• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.4047-4054
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• 2010

We studied the release characteristics of the marine sediment which could facilitate sea eutrophication through some lab-scale simulation experiments. Environmental indicators such as pH, ORP(oxidation reduction potential), nitrogens, and phosphates were measured in order to calculate the corresponding release rates. $CaO_2$, an oxygen releasing compound was used to determine how it would effect on the natural process of sedimental release. COD, ammonia nitrogen, phosphorous compounds were less released under the oxic environment caused by $CaO_2$. This basic data will help developing methodology for reducing marine eutrophication which may be initiated by the sedimental release.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.223-231
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• 2013

This study investigated the physio-chemical water quality and the standing crop of the phytoplankton of Dong-stream in Jeollanam-do from May 2010 to Feb 2011. The indicators and the dominant species of phytoplankton were also measured to investigate the water quality of estuary. Nutrients turned out to be eutrophic to hypertrophic in most sites with total nitrogen ranging 1.023~10.743 mg/L and total phosphorous ranging 0.0182~1.6848 mg/L. The site D6 had the highest BOD ranging 0.6~7.5 mg/L. Total of 205 taxa appeared within the research period, Bacillariophyceae being the highest number of taxa. The appeared species were taxa resistant to pollution including Navicula pupula, N. subminuscula, Nitzschia amphibia and N. palea. The downstream is thought to be greatly affected by the ocean water since marine and estuary phytoplankton such as Skeletonema costatum, Coscinodiscus radiatus, Bacteriastrum delicatulum and Eucampia biconcave appeared. Diatom appeared mainly as dominant species including Cymbella minuta, Melosira varians, Gomphonema parvulum, Stephanodiscus hantzschii. As for Stephanodiscus hantzschii, it dominates during fall and winter when the water temperature drops. Diatom showed 50% or higher dominant rate in all seasons at most sites. Most sites turned out to be eutrophic based on the standing crop of cells and chlorophyll a concentration. Total of 15 polluted water indicating taxa including Oscillatoria limosa appeared. From this result, the Dong-stream was considered to be in the eutrophication.

• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.426-433
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• 2019

Objectives: Zooplankton communities play important roles in aquatic ecosystems as secondary producers that graze on phytoplankton and in turn are preyed upon by planktivorous and juvenile fish. They can shift their distribution, species composition, and abundance in response to environmental changes. Therefore zooplankton communities are important for understanding the energy flow in aquatic ecosystems and can be valuable indicators of environmental conditions. However, zooplankton in streams are still not well-studied, especially in northern Gyeonggi-do Province. This study aims to investigate the zooplankton communities in major streams in northern Gyeonggi-do Province. Methods: Zooplankton is important in the nutrient cycle and energy flow of aquatic ecosystems. Therefore, we surveyed zooplankton and measured temperature, DO, BOD, COD, T-N, T-P, and Chl-a in major streams (Sincheon, Gongneungcheon, Wangsukcheon, and Gapyeongcheon Streams) and stagnant water (Gomoji Reservoir). Results: The water quality in Gapyeongcheon Stream was the highest grade, while that of Gomoji Reservoir was mesoeutrophic and eutrophic during the research period. In the zooplankton community, Nauplius, Rotaria, and Monostyla spp. were dominant in Sincheon, Gongneungcheon, and Wangsukcheon Streams, and the dominance index was also high. In the case of Gapyeongcheon Stream, it was found that water quality and aquatic ecosystem health were good, and the lowest dominance index reflected this. In Gomoji Reservoir, Polyarthra spp., Nauplius, and Bosmina longirostris, which can be easily observed as eutrophication progresses, showed a high dominance rate. Therefore, it is necessary to monitor the progress of eutrophication in further research. Conclusions: We collected data on the zooplankton communities in streams and investigated their characteristics. As a result, specific species were found to be dominant at each survey sites and some of them are known to be observed as eutrophication progresses. Therefore, we should investigate the zooplankton community of streams around us and apply ecological stream management.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.441-448
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• 2008

The purpose of this study was to analyze chemical water quality, fish trophic guilds, tolerance indicators, and fish community conditions in the Gap Stream and to compare the stream conditions between the unimpacted site and impacted site. This study was conducted in the physically stable season (May 2008) to minimize physical impacts such as flow and hydrological disturbance, and applied the study in the Gap Stream with two sites of unimpacted upstream site (Unim-S), mainly surrounded by forested area and impacted site (Im-S), influenced by the wastewater disposal plants and industrial complex in the urban region. Chemical data analysis showed that the degree of organic matter pollution, based on BOD, and COD, was $2{\sim}3$ fold greater in the Im-S than the Unim-S, and that TP, as eutrophication indicators, was 4.7 fold greater in the Im-S. Also, $NH_3-N$ was in 8.2 fold greater in the Im-S ($6.25\;mg\;L^{-1}$) than the Unim-S ($0.76\;mg\;L^{-1}$), indicating a massive influence of wastewater from the disposal plant. Similar results were found in other chemical parameters. Thus, chemical impacts in the Im-S were evident, compared to the unimpacted site. Evaluations of tolerant indicator species indicated that sensitive species were dominant in the Unim-S (23.9%) and tolerant species were dominant (97.8%) in the Im-S. Condition factor (CF) was averaged 0.95 ($0.68{\sim}1.18$) in the Unim-S and 1.08 ($0.93{\sim}1.22$) in the Im-S. Fish community in the Unim-S and Im-S was categorized as Zacco-community and Hemibarbus-community, respectively, and the community diversity index (H') was significantly (p<0.05) higher in the Unim-S (0.810) than the Im-S (0.466). Overall, our results suggest that the comparison approach of various chemical and ecological indicators provide important information in identifying multiple stressors in the stream ecosystems.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.7-24
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• 2008

Masan-Jinhae Bay, in Korea, is known for its frequent algal bloom outbreaks. This study was conducted in order to examine the environmental characteristics of the area, with the aim of identifying indicators that could be used to speculate about future algal blooms. The water temperatures and salinities in Haengam Bay, one of the small inner bays within Jinhae, appeared to re relatively higher than those in Masan and Jinhae bays, across most seasons. Furthermore, stratification begins to develop in all three regions from spring to summer as a result of the local heating effects and an increase in the efficient from the surrounding land. As a result, anoxic conditions appear near the bottom layer of the bay, leading to the deterioration of water quality, which has been identified as one of the causes of bloom outbreaks. Compared to Haengam and Jinhae bays, concentrations of DIN and DIP were remarkably higher in Masan Bay. However, the mean ratio of DIN to DIP was 3.3$\sim$13.6 in all three regions throughout the year, suggesting that nitrogen can function as a growth-limiting factor for phytoplankton. The results of mathematical models showed that cumulative organic pollutants may be a trigger for direct algal bloom occurrences, since residual tidal currents appeared to be less than $3\;cm\;\cdot\;s^{-1}$. Furthermore, computed DO concentrations in the four small inner bays of Jinhae during the summer appeared to be $3\;cm\;\cdot\;l^{-1}$ indicating a hypoxic state. Likewise, computed Chl-a concentrations turned out to be more than $0.01\;mg\;\cdot\;l^{-1}$, indicating eutrophication across most seasons. Based on the overall results, Masan-Jinhae Bay appeared to possess a very high potential for algal bloom outbreaks at anytime during the year.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.14-20
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• 2008

The agricultural reservoir watershed plan suggests three specific indices or ways to measure the potential for maintaining reservoir quality in balance with existing or proposed uses: an index of the reservoir's vulnerability to accelerated eutrophication, an index of the degree of land use intensity in reservoir watersheds, and an index of present water quality. Three items that contribute to reservoir eutrophication are included in the vulnerability index: the ratio of reservoir volume to drainage-basin area, shoreline configuration, and mean depth. The watershed land-use intensity index is based on road proximity and upland watershed land-use intensity. Water quality can be given a COD level. All six indicators are considered separately and then rated as follow: low (1), medium (2), or high (3). Five out of 30survey sites were less than 8points, 17sites were less than 11points and 8sites were less than 14points. This study suggests that the sites in the first ranking were potential areas for preservation, sites in the second ranking were potential areas for environmental friendly planning and sites in the third ranking were potential areas for residential need oriented planning. The advantage of this study is the low cost of gathering data for the development of local policy for the planning, management and protection of reservoir basin.

• Korean Journal of Environmental Biology
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• v.20 no.4
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• pp.325-338
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• 2002

The distribution and standing crop of phytoplankton were investigated at 12 stations of Songjiho, Ssangho, Maeho and Hyangho as of four lagoons in the east coast from May to November, 2001. It turned out to be total of 164 taxa, and classified as four phylums, four classes, 14 orders, 20 families, 59 genera, 139 species, 22 varieties, two forms and 1 unidentified species by Engler's classification system. Among 104 taxa, 16 taxa including Oscillatoria chlorina were identified as indicators of water pollution and only Cocconeis placentula was the indicator of the clean water. Standing crops of all stations investigated appeared to be relatively high values. Based on the present study upon the distribution and standing crop of phytoplankton, it is regarded as the state of the eutrophication in Songjiho, Ssangho, Maeho and Hyangho as of four lagoons in the east coast.

• Journal of Korean Society on Water Environment
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• v.40 no.2
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• pp.67-78
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• 2024

The introduction of a significant amount of phosphorous into aquatic environments can lead to eutrophication, which can in turn result in algal blooms. For the effective management of watersheds and the prevention of water quality problems related to nonpoint organic matter (OM) sources, it is essential to pinpoint the predominant OM sources. Several potential OM sources were sampled from upper agricultural watersheds, such as fallen leaves, riparian reeds, riparian plants, paddy soil, field soil, riparian soil, cow manure, and swine manure. Stream samples were collected during two storm events, and the concentrations of dissolved organic carbon (DOC) and phosphorous (DOP) from these OM sources and stream samples were assessed. DOM indicators using fluorescence spectroscopy, including HIX, FI, BIX, and EEM-PARAFAC, were evaluated in terms of their relevance in discerning DOM sources during storm events. Representative DOM descriptors were chosen based on specific criteria, such as value ranges and pronounced differences between low and high-flow periods. Consequently, the spectral slope ratio (S_R) paired with fluorescence index (FI) using end-member mixing analysis (EMMA) proved to be suitable for estimating the contribution of organic carbon (OC). The contribution of each organic phosphorous (OP) in stream samples was determined using the phosphorous-to-carbon (P/C) ratio in conjunction with the OC contribution. Notably, OP derived from swine manure in stream samples was found to make the most dominant contribution, ranging from 61.3% to 94.2% (average 78.1% ± 12.7%). The results of this research offer valuable insights into the selection of suitable indicators to recognize various OM sources and highlight the main sources of OP in forested-agricultural watersheds.

• Journal of Korean Society on Water Environment
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• v.34 no.2
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• pp.216-225
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• 2018

Over the past 40 years, the public sector has continued to invest in the sewage treatment plants (STPs) in Korea. Currently, the domestic sewage treatment rate is over 90% with the enhancement of operating efficiency of the STPs, and water quality of major rivers has been continuously improved. However, COD and T-N indicators are stagnating or slightly worsening, and though advanced treatment facilities are installed in most of the STPs, there is a limit to the removal of nutrients. Since there are a lot of water pollution sources in the vicinity of the watershed because of high population density in Korea, it is essential to reduce the inflow of the nutrients in order to prevent the eutrophication of the rivers and lakes. While the effluent T-P standard in STPs has greatly strengthened since 2012, which results in the considerable investment for the improvement of treatment process in STPs for the last few years, it is necessary to strengthen the T-N standards, as the effluent standard of T-N has been maintained at 20 mg/L since 2002. In this study, based on the analysis of the effluent T-N standard status of major industrialized countries, and the domestic nitrogen load in public waters, the option of appropriate T-N standard level is reviewed, and the required investment costs and the effect of strengthening the standard are estimated.

• Korean Journal of Environmental Biology
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• v.23 no.1
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• pp.32-46
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• 2005

The distribution and standing crop of the phytoplankton were investigated at five freshwater lakes Suwon-si and Pyongtaek-si, Gyeonggi-do from Mar. to Nov., 2003. In this investigation, 199 taxa in total were found and classified as 5 phylums 5 classes 16 orders 26 families 72 genera 167 species 1 subspecies 28 varieties and 3 forms by Engler's classification system. The indicator species of clean water was Cladophora glomerata, which was appeared in Gwanggyo reservoir on September, 2003. Twenty taxa including Oscillatoria chlorina were identified as the indicators of water pollution, and three taxa of cyanophyte were toxic algae. In terms of Yang and Dickman's standard of chlorophyll-a content in eutrophication of water, four lakes including Seo lake were found to be in the hypereutrophic state, and Gwanggyo reservoir was in eutrophic state except in winter.