• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.263-267
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• 2013

Long-term (from 1995 to 2012) data of phytoplankton biomass (chlorophyll-a, Chl-a) and water quality were analyzed to investigate trends of eutrophication in downstream of Nakdong River (Mulgum). Long-term annual average concentration of water quality parameters and phytoplankton biomass at Mulgum showed an decreasing trends for 18 years. Phytoplankton biomass was high from annually December to March. Trophic state was evaluated as the eutrophic state annually from 1995 to 2012 by TSI (trophic state index) by Aizaki. From the results of simple regression analysis, correlation coefficient between Chl-a concentration and BOD concentration was high ($r^2$ = 0.82).

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.187-196
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• 2000

This paper describes a simple method that uses differences among Carlson's (1977) trophic state index (TSI) values based on total phosphorus (TP), chlorophyll a (CHL) and Secchi depth (SD) to draw inferences regarding the factors that are limiting to phytoplankton growth and the composition of lake seston. Examples are provided regarding seasonal and spatial patterns in a large subtropical lake (Lake Okeechobee, Florida, USA) and inter- and intra-lake variations from a multilake data set developed from published studies. Once an investigator has collected routine water quality data and established TSI values based on TP, CHL, and SD, a number of inferences can be made. Additional information can be provided where it also is possible to calculate a TSI based on total nitrogen (TN). Where TSI (CHL)<>TSI (SD), light attenuating particles are large (large filaments or colonies of algae), and the phytoplankton may be limited by zooplankton grazing. Other limiting conditions are inferred by different relationships between the TSI values. Results of this study indicate that the analysis is quite robust, and that it generally gives good agreement with conclusions based on more direct methods (e.g., nutrientaddition bioassays, zooplankton size data, zooplankton removal experiments). The TSI approach, when validated periodically with these more costly and time-intensive methods, provides an effective, low cost method for tracking long-term changes in pelagic structure and function with potential value in monitoring lake ecology and responses to management.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.31-42
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• 2016

The object of this study was to determine long-term temporal and spatial patterns of nutrients (nitrogen and phosphorus), suspended solids, and chlorophyll (Chl) in Chungju Reservoir, based on the dataset of 1992 - 2013, and then to develop the empirical models of nutrient-Chl for predicting the eutrophication of the reservoir. Concentrations of total nitrogen (TN) and total phosphorus (TP) were largely affected by an intensity of Asian monsoon and the longitudinal structure of riverine (Rz), transition (Tz), and lacustrine zone (Lz). This system was nitrogen-rich system and phosphorus contents in the water were relatively low, implying a P-limiting system. Regression analysis for empirical model, however, showed that Chl had a weak linear relation with TP or TN, and this was mainly associated with turbid, and nutrient-rich inflows in the system. The weak relation was associated with non-algal light attenuation coefficients (Kna), which is inversely related water residence time. Thus, values of Chl had negative functional relation (R² = 0.25, p < 0.001) with nonalgal light attenuation. Thus, the low chlorophyll at a given TP indicated a light-limiting for phytoplankton growth and total suspended solids (TSS) was highly correlated (R² = 0.94, p < 0.001) with non-algal light attenuation. The relations of Trophic State Index (TSI) indicated that phosphorus limitation was weak [TSI (Chl) - TSI (TP) < 0; TSI (SD) - TSI (Chl) > 0] and the effects of zooplankton grazing were also minor [TSI (Chl) - TSI (TP) > 0; TSI (SD) - TSI (Chl) > 0].

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.360-367
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• 2005

We have performed to analyze the trophic state resulting of Lake Yongdam as a result of water quality and nutrient concentration. Lake Yongdam is artifitial multi-purpose Dam resulting from the floods of 2001. The water quality of Lake Yongdam may affect the status of the Geum river basin including the Daecheong reservoir. It is necessary to understand the trophic state to assess water quality until stability after flooding. Water quality was surveyed using depth and hydraulic condition analysis. Further density flow was estimated for stratification and trophic state of Lake Yongdam by chlorophyll ${\alpha}$ concentration (2001~2004). And Environmental factors on chlorophyll ${\alpha}$ concentration were analyzed statistically. Trophic state was evaluated as the oligotrophic state at the main stream of the reservoir and eutrophic state at the upper stream in 2001, but evaluated as eutrophic state in 2002 and 2003 by TSI of Aizaki. From the results of multiple regression analysis using stepwise method, chlorophyll ${\alpha}$ concentration was shown to be very significant when nutrient concentration is high upon initial filling of the Dam. Chlorophyll ${\alpha}$ concentration varied according to sample site, season and year. Concentration were high in the upper stream of Lake Yongdam 4, algae bloom in these watershed were affected by location and high nutrient levels in the summer season which have in turn increased phytoplankton bloom into the reservoir.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.52-52
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• 2002

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.174-189
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• 2012

The objective of this study was to determine the weight-length relations and condition factor (K) of Zacco platypus, along the trophic gradients from oligotrophic to eutrophic state in six reservoir ecosystems ($B_aR$, $Y_yR$, $J_yR$, $G_pR$, $Y_dR$, and $M_sR$), during 2008~2010. The species was selected as a sentinel species for the study, due to its wide distribution and wide trophic gradient. The analysis of trophic state index (TSI), based on total phosphorus (TP) and chlorophyll-a (Chl-a), indicated that reservoirs of $Y_yR$ and $B_aR$ were classified as to be in an oligotrophic state (30~40), the $J_yR$ and $G_pR$ as mesotrophic (40~50), and the $Y_dR$ and $M_sR$ as eutrophic state (50~70). Total 47 species and 26,226 individuals were sampled from 6 reservoirs and sensitive species dominated in the oligotrophic reservoirs ($Y_yR$ and $B_aR$). In the mean time, the tolerant speciesdominated the community in the mesotrophic ($J_yR$ and $G_pR$) and eutrophic ($Y_dR$ and $M_sR$) reservoirs. Regression analysis of body weight, against the total length, indicated that the regression coefficient (b value) was lower in the oligotrophic reservoir (2.77~2.79) than the mesotrophic (3.07~3.17) and eutrophic reservoirs (3.15~ 3.21). This result suggests that the population growth rate Zacco platypus reflected the trophic gradients of the reservoirs. The analysis of condition factor (K) against the total length showed positive slopes (b>3.0) in mesotrophic and eutrophic reservoirs, and a negative slope (b<3.0) in oligotrophic reservoir. The variation of the regression slope of "b" in Z. platypus was accounted for 79.7% [$b=0.012{\times}TSI(TP)+2.395$, p=0.017] by the variation of TSI (TP) and 82.2% [$b=0.013{\times}TSI(Chl-a)+2.36$, p=0.013] by the variation of TSI (Chl-a). The proportion of DELT abnormality increased as the trophic state increases in the reservoirs. The overall data suggest that the growth of the fish populations, based on the length-weight relations and condition factor, reflected the trophic state of nutrient and phytoplankton biomass of the reservoir waters. Thus, in spite of the tolerant characteristics of Z. platypus, hypertrophic states might negatively affect the health of the population.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.587-597
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• 2023

We evaluated the eutrophication of Saemangeum Lake, which causes abnormal growth of algae, using the Carlson index. Eutrophication characteristics of Saemangeum Lake were analyzed. For the study, water quality surveys were conducted at 7 stations in Saemangeum Lake every month in 2021. The concentration of Chl.a was slightly higher in the Mankyeong water system in winter, and slightly higher in the Dongjin water system in spring and summer, but overall, except for some periods, the concentration was similar to or lower than the lake water quality environmental standard of class 3. COD showed water quality similar to or above the lake quality environmental standard of grade 4 in both the Mankyeong and Dongjin water systems in the summer and Autumn. TOC concentrations were within lake water quality standard 3 at all sites. Total phosphorus concentrations exceeded the lake water quality standard of Class 4 and were higher in January and August after rainfall. In the correlation analysis between water quality factors, the correlation of organic matter, total phosphorus, and total nitrogen to salinity was relatively high. This reflected the water quality characteristics of freshwater, brackish water, and seawater areas due to seawater inflow through the drainage gate and freshwater inflow through upstream rivers. According to the characteristics of eutrophication fluctuations in Saemangeum Lake by trophic state index, the indices of Chl.a, SD, and TN showed water quality in the early stage of eutrophication, while the TP index showed a severe eutrophication state. The magnitude of the eutrophication index among water quality components was TSI(TP) > TSI(TN) > TSI(SD) > TSI(CHL) in all water systems. Quadrant analysis of the deviation of TSI(CHL) from TSI(TP) and TSI(SD) on a two-dimensional plane showed that there was no limiting effect of total phosphorus on algal growth in all water systems. In addition, the factors af ecting light attenuation appeared to be dominated by small particulate matter from outside sources.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.296-309
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• 2006

This study aimed to analyze water quality (temperature, secchi depth, DO, $NH_4$, $NO_3$, $PO_4$, TN, TP, chlorophyll a) and trophic state index during the period of year 2000 ${\sim}$ 2004 in Lake Juam, Lake Dongbok and Lake Youngsan. Lakes Juam and Dongbok except Lake Youngsan were stratified during warm seasons. Water turbidity estimated by secchi disk depth was the highest in Lake Youngsan compared with other lakes. DO concentrations were low in the bottom water when chlorophyll a was high in Lake Juam and Dongbok. Nutrient concentrations were higher in Lake Youngsan than other lakes whereas chlorophyll a was highest in Lake Dongbok. Lake Youngsan was the most eutrophic compared to other two lakes based on the Trophic State Idex (TP) and TSI (SD), The TSI (CHL) was high but the TSI (TP) were low in Lake Juam and Dongbok. These results suggest phytoplankton may be limited by phosphates (P) in Lake Juam and Dongbok whereas light availability in the water column may affect growth of phytoplankton in Lake Youngsan.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.382-393
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• 2009

The objectives of this study were to characterize long-term annual and seasonal trophic state of Topjeong Reservoir using conventional variables of Trophic State Index (TSI) and to determine the empirical relations between the trophic parameters. For the analysis, we used water quality dataset of 1995$\sim$2007, which is obtained from the Ministry of Environment, Korea and the number of parameters was 9. Annual ambient mean values of TN and TP were 1.78 mg $L^{-1}$ and 0.03 mg $L^{-1}$, respectively and TN : TP ratios averaged 76, indicating that this system was nitrogen-rich hypertrophic, and was probably phosphorus-limitation for algal growth. Therefore, nitrogen varied little with seasons and years, and total phosphorus (TP) varied depending on season and year. Monsoon dilutions of TP occurred in August and monthly fluctuations of suspended solid (SS) was similar to those of chlorophyll-$\alpha$ (CHL). Annual mean values of BOD and $COD_{Mn}$ were 1.61 mg $L^{-1}$ and 4.23 mg $L^{-1}$, respectively and the interannual values were directly influenced by the intensity of annual rainfall. There were no significant differences in the trophic variables between the two sampling sites. Mean values of Trophic State Index (TSI, Carlson, 1977), based on TN, TP, CHL, and SD (Secchi depth), turned out as eutrophic state, except for the TN (hypertrophic). Regression analyses of log-transformed seasonal CHL against TP and TN showed that variation of the CHL was explained 37% by the variation of TP ($R^2$=0.37, p<0.001, r=0.616), but not by TN ($R^2$=0.03, p>0.05). Regression coefficient of $Log_{10}$CHL vs $Log_{10}SD$ was 0.330 (p<0.003, r=0.580), indicating that transparency is regulated by the organic matter in the system. Results, data suggest that one of the ways controlling the eutrophication would be a reduction of phosphorus from the watershed.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.9-18
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• 2009

The objectives of this study were to evaluate seasonal and interannual variations of water quality and nutrient input (N, P) in Junam Reservoir, a nesting waterbody of migratory birds, over 10 years during 1998$\sim$2007 along with dynamic relations of trophic parameters using empirical models. Concentrations of COD averaged 7.8 mg $L^{-1}$ during the study, while TN and TP were $1.4\;mg\;L^{-1}$ and $83{\mu}g\;L^{-1}$, respectively, indicating an eutrophic-hypereutrophic state. Values of monthly COD had strong positive relations (r=0.669, p<0.001) with conductivity, indicating that summer rainfall resulted in an ionic dilution of the reservoir water by rainwater and contributed better water quality. One-way ANOVA tests showed significant differences (F=$5.2{\sim}12.9$, p<0.05) in TN and TP between the before and after the bird migration. In other words, nutrient levels were greater in the absence of migratory birds than in the presence of the migratory birds, suggesting a no-effect on nutrient inputs by the birds. Also, one-way ANOVA indicated no significant differences (F=$0.37{\sim}0.48$, p>0.05) in $NO_{3^-}N$ and $NH_{3^-}N$ between the before and after the birds migration. Linear empirical models using trophic parameters showed that algal biomass as CHL, had significant low correlations with TN ($R^2$=0.143, p<0.001, n=119) and TP ($R^2$=0.192, p<0.001, n=119). These results suggest that influences of nutrients on the CHL were evident, but the effect was weak. This fact was supported by analysis of Trophic State Index Deviation (TSID). Over 70% in the observed values of "TSI (CHL)-TSI (SD)" and "TSI (CHL)-TSI (TP)" were less than zero, suggesting a light limitation on the CHL by inorganic suspended solids.