• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.605-619
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• 2019

The objective of this study was to analyze eutrophication characteristics, empirical model analysis, and variation of water quality according to monsoon intensity in Hapcheon Reservoir for 16 years from 2002 to 2017. Long-term annual water quality analysis showed that Hapcheon Reservoir was in a meso-nutrition to eutrophic condition, and the eutrophic state intensified after the summer monsoon. Annual rainfall volume (high vs. low rainfall) and the seasonal intensity in each year were the key factors that regulate the long-term water quality variation provided that there is no significant change of the point- and non-point source in the watershed. Dry years and wet years showed significant differences in the concentrations of TP, TN, BOD, and conductivity, indicating that precipitation had the most direct influence on nutrients and organic matter dynamics. Nutrient indicators (TP, TN), organic pollution indicators (BOD, COD), total suspended solids, and chlorophyll-a (Chl-a), which was an estimator of primary productivity, had significant positive relations (p<0.05) with precipitation. The Chl-a concentration, which is an indicator of green algae, was highly correlated with TP, TN, and BOD, which differed from other lakes that showed the lower Chl-a concentration when nutrients increased excessively. Empirical model analysis of log-transformed TN, TP, and Chl-a indicated that the Chl-a concentration was linearly regulated by phosphorus concentration, but not by nitrogen concentration. Spatial regression analysis of the riverine, transition, and lacustrine zones of $log_{10}TN$, $log_{10}TP$, and $log_{10}CHL$ showed that TN and Chl-a had significant relations (p<0.005) while TN and Chl-a had p > 0.05, indicating that phosphorus had a key role in the algal growth. Moreover, the higher correlation of both $log_{10}TP$ and $log_{10}TN$ to $log_{10}CHL$ in the riverine zone than the lacustrine zone indicated that there was little impact of inorganic suspended solids on the light limitation in the riverine zone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.493-501
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• 1993

As the dispersants and the dispersant/oil mixtures are degraded naturally by the microorganisms in the seawater, the consumption of dissolved oxygen may cause marine organisms to be damaged especially in the waters where the dissolved oxygen level is low due to the pollution and the restriction of seawater flow. The biodegradation experiment, the TOD analysis and the element analysis for three dispersants(SG, GL and WC) and a nonionic surfactant(OA-5) were conducted for the purposes of evaluating the biodegradability of dispersants and studying the effect of dispersants on dissolved oxygen in the seawater. The results of biodegradation experiment showed 1mg of dispersants to be equivalent to $0.403{\sim}0.595mg$ of $BOD_5$ and to $0.703{\sim}0.855mg$ of $BOD_{20}$, and 1mg of nonionic surfactant to be equivalent to 0.50mg of $BOD_5$ and to 0.97mg of $BOD_{20}$ in the natural seawater. The results of TOD analysis showed 1mg of dispersants to be $2.37{\sim}2.80mg$ of TOD and 1mg of nonionic surfactant to be 2.45mg of TOD. The results of element analysis showed carbon content and hydrogen content to be $67.6{\sim}76.5\%$ and $10.2{\sim}12.2\%$ for dispersants, and $65.3\%$ and $10.3\%$ for nonionic surfactant, respectively. No nitrogen element was detected in dispersants and a nonionic surfactant. The biodegradability of dispersants shown as the ratio of $BOD_5/TOD$ was found to be in the range of $17{\sim}21\%$, and that of nonionic surfactant was found to be about $20\%$. This means that dispersants and nonionic surfactant belong in the organic matter group of middle-biodegradabilily. The deoxygenation rates($K_1$) and ultimate oxygen demands($L_o$) obtained through the biodegration experiment and Thomas slope method were found to be $0.121{\sim}0.171/day$ and $3.155{\sim}3.810mg/l$ for 4mg/l of dispersants and to be 0.181/day and 1.911mg/l for 2mg/l of nonionic surfactant in the seawater, respectively.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.34-45
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• 2016

Global warming and climate change have been caused by combustion of fossil fuels. The greenhouse gases contributed to the rise of temperature between $0.6^{\circ}C$ and $0.9^{\circ}C$ over the past century. Presently, fossil fuels account for about 88% of the commercial energy sources used. In developing countries, fossil fuels are a very attractive energy source because they are available and relatively inexpensive. The environmental problems with fossil fuels have been aggravating stress from already existing factors including acid deposition, urban air pollution, and climate change. In order to control greenhouse gas emissions, particularly CO2, fossil fuels must be replaced by eco-friendly fuels such as biomass. The use of renewable energy sources is becoming increasingly necessary. The biomass resources are the most common form of renewable energy. The conversion of biomass into energy can be achieved in a number of ways. The most common form of converted biomass is pellet fuels as biofuels made from compressed organic matter or biomass. Pellets from lignocellulosic biomass has compared to conventional fuels with a relatively low bulk and energy density and a low degree of homogeneity. Thermal pretreatment technology like torrefaction is applied to improve fuel efficiency of lignocellulosic biomass, i.e., less moisture and oxygen in the product, preferrable grinding properties, storage properties, etc.. During torrefacton, lignocelluosic biomass such as palm kernell shell (PKS) and empty fruit bunch (EFB) was roasted under an oxygen-depleted enviroment at temperature between 200 and $300^{\circ}C$. Low degree of thermal treatment led to the removal of moisture and low molecular volatile matters with low O/C and H/C elemental ratios. The mechanical characteristics of torrefied biomass have also been altered to a brittle and partly hydrophobic materials. Unfortunately, it was much harder to form pellets from torrefied PKS and EFB due to thermal degradation of lignin as a natural binder during torrefaction compared to non-torrefied ones. For easy pelletization of biomass with torrefaction, pellets from PKS and EFB were manufactured before torrefaction, and thereafter they were torrefied at different temperature. Even after torrefaction of pellets from PKS and EFB, their appearance was well preserved with better fuel efficiency than non-torrefied ones. The physical properties of the torrefied pellets largely depended on the torrefaction condition such as reaction time and reaction temperature. Temperature over $250^{\circ}C$ during torrefaction gave a significant impact on the fuel properties of the pellets. In particular, torrefied EFB pellets displayed much faster development of the fuel properties than did torrefied PKS pellets. During torrefaction, extensive carbonization with the increase of fixed carbons, the behavior of thermal degradation of torrefied biomass became significantly different according to the increase of torrefaction temperature. In conclusion, pelletization of PKS and EFB before torrefaction made it much easier to proceed with torrefaction of pellets from PKS and EFB, leading to excellent eco-friendly fuels.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.325-337
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• 2002

We examined the contamination of stream water and stream sediments by heavy metal elements with respect to distance from the abandoned Backun Au-Ag-Cu mine. High contents of heavy metals (Pb, Zn, Cu, Cd, Mn, and Fe) and aluminum in the waters connected with mining and associated deposits (dumps, tailings) reduce water quality. In the mining area, Ca and SO$_4$ are predominant cation and anion. The mining water is Ca-SO$_4$ type and is enriched in heavy metals resulted from the weathering of sulfide minerals. This mine drainage water is weakly acid or neutral (pH; 6.5-7.1) because of neutralizing effect by other alkali and alkaline earth elements. The effluent from the mine adit is also weakly acid or neutral, and contains elevated concentrations of most elements due to reactions with ore and gangue minerals in the deposit. The concentration of ions in the Backun mining water is high in the mine adit drainage water and steeply decreased award to down stream. Buffering process can be reasonably considered as a partial natural control of pollution, since the ion concentration becomes lower and the pH value becomes neutralized. In order to evaluate mobility and bioavailability of metals, sequential extraction was used for stream sediments into five operationally defined groups: exchangeable, bound to carbonates, bound to FeMn oxide, bound to organic matter, and residual. The residual fraction was the most abundant pool for Cu(2l-92%), Zn(28-89%) and Pb(23-94%). Almost sediments are low concentrated with Cd(2.7-52.8 mg/kg) than any other elements. But Cd dominate with non stable fraction (68-97%). Upper stream sediments are contaminated with Pb, and down area sediments are enriched with Zn. It is indicate high mobility of Zn and Cd.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.51-63
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• 2013

To assess the effect of environmental factors on the sustainability of cultured production shellfish, we investigated the habitat characteristics of tidal flat (Namhae-po in Taean). We measured the physiochemical parameters (temperature, salanity, pH, dissolved oxygen and nutrients) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several site of tidal flat to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain size for research area of tidal flat were similar at the ratio of silt and clay in comparison with the other site of it. The C/N ratio was more than 5.0, reflecting the range arising from the mix of marine organism and organic matter. The C/S ratio (about 2.8) showed that survey area had anoxic or sub-anoxic bottom conditions. The enrichment factor (Ef) and index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. Adult surf clam (Mactra veneriformis) density was highest at St. 2 (middle part of the Namhae-po), on the other hand, surf clam spat density was highest at St. 3 (lower part of the Namhae-po). Heavy rain, terrigenous suspended clay with fresh water from neighboring agricultural land, and severe high air temperature during summer could be thought as detrimental causes of spat and adult mortality in Namhae-po tidal flat. We suggested that the growth of shellfish in the tidal flat was effected by the various environmental conditions, so an improvement in the cultured method was needed.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.95-105
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• 2007

The aim of this study was to determine the residual amounts of PAHs in environmental samples such as crop, soil and water collected from paddy, upland fields and forestlands near industrial zone and/or a thermal power plant in South Korea. All of the samples were analyzed by GC-mass spectrometer. The average contents of total PAHs in soil samples were 140.2 ${\mu}g\;kg^{-1}$ and the range was from 4.3 to $662.9{\mu}g\;kg^{-1}$. The detection of benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene and dibenzo(a,h) anthracene which have strong carcinogenecity was ranged from 14.2 to 167.8 ${\mu}g\;kg^{-1}$. The residual amounts and detection frequency of PAHs in soil samples from the iron and heavy industrial areas near Pohang and Busan were 3-folds more than those of the other areas. Amounts of PAHs in upland soil samples was 1.5 folds higher than those of paddy soil samples, suggesting that it may be related to the content of organic matter in soil. The average contents of total PAHs in crop samples were 9.7 ${\mu}g\;kg^{-1}$ which ranged from 4.5 to 52.2 ${\mu}g\;kg^{-1}$. However, the residual amounts of PAHs in water samples were not detected. These results showed that soils and crops were slightly contaminated with PAHs. Therefore, the investigation should be continued for evaluating a safety or risk assessment through expansion of regions and crops.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.285-292
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• 2008

To investigate the effect of tillage methods on the silage barely growth and the soil environment in paddy field, liquid pig manure(LPM) was applied after harvesting rice at Jisan series soil for 2 years. Five plots, a LPM applied rate as N%; 0, 100, 150, 200(basal dressing) and 100(basal dressing)+50(additional fertilizer) were divided by tillage methods; non-tillage, non-tillage+rice straw and rotary tillage method. Emission amounts of $NH_3$ gas highly decreased in the rotary tillage and the non-tillage+rice straw plot compared to non-tillage plot. The contents of soil organic matter and exchangeable cation were increased in the applied LPM plot. $NH_4-N$ and $NO_3-N$ contents in soil were the highest in the non-tillage+rice straw plot and followed by the rotary tillage and highly decreased along with the growth of plant. Run-off rate of mineral components were higher in order of the rotary tillage plot£æthe non-tillage plot£æthe non-tillage+rice straw plot and then leached to $SO_4$, $NO_3-N$, K plentifully. The yield of silage barley in dry weight was higher in order of the non-tillage+rice straw plot>the rotary tillage plot>the non-tillage plot. To estimate the feed value of silage barley, crude protein, acid detergent fiber(ADF) and neutral detergent fiber(NDF) contents were analyzed. Crude protein and ADF contents were the highest at rotary tillage N150% plot as 9.7 and 29.4%, respectively. NDF contents was the highest at non-tillage+rice straw N150% plot as 56.7%. In conclusion, we recommend not to incinerate rice straw and to apply LPM at non-tillage status in cultivating the silage barley. This may prevent water pollution and increase barley yields.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.380-385
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• 2006

To establish law-put fertilization technique and increase of fertilization efficiency during cultivation of vinyl mulching for plant, the improvement of soil properties, nutrition efficiency and yields by band spotty fertilization(BSF) using band spotty applicator was carried out at garlic(Alltuiti sativum L.) field in Honam Agricultural Research Institute from 2001 to 2002 for 2 years. The value of pH and the content of total nitrogen, organic matter, exchangeable potassium and calcium of soil after experiment were increased but the content of available phosphate was decreased than soil before experiment. Uptake amounts of nitrogen fertilized by plants were more than in BSF plots($89{\sim}111kg\;ha^{-1}$) compared to in CF(conventional fertilization) Plot ($76kg\;ha^{-1}$) and nitrogen use efficiency were high in BSF plots(42.9~58.2%) compared to in CF plot(34.9%). Also Uptake amounts of potassium fertilized by plants were more than in BSF plots($34{\sim}58kg\;ha^{-1}$) compared to in CF plot($33kg\;ha^{-1}$) and potassium use efficiency were high in BSF plots(21.6~41.2%) compared to in CF plot(19.4%). Residual amount of nitrogen fertilized on soil were more than in BSF plots($38{\sim}54kg\;ha^{-1}$) compared to in CF plot($22kg\;ha^{-1}$) while loss amount of nitrogen fertilized on soil were less than in BSF plots($32{\sim}53kg\;ha^{-1}$) compared to in CF plot($120kg\;ha^{-1}$). Also Residual amount of potassium fertilized on soil were more than in 100% BSF plot($109kg\;ha^{-1}$) compared to in CF plot($72kg\;ha^{-1}$) while loss amount of nitrogen fertilized on soil were less than in BSF plots($14{\sim}38kg\;ha^{-1}$) compared to in CF plot($113kg\;ha^{-1}$). The BSF plots were increased plant height, leaf number, leaf sheath diameter, bulb diameter and height compared to CF plot. The total yields of garlic were more increased 14~19% because of high large bulb rate, commercial yields in 70, 100% BSF plots compared to in CF plot($102.9Mg\;ha^{-1}$). It was found that 70% band spotty fertilization was more effective as fertilization method to reduce both environmental pollution and chemical nitrogen fertilizer in plastic film mulching cultivation.

• Korean Journal of Environment and Ecology
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• v.33 no.2
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• pp.187-201
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• 2019

This study examined the physicochemical water quality and evaluated the ecological health in 14 sites of Geum River (upstream, mid-stream, and downstream) using the fish community distribution and guilds and eight multi-variable matrices of FAI (Fish Assessment Index) during June 2008-May 2009. The analysis of the water quality variables showed no significant variation in the upstream and mid-stream but a sharp variation due to the accumulation of organic matter from the point where the treated water of Gap and Miho streams flew. The analysis of physicochemical water properties showed that BOD, COD, TN, TP, Cond, and Chl-a tended to increase while DO decreased to cause eutrophication and algae development from the downstream where Miho and Gap stream merged. The analysis of fish community showed that the species richness index and species diversity index increased in the mid-stream area but decreased in the downstream area, indicating the stable ecosystem in the upper stream and the relatively unstable ecosystem in the downstream. The analysis of the species distribution showed that the dominant species were Zacco platypus that accounted for 20.9% of all fish species and Zacco koreanus that accounted for 13.1%. The analysis of the fish tolerance and feeding guild characteristics showed that the sensitive species, the insectivore species, and the aquatic species were dominant in the mid-stream point. On the other hand, contaminants from the sewage water treatment plant of Miho stream had a profound effect in the downstream to show the dominance of tolerant species, omnivorous species, and lentic species. Therefore, it is necessary to improve water quality by reducing the load of urban pollutants and to pay attention to the conservation and restoration of aquatic ecosystems.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.503-513
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• 2018

In order to continuous watershed management and improve water quality at Yeong-san river system, we analyzed and evaluated data on the monitoring of small stream in city and county boundaries within the watershed. In-period monitoring is estimated to be more frequent in the second quarter than the first quarter, so it should be considered when evaluating the target water quality by setting the target water quality. A small stream in the Yeong-san river system has higher concentration in the downstream area than the upstream area. As a result of calculating the load of the measuring point, Y.b B3(Pungyeongjeongcheon) and Y.b E1(Sampocheon) were high. The result of correlation analysis by monitoring point in order to evaluate the correlation between BOD and T-P items, BOD was highly correlated with COD and TOC, and was affected by emission of pollutants related to organic matter. T-P was highly correlated with SS and COD, and was affected by rainfall. This study will provide basic data and direction for designing efficient and scientific method for water quality management by analyzing accumulated water quality data by conducting long-term monitoring.