• Journal of Microbiology
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• v.41 no.4
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• pp.271-276
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• 2003

The inoculation of some microorganisms into a microcosm containing soil from a barren lakeside area at Lake Paro in Kangwon-do enhanced plant growth significantly. The direct and viable counts of soil bacteria and soil microbial activities measured by electron transport system assay and fluorescein diacetate hydrolysis assay were higher in inoculated soil. The plant growth promoting effect of this inoculation may be caused by phytohormone production and the solubilization of insoluble phosphates by the inoculated bacteria. Three inoculated strains of Pseudomonas fluorescens produced several plant growth promoting phytohormones, including indole-3-acetic acid (auxin), which was confirmed by thin layer chromatography and GC/MS. P. fluorescens strain B16 and M45 produced 502.4 and 206.1 mg/l of soluble phosphate from Ca3(PO4)2 and hydroxyapatite, respectively. Bacillus megaterium showed similar solubilization rates of insoluble phosphates to those of Pseudomonas spp. We believe that this plant growth promoting capability may be used for the rapid revegetation of barren or disturbed land.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2019-2028
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• 2018

Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at $200{\mu}mo/m^2/s$ under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.7
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• pp.530-535
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• 2011

In this work, the adsorption characteristic of the composites by adding loess with aluminum ("Al-loess") and Loess with lanthanum ("La-loess") which have been developed to effectively remove phosphorus, the substance which causes the eutrophic lake has been evaluated. According to the result of the work, as the amount of aluminum or lanthanum put in 1g of loess increases, the combined amount also increases accordingly. When the loess with no aluminum or lanthanum attached was used, the rate of removing phosphorus was different in comparison with the case of using the composites of 0.5, 1 and 2 mg of aluminum and 0.5, 1 and 3 mg of lanthanum in each gram of loess. It was observed the amount required to remove 1 mg $PO_4^{3-}$-P/L of phosphorus completely is approximately 2 to 10 times less for the composite of Al-loess than loess alone. Also, in case of the composite of La-loess, the amount was decreased by about 1.5 to 10 times. In order to observe the rate of adsorption phosphorus with Al-loess and La-loess, the composites were used for the observation up to three times by water washing. As a result, the water washing of the composite did not affect phosphorus removal. According to the effect of pH, there is a high rate of removing phosphorus in the pH range of 5~8. It seems that the developed composite will effectively remove phosphorus when it is spread in the natural water system. Also, since Al-loess and La-loess composites are rapidly precipitated within 30 minutes, it is stabilized quickly at the bottom of the eutrophic lake and becomes responsible for the removal of phosphorus in water and eluted from the water and the sedimentary layer.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.68-76
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• 2008

This study examined the inhibition effects of a freshwater bivalve (Unio douglasiae) and a submerged plant (Potamogeton crispus) on the cyanobacterial bloom (Oscillatoria sp.). The experiment were conducted in aquarium $(50cm{\times}65cm{\times}120cm)$ with lake sediments in the bottom of the aquarium in 10 cm thick. Before the experiments, artificial cyanobacterial bloom was induced with the addition of lake sediment and CB medium. Total 12 transparent acrylic cylinders (${\Phi}19cm$, height 40 cm) were placed in the aquarium, and within which bivalves and plants were placed in various conditions such as the control (C), plant addition (P:5 stems), mussel addition (U:2 individuals), and both mussel and plant addition (PU: the same quantity as used in each treatment). The experiment was conducted in triplicate during 7 days. pH, dissolved oxygen (DO), electric conductivity (EC), salinity, cyanobacterial cell density, chlorophyll-${\alpha}$ concentration, and mussel filtering rate were monitored daily. At the end of the experiment, total phosphorus (TP), total nitrogen (TN), and plant height and weight were measured. Overall, a large degree of cyanobacterial growth inhibition appeared in both P and U treatments, and the effect was highest in the U treatment, followed by P and PU. The combined treatment of both U and P did not show any synergic effects compared to the effect in separated treatment. In all enclosures of the treatments chlorophyll-${alpha}$ (Chl-${alpha}$) concentration decreased until 36 hours after the additions of the plants and mussels. In contrast, Chl-${alpha}$ concentrations increased in PU enclosures after 36 hours. The same trend was shown in the cell density of Oscillatoria. pH and DO gradually decreased until 120 and 144 hours, respectively, in the P and PU enclosures. TP concentration increased in the mussel enclosures (U and PU), while TN concentration largely decreased in the plant enclosures (P and PU). Our results suggest that applied bivalve (Unio) and submerged plant (Potamogeton) seemed to have a potential effect on the growth inhibition of cyanobacteria, but their combined application may have an antagonistic effect to diminish the degree of the inhibition.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.33-37
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• 2010

Rhizobacterial strain isolated from barren soil, Bacillus subtilis RFO41 exhibits a high level of phosphate solubilizing activity and produces some phytohormones. Its promoting effect on the growth of Xanthium italicum Moore, a wild plant growing at lakeside barren land and thus a good candidate plant for revegetation of barren lakeside was evaluated in the in situ test for 19 weeks at Lake Paro, Kangwon-do. Strain RFO41 could enhance the dry weight of X. italicum by 67.7%. It also increased the shoot length of X. italicum plant by 21.1% compared to that of uninoculated control. Both growth enhancements had statistical significance. However, the inoculation did not show any effect on the root growth, which might be due to the breakage of tiny root. Denaturing gradient gel electrophoresis analysis showed that the inoculated bacteria were maintained in the soils, and the indigenous bacterial community did not exhibit any significant change. This plant growth promoting capability may be utilized as an environment-friendly and low cost revegetation method, especially for the sensitive areas such as barren lakeside lands.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.670-679
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• 2017

An experiment to study the effect of temperature, light, and dredging on release of nutrients downstream from Gongjicheon in the Uiam reservoir was carried out in the laboratory using sediments from different depths. At various water temperatures, dissolved total nitrogen was not released, but the average nutrient flux of dissolved total phosphorus was increased (0.034 at $15^{\circ}C$, 0.005 at $20^{\circ}C$, 0.154 at $25^{\circ}C$, $0.592mg/m^2/d$ at $30^{\circ}C$). Dissolved total phosphorous was released in controlled darkness. In contrast, in controlled light, the concentrations of dissolved total phosphorous and dissolved total nitrogen in the overlying water steadily decreased during the study period (70 d), because they were continuously consumed by the growth of photosynthetic algae. However, there was no significant relationship between water nutrient concentration, nutrient release, and the depth of the sediment. We concluded that the dredging of sediment would not affect the nutrient release rate of the sediment, because there were no significant differences in the nutrient concentrations released from the sediment. When the sediment was removed from the surface to 20 cm in depth, the nutrients were not transferred to the water body, implying that the sediment removal had little effect on secondary pollution.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.267-274
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• 2016

Sewerage supply in rural community is the important for water quality protection of water system such as river, lake and wetland. And characteristic of small scale wastewater system that have wide range of inflow and concentration in sewage should be considered for stable operation of small scale wastewater treatment plant. In this research, characteristics of flow ratio (flow / designed flow), effect on treatment efficiency of small scale wastewater treatment plant and assessment of optimal flow ratio were conducted through analysis on operation result of 18 small scale wastewater treatment plant in Bong-hwa gun. As a result, flow ratio shows the higher value during summer. However pollutants concentration in sewage was shown the higher concentration during autumn and winter. Treatment of small scale wastewater treatment plant is increased when flow ratio increased, and nutrient treatment efficiency is more sensitive to change of flow ratio than organic compound and suspended solids. According to this research result, it need to be maintained flow ratio 0.8 over value for stable treatment efficiency of small scale wastewater treatment plant.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.722-725
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• 2007

Geum River Estuary Barrage is very important for the irrigation, municipal and industrial uses in the cities of Gunsan, Iksan and Jeonju. The Geum River Control Office has a flood forecasting system; however, the current system does not consider the backwater effects. As a result, it is very difficult to give correct flood information, and it is difficult to accurately assess the water resource supply and saltwater invasion into freshwater, as frequently occurs due to over-discharge during floods. In this study, we investigate the flood forecasting system for the Geum River reach influenced by the estuary barrage. The current system cannot consider the backwater effect because the estuary barrage blocks the end of the river. We calculated the discharge from the tide lock and evaluated the inside water level of the estuary barrage during floods. The results show that the calculation agrees well with the observed data at the river stage stations in the Geum River. The results also show that this program is a reasonable substitute for the current system.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.556-562
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• 2008

We divided the downstream of South-Han River into three water zones, such as river zone, transition zone and lacustrine zone depending on the flow rate, and elucidated the major effect factors on the growth of phytoplankton and the sources of organic matters in each water zone. The difference of chlorophyll-a concentration which represents the standing crop of phytoplankton was statistically significant among the water zones. From the results of bivariate correlation analysis between chlorophyll-a concentration and water quality parameters in each water zone, the outflow of Chungju dam and hydraulic retention time of Lake Paldang which are directly related with the flow rate seemed to have obvious impact on phytoplankton growth in the downstream of South-Han River. The concentration of nutrients such as phosphorus and nitrogen exceeded the criterion of eutrophication and did not showed significant relationship with chlorophyll-a concentration. There were strong correlations between $BOD_5$ and chlorophyll-a concentrations in transition and lacustrine zone showing autochthonous production of phytoplankton was dominant source of organic matters in these zones especially in dry seasons. The results of this study show that the control of abundance of phytoplankton is the key target for reduction of the organic pollution in the downstream of South-Han River.

• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.81-91
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• 2012

In this study, it is grasped the status of nutrients through an investigation of release characteristics and physicochemical properties of sediments on reservoir. And then the effect of sediments is evaluated on the water quality in reservoir. In the results of physicochemical analysis, the pollution level of midstream is the highest, which shows the traits that the water is more deeper and takes place a deposition consistently. Then, the pollution level of upstream is higher than downstream's because inflow has influence on the upstream directly. The downstream is located near tidal gate so that the soil particles can be moved easily and are difficult to be deposited due to the distribution of seawater by control of tidal gate. Therefore, the downstream is showed the lowest pollution level than the others. Also, the concentration of SOD(Sediment Oxygen Demand) in the upstream which is influenced on the effect of inflow is highest than the others. When it analyzes under anaerobic and aerobic condition to understand the release characteristic of sediment, it shows that the release rate is low or negative under the aerobic condition. Whereas the release rate is usually positive under the unaerobic condition relatively. According to these results, it is necessary to maintain the proper environmental factors of water body for decreasing the release rate of sediment. Because the release rate is changeable under the different condition of water body. Therefore, proper strategies are required for increasing the self-purification of water as well as keeping the aerobic condition of sediment and managing a sediment layer directly to control the inner-pollution by the sediment of reservoir.