• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.340-351
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• 2019

In this study, the relationship between trophic state indices was analyzed based on the monthly or weekly water quality data of 81 lakes (mostly man-made) in Korea between 2013-2017. Carlson's $TSI_C$ and Aizaki's $TSI_m$ were calculated using the summer (Jun.-Sep.) average data at the upper water layer. The previous Korean trophic state index ($TSI_{KO}$) and the newly suggested index ($TSI_{KON}$) was calculated using the annual average data at the whole layer and at the upper layer, respectively. While previous trophic state index (TSI) such as Carlson's TSI included logarithmic function, we devised newly Monod-type $TSI_{KON}$(Chl) that is 50 when half-saturation concentration of chlorophyll ${\alpha}$ ($Chl.{\alpha}$) measured by UNESCO-method is $10{\mu}gL^{-1}$. MMF-type $TSI_{KON}$(TP) was derived based on the relationship between TP and $Chl.{\alpha}$. A comprehensive $TSI_{KON}$ was decided as the larger one of the two $TSI_{KON}$ values. The range of previous TSI was usually 40-50 for the mesotrophic state, which seemed narrow to discriminate trophic characteristics of the class. The upper limits of $TSI_{KON}$ for oligotrophic, mesotrophic, and eutrophic state were set to 23, 50 and 75, respectively. Classification by $TSI_C$ and $TSI_m$ showed higher frequency of eutrophic class compared to $TSI_{KO}$ and $TSI_{KON}$. This means that the estimation by TSIs developed in foreign natural lakes can lead to distorted results in the classification of the trophic state of Korean lakes. This is due to the decrease of transparency by non-algal material and the reduction in phosphorus availability to algal growth, particularly in Monsoon period.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1537-1549
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• 2014

The objectives of this study were to analyze reservoir trophic state, based on Trophic State Index (TSI), spatial variation patterns of three zones (riverine, transition, and lacustrine zone), and empirical models through 20-years long-term data analysis. Trophic variables of TP and CHL-a were highest during the summer monsoon, and decreased along the main axis from the riverine to lacustrine zone. In the mean time, TN did not show the trend. Ratios of N:P and Secchi disc transparency (SD) increased from the riverine to lacustrine zone. The analysis of trophic state index (TSI) showed that mean TSI (TP) and TSI (CHL-a) were 62 and 57, respectively, and these values were highest in the transition zone during the summer. This zone should be managed well due to highest lake water pollution. The analysis of Trophic State Index Deviation (TSID) showed that algal growth was primarily limited by light penetration, and this was most pronounced in the monsoon season. The analysis of empirical models showed that the value of $R^2$, based on CHL-SD model, was 0.30 (p < 0.0001) in the transition zone and the $R^2$, based on TP-SD model, was 0.41 (p < 0.0001) in the transition zone.

• Journal of Korean Society on Water Environment
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• v.35 no.3
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• pp.271-277
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• 2019

Korean Trophic State Index ($TSI_{KO}$) was developed in 2006, and was composed of COD ($COD_{Mn}$ based on permanganate method), Chlorophyll a (Chl.a) and total phosphorus (TP). However, $COD_{Mn}$ usually represents only 50-60% of total organic matter in stream or lake water due to low oxidizing power of permanganate. This study investigated the relationship between TOC and $COD_{Mn}$ based on the average data for the whole layer in 81 lakes in Korea, during the period 2013-2017. As a result, $COD_{Mn}$ was found to be 1.54 times more than TOC in 66 of the freshwater lakes and 3 brackish lakes (TOC measured using thermo-oxidation method). TOC was about a quarter of $COD_{Mn}$ in 8 coastal lakes (TOC measured using UV-persulfate oxidation method), and it appeared to be underestimated due to chloride interference. Using the data of 69 lakes with exception of 12 brackish lakes, $TSI_{KO}$(TOC) was developed based on the correlation between TOC and $COD_{Mn}$, while $TSI_{KO}$(COD) was replaced with $TSI_{KO}$(TOC). However, for trophic state assessment of brackish lakes, the $TSI_{KO}$(TOC) can only be utilized in case that TOC is measured through thermo-oxidation method. The determination coefficient of $TSI_{KO}$(Chl) to $TSI_{KO}$(COD) in 66 freshwater lakes and 3 brackish lakes was 0.83, while that to $TSI_{KO}$(TOC) was 0.68. This difference could be attributed to the recalcitrant organic part of TOC.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.507-514
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• 2018

TSI (TPI-Slope Index) which is the combination of TPI (Topographic Position Index) and slope was newly proposed for landslide and applied to a landslide susceptibility model. To do this, we first compared the TPIs with various scale factors and found that TPI350 was the best fit for the study area. TPI350 was combined with slope to create TSI. TSI was evaluated using logistic regression. The evaluation showed that TSI can be used as a landslide factor. Then a logistic regression model was developed to assess the landslide susceptibility by adding other topographic factors, geological factors, and forestial factors. For this, landslide-related factors that can be extracted from DEM (Digital Elevation Model), soil map, and forest type map were collected. We checked these factors and excluded those that were highly correlated with other factors or not significant. After these processes, 8 factors of TSI, elevation, slope length, slope aspect, effective soil depth, tree age, tree density, and tree type were selected to be entered into the regression analysis as independent variables. Three models through three variable selection methods of forward selection, backward elimination, and enter method were built and evaluated. Selected variables in the three models were slightly different, but in common, effective soil depth, tree density, and TSI was most significant.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.155-171
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• 2011

The research assessed water quality using physico-chemical factors, trophic status index and attached diatom index in 10 reservoirs located in Chungcheongnam-do from October 2007 to June 2008. The physico-chemical water quality assessments revealed that Dangjin-gun (St. 1~5), which displayed a high chemical oxygen demand (V and VI) and chlorophyll-${\alpha}$ (Eutrophic-Hypereutrophic), was more polluted than Yesan and Cheongyang-gun. The sample were also hypereutrophic [trophic status index (TSI) 74.6] and ${\beta}$-mesosaprobic [diatom assemblage index to the organic water pollution (DAIpo) 44.47]. Yesan and Cheongyang-gun. Which were mid-level in their pollution status, were eutrophic (TSI 56.9) and ${\alpha}$-oligosaprobic (DAIpo 60.11). TSI correlated strongly with the attached diatom index (of DAIpo 0.60~0.62, and trophic diatom index of 0.72~0.74). Hence, the attached diatom index can be used with the trophic status assessment of lakes using TSI, and lake trophic status index (LTSI).

• 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.

• Asia-Pacific Journal of Business
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• v.8 no.2
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• pp.57-73
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• 2017

In this paper RCA and TSI has been analyzed based on Korean and Chinese lists of export (HS 6 units) and list of companies and products with competitive advantage has been deduced. The results of RCA and TSI analysis are as follows. From the list of 20 most exported items from Korea to China the RCA index for eleven of them (based on common items from 2011-2015) is bigger than 1, thus showing comparative advantage. As for the TSI index, all of the items has shown (+) value, and has been analyzed as specialization in export. In other words, companies in the fields of mineral fuel; mineral oil; organic chemicals; electrical equipment and parts; as well as optical, precision and medical instrument are industries with competitive advantage. From the list of 20 most exported items from China to Korea the RCA index for twelve of them (based on common items form 2011-2015) is bigger than 1, thus also showing comparative advantage, and the TSI index has also shown (+) value for all of the specified items, meaning specialization in export. Industries of mineral fuel; mineral oil; iron and steel, articles of iron and steel; machinery and mechanical parts, electrical equipment and parts; as well as optical, precision and medical instruments have shown competitive advantage.

• International Commerce and Information Review
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• v.17 no.3
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• pp.93-114
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• 2015

In this study, the national competitiveness of Korean and Chinese medical device industry was analyzed through RCA index, MCA index, and TSI index in order to draw the export specialized items possessing the national competitiveness of Korea in Chinese market. The drawn national competitiveness index was grouped and the change progress was examined by years. Korea should analyze the tendency of Chinese medical device market, confirm our market share in the Chinese market, apprehend the competitive superiority, and draw and excavate the specialized export item in order to strengthen the competitiveness of Korean medical device in the Chinese market.

• 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.

• 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].