• Journal of Ecology and Environment
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• v.38 no.4
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• pp.505-515
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• 2015

The objectives of this study were to determine the effects of stream nutrient regime, N:P ratios and suspended solids on fish tolerance/trophic compositions and stream ecosystem health, based on multi-metric model, during 2008-2013. Also, stream ecosystem health was evaluated in relation to chlorophyll-a (CHL) as a measure of algal productivity or indicators of trophic state to water chemical parameters. Total number of sampled fish species were 50 and showed a decreasing trend from 2008 to 2013. The minnow of Zacco platypus, based on the catch per unit effort (CPUE), was the most dominant species (25.9%) among the all species. Spatial heterogeneity was evident in the fish tolerance guilds that showed the dominance of sensitive species (89%) in the headwaters (S1) and the dominance of tolerant species (57%) in the urban. These conditions were directly influenced by concentrations of nutrients and organic matter (COD). The N:P ratios, as a barometer of water pollution, had a negative linear function (R² = 0.40, P < 0.01) with CHL, and the ratios had an important role in changes of COD concentration (R² = 0.40, P < 0.01). Under the circumstances, the N:P ratio directly influenced the relative proportions of fish trophic/tolerance compositions. According to the regression analysis of omnivore (O_m) and insectivore sp. (I_n) on total nitrogen and total phosphorus, nitrogen had no significant influences (P > 0.05) to the two compositions, but phosphorus influenced directly the two guilds [slope (a) = -32.3, R² = 0.25, P < 0.01 in the I_n; a = 40.7, R² = 0.19, P < 0.01 in the O_m]. Such water chemistry and fish trophic guilds determined the stream ecosystem health, based on the multi-metric fish model.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.1-12
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• 2016

The objective of this study is to analyze the relationship between stream water quality of TN (total nitrogen), TP (total phosphorus), and BOD (Biochemical Oxygen Demand) and TDI (Trophic Diatom Index) score determined by physico-chemical factors, biomass, and standing crops of epilithic diatoms, and to estimate the required amount of ecological streamflow for good water environment of Trophic Diatom. For the main stream of Chungju dam watershed of South Korea, total 100 field data of 3 years (2008~2010) measured in May and September were used to derive the relationship between water quality and TDI. Trophic Diatom had high correlation (0.55 determination coefficient) with TN. Using the relationship, the required streamflow was evaluated by using the Soil Water Assessment Tool (SWAT) for good Trophic Diatom water environment through T-N water quality maintenance. The SWAT simulated 8 years (2003~2010) stream discharges and T-N water quality along the main stream. From present garde C (score range: 30.0~45.0) to grade A (score above 60.0) of TDI, the May needs additional streamflow of $63.1m^3/sec$ (+36.7 % comparing with the present streamflow of $172.0m^3/sec$) at the watershed outlet.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.741-749
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• 2008

Many small-scale ponds that serve as ecological habitat, recreation and irrigation are faced to eutrophication problem, which causes aesthetic nuisance and ultimately loss of their functions. Thus accurate evaluation of the trophic state of these ponds is essential to provide rational information to the stakeholders so that they can develop effective management actions. In this study, the trophic state of a small pond (Wonheung) that experiencing water quality degradation due to vicinity land development was assessed using various Trophic State Indexes (TSIs) and statistical analysis including Principal Components Analysis (PCA) based on the field monitoring data obtained from May to December, 2007. The results showed that the pond is under eutrophic state with average total nitrogen (T-N) and total phosphorus (T-P) concentrations of $708.1{\mu}g/L$ and $59.3{\mu}g/L$, respectively. The factor loading plot obtained from PCA showed distinct two influencing factors, PC 1 and PC 2. PC 1 was grouped by T-P, Chlorophyll a (Chl-a), suspended solids (SS), TN/TP ratio, and transparency that all strongly related to the eutrophication state, while PC 2 by temperature, conductivity, dissolved oxygen (DO) and turbidity that explains the seasonal water quality variations. The limiting factor was identified as light rather than phosphorus by both T-N/T-P ratio and TSI indexes analysis. The results and methodology adopted in this study can be used for water quality assessment for other small ponds and lakes.

• Journal of Environmental Impact Assessment
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• v.21 no.3
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• pp.445-460
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• 2012

In order to evaluate and predict the environmental impact of the low-trophic-level ecosystem to environmental changes in the Yellow Sea and the East China Sea, an ecological modelling study was undertaken. Simulation results of average distribution patterns and concentrations of water quality factors during the summer by the model were acceptable. Phytoplankton and remineralization rate of organic matter were very important parameters by a sensitivity analysis. Water quality factors showed high values in the estuary of the Yangtze River and in the West and South Sea of Korea and low values in the central area of the Yellow Sea. There is a plume of high values, especially nutrients, off the mouth of the Yangtze that expands or contracts with changes in the discharge strength. Characteristics of responses of water quality factors vary for different scenarios of environmental change, such as land-based pollution sources and atmospheric forcing. It is suggested that changes of light intensity, discharges of input sources, and wind play an important role in the marine ecosystem.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1272-1272
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• 2001

Eutrophication processes of aquatic environment are strictly correlated with the concentration levels of nitrogen, phosphorous, organic matter and biological parameters such as phytoplankton and chlorophylla (Tremel, 1996; Burns et al., 1997; Young et al. 1999; Wei et al.,2000). Accordingly, the monitoring and evaluation of these factors will provide useful information about the health of aquatic ecosystem. However, the traditional types of auqatic chemistry analysis and ecological monitoring of phytoplankton are time-consuming, costly, and further resulting in secondary pollution due to the use of reagents. NIR (near-infrared) spectroscopy, as a rapid, non-destructive, little sample preparation and reagents-free technology (Hildrum et al., 1992), has been extensively applied to the characterization of food (Osborne and Fearn, 1988), pharmaceutical (Morisseau and Rhodes, 1995) and textile materials (Clove et al.,2000). Currently, NIR technology has been used indirectly in inferring lake water chemistry by two approaches, suspended (Malley et al., 1996) or seston (Dabakk et al., 1999), and sediments (Korsman et al., 1992; Malley et al., 1999). In addition, the evaluation of trophic state and the identification of the key factors contributed to the trophication are the key step to restore the damaged aquatic environment. Moreover, an understanding of the factors, which regulate the algal proliferation, is crucial to the successful management of aquatic ecosystem. In the paper, NIR technology will be used to study the environmental factors affecting the algal proliferation in combination with the trophic state index and diversity index. This novel developed system can be applied in monitoring and evaluating allopathic water environment and provide real time information services for the aquatic environment management.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.185-200
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• 2022

The risk of various hazardous substances in aquatic environment comprises not only the concentration of substances in the environmental medium but also their accumulation in fish through complex food web and the health risks to humans through the fish. In Korea, the monitoring of residual toxicant in aquatic ecosystems began in 2016 following the enforcement of the Acts on registration and evaluation for the management of chemicals used in daily life (consumer chemical products), and attention has been paid to potentially hazardous substances attributed to them. Recently, studies have been carried out to investigate the distribution of these hazardous substances in the ecosystem and calculate their emission factors. These include the accumulation and transport of substances, such as detergents, dyes, fragrances, cosmetics, and disinfectants, within trophic levels. This study summarizes the results of recently published research on the inflow and distribution of hazardous substances from consumer chemical products to the aquatic environment and presents the scientific implication. Based on studies on aquatic environment monitoring techniques, this study suggests research directions for monitoring the residual concentration and distribution of harmful chemical substances in aquatic ecosystems. In particular, this study introduces the directions for research on trophic position analysis using compound specific isotope analysis and trophic magnification factors, which are needed to fulfill the contemporary requirements of selecting target fish based on the survey of major fish that inhabit domestic waters and assessment of associated health risk. In addition, this study provides suggestions for future biota monitoring and chemical research in Korea.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.11-20
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• 2008

In this study, we applied a Particle Swarm Optimization (PSO) algorithm to predict the changes of chlorophyll-${\alpha}$ related to environmental factors in agricultural reservoirs in Korean national scale. Data were obtained from water quality monitoring networks of reservoirs operated by the Ministry of Agriculture and Forestry and the Ministry of Environment of Korea. From the database of the monitoring networks, 290 reservoirs were chosen with variables such as chlorophyll-${\alpha}$ and 13 environmental factors (COD, TN, TP, Altitude, Bank height, etc.) measured in 2002. Based on Carlson's trophic status index, reservoirs were divided into five groups, and most agricultural reservoirs $(TSI_{CHL}\;64.1%,\;TSI_{TP}\;75.5%)$ were in the eutrophic states. The groups were discriminated with environmental variables, showing that COD, DO, and TP were important factors to determine the trophic states. MLP-PSO (Multilayer perceptron (MLP) with PSO for the optimization) was applied for the prediction of chlorophyll-${\alpha}$ with environment factors, and showed high predictability (r=0.83, p<0.001). Additionally, the sensitivity analysis of the MLP-PSO model showed that COD had the strongest positive effects on the concentration of chlorophyll-${\alpha}$, and followed by TP, TN, DO, whereas altitude and bank height had negative effects on the concentration of chlorophyll-${\alpha}$.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.156-166
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• 2022

Understanding the characteristics of reservoir water quality is fundamental in reservoir ecosystem management. The water quality of reservoirs is affected by various factors including hydro-morphology of reservoirs, land use/cover, and human activities in their catchments. In this study, we classified 83 major reservoirs in South Korea based on nine physicochemical factors (pH, dissolved oxygen, chemical oxygen demand, total suspended solid, total nitrogen, total phosphorus, total organic carbon, electric conductivity, and chlorophyll-a) measured for five years (2015~2019). Study reservoirs were classified into five main clusters through hierarchical cluster analysis. Each cluster reflected differences in the water quality of reservoirs as well as hydromorphological variables such as elevation, catchment area, full water level, and full storage. In particular, water quality condition was low at a low elevation with large reservoirs representing cluster I. In the comparison of eutrophication status in major reservoirs in South Korea using the Korean trophic state index, in some reservoirs including cluster IV composed of lagoons, the eutrophication was improved compared to 2004~2008. However, eutrophication status has been more impaired in most agricultural reservoirs in clusters I, III, and V than past. Therefore, more attention is needed to improve the water quality of these reservoirs.

• Journal of Ecology and Environment
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• v.40 no.2
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• pp.107-119
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• 2016

Background: Previous studies on the biological integrity on habitat and landuse patterns demonstrated ecological stream health in the view of regional or macrohabitat scale, thus ignored the mesoscale habitat patterns of pool, riffle, and runs in the stream health analysis. The objective of this study was to analyze influences on the mesohabitat structures of pool, riffle, and run reaches on the fish guilds and biological integrity in Geum-River Watershed. Results: The mesohabitat structures of pool, riffle, and run reaches influenced the ecological stream health along with some close relations on the fish trophic and tolerance guilds. The mesoscale components altered chemical water quality such as nutrients (TN, TP) and BOD and these, then, determined the primary productions, based on the sestonic chlorophyll-a. The riffle-reach had good chemical conditions, but the pool-reach had nutrient enrichments. The riffle-reach had a predominance of insectivores, while the pool-reach has a predominance of omnivores. Also, the riffle-reach had high proportions of sensitive fish and insectivore fish, and the pool-reach had high proportions of tolerant species in the community composition. The intermediate fish species in tolerance and omnivorous fish species in the food linkage dominated the community in the watershed, and the sensitive and insectivorous fishes decreased rapidly with a degradation of the water quality. All the habitat patterns were largely determined by the land-use patterns in the watershed. Conclusions: Trophic guilds and tolerance guilds of fish were determined by land-use pattern and these determined the stream health, based on the Index of Biological Integrity. This study remarks the necessity to include additional variables to consider information provided by mesohabitats and land-use distributions within the selected stream stretch. Overall, our data suggest that land-use pattern and mesohabitat distribution are important factors to be considered for the trophic and tolerance fish compositions and chemical gradients as well as ecological stream health in the watershed.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.304-312
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• 2004

The transient dynamics of three-trophic populations (prey, predator, and super predator) using ratio-dependent models responding to environmental impacts is analyzed. Environmental factors were divided into two parts: periodic factor (e.g., temperature) and general noise. Periodic factor was addressed as a frequency and bias, while general noise was expressed as a Gaussian distribution. Temperature bias ${\varepsilon}$, temperature frequency ${\Omega}$, and Gaussian noise amplitude ${\`{O}}$ accordingly revealed diverse status of population dynamics in three-trophic food chain, including extinction of species. The model showed stable limit cycles and strange attractors in the long-time behavior depending upon various values of the parameters. The dynamic behavior of the system appeared to be sensitive to changes in environmental input. The parameters of environmental input play an important role in determining extinction time of super predator and predator populations.