• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1093-1097
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• 2006

하천수계는 여러 인자들의 상호작용을 통하여 변화하게 되며, 하천 자정능력에 관한 연구는 이를 중심으로 진행되어 왔다. 여러 환경 요인 중 하상재료는 하천의 조도와 수생태계의 특성을 변화시키게 되며, 유입수의 성상에 따라 수저퇴적물이 쌓이거나, 생물막이 형성되는 매개체 역할을 하게 된다. 특히, 하천의 폭이 좁고 수심이 얕은 개울에서는 하상 퇴적물이 수질에 기여하는 영향이 큰 것으로 알려져 있다. 국내하천의 경우 하상재료가 주로 모래와 자갈이 주를 이루고 있으며, 수심이 낮아 빛의 투과성이 양호하여 부착조류의 증식 및 하상재료(모래 및 자갈 등)를 기질로 한 생물막 형성 등 하상재료는 하천환경의 변화 및 수질변화가 일어나는데 상당한 기여를 하는 것으로 보고되고 있다. 본 연구에서는 하천의 하상재료가 설치된 수로를 이용하여 이화학적요소를 조사, 분석함으로써 하상재료를 통한 수질변화 특성을 비교.검토 하였다. 그 결과 하상재료의 입경이 클수록 DO 변화가 더 큰 폭으로 증가 하였으며, 수위와 유속의 경우 수위가 낮으면서 유속이 적정수준일 경우 DO 증가가 나타나는 것으로 관측되었다. 하천수가 수로에 의해 순환되면서 유기물 저감속도의 측정결과 초기 흡착, 침전 등의 물리적 작용이 부착조류 증식 등의 생물학적 작용보다 우선되면서 입자성 유기탄소(POC)의 제거속도가 용존성 유기탄소(DOC) 의 경우보다 더 빠르고 우선되는 것으로 조사되었다. 영양염류의 경우 부착성조류에 의한 질소 제거능은 실제 질산화작용은 활발히 이루어졌으나 탈질작용에 의한 총질소의 제거는 미비한 것으로 나타났으며, 총인은 입자성유기탄소가 제거되는 것과 유사한 경향을 나타내 제거 기작이 대부분 흡착, 침전에 의한 물리적 자정 작용에 기인한 것으로 조사되었다. 또한 하상재료 입경 변화에 따른 수질변화 특성은 기질(하상재료)의 입경이 작을수록 오염물질의 분해능이 큰 것으로 나타났다. 이와 같이 여러 하천환경 요인 중 하상재료에 의한 하천환경의 다양한 변화는 수질변화 및 자정능력에 큰 영향을 미치게 된다.

• Journal of Korea Water Resources Association
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• v.38 no.3 s.152
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• pp.235-244
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• 2005

This study was carried out in Osan river to quantitatively investigate behavior of attacked microbial community (AMC) for enhancing self-purification process of river. We gained the results such as follows throughout long-term monitoring at in-situ river. The biomass of AMC had higher in the riffle than the almost stagnant pool and they were more developed in the riffle with high current velocity (HCV). Although the fast flowing current affects negatively to growth of the AMC during the early phase when the community gets attached to the benthic substrate, it was observed that it affected positively to their growth during the intermediate and later phase after the community is adapted to the substrate. When turbulence due to external pressure (storm or discharge of dam and reservoir) occurs, the degree of separation depends upon the flowing strength and the type of the external pressure. Since the community is not all separated, recovery is rather fast. Therefore, this study found that the degree of reduction of the pollutant by self-purification of the stream is depended upon the riverbed shape and the AMC contributes to self-purification positively or negatively in river. Therefore, the riverbed shape must be constructed in accordance with the characteristics of water quality in stream. Furthermore, the technique of installing the water channel structure appropriate for each section must be developed to maximize self-purification ability.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.24-38
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• 2021

Microhabitat In the upper stream is created by various environment variables such as the bottom substrate and the physicochemical factors, and may influence the distribution of benthic macroinvertebrates. We investigated the bottom substrate and environmental variables influencing the distribution of benthic macroinvertebrate in 26 stream-type waterways established at upper reaches of Geum River. During study period, total 85 families, 160 species, 9305 individuals of benthic macroinvertebrates were recorded. The stream-type waterways, where the bottom substrates consist mainly of pebble (16~64 mm) and cobble (64~256 mm) or with rapid water velocity (more than 0.2 m/s) and high dissolved oxygen (more than 120%), were supported by high species diversity of benthic macroinvertebrate. Hierological cluster analysis and the nonparametric multidimensional scale (NMDS) divided 26 stream-type waterways into a total of three clusters. In Cluster 1, the invertebrate species, such as Branchiura sowerbyi, Cloeon dipterum, Ischnura asiatica, Paracercion calamorum, and Radix auricularia, closely related to aquatic macrophytes, and Chironomidae spp., Limnodrilus gotoi, and Tanypodinae sp. were abundant in waterways, with high coverage of silt and clay as well as high turbidity and total nitrogen. The benthic macroinvertebrate species (Cheumatopsyche brevilineata, Drunella ishiyamana, Dugesia japonica, Ephemera orientalis, Gumaga KUa, Macrostemum radiatum, Potamanthus formosus, Semisulcospira libertine, Stenelmis vulgaris, and Teloganopsis punctisetae) included in Cluster 2 were dominated in sites with high cover rates of pebble and gravel. Cluster 3 was predominantly covered by the Cobbles, was supported by Simulium sp. Such a clear distinction in the study sites means that each stream-type waterways is governed by a clear habitat environment. In the case of some sites with low species diversity, improvement measures are required to restore nature, such as improving the function of inflows and outflows, creating meandering channel, and inducing the settlement of littoral vegetation.

• Journal of Korean Society on Water Environment
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• v.39 no.4
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• pp.261-268
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• 2023

The benthic macroinvertebrates index (BMI) was developed based on the 5-day biochemical oxygen demand (BOD₅), which is the amount of biodegradable organic matter in stream water. However, benthic macroinvertebrates mainly live in the streambed substrate and are affected by the interaction of water quality and substrate. This study was conducted to examine the interactive relationship between water quality items (BOD₅, total phosphorus (TP), total suspended solids (TSS)) and substrate with BMI by performing statistical analyses (four-way analysis of variance, Pearson's correlation analysis, partial correlation analysis and multiple regression analysis). The data used in the analyses were collected from 19,915 sampling units at 1,937 sites in South Korea from 2010 to 2020. The interaction effect between BOD₅ and substrate types was confirmed through a four-way analysis of variance. Partial correlation analysis and multiple regression analysis estimated the degree of influence on the change in BMI value in the order of mean grain size of the substrate as (𝜱_m) > BOD₅ > TP > TSS. BMI can be regarded as an index that evaluates the comprehensive effects of water quality and streambed status, although it is an index that was developed based on the amount of biodegradable organic matter in a water column.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.212-220
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• 2009

In this study, we analyzed fish compositions and ecological characteristics such as trophic guilds and tolerance guilds in association with water quality characteristics in Masan Reservoir during November 2008. Total number of species were 12 species (6 families) and the dominant species were Zacco platypus, Hemiculter eigenmanni, and Pseudorasbora parva. We found three Korean endemic species and one exotic species, Carassius cuvieri. According to the analysis of ecological indicator characteristics, relative proportion of tolerant and omnivore species was 98% of the total indicating that probably, the fauna was influenced by physical habitat disturbance and physicochemical degradations. Fish distribution analysis along with littoral zone showed that the most fishes (${\sim}$95%) were observed in the littoral zone where emerged macrophytes were well developed. Also, substrate analysis indicated that the most species were found near silt area (11 species, 91.7%), so that the significant differences were found between the substrate types. Analysis of water quality indicated that concentrations of total phosphorus (TP) and chlorophyll-a (ChI-a) as a lake trophic indicator were judged as eutrophic states, respectively and COD as an indicator of organic matter pollution averaged 10.9 mg $L^{-1}$. Based on the water quality, this system were influenced by the nutrient enrichments and organic matter. The degradations of water quality in Masan Reservoir resulted in trophic compositions of fish (increase of omnivore species) and the dominance of tolerant fish. This Monitoring data may contribute changes of fish fauna and compositions in relation to habitat modifications and chemical water quality degradations in the future.

• Journal of Korea Water Resources Association
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• v.52 no.11
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• pp.917-929
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• 2019

Denitrification in streams is of great importance because it is essential for amelioration of water quality and accurate estimation of $N_2O$ budgets. Denitrification is a major biological source or sink of $N_2O$, an important greenhouse gas, which is a multi-step respiratory process that converts nitrate ($NO_3{^-}$) to gaseous forms of nitrogen ($N_2$ or $N_2O$). In aquatic ecosystems, the complex interactions of water flooding condition, substrate supply, hydrodynamic and biogeochemical properties modulate the extent of multi-step reactions required for $N_2O$ flux. Although water flow in streambed and residence time affect reaction output, effects of a complex interaction of hydrodynamic, geomorphology and biogeochemical controls on the magnitude of denitrification in streams are still illusive. In this work, we built a two-dimensional water flow channel and measured $N_2O$ flux from channel sediment with different bed geomorphology by using static closed chambers. Two independent experiments were conducted with identical flume and geomorphology but sediment with differences in dissolved organic carbon (DOC). The experiment flume was a circulation channel through which the effluent flows back, and the size of it was $37m{\times}1.2m{\times}1m$. Five days before the experiment began, urea fertilizer (46% N) was added to sediment with the rate of $0.5kg\;N/m^2$. A sand dune (1 m length and 0.15 m height) was made at the middle of channel to simulate variations in microtopography. In high- DOC experiment, $N_2O$ flux increases in the direction of flow, while the highest flux ($14.6{\pm}8.40{\mu}g\;N_2O-N/m^2\;hr$) was measured in the slope on the back side of the sand dune. followed by decreases afterward. In contrast, low DOC sediment did not show the geomorphological variations. We found that even though topographic variation influenced $N_2O$ flux and chemical properties, this effect is highly constrained by carbon availability.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.10-18
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• 2022

This study analyzed the relationship between the community structure of benthic macroinvertebrates and habitat changes in open estuaries among the sites included in the national estuary monitoring program. The estuary survey was conducted under the "Guidelines for Investigation and Evaluation of Biometric Networks" and classified by sea area, 80 places in the East Sea, 102 places in the South Sea, and 19 places in the West Sea were investigated. In a total of 201 open estuaries, benthic macroinvertebrates were identified with 4 phyla, 9 classes, 41 orders, 139 families, 269 species and 196 species in the East Sea, 182 species in the South Sea, and 90 species in the West Sea. The highest population densities were Insecta in the East Sea, the Malacostraca in the South Sea, and the Annelida in the West Sea. Through SIMPER analysis, species contributing to the similarity of benthic macroinvertebrates communities in each sea area were identified. Some species greatly influenced the similarity of clusters. The benthic community in the East Sea was affected by the salinity, so the contribution rate of freshwater species was high. On the other hand, the benthic communities of the South and West Seas showed species compositions are influenced by the substrate composition. As results, the benthic macroinvertebrate community in Korean estuaries was impacted by salinity and substrate simultaneously, and the close relationship with geographical distance was not observed. The result of this study is expected to be used to respond to environmental changes by identifying and predicting changes in the diversity and distribution of benthic macroinvertebrates in Korea estuaries.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.841-846
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• 2011

This study was conducted to obtain the information about injury caused by continuous cropping of peony (Paeonia lactiflora). Soil physico-chemical properties, characteristics of microbial distribution and diversities in the continuous cropped field with peony were analyzed. As the results, pH and organic matter content were higher in the continuous cropping soil than those in the first cropping soil. Bulk density was decreased but porosity was increased in the continuous cropping soil. As the cultivation period was lengthened in years, the populations of bacteria and actinomyces were gradually decreased, whereas fungal population was increased. It was shown that the metabolic diversity patterns of the microbial communities in the continuous cropping soil differed from that of the first cropping soil. These results indicate that deterioration of soil quality such as physico-chemical properties including a soil depth, bulk density, porosity and soil pH is related with a continuous cultivation periods, and also affect a microbial population, especially fungi.

• Korean Journal of Ichthyology
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• v.27 no.4
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• pp.300-305
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• 2015

The characteristics of 11 spawning sites in the natural environment of the Korean endemic species, Liobagrus somjinensis were investigated in the Yocheon (stream) of Seomjingang (river), located in Sikjeong-dong, Namwon-si, Jeollabuk-do, Korea from May to June 2015. The spawning sites had largely two parts, the upper region close to the surface of the waters and under region at bottom: the upper part was covered with a large and flat boulder over about 256 mm in size, whereas the under part consisted mainly of pebbles and sand. The large boulder put on the upper region may be seen as a bulwark for guarding eggs laid at the under (bottom) region. All the sites under the boulder showed a similar structure having a small hollow filled with an egg mass and an individual (male). The spawning bottoms left clean having no any benthic invertebrates and detritus. The egg shape was spherical, yellow and covered with a transparent membrane and the egg size was $3.31{\pm}0.15mm$ (n=30) in diameter. The development stage of each egg mass under the boulder was almost same from morula stage to formation stage of eye lens. The average number of eggs in 11 spawning sites was $121{\pm}35.5$ (84~176) and the average number of female fecundity in ovary was $143{\pm}31.3$ (110~232).

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.484-484
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• 2022

서식지적합도지수(Habitat Suitability Index, HSI)는 어류의 환경생태유량(Environmental Ecological Flow) 산정과 관련해 국내외에서 PHABSIM (Physical Habitat Simulation System)이나 River2D 모형과 같은 생태수리 모형에 적용되고 있으며, 특히 물리적서식지모의시스템은 흐름특성(유량유속, 수심 등)의 변화에 대한 하도구간 내 대표어종의 물리적 서식지 변화를 예측하여 대상 어종에 대한 가용서식지면적(어류가 살 수 있는 서식지 면적, Weighed Usable Area, WUA)유량 관계를 통해 서식에 필요한 최적 유량을 산정하는 데 목적이 있다. 물리적 서식지적합도지수 산정과 화학적 서식지적합도지수 산정방법은 WDFW (Washington Department of Fish and Wildlife, 2004)방법과 IFASG (Instream Flow and Aquatic Systems Group, 1986)의 방법으로 산정하였다. 섬진강에서 2020년에는 3개지점, 2021년에는 2020년 3개지점과 새로운 3개지점에 대하여 각각 4, 5, 6, 9, 10 및 11월에 어류 조사 및 물리적 조건 등에 대하여 현장 모니터링을 실시하였다. 2차년도 동안 모니터링 결과 섬진강에서는 줄납자루, 섬진자가사리, 참중고기, 참몰개, 잉어, 붕어, 칼납자루, 큰납지리, 누치, 모래무지, 피라미, 치리, 블루길, 배스 14종에 대하여 물리적 및 화학적 HSI를 산정하였다. 주요종의 WDFW 방법에 따른 큰줄납자루는 수심 0.3~0.6 m, 유속 0.1~0.4 m/s, 섬진자가사리는 수심 0.2~0.5 m, 유속 0.3~0.7 m/s, 참중고기는 수심 0.4~0.8 m, 유속 0.1~0.6 m/s, 피라미는 수심 0.3~0.7 m, 유속 0.1~0.5 m/s로 산정되었다. IFASG 방법으로 큰줄납자루는 섬진강에서는 수심 0.64 m에서 최대의 출현도를 보였으며, HSI는 0.46~0.83 m, 유속은 0.59 m/s에서 최대의 출현도를 보였고, HSI는 0.38~0.83 m/s, 하상기질의 선호도는 평균입경(𝚽m) -1.14(grevel)에서 최대의 출현도를 보였으며, HSI -3.35~0.65(grevel~sand)로 산정되었다. 화학적 HSI 산정결과 큰줄납자루는 BOD는 1.0 mg/L에서 최대 출현도를 보였고, HSI는 0.7~1.2 mg/L, T-N은 0.925 mg/L에서 최대 출현도를 보이며 HSI는 0.604~1.277 mg/L, T-P는 0.028 mg/L에서 최대 출현도를 보이며 HSI는 0.021~0.034 mg/L, SS는 3.6 mg/L에서 최대 출현도를 보이며, HSI는 2.1~5.2 mg/L의 범위로 산정되었다. 산정된 범위는 환경부 생활환경기준 BOD 매우좋음(Ia)~좋음(Ib), T-P 매우좋음(Ia)~좋음(Ib) 등급으로 각각 확인되었다. 본 과제는 3차년(2022년)이 아직 남아 있어 HSI에 대하여 약간 보정이 있을 것이며, 최종 HSI가 산정이 되면 향후 환경적 기능을 고려한 중장기 정부 정책의 활용성 높은 기초자료가 될 것이다.