• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.358-368
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• 2011

Responses of plankton populations to nutrient enrichment in mesocosm experiments in Shihwa lake were simulated using FVCOM. Dissoloved oxygen module was added to the FVCOM to simulate impacts of its decreased levels. The ecological model included the major components of the pelagic ecosystem including nutrients, phytoplankton (pico-, nano-, micro-), zooplankton (two groups of protozoa, mesozooplankton), particulate organic matter, dissolved organic matter and bacteria, and was calibrated using trophodynamic data collected from Gyeonggi Bay and Shihwa Lake. The model was able to reproduce major responses of plankton populations to nutrient enrichment, including phytoplankton of different size groups, change of dominance of protozoa from < 20 ${\mu}m$ oligotrichs to scuticociliates, and reponses to bacteria and low levels of dissolved oxygen in water column of the mesocosms.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.651-661
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• 2011

The purpose of this study is to estimate the characteristics and pollutant loadings of non-point pollutants that flowed in the streams on precipitation for pollutant loading reduction of Hwa-sung lake inflow streams. Although it has been made an effort to improve the water quality of Hwa-sung basin through the strategies for the preservation of water quality, it is shown that the water quality is not greatly improved. Because it has been industrialized and urbanized near Hwa-sung basin so that it is difficult to reduce the water pollution due to the increase in pollutant loadings of point and non-point sources. In this study, it is investigated the outflow characteristics of non-point pollutants that discharged with storm runoff and estimated the effect of runoff on Hwa-sung basin. The final goal of this study is to utilize the basic information for proper management and strategies of non-point sources on Hwa-sung basin. At the result of inflow streams, Ja-an stream that has the greatest pollutant loadings on precipitation is strongly influenced on the water quantity of Hwa-sung basin. On the other hand, it is shown that Nam-yang stream is strongly influenced on the SS concentration of Hwasung basin among them. Also, all streams; Nam-yang, Ja-ahn, Ah-eun stream; has the degree of slope more than or near 1 in the correlation results so that they have strong pollutant loading impact and the concentration of SS is the highest among other pollutants. So, specific studies on initial rain phenomena are more necessary to manage the pollutants economically. Also, the proper control of SS concentration is required to manage the effluent pollutants effectively on precipitation. So, it is necessary to consider the strategies for non-point pollutants as well as point pollutants when the new management is imposed to reduce the pollutant load for improvement of Hwa-sung basin.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.243-263
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• 2011

In order to understand the sedimentary environment of the southern intertidal zone of Shihwa Lake, west coast of Gyeonggi-do, 10 surface and 2 core sediment samples were analysed for grain size, water content, AVS (Acid Volatile Sulfide), TOC (Total Organic Carbon), concentrations of metals (Al, Fe, Mn, Cu, As, Pb, Zn, Ni, Cd, and Cr). The surface sediments are generally poorly sorted (0.60~2.31 ${\phi}$) sandy Silt, slightly gravelly muddy Sand, silty Sand, Sand with mean grain size of 2.95 to 6.00 ${\phi}$. The sediments contain Al (1.54%), Fe (1.75%), Cu (9.1ppm), As (1.1ppm), Pb (18.8 ppm), Ni (11.0 ppm), Cd (0.02 ppm), and Cr (30.1 ppm) on the average. Heavy metals are concentrated less than ERL (Effect Range-Low), verified by NOAA (National Oceanic and Atmospheric Administration). In the core sediments, they are also less than the ERL. Based on the uniform vertical distribution of excess radioactivity of $^{210}Pb$, the core sediments seen to have been actively mixed biologically or rapidly deposited after the construction of Shi-Hwa Seawall. The 'enrichment factor' of metals, normalized to Al, shows that the upper sediments of 35 cm in depth are more polluted. infect was significant in 2 core sediment samples in 35 cm below layer.

• Korean Journal of Environmental Biology
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• v.23 no.3 s.59
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• pp.304-314
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• 2005

The occurrence of cyanobacterial bloom in Korean lakes of the summer is generalized. The characteristic of cyanobacterial community was explored. And the developmental stage of cyanobacterial bloom was divided into three phases, 'preparatory phase', 'bloom phase' and 'extinction phase' Cyanobacterial bloom started during the end of June at site 1, transition Bone of Lake Daecheong. The period of water bloom in normal year was about 60~70 days at site 4, lacustrine Bone, but it was unusually 11 days from July 19 in 1999. M. aerugilnosa first occurred in June, had a peak of standing crop curve from the end of August to the beginning of September in 1998 and 2002 and the end of July in 1999 and 2001. The standing crop of M. aeruginosa occupied $68.1\%$ of phytoplankton, $74.2\%$ of cyanobacteria and $88.8\%$ of genus Microcystis, Anabaena spp. first occurred in April, was above 10,000 cells $mL^{-1}$ from the end of August to about the middle of September in 1998. The effect of rainfalls on cyanobacterial bloom was different according to the phases. The rainfalls of preparatory phase assist the growth of cyanobacteria, but accelerate the decrease of cyanobacteria in extinction phase. In bloom phase, the heavy rainfalls reduce the development of the bloom, while the slight ones display only a little effects.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.116-127
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• 2013

At weekly intervals, we monitored continuous changes in water quality by constructed floating wetland equipped with the four different filter media (sponge, volcanic stone, activated carbon and magnesium hydroxide) in a eutrophic lake from March 2011 to May 2012. We also investigated phyto- and zooplankton communities both in the influent and the effluent water through the floating wetland. Over a 10-month time period, average turbidity (66%), suspended solids (79%) and chlorophyll-a (80%) concentrations were remarkably reduced in the effluent water compared to the influent (P<0.001). The average removal rates of $NO_2-N$ and $NH_3-N$ were 24% and 20%, respectively (P<0.05). The average removal rates of $NO_3-N$ and TN were less than 10% (P>0.05). On the other hand, the average removal rates of $PO_4-P$ and TP were more than 65% (P<0.01). Interestingly, the abundance of phytoplankton in the effluent was decreased about 2.6 times compared to that of the influent, whereas the abundance of zooplankton in the effluent was increased about 3.5 times compared to that of the influent. Overall, particulate matters (SS, Chl-a and TP) and dissolved nutrients ($NO_2-N$, $NH_3-N$ and $PO_4-P$) were particularly reduced at high rates. Therefore, application of our constructed floating wetland in a eutrophic lake improved the water quality and demonstrated a potential for algal bloom mitigation.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.150-160
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• 2003

This study was carried out to assess inhibitory effects of light-blocking on water quality and phytoplankton community in Lake Juam from August to November 2000. The values of water temperature, DO, TN, $NO_3-N$, $NH_4-N$, TP, DIP, COD, SS and PH did not show clear differences between inside and outside light-blocked areas. Concentrations of Chl-a decreased -6.6${\sim}$40% (mean 14.7%) from inside of the light-blocked area by light blocking. During the study, 55 species of phytoplankton were indentified, and the dominant species were Microcystis aeruginosa, Aulacoseira granulata, Peridinium sp., Synedra spp., Oscillatoria sp., Fragilaria construens, and Trachelomonas sp. The successional pattern of dominant phytoplankton was diatoms (July)${\to}$ diatoms/cyanophytes (August-September)${\to}$cyanophytes (October)${\to}$ diatoms (October-November). The standing crop of phytoplankton showed maximum density in 22 September with $1.1{\times}10^4$cells/L, and minimum in 25 October with $4.7{\times}10^3$ cells/L. The decreasing efficiency of standing crop by light-blocking was 8${\sim}$38% (mean 19.9%). Through this study we found that blocking light seems to have a decreasing effect on the density of phytoplankton.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.19-25
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• 2009

The effects of artificial floating island on the changes in phytoplankton and zooplankton community structure were investigated monthly from September 2006 to May 2007 in Shingu reservoir. The total cell number of phytoplankton under the artificial floating island was three times less than those of control (without artificial floating island). The dominant species of phytoplankton were Lyngbya sp. on September, Cryptomonas sp. from October to January, Aulacoseira granulata on February and Oscillatoria sp. from March to May at lake water. Cyanophyta was dominated from February to March at lake water but it was dominated from March at artificial floating island area. The total individual number, species number of zooplankton and species diversity of phytoplankton and zooplankton under the artificial floating island were higher than those of lake water.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.161-171
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• 2009

A 'continuous removal of organic matters (CROM) system' using a native freshwater bivalve in Korea Anodonta woordiana, was developed to determine its potential of controlling various sestons in eutrophic lake system, and to evaluate its effect on water quality improvement under consideration of sediment addition as habitat. We designed CROM experiments with four treatments: no mussels and no sediment (W, negative control), no mussels and sediment (WS, positive control), mussels and no sediment (WM), and mussels and sediment (WMS). The experiments were performed at the condition of 18${\sim}$25 L $h^{-1}$ of inflow, mussel density of 486.1 indiv. $m^{-2}$, and temperatures between 15 and $22^{\circ}C$ for 13 consecutive days. Physicochemical and biological parameters were measured at daily (10:00 am) intervals after the mussel addition. Results indicated that mussel stockings without addition of sediment effectively removed sestons (suspended solids and chlorophyll-a) at nearly same level over 80 percentage of the control during the study, while there were no differences in removal activities of sestons between with and without sediment (P>0.5). Therefore, it clearly suggests that CROM system using A. woordiana has a strong potential to control the seston in surface water of eutrophic lake.

• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.105-114
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• 2019

The objective of this study was to investigate the pollution assessment of organic matters, nutrients, and metals in sediment in major lakes (5 lakes and 17 sites) of Buk-han river using various sediment pollution assessment guidelines and indices. The concentrations of organic matters and nutrients were lower than class IV (Sediment pollution assessment guidelines of Korea) and Severe Effect Level (SEL, Sediment pollution assessment guidelines of Ontario). This results indicated that the lakes sediments were unpolluted and tolerable level for sediment dwelling organisms by organic matters and nutrients. However, several sites of Chuncheon and Soyang lakes were evaluated "heavily polluted" level by organic index (Org-index). The order of lakes by metals concentrations from the one with the highest concentration was Hwacheon, Chuncheon, Cheongpyeong, Uiam, Soyang. All lakes except Hwacheon were assessed unpolluted to marginally and tolerable level for sediment dwelling organisms by metals based on sediment pollution assessment guidelines (Korean and Ontario), indices of geoaccumulation ($I_{geo}$), pollution loading (PLI) and ecological risk (RI). In Lake Hwacheon, every investigated sites were polluted with metals, especially Hg, based on sediment pollution assessment guideline of Korea and indices ($I_{geo}$, PLI and RI). The dwelling organisms in sediment of Hwacheon Lake were likely to be severed by metals.

• Analytical Science and Technology
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• v.14 no.2
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• pp.140-146
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• 2001

The study was carried out to analyze the pollutants, Fe, Cu, Cr, Zn, Cd for 3 sediments of 5 sites collected from lake in K river basin. 5cm sediment, which is nearly proximated to water from sediment of depth 30cm, showed higher Fe, Cu, Cr, Zn, Cd data than another 5-10cm and 10cm sediment, which is separated from sediment of depth 30cm. Also, 5cm sediment nearly proximated to water showed the following data: Fe, 34.9-39.8mg/L, Cu, 34.5-44.8mg/L, Cr, 68.0-79.2mg/L, Zn, 147.4-126.0mg/L, Cd, 2.2-1.0mg/L, respectively. From this results, we know the fact that the pollution degree of sediment has an effect on the water quality in like and stream.