• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.87-92
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• 1998

The effect of chemically oxidized intermediates of Polynuclear Aromatic Hydrocarbon (PAH) compounds on the degradation of the parent PAHs was characterized and evaluated for the context of cooxidation. Anthracene and pyrene exhibited extensive degradation (mean percent removal of 57.5%) after 28 days of incubation by introducing the Fenton oxidation intermediate of the PAH compounds, while unoxidized anthracene and pyrene exhibited 12.5% removal The chemical oxidation products can serve as a structually similar analogue substrates for a consortia of soil microorganisms and as a metabolic intermediates in the biodegradation sequence of the parent PAH compounds. These results may be interpreted in the context of cooxidation mechanism whereby high recalcitrant PAH compounds are biodegraded in the soil and suggest a potential tool for bioremediation of PAHs contaminated soils and protection of groundwater.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.06a
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• pp.53-60
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• 1998

The effect of chemically oxidized intermediated of PAH compounds on the degradation of the parent PAHs was characterized and evaluated for the context of cooxidation. Anthracene and pyrene exhibited extensive degradation (mean percent removal of 57.5%) after 28 days of incubation by introducing the Fenton oxidation intermediate of the PAH compounds, while unoxidized anthracene and pyrene exhibited 12.5% removal. Dehydrogenase activities for the oxidized PAH studies ware enhanced two to five folds to the unoxidized PAHs studies. The chemical oxidation products can serve as a structually very similar analogue substrates for a consortia of soil microorganisms and as a metabolic intermediates in the biodegradation sequence of the parent PAH compounds. These results may be interpreted in the context of cooxidation mechanism whereby high recalcitrant PAH compounds are biodegraded in the soil and suggest a potential tool for bioremediation of PAHs contaminated soils and protection of groundwater.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.2
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• pp.169-175
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• 1988

A laboratory experiment was conducted to investigate the effects of pH, organic matters and anion on the adsorption and degradation of surfactant by different soils; Anmi series (limestone region), Gangseo series (alluvial soil). For this study, Alkyl Benzene Sulfonate (ABS ; Sodium Dodecylbenzenesulfonate) was used as a surfactant. The results were as follows: 1. Adsorption of ABS by soils was correlated positively with the equilibrium concentration of ABS in a soil suspension. (Anmi seris : r=0.9855, Gangseo series : r=0.9931). 2. Adsorption rate of ABS by soils was about 70% of the treated concentration ($600{\mu}g$ ABS/g soil) in a range of pH 4 to pH 5, and about 20% for pH 8. 3. Addition of electrolytes increased ABS adsorption by soils in a soil suspension; the higher concentration, the higher adsorption. But the influence among electrolytes was not significant. 4. Adsorption of ABS by soils was not affected by soil organic matter content in this experiment. 5. Degradation rate of ABS in a soil suspension was about 85% at $30^{\circ}C$, and about 10 to 15% at $10^{\circ}C$. Addition of sewage accelerated the degradation rate regardless of temperature and reached about 85% in a week.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.298-313
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• 1994

Residue of herbicide napropamide [N,N-dimethyl-2-(1-napthoxy)-propionamide] and change of micro-organism were investigated in upland soil under different environmental conditions. Half-lives of degradation were 28.3 days in the sterile soil and 14.6 days in the nonsterile soil, respectively. These results suggest that microorganism remarkably affected the decomposition of napropamide. Napropamide was rapidly degraded in order of 60% > 80% ${\geq}$ 40% soil moisture content of field water-holding capacity. Numbers of bacteria and total microbes in 60% moisture content was more than those in 40% moisture content. The more the napropamide degradation was rapid in lower soil pH. The total number of microorganism increased by lapse of time after treatment of napropamide at pH 5.5. The decomposition rate of napropamide was rapid in the order of $27^{\circ}C$ > $37^{\circ}C$ > $17^{\circ}C$. At $17^{\circ}C$ of soil temperature actinomycetes in napropamide treatment plot was more than these in nontreatment plot and also at $27^{\circ}C$ and $37^{\circ}C$ bacteria in napropamide treatment plot was more than those in nontreatment plot. Napropamide degradation was more rapid and number of microorganism was more abundant at the concentration of 10ppm than at that of 20ppm. The half-life of napropamide was longer in the clay loam soil than in the silty loam soil. The half times in laboratory test than in upland field. Numbers of microbes in the experiment under all the test environmental condition was not significantly different between treatment and nontreatment of napropamide.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.185-191
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• 2001

To obtain the basic information for degradation of remaining pesticide accumulated in cultivated soil of Honam area, the resistant bacterial strains were investigated in Chlorothalonil(TPN). Mancozeb, Bentazone, and Butachlor levels of 100, $500{\mu}g\;ml^{-1}$, and degradation of TPN by TPN-resistant bacteria in sterilized soil was studied under TPN levels 0, 10, 50 and $100{\mu}g\;g^{-1}$. A number of resistance strains were decreased with higher at concentration level of pesticide, and were higher in greenhouse than upland or paddy soil. The resistance of bacteria was strong in other of Bentazone> Butachlor> TPN> Mancozeb. The percentage of bacterial strains of resistance for pesticides isolated from the cultivated soil were the highest in Acinetobacter spp. and Corynebacterium spp., and the lowest in Moraxella spp. A number of TPN-resistant strains were the highest at the TPN level of $10{\mu}g\;g^{-1}$, and 5 days after strains inoculation, and were higher in Pseudomonas spp. TD-25 than TC-23 or strains in non-sterilized soil. The degradation of TPN was fast in order of strain TD-25>strain in non-sterilized soil >TC-23.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.314-314
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• 2000

• Geomechanics and Engineering
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• v.23 no.3
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• pp.227-244
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• 2020

Earthen structures have an excellent bioclimatic performance, but they are vulnerable against earthquakes. In order to investigate the edification process and costs, a full-scale rammed soil house was constructed in 2004. In 2016-2019, it was studied its seismic damage, durability and degradation process. During 2004-2016, the house presented a relatively good seismic performance (M_w=5.6-6.4). The damaged cover contributed in the fast deterioration of walls. In 2018 it was observed a partial collapse of one wall due to recent seismicity (M_w=5.6-6.1). The 15-year-old samples presented a reduced compressive strength (0.040 MPa) and a minimum moisture (1.38%). It is estimated that the existing house has approximately a remaining 20% of compressive strength with a degradation of about 5.4% (0.0109 MPa) per year (considering a time frame of 15 years) if compared to the new soil samples (0.2028 MPa, 3.52% of moisture). This correlation between moisture and compressive strength degradation was compared with the study of new soil samples at the same construction site and compared against the extracted samples from the 15-year-old house. At 7-14-days, the specimens presented a similar compressive strength as the degraded ones, but different moisture. Conversely, the 60-days specimens shown almost five times more strength as the existing samples for a similar moisture. It was observed in new rammed soil that the lower the water content, the higher the compressive/shear strength.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1617-1626
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• 2013

The Bacterial community structure and its complexity of the enrichment culture during the isolation and screening of imidacloprid-degrading strain were studied using denaturating gradient gel electrophoresis analysis. The dominant bacteria in the original tea rhizosphere soil were uncultured bacteria, Rhizobium sp., Sinorhizobium, Ochrobactrum sp., Alcaligenes, Bacillus sp., Bacterium, Klebsiella sp., and Ensifer adhaerens. The bacterial community structure was altered extensively and its complexity reduced during the enrichment process, and four culturable bacteria, Ochrobactrum sp., Rhizobium sp., Geobacillus stearothermophilus, and Alcaligenes faecalis, remained in the final enrichment. Only one indigenous strain, BCL-1, with imidacloprid-degrading potential, was isolated from the sixth enrichment culture. This isolate was a gram-negative rod-shaped bacterium and identified as the genus Ochrobactrum based on its morphological, physiological, and biochemical properties and its 16S rRNA gene sequence. The degradation test showed that approximately 67.67% of the imidacloprid (50 mg/l) was degraded within 48 h by strain BCL-1. The optimum conditions for degradation were a pH of 8 and $30^{\circ}C$. The simulation of imidacloprid bioremediation by strain BCL-1 in soil demonstrated that the best performance in situ (tea soil) resulted in the degradation of 92.44% of the imidacloprid (100 mg/g) within 20 days, which was better than those observed in the ex situ simulations that were 64.66% (cabbage soil), 41.15% (potato soil), and 54.15% (tomato soil).

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.257-261
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• 1998

This study was carried out to investigate the adsorption and the degradation of herbicide napropamide in soils tinder laboratory conditions. The adsorption distribution coefficients(Kd) of napropamide in 3 soils varied from 5.38 to 11.39. With higher content of organic matter in soils, the extent of adsorption was high. The rapid degradation of napropamide took place after a lag period. The time to 50% loss of napropamide was approximately 65, 45 and 30 days in soil incubated at 10, 20 and $30^{\circ}C$, respectively. The time to the 90% loss varied from about 90 days at $10^{\circ}C$ to about 45 days at $30^{\circ}C$. In the soil pre-incubated with napropamide, the herbicide degraded without a lag time, and the rate of degradation was also accelerated. This should be a evidence on enhanced biodegradation of napropamide in soil with the repeat-application.

• Journal of the Korean GEO-environmental Society
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• v.11 no.11
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• pp.47-54
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• 2010

Nowadays, geosynthetics for reinforcement and protection are widely applied to the waste landfill site. Current research indicates the potential for progressive failure in geosynthetic-soil system depends on the interface shear strength governed by several intrinsic factors such as moisture, normal stress, chemical, etc. In particular, the effect of the acidity and basicity from the leachate is intensively reviewed to assess the chemical reaction mechanism of interface shear strength under the cyclic loading condition. New multi-purpose interface apparatus(M-PIA) has been manufactured and the cyclic direct shear tests using submerged geosynthetics and soils under the different chemical conditions have been performed, consequently, the thickness of interface and shear stress degradation are verified. The basic schematic of the Disturbed State Concept(DSC) is employed to estimate the shear stress degradation in the interface, then, normalized disturbed function is obtained and analyzed to describe the shear stress degradation of geosynthetic-soil interface with chemical influence factors under dynamic condition.