• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.239-246
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• 2022

Lactuca scariola L. is one of ecosystem-disturbance plants that grow everywhere such as roadsides, grasslands, railroads, banks, and fields. L. scariola usually occurs in autumn. It overwinters in rosette form. It flowers and produces seeds in early summer of the next year. Seeds of L. scariola can germinate immediately without dormancy when the temperature is over 20℃. Due to endogenous bacteria in seeds of L. scariola, it has a strong drought tolerance. Thus, it can grow well on roadsides. L. scariola should be controlled as it can result in 60-80% of soybean yield loss at densities above 50 plants m^-2. It is advisable to remove L. scariola as it competes with native plants by acting as a pioneer to other ecosystem-disturbance plants. Among various control methods, chemical control is the most effective method that is widely used. Soil treatment with herbicides such as oxyfluorfen EC and pendimethalin EC can inhibit the development of L. scariola. Foliar treatment herbicides glyphosate and glufosinateammonium are widely used. L. scariola is resistant to 2,4-D, dicamba, and MCPA among foliar treatment herbicides. Thus, it is recommended to apply herbicides with different modes of action.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.165-170
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• 2013

In this study, physico-chemical properties and environmental fate were investigated and ecotoxicity tests using fish, daphnia and algae were conducted for an initial ecological risk assessment of 1,2-Benzisothiazol-3-one. Due to low volatility of the test substance under environmental conditions, it is likely to distributed in soil and water environment. The compound has low adsorption in the soil, with low bioconcentration potential. Acute toxicity results showed that 96 h-$LC_{50}$ for Oryzias laties was 4.7 mg/L (measured) and 48h-$EC_{50}$ for Daphnia magna was 3.3 mg/L (measured). In a growth inhibition test with Pseudokirchneriella subcapitata, 72 h-$EC_{50}$ was 0.456 mg/L (growth rate, nominal) and 0.262 mg/L (yield, nominal). Using the acute toxicity value of algae, predicted no-effect concentration (PNEC) in the aquatic environment was determined to be 2.62 ${\mu}g/L$ using an factor of 100. According to globally harmonized system (GHS), the compound was categorized as aquatic acute 1 for algae, while it was categorized as aquatic acute 2 for fish and daphnia. This screening assessment suggests that the test substance may pose ecological risks in the aquatic environment.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.227-235
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• 2020

In this study, we discussed the limitations of gross alpha measurements for the characterization of radioactive wastes produced in nuclear facilities through experimental tests and Monte Carlo N-particle transport simulations. The determination of gross alpha is essential for the disposal of radioactive waste produced in nuclear facilities in Korea. The measurements of gross alpha are easy to perform and yield rapid analytical results, but it cannot be used for quantitative analysis. The error of counting efficiency for gross alpha with various masses of the deposit on planchets using KCl and ²⁴¹Am was determined. The relative deviation of the counting efficiency in samples having the same mass was 20%. Uranium was extracted from the soil through acid leaching and extraction chromatography, and the concentration of U determined by inductively coupled plasma-mass spectrometry (ICP-MS) was compared with the results for gross alpha. The gross alpha was underestimated by 50% compared to the U concentration by ICP-MS. The counting efficiency depended on the energy from the alpha emitters, which differed by up to three times in determination of the counting efficiency depending on the kinds of alpha radionuclides of interest. Therefore, the gross alpha is not compatible with the sum of radioactivity for each alpha emitter and is suitable as a screening method.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.5-10
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• 1998

The microbial degradation, photosensitizer-mediated photolysis, and bioceramic- accelerated degradation of the herbicide imazapyr were investigated using four types of soil. 1. Seven strains of microorganisms isolated from the soil A and the active sludge collected from the waste water disposal plant in CheongJu did not give any distinct degradation products in pure culture. When imazapyr (10ppm) was incubated for 14days with each of the 6strains of the known bacteria, they did not produce any noticeable products, either, suggesting that imazapyr was degraded very little by microorganisms in aqueous media. Meanwhile, when 50ppm of imazapyr was incubated in soil A and B for 6months, a degradation product of m/z 279 was detected. It turned out to be 2-[(1-carbamoyl-1,2-dimethylpropyl)carbamoyl]nicotinic acid, which was formed by the hydrolytic cleavage of the imidazolinone ring and by tautomerism. When imazapyr was exposed to sunlight, degradation rates were 14.6% under the control and 66.0, 76.5, 26.7, and 90.0% in the presence of PS-1 (100ppm), PS-1 (200ppm), PS-2(100ppm), and PS-3(100ppm), respectively, and a degradation product of m/z 149 was tentatively identified in the treatment of PS-1. 2. When soil C and D treated with bioceramic were incubated for 7weeks, the $^{14}C$-activities of $^{14}CO_2$ evolved were 2.03 and 1.12% of the originally applied ones, respectively, whereas those in control soils without bioceramic were 1.88 and 0.82% showing no significant defferences.After 5 weeks, however,the differences in the amounts of $^{14}CO_2$ between the two treatments increased gradually, suggesting the bioceramic effect.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.414-419
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• 2005

This study was performed to compare the treatment efficiencies of two media, newly developed Bio-rock and conventional gravel, in soil clothing contact oxidation process. The composition of synthetic wastewater were $COD_{Cr}$ $150{\sim}370\;mg/L$, $BOD_5$ $150{\sim}270\;mg/L$, T-N $20{\sim}60\;mg/L$, T-P $5{\sim}25\;mg/L$, pH 7 and 2 mL/L of trace element solution. The experiment using two reactors was comparatively conducted for the flow rate of 40 L/d for 13 months, respectively. Initially Bio-rock reactor was increased to pH 12 due to $Ca(OH)_2$ with hydration of cement, but gravel reactor was dropped to pH 4 due to the degradation of organic material and nitrification. This significant pH variation deteriorated the growth and activity of microorganism. But the high pH of Bio-rock seems favorite to ammonia stripping and precipitation of phosphate. Such pH variation of Bio-rock and gravel reactors were finally stabilized to pH 8 and pH 6, respectively. The removal efficiencies of organic compounds from Bio-rock reactor were 96% of $COD_{Cr}$, 98% of $BOD_5$, 80% of T-N and 85% of T-P which stably coping against variation of influent concentration. But those of gravel reactor were 96% of $COD_{Cr}$, 96% of $BOD_5$, 42% of T-N and 40% of T-P, respectively. The Bio-rock was 2 times higher than T-N and T-P in treatment efficiency. And electron-microscopic examination showed that Bio-rock was more favorable to microbial adherence than gravel. The microbial populations were $5.2{\times}10^6\;CFU/mL$ of Bio-rock reactor compared to $2.6{\times}10^6\;CFU/mL$ in gravel reactor. In result Bio-rock was favor to microbial adherence and high treatment efficiency in spite of variation of influent concentration which had the advantages in saving running time and reducing site requirement.

• Journal of Soil and Groundwater Environment
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• v.11 no.3
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• pp.31-42
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• 2006

Drought indices, such as PDSI (palmer Drought Severity Index), SWSI (Surface Water Supply Index) and SPI (Standardized Precipitation Index), have been developed to assess and forecast an intensity of drought. To find the applicability of groundwater level data to a drought assessment, a correlation analysis between SPI and groundwater levels was conducted for each time series at a drought season in 2001. The comparative results between SPI and groundwater levels of shallow wells of three national groundwater monitoring stations, Chungju Gageum, Yangpyung Gaegun, and Yeongju Munjeong, show that these two factors are highly correlated. In case of SPI with a duration of 1 month, cross-correlation coefficients between two factors are 0.843 at Chungju Gageum, 0.825 at Yangpyung Gaegun, and 0.737 at Yeongju Munjeong. The time lag between peak values of two factors is nearly zero in case of SPI with a duration of 1 month, which means that groundwater level fluctuation is similar to SPI values. Moreover, in case of SPI with a duration of 3 month, it is found that groundwater level can be a leading indicator to predict the SPI values I week later. Some of the national groundwater monitoring stations can be designated as DIW (Drought Index Well) based on the detailed survey of site characteristics and also new DIWs need to be drilled to assess and forecast the drought in this country.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.325-345
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• 2020

Determination of Best available technology (BAT) was suggested to reduce volatile organic compounds (VOCs) in a petrochemical industrial complex, by conducting human health risk, environmental, and economic assessment based on multimedia fugacity model. Fate and distribution of benzene, toluene, ethylbenzene, and xylene (BTEX) was predicted by the multimedia fugacity model, which represent VOCs emitted from the industrial complex in U-city. Media-integrated human health risk assessment and sensitivity analysis were conducted to predict the human health risk of BTEX and identify the critical variable which has adverse effects on human health. Besides, the environmental and economic assessment was conducted to determine the BAT for VOCs reduction. It is concluded that BTEX highly remained in soil media (60%, 61%, 64% and 63%), and xylene has remained as the highest proportion of BTEX in each environment media. From the candidates of BAT, the absorption was excluded due to its high human health risk. Moreover, it is identified that the half-life and exposure coefficient of each exposure route are highly correlated with human health risk by sensitivity analysis. In last, considering environmental and economic assessment, the regenerative thermal oxidation, the regenerative catalytic oxidation, the bio-filtration, the UV oxidation, and the activated carbon adsorption were determined as BAT for reducing VOCs in the petrochemical industrial complex. The suggested BAT determination methodology based on the media-integrated approach can contribute to the application of BAT into the workplace to efficiently manage the discharge facilities and operate an integrated environmental management system.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.237-243
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• 2008

Chemical and microbial characteristics of bacterial populations were investigated in a quercus and pine humus forest soil. Soil pH was $5.3\pm0.4$ and $4.1\pm0.9$ from each sample of a quercus and pine humus forest soil; C/N ratio of humus forest soil was $17.84\pm4.6%$ and $21.76\pm8%$, respectively. Total organic acid was investigated as 69.57 mM/g dry soil and 53.72 mM/g dry soil in each humus forest soil. Glutamine, pyruvate, succinate, lactic acid and acetic acid of pine humus forest soil were $1.5\sim4.5$ times higher than those of quercus humus forest soil. As we evaluated phylogenetic characteristics of bacterial populations by 16S rRNA-ARDRA analysis with DNA extracted from each humus forest soil. Based on the 16S rRNA sequences, 44 clone from ARDRA groups of quercus humus forest soil were classified into 7 phyla: ${\alpha},{\beta},{\gamma},{\delta}$-Proteobacteria, Acidobacteria, Actinobacteria, and Firmicutes. Thirty-two clone from ARDRA groups of pine humus forest soil were classified into 8 phyla: ${\alpha},{\beta},{\gamma}$-Proteobacteria, Acidobacteria, Bacteroides, Verrucomicrobia, Planctomycetes, and Gemmatomonadetes. According to PCA (Principal Component Analysis) based on 16S rRNA base sequence, there were three main groups of bacteria. All clone of Cluster I were originated from quercus humus forest soil, while 67% clone of Cluster II and 63% clone of Clusters III were separated from pine humus forest soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.103-111
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• 1988

This study was carried out with two cultivars under two levels of pH and four levels of nitrogen fertilization in a field and nutri-culture experiments to obtain the information about the effects of pH and nitrogen fertilization on the growth and yield of soybean. Acidic condition suppressed the growth of soybean plants, and thus yield and yield components of soybean decreased under acidic condition. But they increased with increased nitrogen fertilization. Especially, these respones were more remarkable under acidic condition and in the variety Jangbaegkong. Grain yield of soybean were highly correlated with the content of allantoin and total nitrogen of soybean plants in the variety Jangbaegkong, but this was not in the variety Danyeobkong. The content of protein and fat of soybean seeds decreased under acidic condition, and more nitrogen fertilization increased the protein content, but decreased the fat content.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.804-809
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• 2015

Since Korea is home to Reticulitermes speratus, a kind of subterranean termites that prefer dark and humid conditions, there have been increasing damages to wooden structures by termites. One noticeable attribute of Korean subterranean termites is that they prefer than Pinus densiflora, the major construction material for Korean traditional houses. And because wide varieties of termites are distributed all over the world, it is not so easy to choose appropriate control methods depending on specific areas. This necessitates careful applications of the following control methods depending on the kinds of termites: fumigation treatment, soil termiticide, preservatives and insect treatment, termite colony elimination system, chemical treatment, and other physical and biological treatment methods. The purpose of this study is to investigate the control effects of environmentally-friendly Alkaline copper quaternary (ACQ), Copper Azole (CuAZ) and Micronized copper quarter (MCQ) on the termites contributing to the damage of wooden structures. It was found in this study that wood with preservative treatment produced a significantly higher termicidal efficacy than untreated wood.