• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.420-431
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• 2010

Simple material budget models were developed to predict the dry season water quality for a river-type reservoir in Paldang, Republic of Korea. Of specific interest were the total phosphorus (TP), chlorophyll ${\alpha}$ (Chl. ${\alpha}$), 5-day biochemical oxygen demand (BOD), and chemical oxygen demand (COD). The models fit quite well with field data collected for 20 years and have enabled the identification of the origins of organic materials in the reservoir. The critical hydraulic load that determines the usability of phosphorus for algal production appeared to be about $1.5m\;d^{-1}$. When a hydraulic load was smaller than the critical value, the concentrations of $Chl.{\alpha}$, COD, and BOD in the reservoir water became sensitive to internal algal reactions such as growth, degradation, and settling. In spite of the recent intensive efforts for organic pollutant removal from major point sources by central and local governments, the water quality in the reservoir had not been improved. Instead, the concentration of COD increased. The model analysis indicated that this finding could be attributed to the continuing increase of the algal production in the reservoir and the allochthonous load from non-point sources. In particular, the concentrations of COD and BOD of algal origin during 2000~2007, each of which is comprised of approximately one half of the total, were approximately 2.5 times higher than those observed during 1988~1994 and approximately 1.3 times higher than those between 1995~1999. The results of this study suggested that it is necessary to reduce the algal bloom so as to improve the water quality of the reservoir.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.109-113
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• 1998

The clay and yellow loess have capability to adsorb and precipitate particles. The removal efficiencyes of those flocculents on the dinoflagellate, Cochlodinium polykrikoides, have been studied in laboratory and in field near Tongyong fish farm in September, 1996. The removal efficiencyes in the laboratory experiment was $43\%$ for $2\;g/{\ell}$, $64\%$ for $6g/{\ell}$ and $88\%$ for $10\;g/{\ell}$ in one hour after dispersion. No big difference of removal efficiency was found between the raw and the acid-activated loess. In the field survey, the removal rates ranged from 72 to $80\%$ in 30 min after the dispersion. The effect of loess scattering on water quality was estimated. The concentrations of dissolved inorganic nitrogen (DIN), chemical of gen demand (COD) and chlorophyll a decreased more or less after dispersion, while the concentration of suspended solid (SS) increased. The concentrations of dissolved oxygen (DO) and dissolved inorganic phosphorous (DIP) were kept constant. These results indicated that the dispersion concentration of more than $10g/{\ell}$ has a good removal efficiency of above $80\%$ without big variation of water quality after dispersion of yellow loess.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.1-8
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• 2019

The purpose of this study is to evaluate the nutritional status of Lake Jinyang using Landsat 8 satellite image band correlated with chlorophyll-a, which is also related to algae proliferation. We selected 20 Landsat 8 images dating from 2013 to 2017, taken close to water quality measurement date when the cloud cover was less than 20 %. Based on the results of the previous studies, analyzing the correlation between chlorophyll-a, and Landsat 8 satellite image band, we selected near infrared wavelength, band 5 which is closely related to the population of algae. The nutritional status was classified using the Aizaki trophic state index (TSIm). The results of the regression equation between band 5 and the observed chlorophyll-a data was used to calculate chlorophyll-a for the image data from 2013 to 2017. The concentration of chlorophyll-a ranged from 3 to $16.1mg/m^3$. To illustrate the spatial distribution of chlorophyll-a within the lake, the chlorophyll-a concentration was divided into five grades. The images on October 14, 2014 and April 10, 2016 showed relatively high value of chlorophyll-a, while January 18, 2015 and December 6, 2016 chlorophyll-a value were below 5. The images on October 14, 2014 and April 10, 2016 were rated as eutrophic status in most areas. The results of simulating water quality for the day when the water quality was not measured resulted to an approximate value for the Panmun station while the Naedong station needed some corrections.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.1
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• pp.8-18
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• 2003

In order to investigate the oceanic condition of fishing ground in the adjacent sea of Naro Island, the oceanographic observation were carried out by the training vessel of Yosu National University on winter, spring, summer, and autumn in 2000. Main features in the observation are as follows; 1) the ranges of temperature, salinity, and chlorophyll-a were from 4.$3\circ_C$ to 10.$1\circ_C$, from 33.1 psu to 34.9 psu, and from 0.1 $ug$/$\Omega$ to 26.2 $ug$/$\Omega$ in winter, from 8.$1\circ_C$ to 13.$7\circ_C$, from 33.1 psu to 34.3 psu, and from 0.1 $ug$/$\Omega$ to 24.4 $ug$/$\Omega$ in spring, from 14.$5\circ_C$ to 24.$2\circ_C$, from 30.5 psu to 34.1 psu, and from 0.1 $ug$/$\Omega$ to 30.0 $ug$/$\Omega$ in summer, and from 14.$8\circ_C$ to 18.$6\circ_C$, from 30.1 psu to 34.0 psu, and from 0.1 $ug$/$\Omega$ to 19.1 $ug$/$\Omega$ in autumn, respectively, 2) the temperature in the coastal region was higher than that in the open ocean while salinity was lower, and the convection was identified between the surface and the bottom during in winter and autumn, and the thermocline were made between surface and 20m layer with vertical gradients of 4.$0\circ_C$/7m in summer, 3) the chlorophyll-a in the this region was varied in each season, being highly distributed in spring, on bottom and coastal region, and 4) an evidence of sea water intrusion toward Sori Island was observed, and of inner water intrusion from Yeoja Bay was observed.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.213-213
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• 2020

최근 나타나는 지구온난화와 이상기후로 인해 가뭄과 홍수피해 같은 자연재해 발생 빈도가 높아졌고, 하천에서는 오염된 수질과 수생태계 복원 및 수변공간 조성, 수자원 관리 등의 목적으로 수질환경 개선사업이 진행되고 있다. 수질환경 측면에서 하천에서 발생하는 가장 큰 문제점으로는 녹조 즉, 남조류의 발생을 예로 들 수 있다. 본 연구에서는 최근 보 개방을 통하여 수질개선 효과가 나타나고 있는 금강을 대상으로 세종보, 공주보, 백제보 구간에 대하여 주요 수질인자에 대한 상관관계 분석을 수행하였다. 특히 남조류 세포수와 주요 하천 수질인자를 Pearson's correlation analysis를 이용하여 상관관계를 분석하였고, 보 위치별 남조류 세포수를 종속변수로 하고, 상관도가 높은 수질인자를 독립변수로 하는 다중회귀식을 도출하여 금강 내 주요 하천 수질인자의 농도에 따른 남조류 세포수 관계를 규명하고자 하였다. 분석기간은 2012년 1월부터 2019년 12월까지 보 건설 이후 시점으로 선정하였고, 월 평균 남조류 개체수가 조류경보제 발령기준 관심단계이상에 해당하는 금강수계의 3개 보에 대하여 남조류 세포수와 수질에 영향을 끼치는 인자인 강수량, (수온)W·T, (수소이온농도)pH, (용존산소)DO, (생물화학적산소요구량)BOD, (화학적산소요구량)COD, (부유물질량)SS, (총질소)TN, (총인)TP, (클로로필-a)Chl-a, (전기전도도)EC, (질산성질소)NO₃-N, (암모니아성 질소)NH₃-N, (인산염 인)PO₄-P, (용존총질소)DTN, (용존총인)DTP, (총유기탄소)TOC 와의 상관관계를 분석하였다. 분석 결과 측정 지점별 남조류 세포수와 상관관계가 있는 인자는 서로 상이했지만 (수온)W·T과 pH의 경우 모든 지점에서 남조류 세포수와 양의 상관관계가 나타났다. 세종보는 W·T(0.383, P<0.01), pH(0.391, P<0.05)의 양의 상관계수를 나타냈고, 공주보에서는 (수온)W·T(0.436, P<0.05), pH(0.412, P<0.05)의 양의 상관관계를 나타냈다. 백제보에서는 (수온)W·T(0.415, P<0.01), pH(0.221, P<0.01)의 양의 상관성을 나타냈다. 남조류 세포수와 수질인자 간의 상관관계 분석에 따라 통계적으로 유의한 인자 중 (수온)W·T과 pH에 영향을 받는 영양염류와 퇴적물에 대한 후속 연구가 필요할 것으로 사료되며, 연구를 통해 제시된 남조류 세포수 다중회귀식은 주요 수질인자 농도에 따라 발생 가능한 남조류세포수를 예측하여 금강의 수질 관리에 활용될 수 있을 것으로 기대된다.

• 한국해양학회지
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• v.26 no.1
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• pp.67-76
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• 1991

Masan Bay is infamous for its severe eutrophication, exemplified by frequent red tide incidences and anoxic conditions. We carried out daily observations for 16 days at one site immediately after the summer rainy season in 1988 on the basis that shorter observation intervals be necessary to observe a process with high turnover rate. in spite of the relatively short survey period, we could observe dramatic changes in abundance and composition of the phytoplankton populations. Cell densities and chlorophyll concentrations changed in the magnitude of 70 and 10 times, respectively, Skeletonema costatum, a diatom species, dominated the first peak of phytoplankton biomass and was followed by Prorocentrum minimum, a dinoflagellate species, which occurred dominantly in the second peak after about a week, form the viewpoint of time scale, we suggest that at least a weekly sampling might be appropriate in complex coastal environments as Masan Bay. While stratification enabled high production in the surface layer, it hindered the transport of silicate from bottom to the surface, which in turn limited the prolonged growth of diatoms. Ensued second peaks of silicate and diatom abundance in the surface layer suggest periodic flux of silicate from bottom across the discontinuity driven by tidal currents.

• Journal of Navigation and Port Research
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• v.35 no.3
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• pp.259-263
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• 2011

This study explores ways to improve the actual conditions of ocean environment by conducting a comparative study on the current sea-water quality of Busan Metropolitan City and Incheon Metropolitan City that are representative sea port cities in Korea. The indices used to evaluate the sea-water quality include water temperature, salt content, PH, DO, COD, DIN, T-N, DIP, T-P, Sio2-Si, floating materials, and Chi-a. The findings of the analysis can be summarized as follows: First, ocean environmental states of Busan Metropolitan City and Incheon Metropolitan City are getting increasingly worse between the year of 2000 and 2003. Second, T-N, DIP and T-P have been main contributors in worsening ocean environmental states of Busan Metropolitan City and Incheon Metropolitan City.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.56-63
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• 2010

In order to clarify the ecological properties of phytoplankton community, the distribution of phytoplankton and the relation of water temperature and size-fractionation measurements were studied from November 2004 to August 2005 in Youngsan River, Korea. A total of 265 phytoplankton species was identified. It consists of 48 genera and 123 species (46%) of Chlorophyceae, 27 genera and 89 species (34%) of Bacillariophyceae, 12 genera and 25 species (9%) of Cyanophyceae, respectively. From size fractionation analysis, nanophytoplankton (2~20 ${\mu}m$) dominated from early spring to early summer, and microphytoplankton (20~200 ${\mu}m$) from summer to winter. The relationship between chl-a and nanophytoplankton showed high correlation coefficient value ($r^2$=0.93) from Najudaegyo site. The correlation coefficient values between water temperature and nanophytoplankton were low except Dongkangdaegyo site which showed high value ($r^2$=0.73).

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.325-331
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• 2009

This study was performed to evaluate characteristics of algal occurrence in Lake Paldang. Chlorophyll a concentration was highest during spring, based on weekly measurements from 2006 to 2008, which revealed a different trend compared to the data before 2000 that showed the highest level during summer. Total algae cell quantity was also highest during spring, based on monthly data. Overall, Bacillariophyceae was dominant and represented 87% of total algae cells and occupation was more significant during spring and winter. Cyanophyceae was dominant during summer. 2-MIB and geosmin originating in algae which caused odor problems was high in July 2008, and more research on the relationship between algae and production of odor causing material is needed.

• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.367-376
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• 2008

The seasonality of phytoplankton in Dongbok lake was analysed from March to November 2003. The concentrations of TN and TP showed nearly constant level except high concentrations in May at dam site of Dongbok lake. Chlorophyll ${\alpha}$ concentration was highest at dam site in May with 225.3 ${\mu}g$ L$^{-1}$ and high in spring and fall and low in summer at upper and central regions of Dongbok lake. A total of 108 phytoplankton species was identified as an algal flora of Dongbok lake. They were 54 Chlorophyceae, 30 Bacillariophyceae, 12 Cyanophyceae, and 12 species of other taxa. Total cell biomass of phytoplankton showed peaks in May$\sim$June and August$\sim$September, and low biomass in July at dam site. However, upper and central regions of Dongbok lake showed no clear patterns in cell biomass. Maximum biomass was 7,158 cells mL$^{-1}$ at dam site in May with the blooms of Peridinium bipes f. occulatum. The general seasonality of phytoplankton in Dongbok lake was Bacillariophyceae-Dinophyceae/Bacillariophyceae-Cyanophyceae/Chlorophyceae/Bacillariophyceae-Bacillariophyceae in 2003.