• Ocean and Polar Research
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• v.30 no.4
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.1-8
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• 2016

This study assessed the feasibility of odor removal by the application of Bacillus sp. that has many advantages in sewage treatment to sewage sludge. The NH3 removal rates in the treatment of primary sludge using only aeration were measured at 24, 48, and 72 hours of treatment and the results were 12.5 %, 12 %, and 42.1 %, respectively. The NH3 removal rates of a reactor injected with BIO-CLOD made by solidifying Bacillus sp. concentrated 10 % together with other substances were measured after 24, 48, and 72 hours of treatment and the results were 43 %, 70 %, and 81 % respectively. In the cases where the Bacillus sp. cultured in NB medium was injected into the primary sludge reactor to reach injection rates of 0 %, 1.7 %, 3.3 %, and 6.7(v/v%), the TVOC removal rates measured when 72 hours had passed after the injection were 59 %, 71 %, 88 %, and 98 % respectively, which were higher than the NH3 removal rates as the NH3 removal rates measured at the same time were shown to be 29 %, 25 %, 31 %, and 48 %, respectively. In the sludge dewaterability conducted with various Bacillus sp. injection concentrations, a Bacillus sp. concentration of 4(v/v%) was considered to be suitable. The Bacillus sp. concentrations and reduction in the bad odor substances were correlated with each other. The results showed that aeration and Bacillus sp. injection will assist biological oxidation so that the bad odor substances can be removed. Based on the SRF values of the primary sludge and digested sludge, in which Alum and PAC were used, the appropriate amount of Alum aggregate reagent was judged to be 500 mg/L, and when PAC was used, 6 mg/L was judged to be appropriate.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.78-85
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• 2004

As an ozone contactor, we newly adopted HJLR (High-performance Jet Loop Reactor) for the decolorization of Reactive black 5 and the mineralization of oxalic acid, which has been applied exclusively in biological wastewater treatments and well-known for high oxygen transfer characteristics. The ozonation efficiency for organic removals and ozone utilization depending on the mass transfer rate were compared to those of Stirred bubble column reactor, which was controlled by varing energy input in the HJLR and Stirred bubble column reactor. The results were as follows; first, the decolorization rate of Reactive black 5 in the HJLR reactor was nearly proportional to the increasing $k_La$. When the $k_La$ was increased by 25 % from $13.0hr^{-1}$ to $16.4hr^{-1}$, 30 % of the k' (apparent reaction rate constant) was increased from 0.1966 to $0.2665min^{-1}$ (Stirred bubble column; from 0.1790 to $0.2564min^{-1}$). Ozone transfer was found to be a rate-determining step in decolorizing Reactive black 5, which was supported by that no residual ozone was detected in all of the experiments. Second, the mineralization of oxalic acid was not always proportional to the increasing $k_La$ in the RJLR reactor. The rate-determining step for this reaction was OH(OH radical) production with ozone transfer, because residual ozone was always detected during the ozonation of oxalic acid in contrast with Reactive black 5. This result indicates that the increase of $k_La$ in the HJLR reactor is beneficial only when there are in ozone transfer limited regions. In addition, regardless of $k_La$, the mineralization of oxalic acid was nearly accomplished within 60 minutes. It was interpreted as that the longer staying of residual ozone by whirling liquid in the HJLR reactor contributed to an high ozone utilization(83-94%), producing more OR radicals.

• The Journal of the Petrological Society of Korea
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• v.28 no.4
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• pp.227-236
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• 2019

Medium to coarse-grained biotite granodiorite was used to build the Standing Buddha Statue in the Gwanchoksa temple. An ancient document revealed the period and place of constructing the statue: it was made in the northwest of Mt. Banyasan and then moved eastward. Also, the comparison of standing Buddha statue and basement rock in terms of texture, magnetic susceptibility, and gamma spectrometer shows that they have similar characteristics, which is considered to be the same provenance rock. The damage caused by surface contaminants observed in the statue seems to be a combined effect of environmental factors and aging of the epoxy resin. After removal of the contaminants in 2007, the contamination has resumed, and continuous monitoring is necessary. Algal engraftment becomes faster when biological contamination occurs on the surface of stone cultural heritage. Since the secondary lichen growth forms a symbiosis with mold, it is necessary to observe the spatial and distributional changes. Also, the aging epoxy resin may cause secondary damage due to contaminants generated due to the determination of salts, and deterioration of bonding strength due to breaking out. Thus it is desirable to secure stability through proper conservation management.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.282-293
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• 2020

This study investigated a long-term variation trend of water quality, fish compositions, and ecological health conditions in the Gwanpyeong stream located in the nearby Daejeon metropolitan city to understand the impact of urban development projects on the aquatic ecosystem. The sampling was made in four surveys (2009, 2010, 2016, 2019) before and after urbanization. The urban development was conducted in 2008, resulting in the stream's ecological disturbance, and the stream restoration was conducted in 2012. Thus, stream monitoring was conducted to analyze the ecological trends before and after the restoration. The multi-metric models for Fish Assessment Index(FAI) and necropsy-based Health Assessment Index(HAI) were applied in the fish community and organ-level, respectively, to assess the ecological health of the stream. Minimum turbidity and chlorophyll-a(Chl-a) occurred in the mid-stream(St. 2), and this was probably due to rapid current velocity in the riffle zone. We collected 18 fish species, and the dominant species was Zacco platypus (40.6%). In 2016 immediately after the stream restoration, the relative proportions of sensitive species and insectivore species were the highest along with highest values in the species diversity and species richness index, resulting in the best condition in the ecological health, based on FAI model values. However, the ecological health, based on the FAI, became worse in the latest survey conducted in 2019. The analysis of the HAI model based on the organ-level approach showed skin erosion in the fish of upper stream, kidney defects in downstream, and the liver and gill defects observed in all sites, indicating that the anatomical health was also affected.

• Korean Journal of Ichthyology
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• v.7 no.1
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• pp.56-63
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• 1995

Ecological study of the Cynoglossus joyneri was conducted based on the specimens from the western coast of Korea from 1992 to 1994. Ecological characteristics of this species such as gonadal development, occurrence of larvae, stomach contents, and environmental conditions were investigated. Few larvae of Cynoglossus joyneri occurred in Kunsan coast. This coast is influenced by the freshwater input of the Mangyong and Kum River, especially during the summer. Therefore, the larvae of C. joyneri were considered to be spawned and grown during their early life stage in the high saline water in outer bay. Spawning occur from June to September, having the peak spawning period from July to August. Biological minimum size of matured fishes containing mature oocytes is about 143.5mm in total length, which requires about 20 months after hatching. The ranges of total length by age are as follows : 0-ring group(floating stage), 30~70mm ; 1-ring group, 49.0~133.0mm 2-ring group, 128.6~167.0mm ; 3-ring group, 169.0~202.0mm ; 4-ring group, 200.7~240.0mm. The major food items of young fish under 8cm were copepods and invertebrate larvae, and those of adult fishes were annelids(polychaets) in winter, and bivalves and shrimps in summer and autumn. Therefore, it can be assumed that the population of C. joyneri could be reduced due to the decrease of food organisms caused by the continuous reclamation activities in the inner bays of the west coast of Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.23-31
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• 1987

In land treatment systems for organic waste removal, especially rapid intiltration method is well known as less climatic restrictions and less field area requirements as against the others. Therefore the present study on rapid infiltration is aimed to survey the waste removal rate, infiltration rate, variation of dissolved oxygen due to biological oxygen absorption and pH decrement using pilot infiltration column filled with permeable soil(sand) as media, also to find the waste load(COD) per unit area and nitrate conversion ratio from TKN. The results obtained here are as follows. 1) When the depth of sand layer is more than 1 meter, the COD removal would be reached steadly to 90% or more under the infiltration rate below 15~20cm/day, and would be no problem due to leached organic pollutants considering the depth of ground water table. 2) The COD removal per unit area($m^2$) can readily be expected to 10~14g/day with proper operation, and the decomposition of substrate would be attained mostly at the surface layer of the media. 3) Generally the conversion of TKN to the $NO_3{^-}$-N is seemed to be proportional to the COD removal rate if provided proper retention time.

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

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.356-356
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• 2017

A field experiment was performed to evaluate the effects of tillage systems and fertilizer management on yield and nutrient uptake in Soybean. The plant height, fresh weight and dry weight of conventional tillage were much higher those observed for no-tillage. Significant differences in plant height were observed under tillage practices combined with fertilizer treatment. However, the greatest plant height (128.47 cm) was observed in conventional tillage with chemical fertilizer, and the lowest (45.4 cm) was observed in the no-tillage with green manure treatment. The highest fresh weight (172.4 g) and dry weight (44.1 g) were observed from the no-tillage chemical treatment in the late flowering stage of soybean. The plant concentration of nitrate was higher (2.29%) in no-tillage with green manure than it was with chemical fertilization. However, nitrogen increased steadily in all treatments, and the highest quantity of total nitrogen (476.7 Kg/ha) was observed in no-tillage with green manure. The N content in the soil decreased gradually just after the vegetative stage. Tillage practices and additional fertilizer application had an adverse effect on the uptake of N, P and K in soybean seeds. The nitrogen concentration in seeds was found to be increased in the no-tillage with green manure treatment. The uptake of more nitrogen induced a better yield. Thus, the no-tillage with green manure treatment had the greatest yield, although no significant difference was observed among foliar-applications and additional fertilization. Additionally, the phosphorus and potassium concentrations in seeds remained the same between the conventional tillage and no-tillage treatments. The results obtained in this study indicate that no-tillage strategies with fertilizers may influence the growth characteristics and mineral uptake in soybean.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.124-124
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• 2017

Cadmium (Cd) is of particular concern because of its widespread occurrence and high toxicity and may cause serious morpho-physiological and molecular abnormalities in in plants. The present study was performed to explore Cd-induced morpho-physiological alterations and their potentiality associated mechanisms in Sorghum bicolor leaves at the protein level. Ten-day-old sorghum seedlings were exposed to different concentrations (0, 100, and $150{\mu}M$) of $CdCl_2$, and different morpho-physiological responses were recorded. The effects of Cd exposure on protein expression patterns in S. bicolor were investigated using two-dimensional gel electrophoresis (2-DE) in samples derived from the leaves of both control and Cd-treated seedlings. The observed morphological changes revealed that the plants treated with Cd displayed dramatically altered shoot lengths, fresh weights, and relative water content. In addition, the concentration of Cd was markedly increased by treatment with Cd, and the amount of Cd taken up by the shoots was significantly and directly correlated with the applied level of Cd. Using the 2-DE method, a total of 33 differentially expressed protein spots were analyzed using MALDI-TOF/TOF MS. Of these, treatment with Cd resulted in significant increases in 15 proteins and decreases in 18 proteins. Significant changes were absorbed in the levels of proteins known to be involved in carbohydrate metabolism, transcriptional regulation, translation and stress responses. Proteomic results revealed that Cd stress had an inhibitory effect on carbon fixation, ATP production and the regulation of protein synthesis. In addition, the up-regulation of glutathione S-transferase and cytochrome P450 may play a significant role in Cd-related toxicity and stress responses. Our study provides insights into the integrated molecular mechanisms involved in response to Cd and the effects of Cd on the growth and physiological characteristics of sorghum seedlings. The upregulation of these stress-related genes may be candidates for further research and use in genetic manipulation of sorghum tolerance to Cd stress.