by the acid drainage from the abandoned coal mines in the area, while the East Sea is still not much affected by the pollution of the same kind.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.35-48
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• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.204-216
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• 2019

To evaluate the biological integrity of aquatic ecosystems, we developed Korean multimetric diatom index (KMDI) using metrics that many researchers have been previously described, and compared to single-metric diatom index such as trophic diatom index (TDI) and diatom assemblage index to organic pollution (DAIpo). For the biological and environmental data, we investigated the epilithic diatoms, water quality and the land-use for 923 sites in Korean streams between 2013-2017, and estuaries between 2010-2017, respectively. Five appropriate metrics were selected according to the following steps; 1) extraction of 300 potential metrics (biological, chemical, physical, and geographical) based on previous references, of these, 2) 46 samples having high separation power were selected, 3) the selected metrics were each tested for variability, redundancy, and sensitivity to the environments, finally 4) construction of multi-metric diatom index comprising single type metrics such as TDI, DAIpo, % motile diatoms, % Achnanthes / (Achnanthes+Navicula), and % number of Gomphonema species. The biological integrity of the 233 sites from the Geum River basin were independently investigated using KMDI. Collectively, the new KMDI showed high sensitivity and explanatory power for environmental factors such as land-use, biochemical oxygen demand, total nitrogen, and electric conductivity. However, it had slightly higher biological integrity for the same sites as compared to single type diatom metrics. Finally, more data accumulation from all over Korea and the development of acceptable diatom metrics were required.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.381-392
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• 2011

Pollutant loads calculated with unit factor method can not identity seasonal variations of pollutant inputs. Estimation of pollutant loads considering rainfall runoff can overcome these limits. SCS curve number method was applied to estimate runoff of each event of Koeup watershed of Koheung estuary lake. SCS curve numbers were calculated based upon land use, soil types of the catchment using GIS. Point and nonpoint source pollutant loads were summed up for total loads estimation. Those from nonpoint source were estimated by multiplying the calculated runoff and expected mean concentrations (EMC) presented by the Minister of Environment of Korea. DEM can present three dimensional views of a terrain, identity stream networks and flow accumulation. Furthermore, it can examine accumulated pollutant loads of specific point of a catchment. Therefore, cell based pollutant load estimation was attempted using DEM. ArcView was utilized to collect, store and manipulate spatial and attribute data of pollutant sources and features of the catchment. Cell-based DEM which was established by the GRID module of ARC/INFO was employed to estimate flows and pollutant loads.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.99-106
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• 2015

To estimate the effects of suspended sediments flowing into the Saemangeum Reservoir on the extent of contamination of the reservoir, the suspended sediments were collected with sediment traps, which were installed from the upstream of the Mankyung and Dongjin Rivers to estuary of the reservoir, respectively, and the sedimentation rates and the chemical characteristics of suspended sediments were analyzed. The sedimentation rates in the Mankyung and Dongjin Rivers were ranged from 0.01~5.06 and $0.01{\sim}8.75kg/m^2/day$, respectively. Those were higher to the upstream of rivers, and were mainly affected by flood events. The concentrations of organic matters were from 3.3 to 9.6 times higher than those in the stream sediments and were higher after flood season, indicating the contaminants come from the non-point sources on the basin. The concentrations of total nitrogen and total phosphorus in the suspended sediments showed the same trend with the organic matters. These results indicate that the suspended sediments from the basin of the Mankyung and Dongjin Rivers are highly contaminated and the countermeasures to manage the sources of contamination on the basin are required to maintain the water quality of the Saemangeum Reservoir.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.368-377
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• 2012

This study evaluated the water quality of Yeongsan River by multivariate analysis using the data collected during 2001~2010. Water quality in Yeongsan River could be explained up to 75.2% by four factors, which were included in loading of nutrients (32.021%) and organic matters (17.453%), seasonal variation (14.775%) and microbes (10.951%). The results of cluster analysis were classified into three groups by factor 1 and 2, which has different water quality characteristics. Group 1 included sampling stations located in the upper stream and estuary dyke of Yeongsan River, group 2 included Gwangju 1 and Gwangsan affected by domestic sewage of Gwangju-cheon, and group 3 included sampling stations located in the midstream around the livestock farm and farmland.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.551-560
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• 2013

Environmental factors and epilithic diatom communities in the lower streams near the harbor region of South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water and epilithic diatoms was conducted at both streams, 19 regulated streams (RS) that there are one or several dams constructed in the river system, and 19 un-regulated streams (US) that there are no dams within the river. A cluster analysis based on the number of species and abundance of epilithic diatoms through the stations, divided into three groups such as groups I (mainly US), II (mixed with US and RS) and III (mainly RS), respectively. Group I showed that water quality is good and high diversity of diatom, while Group II and III was water quality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had high conductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant species were Nitzschia palea (17%) and Navicula seminuloides (11%) in Group I, Nitzschia inconspicua (19%) and Navicula perminuta (9%) in Group II, and Nitzschia inconspicua (15%) and Nitzschia palea (14%) in Group III, respectively. These taxa were widely distributed in brackish water, and not closely related with specific water quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass, but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine the effect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom in the estuary, also was considered to be a parallel investigation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.2
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• pp.78-91
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• 2015

Macrobenthic community was studied at 87 stations including intertidal and subtidal area in Yoja Bay, south coast of Korea in summer season of July 2001. Duplicate sediment samples were taken using a van Veen grab ($0.1m^2$) in each station. Mud facies of the sediments were widly distributed in the bay. And relatively high content of sand was shown in the Bulgyo-cheon stream estuary. A total of 274 species was occurred with a mean density of $2,346ind./m^2$ and a mean biomass of $78.2g/m^2$. The polychaetes were species- and density-dominant faunal group with a total of 122 species (44.5% of the total number of species), and mean density of $1,543ind./m^2$ (65.8% of the mean density). Meanwhile, molluscs were biomass-dominant faunal group with $44.4g/m^2$. Bio-Env. analysis showed that the combination of bottom salinity and sand content of the surface sediments was highly correlated to the major macrobenthic communities. The macrobenthic species number, decreasing toward inner bay from mouth of the bay, was significantly correlated to the sediment environmental variables and bottom water salinity. The spatial distribution of abundance showed significant correlation to the sand and mud contents and mean grain size of the surface sediments. Major dominant species were Minuspio japonica (polychaete) with a mean density of $1,167ind./m^2$ at upper part of the bay where salinity was low and Eriopisella sechellensis (amphipod) with $152ind./m^2$ in central part of the bay. Species diversity (H') was $3.0{\leq}$ in the mouth part of the bay and ranged 2.0-3.0 in the inner part of the bay, which showed a significant positive correlation to bottom salinity. Total number of species also showed significant correlations to the sediment composition and bottom salinity. Based on the cluster analysis the macrobenthic community of the bay was classified into five station groups from the bay mouth toward the inner part of the bay depending on the species composition. From the SIMPER analysis Minuspio japonica, Eriopisella sechellensis and Sternaspis scutata mainly contributed to the classification of station group. These results suggested that the macrobenthic communities of the bay were mainly influenced by bottom salinity together with sediment composition, and that the studies of spatial distributions of major dominant species and benthic communities should be conducted continuously to monitor the Yeoja Bay benthic environment.