• Korean Journal of Ecology and Environment
• /
• v.36 no.3 s.104
• /
• pp.295-303
• /
• 2003

Sorption kinetics of hydrophobic organic compounds (chlorobenzene and phenanthrene) in natural wetland soils was investigated using laboratory batch adsorbers. One -site mass transfer model (OSMTM) and two compartment first-order kinetic model (TCFOKM) were used to analyze sorption kinetics. Analysis of OSMTM reveals that apparent sorption equilibria were obtained within 10 to 75 hours for chlorobenzene and 2 hours for phenanthrene, respectively. For chlorobenzene, the sorption equilibrium time for surface soil was longer than that of deeper soil presumably due to physico-chemical differences between the soils. For phenanthrene, however, no difference in sorption equilibrium time was observed between the soils. As expected from the number of model parameters involved, the three-parameter TCFOKM was better than the two-parameter OSMTM in describing sorption kinetics, The fraction of fast sorption ($f_1$) and the first-order sorption rate constants for fast ($k_1$)and slow ($k_2$) compartments were determined by fitting experimental data to the TCFOKM. The results of TCFOKM analysis indicate that the sorption rate constant in the fast compartment($k_1$) was much greater than that of slow fraction($k_2$) . The fraction of the fast sorption ($f_1$) and the sorption rate constant in the fast compartment($k_1$) were increasing in the order of increasing $k_{ow}$, phenanthrene > chlorobenzene. The first-order sorption rate constants in the fast ($k_1$) and slow ($k_2$) compartments were found to vary from $10^{-0.1}\;to\;-10^{1.0}$ and from $10^{-4}\;to-10^{-2}$, respectively.

• Korean Journal of Ecology and Environment
• /
• v.36 no.3 s.104
• /
• pp.277-285
• /
• 2003

Temperature profiles were observed to understand seasonal variation of thermal structures in the Juam reservoir from March 2000 to May 2001. Heat flux which affects thermal structures was calculated by observed water temperature and meteorological data. Temperature became homogeneous vertically by convection due to the surface cooling in winter. Maximum heat loss through the surface (109.45W/$m^2$) occurred in December. There was a horizontal gradient of water temperature in winter. The temperature was $3^{\circ}C$ at upstream and $5^{\circ}C$ near the dam. The surface temperature increased by the increase of solar radiation in spring and summer. Maximum heat gained through the surface was 101.95 W/$m^2$ in July. Maximum surface temperature was $29^{\circ}C$ in August, whereas the bottom water was $7^{\circ}C.$ Surface mixed layer became thicker and its temperature decreased by surface heat loss in fall and winter.

• Korean Journal of Ecology and Environment
• /
• v.49 no.2
• /
• pp.142-146
• /
• 2016

The purpose of this study is to evaluate topographic characteristics revealed in the predicted distribution areas of Aporia crataegi, according to climate change. Towards this end, this study compared the differences of topographic factors, such as altitude, mountain slope and the aspect of slope, in the distribution areas with different potential inhabitation possibilities of the Aporia crataegi. The inhabitation possibilities of the Aporia crataegi were different, according to altitude and topographic slope, and the inhabitation possibility is judged to be affected more by the topographic conditions including altitude and mountain slope than by the aspect of slope. Especially, the inhabitation possibility of the Aporia crataegi was higher in the higher altitude area, as time goes on furthermore. The reason is that the current climate environment, which is suitable for the potential inhabitation of the Aporia crataegi, is forecast to be formed with an area with high altitude. Although the difference in the aspect of slope was not statistically significant according to inhabitation possibility, the reason why the inhabitation possibility of the Aporia crataegi varies in the mainly southeast slope is conjectured to be derived from the warmer heat environmental condition to grow from a larva into an imago. The result drawn in this study is expected to be utilized as basic data to establish a policy soundly preserving and managing the habitat of biospecies in consideration of climate change and topographic conditions in the natural ecosystem field by using the already built up various biological resources information.

• Korean Journal of Ecology and Environment
• /
• v.46 no.2
• /
• pp.166-174
• /
• 2013

Analysis of the fish community in the Lagoon Cheongcho, Korea, was investigated in 2008 and in 2012. A total 48 species, belonging to 26 falmilies, were sampled during the period. The dominant species was Tribolodon hakonensis (75.2%), and subdominant species were Acanthogobius flavimanus (5.4%), Pungitius kaibarae (3.1%). The results of the fish ecotypes according to origin of water body was compared by surveyed year, freshwater fish was reduced, whereas those of brackish water and seawater fishes were increased. Moreover, the result of similarity analysis based on species and individuals in five lagoons were divided into 2 major groups based on their similarity, and Lagoon Cheongcho was included group 'A' with Lagoon Gyeongpo, as having a montinous inflow of seawater. Hence, according to the characterization according to the analysis of fish community, Lagoon Cheongcho has lost the characteristics of a lagoon, and oceanization is considerably progressed. Therefore, we are considering the provision of a management strategy for hydrarch succession, as well as continuous research, in order to manage the recovery of essential characteristics of the lagoon ecosystem. Hence, according to the characterization according to the analysis of fish community, Lagoon Cheongcho has lost the characteristics of a lagoon, and oceanization is considerably progressed. Therefore, we are considering the provision of a management strategy for hydrarch succession, as well as continuous research, in order to manage the recovery of essential characteristics of the lagoon ecosystem.

• Korean Journal of Ecology and Environment
• /
• v.46 no.4
• /
• pp.581-587
• /
• 2013

The amounts of carbon (C), nitrogen (N) and phosphorus (P) in relation to dry weight (D.W.) were measured in zooplankton from the large four rivers (Han R., Geum R., Yeongsan R. and Seomjin R.) during 2004~2008. The stoichiometry of total zooplankton in four river systems was highly variable. The ranges of average C, N and P-contents were $70{\sim}620mgC\;mg^{-1}$ D.W., $7.1{\sim}85.5{\mu}gN\;mg^{-1}$ D.W. and $2.5{\sim}7.4{\mu}gP\;mg^{-1}$ D.W., respectively. The mean C :N: P atomic ratios reflected large spatial differences. The C : P and N : P ratios of the zooplankton community ranged from 38 to 392 : 1 and from 4 to 65 : 1 in all sampling sites. Self-Organizing Map (SOM) was applied to the survey data, and the study sites were clearly classified into 3 clusters. Clustering was largely affected by the distribution pattern of C, N, P-contents, which is related with characteristics of river systems on the basis of stoichiometry.

• Korean Journal of Ecology and Environment
• /
• v.46 no.2
• /
• pp.301-309
• /
• 2013

Between May and August 2012, a massive cyanobacterial bloom with Anabaena has been occurred throughout the North Han River. Sampling was conducted at one station on each lake, L. Uham, L. Cheongpyung, and L. Paldang, where occurred a dense bloom, in 13 July. According to the microscopic examination, the blooms was dominated by one specific filamentous cyanobacterium Anabaena and other phytoplankton. Morphologically, previous literature proven that this Anabaena species is A. crassa (Lemmermann) Komark.-Legn. & Cronberg. However, identification of species in a mixed population is complicated due to limited morphological differences. Therefore, with live sample including trichome, akinete and heterocyst, the sequences of 16S rRNA gene of Anabaena isolates were cloned and analyzed, and three 16S rRNA gene sequences of 1188~1520 bp in length were obtained. It was shown from the homologous analysis results that the obtained 16S rRNA sequences were highly homologous to the relevant sequences of A. crassa in GenBank. The 16S rRNA sequences of 63 species were retrieved from GenBank, and the phylogenetic tree was constructed by using these sequences.

• Korean Journal of Environment and Ecology
• /
• v.26 no.2
• /
• pp.247-256
• /
• 2012

We evaluated the landscape ecological value of selected minefields and wetland patches as a habitat of the forest bird community. The avian fauna of three minefields of 8.5ha, 17.4ha, and 40.6ha were evaluated by comparing that of three control sites of mountain area. Average number of forest bird species, number of individuals, species diversity index, species richness, and species evenness were analyzed according to the size of patch and environmental characteristics such as the presence of wetland and connectivity. Community similarity was evaluated between test and control plots. Avian fauna can be summarized as follows. First, 63 species were recorded, and the sum of maximum counts was 828 individuals. Species diversity index was 3.8, and the species richness was 9.2. Species evenness was 93.3. Second, small, isolated forest patch had a low average number of species and individuals as expected. But, small forest patches with streams had higher bird density than patches without water surface. Third, forest patches with marsh wetland were evaluated as lower habitat quality than forest patches with stream wetland in terms of the number of bird species per unit area, number of individuals per unit area, species diversity index, species richness index, and species evenness. Finally, Community similarity of the small forest patches with streams was similar with large connected forest. As a result, lowland forest patch was shown the good quality for the forest bird community in spite of small extents, and community structure was similar with mountain forest bird community. Thus, riparian forest restoration could improve the biodiversity of the forest bird community.

• Korean Journal of Ecology and Environment
• /
• v.35 no.1 s.97
• /
• pp.36-44
• /
• 2002

The spatial and temporal trends of water qualities in Lake Soyang was statistically analyzed in this study. The water qualities include nutrients, ionic contents and chlorophyll-a (Chl-a) measured during 1993${\sim}$2000. The rainfall intensity and runoff from the catchment appeared to play an important role in water quality trends in the lake. According to seasonal Mann-Kendall test, conductivity, TP, and Ctl-a did not show any trends of increase or decrease over the 8 year period, while TN declined slightly. It was found that the variation of TP was a function of interannual inflow and rainfall. In the analyses of spatial trend, conductivity, based on the mean by site, showed a downlake decline over the eight year period. Minimum conductivity was found in the headwaters during summer monsoon of July to August and near the dam during October. This result indicates a time-lag phenomenon that the headwater is diluted by rainwater immediately after summer monsoon rain and then the lake water near the dam is completely diluted in October. During summer period, TP and TN had an inverse relation with conductivity values. Concentrations of TP peaked during July to September in the headwaters and during September in the downlake. Also, TN increase during the summer and was more than 1.5 mg/L regardless of season and location, indicating a consistent eutrophic state. Values of Chl-a varied depending on location and season, but peaked in the midlake rather than in the headwaters during the monsoon. Regression analyses of log-transformed seasonal Chl-a against TP showed that value of $R^2$ was below 0.003 in the premonsoon and monsoon seasons but was 0.82 during the postmonsoon, indicating a greater algal response to the phosphorus during the postmonsoon. In contrast, TN had no any relations with Chl-a during all seasons.

• Korean Journal of Ecology and Environment
• /
• v.33 no.4 s.92
• /
• pp.350-357
• /
• 2000

This paper evaluated the influence of point source and flow events on inorganic nitrogen fractions at 17 sites of Taechung Reservoir during 1993${\sim}$1994. Total nitrogen (TN) averaged 1.53 mg/L during the study and ranged between 0.70 and 2.56 mg/L. Dissolved inorganic nitrogen(DIN) accounted for >90% of TN regardless of season and location, indicating a nitrogen-rich system showing eutrophic${\sim}$hypereutrophic conditions. Some 67${\sim}$94% of DIN was NO$_{3}$-N, whereas mean level of NH$_{4}$-N was less than 5% of DIN. During monsoon 1993, dilution of NO$_{3}$-N was evident in the headwaters as a result of mixing of lake water with rain water, while NH$_{4}$-N increased>100% compared to the premonsoon. Values of NH$_{4}$-N had a positive correlation with rainfall (r=0.85; p<0.001) and negative correlations with theoretical water residence time(r=-0.90; p<0.001) and conductivity(r=-0.78, p<0.001), respectively. These outcomes suggest that NH$_{4}$-N came from external input from the watershed during the monsoon. In both years, mean TN was greater in the mid-lake sites than any other sites. A great amount of TN in the mid-lake was most pronounced in monsoon 1994 because of an accumulated influence of the point sources during low inflow. Overall data suggest that concentrations of TN in this system did not show large differences along the longitudinal gradients and its distributions is likely determined by point-sources rather than inflow regime.

• Korean Journal of Ecology and Environment
• /
• v.33 no.4 s.92
• /
• pp.319-327
• /
• 2000

The feeding behavior of 1-year-old silver carp, Hypophthalmichthys molitrix (Val.) on phytoplankton species in a shallow hypertrophic lake was studied from 22 May to 18 September, 1997. Over the experimental period, the filter-pore sizes of the fish, the total biomass of the phytoplankton and the water temperature in each enclosure changed little with time. The fish biomass in each enclosure increased with time, while their percentage of weight gain correlated negatively to the stocking density, due perhaps to competition for prey. An analysis of gut contents of silver carp showed a strong similarity between the algal communities in the foregut and the water, and was significant for the fish enclosure with a low density (p<0.05). The presence of silver carp rarely suppressed the abundance of phytoplankton such as Oscillatoria, Anabaena and Melosira even at high ingestion levels. There were weak relationships between the IU values of each phytoplankton and the selectivity of fish on them (r = 0.001, p>0.5). There was no doubt that the silver carp fed unselectively when cyanobacteria populations were high, even though the selectivity index for diatoms was slightly higher than those for cyanobacteria, green algae and cryptomonads. Improvements in methodologies are needed to clearly understand and generalize the feeding behavior of silver carp.