• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.102-114
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• 2013

The basin of Lake Shihwa is one of highly industrialized region of Korea and a current environmental issue of study area is the operation of tidal power plant (TPP) to improve water quality. The application of water quality index (WQI) which integrates five physiochemical parameters (transparency, DO, DIN, DIP and chlorophyll-a) of water quality in Lake Shihwa and outer sea during 2011~2012 were performed not only to evaluate the spatial and temporal distribution of the water quality but also to assess the effect of water quality improvement by the operation of tidal power plant. The higher WQI values were observed in monitored sites near the industrial complexes in Lake Shihwa and the outfall of wastewater treatment plants (WWTPs) in outer sea. This indicates that the quality of seawater is influenced by diffuse non-point sources from industrial, municipal and agricultural areas in Lake Shihwa and by point sources from the effluence of municipal and industrial wastewater throughout WWTPs in outer sea. Mean WQI value decreased from 53.0 in 2011 to 42.8 in 2012 of Lake Shihwa. Water quality has improved significantly after TPP operation because enhancement of seawater exchange between Lake Shihwa and outer sea leads to improve a hypoxic condition which is primarily a problem in Lake Shihwa. Mean WQI of outer sea showed similar values between 2011 and 2012. However, the results of hierarchical cluster analysis and the deterioration of water quality in summer season indicate that the operation of tidal power plant was not improved the water quality in the upper most area of Lake Shihwa. To successfully improve overall water quality of Lake Shihwa, it is urgently necessary to manage and reduce of non-point pollution sources of the basin of Lake Shihwa.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.257-263
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• 2016

Recently, an interest has developed in the use of whole green grains as functional food materials. The present study was conducted to provide the baseline data for the stable production of whole green grains in 20 cultivars of wheat by investigating the greenness of grain with maturation (from $20^{th}$ to $41^{st}$ day after heading, at an interval of 3 days). On the $20^{th}$ day after heading, the grains were dark green with a wrinkled long-oval shape. After the $35^{th}$ day of heading, the grains turned almost yellow with an oval shape. Their redness ('a' value of chromaticity) increased from the $20^{th}$ to $41^{st}$ days after heading, indicating a negative value up to the $32^{nd}$ day after heading. A significant decrease in their chlorophyll content was observed with maturation. The yield of whole green wheat grain (including greenish yellow grain) was the highest from the $32^{nd}$ to $35^{th}$ after heading. Therefore, we concluded that the optimal harvesting period for whole green wheat grain was from the $32^{nd}$ to $35^{th}$ day after heading. The heading time of various cultivars ranged from April 28 to May 5, the time of Jopummil cultivar grew the fastest among them, such as Gurumil, Alchanmil, but Dahongmil got the latest in heading time. The greenness of seven cultivars (Jeokjungmil, Keumkangmil, Jogyeongmil, Jopummil, Baekjungmil, Yeonbaekmil, and Milseongmil) was relatively higher than that of the others. The yield of greenish whole grain was relatively high in six cultivars (Alchanmil, Baekjungmil, Eunpamil, Yeonbaekmil, Dahongmil, and Urimil). Based on their greenness and yield, the Baekjungmil and Yeonbaekmil cultivars have been considered to be optimal for the production of whole green wheat grain.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.18-29
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• 2016

The effects of water temperature, salinity, water column nutrient contents, and phytoplankton primary productivity on pigment composition and concentration, as well as primary productivity of Pyropia yezoensis Ueda purple lavers were studied at the primary cultivation areas in the Manho (Jindo-Haenam) region on the southwestern coast of Korea in March 2014. The water temperature was $9.1{\sim}9.6^{\circ}C$, salinity was 32.5~33.1, and transparency was 0.7~1.5 m. The shallow euphotic depth resulted from the high turbidity. Water column dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and silicate concentrations were $3.59{\sim}5.73{\mu}M$, $0.16{\sim}0.41{\mu}M$, and $12.41{\sim}13.94{\mu}M$, respectively. Chlorophyll a (Chl a) concentration was $0.51{\sim}1.25{\mu}g\;L^{-1}$. Nanoplankton ($0.7{\sim}20{\mu}m$ size class) accounted for 58% of the total Chl a concentration. Fucoxanthin was the dominant photosynthetic pigment at all sites. Microplankton ($20{\sim}200{\mu}m$ size class) accounted for 64% of the total fucoxanthin concentration. The primary productivity of phytoplankton was $57.72{\pm}4.67(51.05{\sim}66.71)mg\;C\;m^{-2}d^{-1}$. The nanoplankton ($0.7{\sim}20{\mu}m$ size class) accounted for 77% of the total phytoplankton primary productivity. The calculated phytoplankton primary productivity was $11,337kg\;C\;d^{-1}$. The primary productivity of Pyropia blades was $1,926{\pm}192(1,102{\sim}2,597)mg\;C\:m^{-2}d^{-1}$, i.e., calculated as $39,295kg\;C\;d^{-1}$. The total primary productivity of phytoplankton and Pyropia blades was $50,632kg\;C\;d^{-1}$. The primary productivity of Pyropia blades was 3.5 times greater than that of phytoplankton in the Manho region on the southwestern coast of Korea.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.303-312
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• 2007

In order to investigate the dynamics of phytoplankton standing crops affecting by environmental factors, biological and environmental factors, this study was examined in the marine ranching ground of Tongyeong coastal waters from 2000 to 2007. During the study, mean water temperature and salinity were 16.7$^{\circ}C$ and 32.9 psu, respectively. pH, DO and SS varied from 7.81$\sim$8.09, 3.02$\sim$8.97 mg $L^{-1}$ and 2.7$\sim$32.2 mg $L^{-1}$, respectively. Mean concentrations of dissolved inorganic nitrogen, phosphate and silicate were 21.75 ${\mu}M$, 0.90 ${\mu}M$ and 14.38 ${\mu}M$, respectively. Chlorophyll a concentrations varied from 0.02 ${\mu}g$ $L^{-1}$ to 25.29 ${\mu}g$ $L^{-1}$ with mean a value of 2.0 ${\mu}g$ $L^{-1}$. These factors did show significant differences on each layer and season, while did not show on the sampling stations. Phytoplankton standing crops varied from $4.21\times10^3$ cells $L^{-1}$ to $1.44\times10^6$ cells $L^{-1}$ with a mean value of $1.92\times10^5$ cells $L^{-1}$. Especially, variations of phytoplankton standing crops had an unimodal pattern as only bloomed in autumn rather than a bimodal pattern as generally bloomed in spring and autumn. In results of stepwise multiple regression analysis, the coefficient of determination $(R^2)$ for total standing crops was 0.35 and the standing crops were affected by water temperature, salinity, phosphate and silicate. The factors affected were different seasonally; water temperature in spring, salinity in summer, water temperature, salinity and silicate in autumn and water temperature, salinity and suspended solids in winter. Therefore, the results from the statistical analysis showed that the environmental factors influencing on the variations of the phytoplankton standing crops were predominantly water temperature and salinity.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.221-230
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• 2016

Multi-functional floating wetland island (mFWI) was developed in order to prevent algal bloom and to improve water quality through several unit purification processes. A test bed was applied in the stagnant watershed in an urban area, from the summer to the winter season. For the advanced treatment, an artificial phosphorus adsorption/filtration medium was applied with micro-bubble generation, as well as water plants for nutrient removal. It appeared that the efficiency of chemical oxygen demand (COD) and total phosphorus (T-P) removal was higher in the warmer season (40.9%, 45.7%) than in the winter (15.9%, 20.0%), and the removal performance (suspended solid, chlorophyll a) in each process differs according to seasonal variation; micro-bubble performed better (33.1%, 39.2%) in the summer, and the P adsorption/filtration and water plants performed better (76.5%, 59.5%) in the winter season. From the results, it was understood that the mFWI performance was dependent upon the pollutant loads in different seasons and unit processes, and thus it requires continuous monitoring under various conditions to evaluate the functions. In addition, micro-bubbles helped prevent the formation of anaerobic zones in the lower part of the floating wetland. This resulted in the water circulation to form a new healthy aquatic ecosystem in the surrounding environment, which confirmed the positive influence of mFWI.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.31-39
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• 2002

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water column can accumulate in sediments at much higher levels. The purpose of this study was to make optimal treatment and disposal plan o( sediment for water quality improvement in small-scale resevoir based on an evaluation of degree of contamination. The degree of contamination were investigated for 23 samples of 9 site at different depth of sediment in small-scale J river. Results for analysis of contaminated sediments were observed that copper concentration of 4 samples were higher than the regulation of hazardous waste (3 mg/L) and that of all samples were exceeded soil pollution warning levels for agricultural areas. Lead and mercury concentration of all samples were detected below both regulations. Necessary of sediment dredge was evaluated for organic matter and nutrient through standard levels of Paldang lake and the lower Han river in Korea and Tokyo bay and Yokohama bay in Japan. The degree of contamination for organic matter and nutrient was not serious. Compared standard levels of Japan, America, and Canada for heavy metal, contaminated sediment was concluded as lowest effect level or limit of tolerance level because standard levels of America and Canada was established worst effect of benthic organisms. The optimal treatment method of sediment contained heavy metal was cement-based solidification/stabilization to prevent heavy metal leaching.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.250-259
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• 2011

This study was conducted to assess the possibility of 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) as a environmental friendly herbicide candidate. Foliar application of DHNQ showed excellent herbicidal effect to the 3 grasses and 5 broad-leaved weeds. Among them, Digitaria sanguinalis and Solanum nigrum were completely controlled by $250{\mu}g\;mL^{-1}$ of DHNQ with main symptoms of desiccation or burndown within 24 hours. Aeschynomene indica was also sensitive to DHNQ treatment. All of the eight weed species were controlled by 90~100% at a concentration of $1000{\mu}g\;mL^{-1}$. However, soil application of DHNQ to Digitaria sanguinalis did not show any herbicidal symptoms. DHNQ strongly inhibited KAPAS activities in vitro and the $IC_{50}$ was $4.4{\mu}M$. Cellular leakage from cucumber leaf squares treated with DHNQ increased depending on the concentrations increased from 6.25 to $100{\mu}M$ after 24 hours incubation with or without light. However, chlorophyll loss in cucumber leaf squares was negligible. Biotin supplements significantly rescued the inhibition of germination rate of Arabidopsis thaliana seeds previously inhibited by the DHNQ. According to above results, DHNQ is a good natural herbicide candidate having a new target KAPAS, which is involved in biotin biosynthesis pathway, with environmental friendly.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.187-196
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• 2000

This paper describes a simple method that uses differences among Carlson's (1977) trophic state index (TSI) values based on total phosphorus (TP), chlorophyll a (CHL) and Secchi depth (SD) to draw inferences regarding the factors that are limiting to phytoplankton growth and the composition of lake seston. Examples are provided regarding seasonal and spatial patterns in a large subtropical lake (Lake Okeechobee, Florida, USA) and inter- and intra-lake variations from a multilake data set developed from published studies. Once an investigator has collected routine water quality data and established TSI values based on TP, CHL, and SD, a number of inferences can be made. Additional information can be provided where it also is possible to calculate a TSI based on total nitrogen (TN). Where TSI (CHL)<>TSI (SD), light attenuating particles are large (large filaments or colonies of algae), and the phytoplankton may be limited by zooplankton grazing. Other limiting conditions are inferred by different relationships between the TSI values. Results of this study indicate that the analysis is quite robust, and that it generally gives good agreement with conclusions based on more direct methods (e.g., nutrientaddition bioassays, zooplankton size data, zooplankton removal experiments). The TSI approach, when validated periodically with these more costly and time-intensive methods, provides an effective, low cost method for tracking long-term changes in pelagic structure and function with potential value in monitoring lake ecology and responses to management.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.128-135
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• 2000

The authors surveyed the seasonal variations of environmental factors, the distributions of heterotrophic bacteria and Anabaena cylindrica growth-inhibiting bacteria at each water layer in Daechung Reservoir to verify the role of bacteria during the extinction of bloom. Average water depth at site 1, 2, and 3 were 25.5 m, 15.0 m and 12.3 m, respectively. Water temperature showed a typical pattern seasonally. The variation of DO was relatively inverse proportional to that of water temperature, although it was irregular during summer time. DO decreased gradually to early May, fluctuated sharply after then, and followed by gradual increasement after middle of September. This variation pattern was notable at surface layer. There was remarkable difference in DO concentraion between surface layer and the other water layers during the period in which DO irregulary varied. The variation range of chlorophyll-a concentraion at surface layer in summer time was broad, and it was relatively high when DO was high. The population size of heterotrophic bacteria was high from Spring to Autumn, an declined after September when the water temperature droped rapidly. Especially this variation pattern was prominent at the surface layer. Bacteria that inhibit the growth of A. cylindrica was almost not detected by June, and its distribution increased in July. Afterward, it showed different variation pattern between each site. The distribution of A. cylindrica growth-inhibiting bacteria was higher at the middle and bottom layer than the surface layer in July and October, when it was larger at all sites for the study period. This result suggests that the antagonistic bacteria exhibit higher activity when host activity drops. These results also suggest that natural water bacteria control the distirbution of cyanobacteria, especially its activity as controller is remarkable when cyanobacterial growth declines.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.176-186
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• 2000

The present study was carried out to clarify the structure and dynamics of copepod community and the relationship between this community and environmental factors during the period from February 1998 to July 1999. Copepods consists of 21 genera and 32 species, monthly variations of number of species were 15 species in May, 1998 and 2 species November, 1998. The number of species were 22 species in station 12 and station 1, 2, 3 occurred nauplii of copepoda only. Average abundance ranged from $8,330\;ind./m^3$ (in June, 1999) to $177\;ind./m^3$ (in November, 1998). Relationships between water temperature and number of species were as follows: 20 species occurred from 20.1 to $25.0^{\circ}C$ and nuplii of copepoda only occurred from 0.0 to $5.0^{\circ}C$. The number of species by salinity range were 19 species in $20.1{\sim}25.0%_o$ and 9 species in $0{\sim}0.5%_o$. The number of species by trophic state index (TSIm) of chlorophyll a were 25 species in oligotrophic state and 9 species in eutrophic state. Relationships between pH and number of species were as follows: 20 species occurred from 7.6 to 8.0 and from 9.1 to 9.5 was none. The number of species by DO range were 22 species in 6.5 to 7.5 mg/l and 1 species in 14.5 to 15.5 mg/l. The percentage calculated effect by stepwise multiple regression of the pearson correlation coefficient value of environmental factors and copepoda abundance (station 1-station 4) revealed that positive effect was 15.49% in COD, 25.86% in $Cl^-$, 19.75% in $NO_2-N$ and negative effect was 28.30% in $NO_3-N$. Also, Positive effect (station 5-station 12) revealed that 29.49% in water temperature, 28.27% in $NO_3-N$, 22.87% in $NO_2-N$ and negative effect was 30.18% in conductivity and 13.53% in DO.