Physicochemical tolerance ranges and ecological characteristics in two different populations of Carassius auratus and Cyprinus carpio

안광국,Seung Gu Kang,최지웅 한국생태학회 2015 Journal of Ecology and Environment Vol.38 No.2

The objectives of this research were to determine mean and maximum tolerance ranges of Carassius auratus (Ca) and Cyprinus carpio (Cc) populations on various physico-chemical parameters and ecological indicator metrics. Little is known about chemical tolerance ranges of the two species, even though these species are widely distributed species in aquatic ecosystems. Maximum tolerance ranges of Ca-population to total nitrogen (TN) and total phosphorus (TP) were 20.3 mg L-1 and 2.0 mg L-1, respectively. Optimal ranges of TN and TP in the Ca-population were 1.7-5.0 mg L-1 and 0.06-0.30 mg L-1, respectively. Such nutrient regimes of the Ca-population were evaluated as hypereutrophy, indicating high tolerance limits. The Cc-population had similar ecological characteristics to Ca-population, but the mean tolerance ranges of TN, TP, BOD, and COD were significantly (p < 0.05) greater than the Ca-population. Ecological patterns of tro¬phic composition and tolerance guilds in the Ca-population were similar to those of the Cc-population. The model value of Index of Biological Integrity (IBI) of the habitat where C. auratus and C. carpio co-occurred averaged 15.0 ± 4.3 and 12.9±3.6, respectively. Based on the modified criteria of the United States Environmental Protection Agency (Klemm et al. 1993), it indicated poor ecological health of both species. These results suggest that both species are highly tolerant to chemical and physical habitat conditions of waterbodies, and that the chemical tolerance range of Cc-population was higher than Ca-population.

준설 점토사면의 변형양상에 관한 원심모델링

안광국,김정열,정소전,이처근 한국지반환경공학회 2007 한국지반환경공학회논문집 Vol.8 No.2

본 연구에서는 준설에 따른 점토사면의 변형 및 변위양상과 파괴형태를 평가하기 위하여 준설사면의 기울기를 변화시키면서 원심모형실험을 실시하였다. 준설사면의 기울기는 1:2, 1:2.5, 1:3으로 변화시키면서 모형실험을 수행하였다. 실험 결과 기울기 1:3인 경우에는 4개월 경과시점까지 사면부내에서 변위는 발생되었지만, 초기단면과 유사하게 사면을 유지하고 있어 준설후 사면 안정성의 확보에는 문제가 없는 것으로 평가되었다. 준설사면 기울기가 1:2.5인 경우에는 4개월 경과시점에서 사면부내에서 국부적인 사면파괴가 발생하였으며, 기울기가 1:2인 사면의 경우 경과시간 2개월 후 원호파괴형태의 사면내 파괴가 발생되었다. 실험결과 지반의 최대 연직변위는 사면의 비탈머리에서 발생하였으며, 최대 수평변위는 비탈머리를 기준으로 0.5~1H(H : 초기 점토층의 높이) 떨어진 지점의 사면부 아래에서 발생하였으며, 최대 수평변위는 최대연직변위의 약 2배 정도인 것으로 나타났다. In this study, the centrifugal tests were performed with varying the angle of slope such as 1:3, 1:2.5, and 1:2 in order to analyze the deformation and failure type of dredged clay slope for a short term. The displacement mode, displacement vector and the variation of pore pressure with the different slope angle were measured. As a results, even though the displacement in the slope after 4 months were developed in the case of 1:3 for the dredged slope, there are little problems to obtain the stability of dredged slope because the original construction section maintains. Also, in the case of 1:2.5 after 4 months the local slope failure occurred and in the case of 1:2 after 2 months the circle failure starting from the point of the tensile crack occurred. After reviewing the results, the maximum vertical displacement occurred at the crest of slope and maximum horizontal displacement was about double of maximum vertical displacement.

제방축조에 의한 연약지반의 변위특성

안광국,배우석 한국지반환경공학회 2007 한국지반환경공학회논문집 Vol.8 No.2

In this study, the centrifugal tests were fulfilled to analyze the displacement characteristics caused by the embankment construction on soft ground. Embankment of height, undrained shear strength and with or without geotextile were selected to evaluate the displacement characteristics of soft ground by embankment. As a result, the replacement section without geotextile showed the parabola shape. The replacement section with geotextile showed the trapezoidal shape which represents the uniform settlements. The replacement angle is increasing nearly lineally with increasing the height of embankment and G-level. The position, where the maximum horizontal displacement occurred, was between 0.24H0 and 0.35H0 and was at 0.3H0 on the average. In the case of with and without geotextile, the relationship between the maximum settlement of ground(S) and maximum horizontal displacement(δm) was δm=0.60S, δm=0.54S, respectively. 본 연구에서는 제방축조에 의해 연약점토지반에서 발생되는 지반의 변위 및 변형형태를 파악하기 위하여 제방높이, 지반의 비배수 전단강도, geotextile의 설치여부와 중력수준을 변화시키면서 원심모형시험을 실시하였다. 실험결과, 제방하중에 의한 지반의 치환단면은 geotextile을 설치하지 않은 경우 포물선 형태를 나타내었고, geotextile을 설치한 경우에는 제방하부에서 균일한 침하단면을 나타내는 사다리꼴 형태를 나타내었다. 치환각도는 제방높이와 중력수준이 증가할수록 그리고 지반의 비배수 전단강도가 작을수록 거의 선형적으로 증가하는 것으로 나타났다. 최대 수평변위가 발생하는 위치는 지표면에서 점토층 깊이의 0.24~0.35H0(H0 : 초기 모형지반의 높이) 지점으로 평균 0.3H0인 것으로 나타났으며, geotextile을 설치하지 않은 경우 지반의 최대침하량(S)과 최대 수평변위(δm)는 δm=0.54S, geotextile을 설치한 경우에는 δm=0.60S의 관계를 나타내었다.

Modifications of Ecological Trophic Structures on Chemical Gradients in Lotic Ecosystems and Their Relations to Stream Ecosystem Health

안광국,최지웅,이영준 한국통합생물학회 2013 Animal cells and systems Vol.17 No.1

The objectives of this study were to evaluate how chemical gradients and physical habitats influence trophic dynamics and chemical tolerance in relation to ecological health, based on biological integrity model in the absence of cascading pressures (cascading theory) as a control mechanism of aquatic ecosystems. We conducted physical,chemical, and biological surveys from 76 national streams and rivers of four major watersheds during 20042005along with surveys of 80 reference streams. Maximum species richness lines (MSRLs) in reference sites vs. regular sampling sites indicated that the third- to fifth-order streams were evidently impaired in the metrics of trophic and tolerant components. These trophic modifications were linked with land-use patterns, which resulted in differences of nutrients (N, P), organic matter contents and the N:P ratios on trophic structures. Overall, these trophic factors influenced ecological health, based on multimetric index of biological integrity model in these systems, so that trophic compositions and tolerance were regulated by bottom-up hypothesis.

Ecological health assessments using multiple parameters of fish blood tissues to community along with water chemistry in urban streams

안광국,강한일,최지웅,황석연 한국생태학회 2015 Journal of Ecology and Environment Vol.38 No.3

The objectives of this study were to identify multi-level stressors from blood biomarkers to community-level bioindica¬tors and diagnose the stream ecosystem health in polluted streams. Blood chemistry such as total protein (TPro), blood urea nitrogen (BUN), total cholesterol (TCho) and albumin (Alb) were analyzed from sentinel fish tissues; the functions of kidney, gill and liver were significantly decreased in the impacted zone (Iz), compared to the control zone (Cz). Histo¬pathological analysis showed that fish liver tissues were normal in the Cz. Fish liver tissues in the Iz, however, showed large cell necrosis and degeneration and also had moderate lobular inflammation and inflammatory cell infiltration of lymphocytic histocytes. Species biotic index (SBI) at species level and stream health assessment (SHA) at community level indicated that chemical impacts were evident in the Iz (ecological health; poor - very poor), and this was matched with the blood tissue analysis and histopathological analysis. The impairments of the streams were supported by water chemistry analysis (nitrogen, phosphorus). Tolerance guild analysis and trophic guild analysis of fish were showed sig¬nificant differences (P < 0.01) between Cz and Iz. Overall, multiple parameter analysis from biomarker level (blood tissues) to bioindicator level (community health) showed significantly greater impacts in the Iz than Cz. This approach may be effective as a monitoring tool in identifying the multilateral and forthcoming problems related to chemical pollution and habitat degradation of stream ecosystems.

강바람 산바람

안광국 새가정사 1978 새가정 Vol.- No.-

Long-term Seasonal and Interannual Variability of Epilimnetic Nutrients (N, P), Chlorophyll-a, and Suspended Solids at the Dam Site of Yongdam Reservoir and Empirical Models

안광국 한국하천호수학회 2011 생태와 환경 Vol.44 No.2

The objectives of the study were to evaluate seasonal patterns of epilimnetic water quality, and determine interannual eutrophication patterns at the dam site of Yongdam Reservoir using long-term data during 2002~2009. Ionic dilutions, based on specific conductivity, occurred in the summer period in response to the intense monsoon rain and inflow, and suspended solid analysis indicated that the reservoir was clear except for the monsoon. Seasonality of nitrogen contents varied depending on the types of nitrogen and responded to ionic dilution; Ammonia-nitrogen (NH_4-N) peaked at dry season but nitrate-nitrogen (NO_3-N) peaked in the monsoon when the ionic dilution occurred. The maxima of NO_3-N seemed to be related with external summer N-loading from the watershed and active nitrogen fixation of bluregreens in the summer. NO_3-N was major determinant (>50%) of the total nitrogen pool and relative proportion of NH_4-N was minor. Long-term annual NO_3-N and TDN showed continuous increasing trends from 2004 to 2009, whereas TP and TDP showed decreasing trends along with chlorophyll-a (CHL) values. Empirical model analysis of log-transformed nutrients and N : P ratios on the CHL showed that the reservoir CHL had a stronger linear function with TP (R^2=0.89, p<0.001) than TN (R^2=0.35, p=0.120). Overall results suggest that eutrophication progress, based on TP and CHL, is slow down over the study period and this was mainly due to reduced phosphorus, which is considered as primary nutrient by the empirical model.

지난 2년을 돌아보며

안광국 한국지반환경공학회 2023 지반환경 Vol.24 No.3

우리나라에서 어류를 이용한 하천 생태건강도 평가 모델 개발

안광국,An, Gwang-Guk 한국수자원학회 2012 물과 미래(한국수자원학회지) Vol.45 No.12

수평력을 받는 군말뚝에서의 말뚝의 상호작용

안광국,김홍택 한국지반공학회 2005 한국지반공학회논문집 Vol.21 No.2

본 연구에서는 점토지반에서 수평력을 받는 군말뚝과 단말뚝의 수평저항력을 파악하기 위하여 유한요소 해석 프로그램인 ABAQUS를 이용하여 수치해석을 행하였다. 수치해석은 말뚝직경(1.0, 0.5m), 말뚝길이(7, 10m) 그리고 두부조건(두부자유와 말뚝캡을 적용한 두부구속조건)을 변수로 하여 실시하였다. 수평력 작용시 선말뚝(leading pile)의 캡에 의한 영향과, 군말뚝내의 각각의 말뚝에 대한 수평저항력의 크기와 분포를 평가하기 위하여 1×3군말뚝을 사용하였다. 점토지반은 Cam-clay 모델을 사용하였고, 말뚝은 원형의 콘크리트로 탄성모델을 사용하여 3차원 해석을 수행하였다. 해석결과 말뚝캡의 크기는 단말뚝의 수평저항력에 영향을 미치는 것으로 나타났으며, 군말뚝내의 선말뚝은 군말뚝의 효과에 의해 수평저항력이 증가하면서 Brown이 제안한 p-multiplier 값이 1보다 크게 평가되었다.