• 한국물환경학회지
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• 제33권4호
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• pp.424-433
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• 2017

The purpose of this study is to understand the changes on species composition of the epilithic diatoms and the appearance of morphological abnormalities in the upper region of the Nakdong River where heavy metal inflow is observed. The samples were collected once a week for a month of September 2016 from selecting 7 sampling stations. The heavy metals of cadmium (Cd) and arsenic (As) were not detected during the survey period, but zinc (Zn) was detected in st.4 - st.6 with the range of $0.015{\sim}0.188mg\;L^{-1}$. Metal sensitive species such as Achnanthes convergens, Cocconeis placentula, Cocconeis placentula var. euglypta, Cocconeis placentula var. lineata showed high dominance in st.1 - st.3, st.7. However, metal tolerant species such as Nitzschia palea, Achnanthes minutissima showed high dominance in st.4 - st.6. It is concluded that heavy metal inflow directly affects the changes in species composition of epilithic diatoms. As a result of CCA, the characteristics of the sampling sites were divided into 3 groups. Group 1 was represented the non-detected Zn sites with C. placentula, C. placentula var. euglypta, C. placentula var. lineata. Group 2 was showed the detected Zn sites with Navicula minima and Nitzschia palea. Group 3 was included st.3 - st.7 on 4th week that was stabilized the community structure. Total 8 taxa of abnormal frustules observed. This occurrence of abnormal frustules reflected the temporal and quantitative indicators of heavy metal pollution, in particular, it was confirmed that genus Fragilaria, which has a high abnormality according to heavy metal pollution, can be used as an indicator species.

• 한국물환경학회지
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• 제33권5호
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• pp.538-545
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• 2017

The purpose of this study is to investigate growth response and toxigenicity under various temperature and nutritional conditions, in order to understand the physioecological characteristics of Aphanizomenon flos-aquae, which is a bloom-forming cyanobacterium in the Nakdong River. The strain was inoculated into media under combinations of four temperatures (4, 12, 21, $30^{\circ}C$) and three nutrients (modified CB medium, P-depleted CB medium, N-depleted CB medium) for 28 days. The algae-inhibition tests were performed to assess the potential allelopathic effects of the strains' filtrates on the growth of four algae strains (Microcystis aeruginosa, Aulacoseria ambigua f. spiralis, Aphanizomenon flos-aquae, Scenedesmus obliquus). Toxin production of a strain was measured by Enzyme-Linked ImmunoSolbent Assay (ELISA). The optimal growth temperature (Topt) of strains was $19.9^{\circ}C$ ($18.3-21.2^{\circ}C$), and the temperature range for growth was from $-0.3^{\circ}C$ to $34.3^{\circ}C$. Specific growth rate (${\mu}$) in modified CB medium varied from 0.10 to $0.16day^{-1}$, and the maximum growth rate (${\mu}_{max}$) was $0.17day^{-1}$. Although growth curves under N-existed and N-depleted conditions were almost the same, growth under N-depleted condition was relatively slowed (${\mu}=0.09$ to $0.14day^{-1}$), with a decreased maximum cell density. However, growth under the P-depleted condition was restricted for all temperatures, Two stains of Aphanizomenon flos-aquae were confirmed as not producing toxins, because saxitoxin and cylindrospermopsin were not detected by ELISA. The exudates or filtrates from the Aphanizomenon flos-aquae (DGUC003) resulted in significant inhibition of algal growth on the Aulacoseira ambigua f. spiralis (DGUD001) and Aphanizomenon flos-aquae (DGUC001) (p < 0.01).

• 한국물환경학회지
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• 제36권6호
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• pp.559-567
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• 2020

The abnomal responseses on growth and morphology of attached diatoms by various heavy metals were studied. Ulnaria ulna (Nitzsch) Compère was employed as experimental species and exposed to the five heavy metals such as Cu, Zn, Pb, Cd, and As with four concentrations (0, 0.01, 0.1, and 2 mg L-1), respectively. The samples of Ulnaria ulna were examined on the changes of cell growth and teratological forms on the 7th, 14th, 21th, and 28th day, respectively, after exposure to the heavy metals. The samples exposed to the highest concentration, 2.0 mg L-1, of all the heavy metals showed the most obvious decreases of growth. The samples exposed to Cd (μ=0.049day-1) and As (μ=0.048day-1) showed the highest decreasing rate of growth (p=0.021(Cd), p=0.002(As)) and the highest morphological changes of diatom valves were also samples exposed to Cd (10.41%) and As (10.13%) (p=0.009 (Cd), p=0.005(As)). In contrast, Pb induced the lowest decreasing rate (μ=0.090 day-1) and the least change in valve morphology (3.31%). The Cd and As showed relatively stronger effects on growth rates compared to Cu, Zn, and Pb. For the percentage of emergence of morphological species by the type, the highest percentage were observed in sampled exposed to type 1 (43.4%) and followed by type 2 (29.1%). The type 2 and 4 were most abundant in samples exposed to Zn and Pb while the type 3 was most abundant in Cd and As. The Cu induced only type 1, suggesting that the frequency of emergence of each type varied among hevay metals. This research suggests that the degrees of abnomal changes on growth rate and valve morphology of Ulnaria ulna can be used as a bioindicater species for heavy metal contamination in freshwater.

• Journal of Ecology and Environment
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• 제39권1호
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• pp.43-49
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• 2016

Fishways are constructed to provide longitudinal connectivity of streams or rivers where their flow has been altered by in-stream structures such as dams or weirs. Nature-like fishways have an additional function of providing fish habitats. In the study, we estimated the role of a nature-like fishway (length: 700 m, slope: 1/100) for fish habitat by using two dominant species in the Sangju Weir, Nakdong River, to calculate the optimal ecological flow rate using Physical HABitat SIMulation (PHABSIM). To identify the dominant species that used the fishway, we conducted trap monitoring from August to November 2012 at the fishway exit. The dominant species were Zacco platypus and Opsariichthys uncirostric amurensis with a relative abundance of 62.1% and 35.9%, respectively. Optimal habitat suitability indices (HSIs) for Z. platypus and O. u. amurensis were calculated as 0.6-0.8 m/s (water velocity) and 0.2-0.4 m (water depth), and 0.5-0.7 m/s (water velocity) and 0.1-0.3 m (water depth), respectively. The optimal ecological flow rates (OEFs) for Z. platypus and O. u. amurensis were 1.6 and 1.7 cubic meter per second (CMS), respectively. The results of the study can be used in a management plan to increase the habitat function of nature-like fishways in the Sangju Weir. This methodology can be utilized as an appropriate tool that can determine the habitat function of all nature-like fishways.

• 환경영향평가
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• 제16권6호
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• pp.393-405
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• 2007

To examine the sedimentary geochemical characteristics of sediment in the Tamjin River and Doam bay, the analysis was conducted, using the sample obtained in February 2000, on the grain size and the contents of metallic elements and organic carbon. The factors that influence the geochemical behavior of metallic elements in the surface sediment are grain size, organism, surrounding soil and $CaCO_3$. To find out the pollution level of metallic elements, the enrichment factor (EF) and the index of geoaccumulation ($I_{geo}$) were researched. The majority of metallic elements sustain their values in natural state. The elements such as K, Ba, Zr, etc. appear to be rich in some places. The EF and $I_{geo}$ of P, Cu, Zn, and Pb, which belong to toxic heavy metals, are partly related with man-made pollution. P and Cu have a high EF, Pb has a high $I_{geo}$ and Zn is high in both EF and $I_{geo}$. The low contents of P and Cu are not likely to be related with the pollution of water environment. However, given the development of relative pollution, the research and the management regarding the pollutants are needed. Because Pb, naturally enriched by geological characteristics, has a large influence on water environment along with Zn, the adequate measures against man-made pollution should be worked out.

• 한국물환경학회지
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• 제39권2호
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• pp.162-174
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• 2023

In order to prevent water pollution caused by organic matter, Total Organic Carbon(TOC) has been adopted indicator and monitored. TOC can be divided into Dissolved Organic Carbon(DOC) and Particulate Organic Carbon(POC). POC is largely precipitated and removed during stream flow, which making DOC environmentally significant. However, there are lack of studies to define spatio-temporal distributions of DOC in stream affected by various land use. Therefore, it is necessary to estimate the past DOC concentration using other water quality indicators to evaluate status of watershed management. In this study, DOC was estimated by correlation and regression analysis using three different organic matter indicators monitored in mixed land-use watersheds. The results of correlation analysis showed that DOC has the highest correlation with TOC. Based on the results of the correlation analysis, the single- and multiple-regression models were developed using Biochemical Oxygen Demand(BOD), Chemical Oxygen Demand(COD), and TOC. The results of the prediction accuracy for three different regression models showed that the single-regression model with TOC was better than those of the other multiple-regression models. The trend analysis using extended average concentration DOC data shows that DOC tends to decrease reflecting watershed management. This study could contribute to assessment and management of organic water pollution in mixed land-use watershed by suggesting methods for assessment of unmeasured DOC concentration.

• 한국물환경학회지
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• 제27권6호
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• pp.794-803
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• 2011

Self Organizing Map (SOM) was applied for pattern classification of hydrological and water quality data measured at Jangseong Reservoir on a monthly basis. The primary objective of the present study is to understand better data characteristics and relationship between the data. For the purpose, two SOMs were configured by a methodologically systematic approach with appropriate methods for data transformation, determination of map size and side lengths of the map. The SOMs constructed at the respective measurement stations for water quality data (JSD1 and JSD2) commonly classified the respective datasets into five clusters by Davies-Bouldin Index (DBI). The trained SOMs were fine-tuned by Ward's method of a hierarchical cluster analysis. On the one hand, the patterns with high values of standardized reference vectors for hydrological variables revealed the high possibility of eutrophication by TN or TP in the reservoir, in general. On the other hand, the clusters with low values of standardized reference vectors for hydrological variables showed the patterns with high COD concentration. In particular, Clsuter1 at JSD1 and Cluster5 at JSD2 represented the worst condition of water quality with high reference vectors for rainfall and storage in the reservoir. Consequently, SOM is applicable to identify the patterns of potential eutrophication in reservoirs according to the better understanding of data characteristics and their relationship.

• Journal of Ecology and Environment
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• 제32권2호
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• pp.83-86
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• 2009

We conducted a landscape analysis to investigate the possibility of adverse effects of anthropogenic light sources, such as roads and residential buildings, on Lethocerus deyrollei on Jeju Island, Wetlands inhabited by L. deyrollei had fewer anthropogenic structures within a 3 km radius that had the potential to produce artificial light at night than wetlands not inhabited by L. deyrollei, In particular, the presence of artificial lights within a 1 km radius appears to reduce the probability of inhabitation by L. deyrollei, Our results suggest that artificial light sources may be critical determinants of L. deyrollei inhabitation patterns in a landscape, and that habitats that have a buffer area of at least 600$\sim$700 m radius free from residential buildings are the most appropriate habitats for L. deyrollei.

• Journal of Ecology and Environment
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• 제43권2호
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• pp.98-103
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• 2019

We compared the functional traits of leaf blades and culms of common reed (Phragmites australis) in four habitat types of distinguished environments such as temperature, precipitation, water characteristics, and indices related to biomass production (montane fen, MF; riparian marsh, RM; lagoon, LG; and salt marsh, SM). We also examined the relationships between the functional traits within and among populations. Four populations showed remarkable differences in the functional traits of leaf blades and culms. MF and RM had relatively tall (> 300 cm) and thick (> 8 mm) culms bearing long leaf blades (> 40 cm), whereas LG and SM had relatively shorter and thinner culms bearing shorter leaf blades than MF and RM. Some relationships between the functional traits of leaf blades and culms showed negative or not significant correlations within the population, whereas most of the relationships between the functional traits showed positive correlations particularly when all the data from four populations was included into the correlation analysis.

• 생태와환경
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• 제43권4호
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• pp.513-517
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• 2010

The diel swarming of Moina macrocopa and the relationship between environmental factors were evaluated in a shallow reservoir. The littoral density of Moina macrocopa maintained low from night to noon, reached maximum density at the afternoon with compact swarms at the waters' edge, and dispersed after sunset. The recruitment of Moina macrocopa and changes of water temperature (r=0.709, p<0.001) and juvenile fish density (r=0.511, p=0.002) in the littoral zone showed a significant positive relationships. After the induction of diel horizontal migration toward littoral zone, therefore, direct juvenile fish predation pressure should be induced Moina macrocopa swarming.