• The Plant Pathology Journal
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• v.17 no.6
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• pp.342-346
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• 2001

The physiological changes in sorghum (Sorghum vulgare Pers.) leaves infected with Drechslera sorghicola were investigated through five recognizable stages of disease development. Water-soaked yellowish brown spots developed two days after inoculation, turned brown with yellow halo, enlarged and coalesced at later stages of disease development. Healthy and infected leaves were analyzed for different biochemical constituents. The chlorophyll contents were decreased significantly with the progress of infection. The levels of reducing and total sugars increased while non-reducing sugars decreased to a significant extent with the progress of disease. The concentration of total phenolics, orthodihydroxy phenols, free and glycosidic phenols showed significant changes due to infection, whereas basic and acid phenols showed little or no change with disease development. Levels of phenolic compounds increased four days after inoculation and decrease thereafter, but the concentration was higher at every stage of disease development relative to healthy tissues. Polyphenol oxidase and peroxidase enzyme activities increased to varying degrees at different stages of infection. Analysis of protein fractions showed a significant increase with the progress of disease.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.311-319
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• 2008

To understand the relative immigration activities (RIA) of hibernal diatom community in Lake Ilgam (at the station with and without macrophyte) and River Han (at the station with different current and nutrient), a natural and artificial bed substrate was deposited from 15 to 29 January 2008. For the study period, both waters comprised huge biomass of diatom, over 75% of total abundance. Nutrients in water column, ash-free dry matter (AFDM) and chlorophyll-a (Chl-a) concentration in substrates were decreased with increasing of current in rivers, while in lakes the macrophyte largely affected the diatom community and water quality. Algal RIA in rivers was high at stations with high concentration of nutrient, AFDM and Chl-a, and in high nutrients and no macrophytes in lakes, respectively. The species showing a higher RIA was Nitzschia amphibia in rivers and Aulacoseira italica in lakes, while the dominant species were Navicula sp. in rivers and Syndera acus in lakes, suggesting no relationship between water algal biomass and its RIA. These results suggest that the RIA of stream diatom community depends exclusively on the current, while the planktonic diatom in lake was of the macrophyte.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.209-216
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• 2004

This study was aimed to assess the effects of microclimate factors on lettuce chlorophyll fluorescent responses and to develop an environment control system for plant growth by adopting a simple genetic algorithm. The photosynthetic responses measurements were repeated by changing one factor among six climatic factors at a time. The maximum Fv'/Fm' resulted when the ambient temperature was $21^{\circ}C,\;CO_2$ concentration range of 1,200 to 1,400 ppm, relative humidity of $68\%$, air current speed of $1.4m{\cdot}s^{-1}$, and the temperature of nutrient solution of $20^{\circ}C$. In PPF greater than $140{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, Fv'/Fm' values were decreased. To estimate the effects of combined microclimate factors on plant growth, a photosynthesis efficiency model was developed using principle component analysis for six microclimate factors. Predicted Fv'/Fm' values showed a good agreement to measured ones with an average error of $2.5\%$. In this study, a simple genetic algorithm was applied to the photosynthesis efficiency model for optimal environmental condition for lettuce growth. Air emperature of $22^{\circ}C$, root zone temperature of $19^{\circ}C,\;CO_2$ concentration of 1,400 ppm, air current speed of $1.0m{\cdot}s^{-1}$, PPF of $430{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and relative humidity of $65\%$ were obtained. It is feasible to control plant environment optimally in response to microclimate changes by using photosynthesis efficiency model combined with genetic algorithm.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.21-25
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• 2001

The Keum river has been utilized for drinking water supply of several city including Kunsan city and is deepening pollution state due to numerous municipal and industrial discharges. The concentration BOD in river is affected by the organic loading from a tributary and the algae biomass that largely happen to under eutrophication state. In the eutrophic water mass such as the Keum river, the autochthonous BOD was very important part for making a decision of water quality management, because it was accounted for majority of the total BOD. The predict of water quality has important meaning for management of water quality pollution of the Keum river. The purpose of this study will manage and predict water quality of the Keum river using QUAL-2E model considering the autochthonous BOD. The estimation of autochthonous BOD represented that the relationship between BOD and chlorophyll a. The regression equation was shown to be autochthonous BOD=$\beta$(sub)5$\times$chlorophyll a. The results of this study may be summarized as followed; The QUAL-2E model was calibrated with the data surveyed in the field of the study area in June, 1998. The calculated value by QUAL-2E model are in good agree to measured value within relative error of 7.80~20.33%. Especially, in the case of the considering autochthonous BOD, the calculated value of BOD were fairly good coincided with the observed values within relative error of 15%. But the case of not considering autochthonous BOD, relative error of BOD was shown to be 43.2%. In order to attain II grade of water quality standard in Puyo station which has a intake facility of water supply, we reduced to the pollutants loading of tributaries. In the case of removed 100% BOD of tributaries, the BOD of Puyo station was 4.07mg/$\ell$, belong to III grade of water quality standard. But in the case of removed 88% nutrient of tributaries, it was satisfied to II grade of water quality standard as below 3mg/$\ell$ of BOD. For estimation of autochthonous BOD in Keum river, we are performed simulating in accordance with reduction of nutrient load(50~100%) under conditions removal 90% organic load. Occupancy of autochthonous BOD according to nutrient loading reductions were varied from 25.97~79.51%. Occupancy of autochthonous BOD was shown to be a tendency to increasing in accordance with reduction of nutrient loading. Showing the above results, the nutrient that one of the growing factor of algae was important role in decision of BOD in the Keum river. For the water quality management of the Keum river, therefore, it is necessary to considering autochthonous BOD and to construction of advanced sewage treatment plant for nutrient removal.

• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.165-180
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• 2019

Water quality data of 81 lakes in Korea, 2013 ~ 2017 were analyzed. Most water quality parameters showed left-skewed distribution, while dissolved oxygen showed normal distribution. pH and dissolved oxygen showed a positive correlation with organic matter and nutrients, which appeared to be a nonsense correlation mediated by the algae. The ratio of $BOD_5$ and $COD_{Mn}$ to CBOD was 21 % and 52 % in the freshwater lakes, respectively. TOC concentration appeared to be underestimated by the UV digestion method, when salinity exceeds $700{\mu}S\;cm^{-1}$. In terms of nitrogen/phosphorus ratio, the limiting factor for algal growth seemed to be phosphorus in most of the lakes. Chlorophyll ${\alpha}$ increased acutely with decrease of N/P ratio. However, it seemed to be a nonsense correlation mediated by phosphorus concentration, since the N/P ratio depended on phosphorus. The N/P ratio of brackish lakes was lower than that of the freshwater, at the same concentration of phosphorus. It is worth examining denitrification that occurs, in bottom layer and sediment, during saline stratification. $Chl.{\alpha}$ concentration decreased in the form of a power function with increase of mean depth. The primary reason is that deep lakes are mainly at the less-disturbed upstream. However, it is necessary to investigate the effect of sediment, on water quality in shallow lakes. Light attenuation in the upper layer, was dominated by tripton (non-algal suspended solids) absorption/scattering (average relative contribution of 39 %), followed by CDOM (colored dissolved organic matter) (average 37 %) and $Chl.{\alpha}$ (average 21 %).

• Journal of Environmental Science International
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• v.1 no.1
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• pp.13-21
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• 1992

The inhibitory effects of mercury ions on the growth of barley seedlings were studied and the distribution of metal elements in the organs of treated plants was investigated by using synchrotron radiation induced X-ray emission (SRIXE). Although the treatment of mercury ions caused growth inhibition, the mercury-specific increase in variable fluorescence and the abolishment of energy-dependent quenching in broken barley chloroplasts as shown by Moon et at. (1992) were not observed in the leaves of growth-inhibited seedlings. Instead the treatment of mercury decreased Fmax and Fo values. However, Fmax/Fo ratio and photochemical and nonphotochemical quenching coefficients were not affected significantly. By SRIXE analysis of $10\mu\textrm{m}$ mercury chloride treated seedlings, accumulation of mercury in roots was observed after 1 hour of treatment and similar concentration was sustained for 48 hours. Relative contents of mercury was high in roots and underground nodes where seeds were attachedl but was very low in leaves. Iron and zinc were also distributed mainly in the lower parts of the seedlings. However after 72 hours of treatment the contents of these metals in roots decreased and their distribution became more uniform, which may lead to death of the plants. These results suggest that the observed inhibitory effects on barley seedlings upto 48 hours after the treatment is not due to direct damages in the photosynthetic apparatus, but due to its accumulation in roots and the consequent retardation of the growth of barley seedlings. The decrease in Fmax and Fo is probably due to the decrease in chlorophyll and protein contents caused by the retardation of growth. The observed slow expansion of primary leaves could be also explained by the retardation of growth, but the fluorescence induction pattern from the leaves did not show characteristic symptoms of leaves under water stress.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.505-515
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• 2015

The objectives of this study were to determine the effects of stream nutrient regime, N:P ratios and suspended solids on fish tolerance/trophic compositions and stream ecosystem health, based on multi-metric model, during 2008-2013. Also, stream ecosystem health was evaluated in relation to chlorophyll-a (CHL) as a measure of algal productivity or indicators of trophic state to water chemical parameters. Total number of sampled fish species were 50 and showed a decreasing trend from 2008 to 2013. The minnow of Zacco platypus, based on the catch per unit effort (CPUE), was the most dominant species (25.9%) among the all species. Spatial heterogeneity was evident in the fish tolerance guilds that showed the dominance of sensitive species (89%) in the headwaters (S1) and the dominance of tolerant species (57%) in the urban. These conditions were directly influenced by concentrations of nutrients and organic matter (COD). The N:P ratios, as a barometer of water pollution, had a negative linear function (R² = 0.40, P < 0.01) with CHL, and the ratios had an important role in changes of COD concentration (R² = 0.40, P < 0.01). Under the circumstances, the N:P ratio directly influenced the relative proportions of fish trophic/tolerance compositions. According to the regression analysis of omnivore (O_m) and insectivore sp. (I_n) on total nitrogen and total phosphorus, nitrogen had no significant influences (P > 0.05) to the two compositions, but phosphorus influenced directly the two guilds [slope (a) = -32.3, R² = 0.25, P < 0.01 in the I_n; a = 40.7, R² = 0.19, P < 0.01 in the O_m]. Such water chemistry and fish trophic guilds determined the stream ecosystem health, based on the multi-metric fish model.

• Journal of Ecology and Environment
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• v.31 no.2
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• pp.161-165
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• 2008

This study was performed for the purpose of monitoring monthly levels of two pathogenic microorganisms, Cryptosporidium and Giardia, from November 2005 to August 2007 in Sangsa Lake. Water temperatures, pH and DO fluctuated seasonally at the study site. Annual mean values of BOD, COD and SS were $0.8\;mg\;L^{-1}$, $2.3\;mg\;L^{-1}$ and $1.9\;mg\;L^{-1}$ respectively. Although there was distinct seasonal variation in water chemistry and chlorophyll $\underline{a}$ concentration, the lake generally contains low concentrations of nutrients and chlorophyll $\underline{a}$. The relative abundance of coliform bacteria was always greater than that of fecal coliform. The fecal coliform bacteria comprised $8.5{\sim}22.1%$ of total coliform bacteria. Seasonal analysis of Cryptosporidium and Giardia levels in the study site showed that in winter (November through February), Cryptosporidium oocysts and Giardia cysts were most abundant ($1.1{\sim}1.8\;{\times}\;10\;cells\;L^{-1}$ and $3.8{\sim}5.1\;{\times}\;10\;cells\;L^{-1}$, respectively), while in summer (July through September) the abundance was lowest ($0.0{\sim}0.3\;{\times}\;10\;cells\;L^{-1}$ and $0.9{\sim}2.9\;{\times}\;10\;cells\;L^{-1}$, respectively). Molecular identification revealed two subtypes of Cyrptosporidium parvum in Sangsa Lake.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.120-125
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• 2014

Halophytes are plants of saline habitats that grow under conditions that may vary in extremes of temperatures (freezing to very hot), water availability (drought to water logging) and salinity (mild to almost saturation). Halophytes may also face sudden micro-environmental variations within their habitats. In this study, we examine some of the factors that determine the ability of seeds of Artemisia fukudo to germinate when conditions are optimal for seedling growth and survival. Germination percentage was the highest at 77.5% when treated in 0% seawater and seedling growth was best in 0% seawater plug cell tray. Physiological quality (chlorophyll contents) and mean germination time were best in the condition in which seeds were treated with 0% seawater (control). Germination performance index in the control group showed the highest value to 3.8. Seedling growth, seedling vigor index in the length of seedling growth andthe relative growth rate were the highest values of 0.76 cm, 1.43, 0.0099, respectively.

• ALGAE
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• v.21 no.1
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• pp.83-90
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• 2006

Phytoplankton community in the coastal waters off the northeastern Korean Peninsula were characterized from May 2002 to August 2003. Taxonomic composition, abundance and biomass were determined at two water depths at 10 sample sites. A total of 153 phytoplankton species including 121 diatoms, 28 dinoflagellates, 7 green algae and 7 other species were identified. The mean abundance of phytoplankton varied from 15 to 430 cells mL–1 in the surface layer and from 11 to 545 cells mL–1 in the bottom layer, respectively. Phytoplankton was more abundant in coastal stations relative to those in more open ocean. The most dominant species were marine diatoms such as Thalassionema nitzschioides, Licmorphora abbreviata, Chaetoceros affinis and Chaetoceros socialis. In addition, a few limnotic diatoms including Fragilaria capucina v. rumpens, the green alga Scenedesmus dimorphus, some marine dinoflagellates and Cryptomonas sp. appeared as dominant species. Mean concentration of total chlorophyll-a varied from 0.22 to 7.87 μg chl-a L–1 and from 0.45 to 6.79 μg chl-a L–1 in the surface and bottom layers, respectively. The contribution of phytoplankton each size-fractionated varied highly with season. The contribution of microphytoplankton to total biomass of phytoplankton in the surface and bottom layer was high in February and August 2003, and that of nano-phytoplankton was high in May 2002 in both surface and bottom layers.