• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.73-84
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• 2006

The objective of this study was to analyze long-term temporal trends of water chemistry and spatial heterogeneity for 10 sampling sites of the Yeongsan River watershed using water quality dataset during 1995 to 2004 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (Do), total phosphorus (TP), total nitrogen (TN) and total suspended solids (TSS), largely varied depending on the sampling sites, seasons and years. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summmer monsoon rain. Conductivity, used as a key indicator for a ionic dilution during rainy season, and nutrients of TN and TP had an inverse function of precipitation (absolute r values> 0.32, P< 0.01, n= 119), whereas BOD and COD had no significant relations(P> 0.05, n= 119) with rainfall. Minimum values in conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of total suspended solids (TSS) occurred during the period of summer monsoon. BOD values varied with seasons and the values was closely associated (r=0.592: P< 0.01) with COD, while variations of TN were had high correlations (r=0.529 : P< 0.01) with TP. Seasonal fluctuations of DO showed that maximum values were in the cold winter season and minimum values were in the summer seasons, indicating an inverse relation with water temperature. The spatial trend analyses of TP, TN, BOD, COD and TSS, except for conductivity, showed that the values were greater in the mid-river reach than in the headwater and down-river reaches. Conductivity was greater in the down-river sites than any other sites. Overall data of BOD, COD, and nutrients (TN, TP) showed that water quality was worst in the Site 4, compared to those of others sites. This was due to continuous effluents from the wastewater treatment plants within the urban area of Gwangju city. Based on the overall dataset, efficient water quality management is required in the urban area for better water quality.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2005.12a
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• pp.130-130
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• 2005

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.294-297
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• 2007

유기유기물 증가원인의 파악과 근본적인 대책에 대한 연구의 일환으로 부영양화된 연안해역에 대하여 태풍 발생 전후의 수질변동에 대하여 조사하였다. 그 결과를 요약하면 다음과 같다. 1) 용존산소 포화도는 수온과 염분 약층이 형성된 시기에 저층에서 54% 이하로 관측되었다. 태풍이 지나간 직후에는 표층과 저층에서 거의 비슷한 용존산소 포화도$(78{\sim}88%)$가 조사되었다. 그리고, 태풍이 지나간 3일 후 식물플랑크톤이 대량으로 증식한 표층에서 용존산소 포화도가 234%로 아주 높은 값이 관측되었고, 저층(5m)에서도 90%가 조사되어, 태풍과 식물플랑크톤의 이상 증식이 저층의 용존산소 포화도를 높이는 작용을 한 것으로 보인다. 2) 염분이 가장 낮았던 시기에 표층에서 $NA_4-N$, $NO_3-N$, $SiO_2-Si$의 농도가 각각 18.22, 38.90, 52.10uM로 아주 높게 조사되었으며, $NH4-N$, $PO_4-P$, $SiO_2-Si$는 용존산소가 낮은 저층에서도 높게 나타났다. 3) 클로로필은 최고 $311.0{\mu}g/L$가 태풍 후에 관측되었으며, 그 원인 생물은 Scrippsiella trochoidea (42,000cells/mL)였다. 조류성장잠재능력은 태풍발생 후에 아주 높게 조사되었으며, 항상 질소가 부족한 것으로 조사되었다. 4) 화학적 산소요구량은 최고 10.55 mg/L였으며, 태풍으로 저층 퇴적물로부터 부유되는 유기 오탁 물질이 화학적 산소요구량 증가에 미치는 기여도는 크지 않은 것으로 보이며, 화학적 산소요구량 증가의 대부분이 식물플랑크톤의 증식에 기인한 것($r^2=0.612$, p<0.0001)으로 조사되었다.

• Environmental engineer
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• v.23 s.244
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• pp.56-60
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• 2006

최근 수질환경보전법의 개정법률(안)에 의거하여 폐 · 하수종말처리장에 수온, pH, 생물학적산소요구량(BOD), 화학적산소요구량(COD), 총질소(TN), 총인(TP) 및 부유물질(SS)의 자동으로 측정할 수 있는 수질 자동측정기의 부착이 의무화될 예정에 있다. 그러나, 현재 전국적으로 화학적산소요구량 측정장비와 같이 일부 항목에 대한 자동측정장치는 설치 · 운영 중인 곳이 많이 있으나, 수질 TMS 설치 규정에 나와 있는 전 항목을 측정할 수 있는 장비가 설치되어 운영하는 곳은 극히 일부에 불과한 실정이다. 따라서, 수온, ph, 화학적 산소요구량(COD), 총질소(TN), 총인(TP), 부유물질(SS) 자동측정 장치를 설치하고, 무선통신(CDMA)방식을 이용하여 ‘방류수 수질 원격감시체계(TMS) 시범 운영'을 통하여, 측정 장비들에 대한 자료의 정확성, 신뢰성을 파악하여 설치된 장비들에 대한 성능을 사전에 평가하고, 수질 TMS 시스템에 대한 현장 적응 능력 및 안정성을 파악하여 실질적으로 운영되는 시점에 좀 더 정확하고 실용적인 시스템의 적용하고자 한다.

• The Korean Journal of Ecology
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• v.27 no.6 s.122
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• pp.375-381
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• 2004

We investigate the biological treatment of processed-leachate from SUDOKWON landfill site in Korea by the reed (Phragmites australis)-bed with a continuous flow system. The reed individuals showing superior growth in processed-leachate experiment were selected among the reeds of thirteen natural habitats by means of the comparisons between the removal rates of nutrient salts, eco-physiological responses and growth. The reed-beds (combination of the reed individuals showing superior growth with helper microorganisms) were continuously supplied with processed-leachate. We monitored the effluents that passing through the reed-beds during the experiment period. After five weeks, analysis results of effluent from each reed-bed were as follows; chromaticity, total nitrogen, total phosphorus, biological oxygen demand, chemical oxygen demand, total dissolved solid and salinity decreased $29.5{\sim}36.9\%,\;49.4{\sim}67.2\%,\;42.1{\sim}94.6\%,\;74.5{\sim}88.8\%,\;15.6{\sim}20.8\%,\;17.5{\sim}35.4\%\;and\;15.3{\sim}34.7\%$, respectively. These results represented the substantial improvement of water-quality after passing through reed-bed in a continuous flow system.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1037-1051
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• 2021

Biochemical oxygen demand (BOD) concentration, one of important water quality indicators, is treated as the measuring item for the ecological chapter in lakes and rivers. This investigation employed novel two-stage hybrid paradigm (i.e., wavelet-based gated recurrent unit, wavelet-based generalized regression neural networks, and wavelet-based random forests) to predict BOD concentration in the Dosan and Hwangji stations, South Korea. These models were assessed with the corresponding independent models (i.e., gated recurrent unit, generalized regression neural networks, and random forests). Diverse water quality and quantity indicators were implemented for developing independent and two-stage hybrid models based on several input combinations (i.e., Divisions 1-5). The addressed models were evaluated using three statistical indices including the root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), and correlation coefficient (CC). It can be found from results that the two-stage hybrid models cannot always enhance the predictive precision of independent models confidently. Results showed that the DWT-RF5 (RMSE = 0.108 mg/L) model provided more accurate prediction of BOD concentration compared to other optimal models in Dosan station, and the DWT-GRNN4 (RMSE = 0.132 mg/L) model was the best for predicting BOD concentration in Hwangji station, South Korea.

• Journal of Aquaculture
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• v.13 no.1
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• pp.87-99
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• 2000

Field survey on the variational characteristics of water quality and chlorophyll a concentraion were carried out at the 25 stations for four seasons in Kogum-sudo(Straits) southern coast of Korean Peninsula from Feburuary to October in 1993. We made an analysis on biological factor as chlorophyll a concentraion as well as physicio-chemical factors such as water temperature salinity sigma-t transparency dissolved oxygen(DO) chemical oxygen demand(COD) nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and suspended solid(SS). The waters in the Kogum-sudo were not stratified due to the tidal mixing. And the high productivity in photic layer were supported by high nutrients concentration from bottom waters. The high concen-trations of suspended solid in straits had a bad influence upon marine biology of nature and cultivations. In Kogum-sudo had a sufficient nutrients for primary productivity during a year. Especially phosphate and inorganic nitrogen were high the other side silicate was very low. The source of nutrients supply depend on rather mineralization of organic matters and input of seawater from outside than input of freshwaters from lands. Phytoplankton biomass as measured by chlorphyll a concentratiion was very high all the year round and it was controlled by the combination o f several environmental factors especially of phosphate in summer and dissolved nitrogen in other seasons.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.479-480
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• 2006

폐수의 부하량 감소를 위하여 전처리단계에서 전기응집장치를 이용한 총인 및 총질소, 생물화학적산소요구량과 화학적 산소요구량 등을 측정하고자 실험을 하였다. 실험결과 철 전극에서는 총인제거효율이 가장 높았으며, 총질소 제거 효율은 두 회사 폐수 모두 낮았다. Sus 및 Ti전극에서는 제거효율이 미미하였다. 따라서 부하량 감소를 위한 폐수의 전처리시 철전극사용시 가장효율이 좋으며, 부하량 감소는 90%이상임을 알 수 있었다.

• Journal of Life Science
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• v.22 no.10
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• pp.1286-1294
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• 2012

Biological assessments of the macrobenthos community were carried out in the Seomjin River from May 2009 to November 2010. Fishes from 106 species belonging to 24 families and 10 orders were collected from the survey sites. Locational dominant species differed among sites, and the numbers of species and individuals differed depending on site, although six sites were not significantly different on the same survey dates. Across sites, the average number of species was 38.3, ranging from five at site 1 to 66 at site 2 in May 2009. Site 2 had the highest number of species on November 2009, while site 3 had the lowest. Arthropods dominated the macrobenthic community at species (63.2% May) and individual (60.9% November) levels. DO, BOD, and COD were shown to have the greatest effect on the numbers of macrobenthos. Peaks in the diversity index trended downwards from upstream to downstream sites.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.117-123
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• 2006

The water quality before and after a typhoon was investigated as a part of a study on the increase of organic matter and on the fundamental measures to counter chemical oxygen demand (COD) in the eutrophic Soho coastal seawaters of Gamak Bay. The dissolved oxygen (DO) saturations were <54% when water column was stratified. The DO saturation was similar at surface and in the bottom layer after a typhoon $(78\sim88%)$, and a very high DO saturation (234%) was observed in the surface water after mass phytoplankton growth. The highest values of $NH_4-N,\;NO_3-N,\;PO_4-P$, and $SiO_2-Si$ were 18.22, 38.90, 1.58, and $52.10{\mu}M$, respectively, when freshwater entered after heavy rainfall events. In addition, high concentrations of $NH_4-N,\;PO_4-P$, and $SiO_2-Si$ were detected with low DO saturations in bottom water (>5m). A maximum chlorophyll (Chl.) concentration of $311.0{\mu}gl^{-1}$ was observed after typhoon, when a high-density Scrippsiella trochoidea red tide occurred with cell density of 42,000 cells $ml^{-1}$. The algal growth potential (AGP) was high after the typhoon. Nitrogen was always a limiting nutrient for phytoplankton growth. The highest COD level was $10.55mgl^{-1}$, and the main reason of the variation in COD was likely to be phytoplankton growth $(r^2=0.612,\;p=0.000)$. Organic matter, which entered the water column when the typhoon stirred the sediments, seems to have little effects on COD increase.