• Journal of Environmental Health Sciences
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• v.44 no.4
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• pp.315-322
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• 2018

Objectives: A lake is a place used by many people, and compared to rivers it is easy for them to become polluted. The water quality in lakes and reservoirs has been worsening recently. The purpose of this study is to evaluate the water pollution characteristics of major lakes in northern Gyeonggi-do Province. Methods: Six lakes were selected as major lakes and were evaluated in terms of water pollution characteristics and eutrophication (as defined by results for $COD_{Mn}$, TOC, SS, Chl-a, T-N and T-P) over one year (from December 2016 through November 2017) in northern Gyeonggi-do Province. Results: The annual average $COD_{Mn}$ was found to be 3.1 mg/L in Onam, 3.6 mg/L in Sanjeong, 4.7 mg/L in Gisan, 4.8 mg/L in Ilsan, and 6.1 mg/L in Jangja. The results of the Korean trophic state index ($TSI_{KO}$ ) value indicated a eutrophic state ($TSI_{KO}$ 59.0) in Jangja lake. The other lakes were classified as being in a mesotrophic state ($TSI_{KO}$ of 38.1 in Sanjeong, 40.2 in Ilsan, 41.9 in Onam, 46.1 in Gisan, and 47.8 in Gomo). Conclusions: Ilsan Lake's water quality is being well maintained. Sanjeong, Onam, and Gisan are appropriate for use as agricultural water. Jangja lake requires efforts for water quality improvement and to prevent the inflow of non-point pollutant sources.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.699-712
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• 2000

Juam lake is a major water resource for the industrial and agricultural activities as well as the resident life of Kwangju and Chonnam regions. However, the water quality of the lake is getting worse due to a large quantity of pollutant inflowing to the lake. Thus, the strategy for achieving the water quality goal of the lake should be developed as soon as possible. When there are various alternatives that can be used as the strategy, several criteria based on the achievement degree of water quality goal, the applicability of technique and social environment, and the reasonableness of the cost required are made to evaluate and rank the alternatives. However, it is difficult to make a decision when there are multiple criteria and conflicting objectives and specifically the estimated values of criteria contain elements of uncertainty. The uncertainty stems from the lack of available information, the randomness of future situation, and the incomplete knowledge of expert. As the degree of uncertainty is higher, the decision becomes more difficult. In this study, a fuzzy decision-making method is presented to assist decision makers in evaluating various alternatives under uncertainty. The method allows decision makers to characterize the associated uncertainty by applying fuzzy theory and incorporate the uncertainty directly into the decision making process for selecting the "best" alternative so decisions can be made that are more appropriate and realistic than those made without taking uncertainty in account.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.15-21
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• 2005

This study is to trace the change of stream shape using the past series of aerial photographs, and to compare the land use changes of riparian area along the stream. For the Gyeongan national stream, aerial photographs of 1966, 1981 and 2000 were selected and ortho-photographs were made with interior orientation and exterior orientation, respectively. Apparent changes of the stream were found that the consolidated reaches of stream by levee construction became straight together with widening of their stream widths. Especially the stream width of inlet part of Paldang lake widened almost twice because of the rise of water level by dam construction in 1974. The land use of riparian areas of three selected years were classified into six categories (water, forest, agricultural land, urban area, road, sandbar) by digitizing method. The forest and agricultural lands decreased and urban area increased as the stream maintenance had been performed.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.183-191
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• 2013

Dissolved organic carbon (DOC) concentrations and zooplankton and particulate organic matter (POM) ${\delta}^{13}C$ values were measured in five reservoirs in Korea. Zooplankton ${\delta}^{13}C$ and POM ${\delta}^{13}C$ showed large range from -33‰ to -22‰ and a significant difference among the reservoirs. One eutrophic reservoir, Lake Masan, showed unique characteristics with the highest zooplankton density, the highest ${\delta}^{13}C$, and the highest DOC. Zooplankton ${\delta}^{13}C$ was similar to POM ${\delta}^{13}C$, implying that zooplankton occupies substantial portion of POM or that zooplankton isotopic composition is related to selective grazing and assimilation of food sources from bulk POM. Except Lake Masan zooplankton ${\delta}^{13}C$ values were negatively correlated to DOC concentration in four reservoirs with mostly forest land use. This pattern can be probably attributed to intensive agricultural land use in the watershed of Lake Masan compared to the mostly forest land use in the other watersheds. Understanding the relationship between zooplankton ${\delta}^{13}C$ values and the origin of organic matter associated with watershed characteristics will be valuable to better understand trophic relationships in reservoirs in the summer monsoon region.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.157-167
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• 2023

Background: The most hazardous wastewater sources in the northern part of the Middle Nile Delta, Egypt; receiving a massive amount of agricultural, industrial, and sewage drainage are Kitchener drain which is one of the tallest drainage systems, and Burullus Lake which represents the 2nd largest Egyptian coastal lake. Results: The current work is to determine the abundance and frequency of cyanophytes, chlorophytes, and bacillariophytes and the correlation between them and environmental abiotic components. Among sixty nine microalgal species, 19 species are belong Cyanophyta, 26 belong Chlorophyta and 24 belong Bacillariophyta. Genus Scenedesmus (Chlorophyta) was the most abundant in the study area (13 species), followed by Genus Oscillatoria (9 species) and Genus Navicula (7 species). Nostoc muscorum and Chlorella vulgaris were the most common and recorded in all sites (100% of the locations) under study. The application of the two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis revealed agglomerating of 4 groups (communities) at 4th level of classification and reasonable segregation between these groups. Zinc, cadmium and lead were showed the highest levels (0.26±0.03, 0.26±0.06, and 0.17±0.01 ppm, respectively). Conclusions: The correlation analysis between water and community variables indicated a high negative correlation of total algae richness with nickel (r = -0.936, p < 0.01). Cyanophyta and Bacillariophyta were correlated negatively (r = -0.842, p < 0.01). However, Chlorophyta showed a negative richness with each of Ni and Pb (r = -0.965, -0.873, respectively) on one hand and a high positive correlation was revealed (r = 0.964) with all environmental variables on the other hand.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.7-16
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• 2007

The objective of this research was to review the correlation between microalgae and agricultural water quality. Although microalgae has been considered as an essential factor for control1ing of water ecosystem, little attention has been paid for evaluating of microalgae as an important factor for water quality management. But it can be use to make us know the water pollution state at saprobic system, LTSI (Lake Tropic State Index), DAIpo (Diatom Assemblage Index to Organic Pollution), and AGP (Algal growth potential). In saprobic system, it is used microalgae such as Actinastrum hantzschii var. fluviatile, Asterionella gracillima, Coelastrum microporum, Synedra acus, Dictyosphaerium pulchellum, Micractinium pusillum, Cyclotella meneghiniana, Microcystis aeruginosa, Scenedesmus quadricauda, and Nitzschia palea for assessment water quality. In addition, they have ecologically significant characteristics such as dominant species, cosmopolitan species, redtide causative species etc. Also, microalgae such as Botryococcus braunii, B. sp., Chlorella vulgaris, C. sp., Phormidium sp., Scenedesmus quadricauda, Selenastrum capricornutum, Spirulina maxima, and S. platensis have an effect on improvement of water quality.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.430-437
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• 2010

The continuous release of nutrient sources into natural water resource can be a continuing problem in eutrophication, as well as severe reductions in water quality. However, any desirable measure is not developed yet even though so many researches and efforts have been done to solve this problem. Forest as one of troublesome nonpoint sources may contributes most to nutrient loading, but the loading of N and P from forest in order to grasp the eutrophication potential of nonpoint sources has not been evaluated. The nutrient sources from the organic litter accumulated on the surface of forest soils can be a critical factor in continuity of eutrophication of a lake. The decomposition rate of litter can be estimated to predict release of N and P from the forest stand. The loss rate of nitrogen is complicated but depends in part upon the physical matrix of the element. Therefore, long-term nutrient budget and flux estimates at stand would be useful tools in calculating potential nutrient fluxes into the watercourses in a sustainable way. The present investigation can give insight to the actual situation of the eutrophication potentials of forest as the practical nonpoint sources.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.1027-1033
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• 2009

For the assesment of pollutant loads, a monitoring has been conducted to identify hydrologic conditions and water quality of the Oenam watershed in Juam Lake, and the SWAT model integrated with GIS was applied to the watershed and evaluated for its applicability through calibration and verification using observed data. For the model application, digital maps were constructed for watershed boundary, land-use, soil series, digital elevation, and topographic input data of the Oenam watershed using Arcview. The observed runoff was 832.8 mm while the simulated runoff was 842.8 mm in 2003. The model results showed that the simulated runoff was in a good agreement with the observed data and indicated reasonable applicability of the model. In terms of nutrient load, the simulation results of T-N, T-P showed a similar trend to observed values. The observed T-N load was 10.8 kg/ha and the simulated T-N load was 7.6 kg/ha while the observed T-P load was 0.21 kg/ha and the simulated T-P load was 0.18 kg/ha. In general, SWAT model predicted observed runoff and loads of T-N and T-P after calibration with observed data in acceptable range. Overall, SWAT model was satisfactory in estimation of nutrient pollutant loads of the rural watershed.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1445-1456
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• 2010

This study presented seasonal changes of the phytoplankton community in Junam reservoir by pollution and water quality of the lake. The water storage of the reservoir is 5.3 million ton, most of which are being utilized for agricultural, industrial and residential purposes. The annual precipitation during the investigation period was 1,868.9 mm, increasing by 20% from the average annual level of 1,506.7 mm in 2009. The annual average water storage was 57.3%. It decreased during agricultural season and then increased again after monsoon rainfall. The loads of BOD were $3,799kgday^{-1}$, and 81% of them came from livestock and household. The TN and TP loads were $1,164kgday^{-1}$ and $170kgday^{-1}$, respectively, and 76% of them came from livestock. We assessed water quality of the Junam reservoir using 17 variables. According to the result, the reservoir met the fourth grade, meaning slightly bad, because of high concentration of COD, SS and chlorophyll-a. Eutrophication assessment was conducted by revised Carlson's Index (TSIm, Aizaki), and it was found that the entire lake was eutrophicated with high chlorophyll-a concentration all through the year, except during February to April and in July. A total of 76 phytoplankton species were identified from the samples. Among them, the largest number of species were Chlorophyceae with 33 species(43.4%), followed by Bacilliophyceae with 27 species(35.5%), Cyanophyceae with 8 species(10.5%), and Cryptophyceae with species(10.5%). The total cell number of phytoplankton was the highest in October(7,884 cells $mL^{-1}$) among Cyanophyceae and Bacilliophyceae. The seasonal succession of Chlorophyceae (Chlamydomonas spp.), Cyanophyceae(Microcystis aeruginosa) and Cryptophyceae(Rhodomonas spp.) was observed during January to May, July to September and October to December respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.93-102
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• 2005

A prototype surface flow constructed wetland was built in the upstream area of Sihwa reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, we monitored hydrology, macrophyte (Phragmites communis Trin,) growth, and water quality in the Banwol and Donghwa wetlands to evaluate their performance during the initial period after the completion of wetland construction, The average removal efficiency($\%$) in each wetland was relatively low compared with the performance data from the North America Wetland Treatment System Database (NADB), which mainly includes urban sewage-treatment wetlands. However, the average removal rates per unit area ($g/m^{2}/day$) were 0.72, 0.72 and 0.51 (BOD), 2,04, 2.46 and 0.70 (SS), 0.89, 0.43 and 1.09 (TN) and 0.02, 0.02 and 0.02 (TP) in the Banwol and Donghwa wetlands and NADB, respectively. The overall performance of the Banwol and Donghwa wetlands was within the expected range of the wetland system processes contributing the reduction of the pollutant load to Lake Sihwa during the initial period of wetland operation. Considering the low influent concentration, high hydraulic loading rate, and insufficient macrophyte growth since the wetland was constructed, better performance is expected if an improved operational scheme is adopted.