• Korean Journal of Soil Science and Fertilizer
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• v.34 no.4
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• pp.245-254
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• 2001

Effects of soil moisture and temperature on the degradation rate of imazamethabenz were studied in two soils, a Declo sandy loam soil with 1.5% organic matter and pH of 8.0, and a Pancheri silt loam soil with 2.1% organic matter and pH of 7.7. Soils were incubated for 12 weeks under controlled conditions. Treatments were a factorial arrangements with combinations of three soil moistures (45, 75, 100% of field capacity) and two soil temperatures (20, 30C). Imazamethabenz degradation followed first-order kinetics for all soil moisture-soil temperature combinations. Imazamethabenz degradation rate was proportional to increase of soil moisture and temperature. Soil moisture effect on imazamethabenz degradation was greater when soil moisture was increased from 45 to 75% of field capacity (half-life decreased 2.6 fold) than when moisture increased from 75 to 100% of field capacity (half-life decreased 1.2 fold). Imazamethabenz degradation occurred more rapidly in the Pancheri silt loam than the Declo sandy loam soil. Formation of imazamethabenz acid from imazamethabenz followed a quadratic trend for most soil-moisture-soil temperature combinations. Imazamethabenz acid formation initially increased at earlier stages, but later gradually decreased. In most cases, increasing soil moisture and temperature appeared to accelerate it's acid breakdown to other metabolites.

• Geomechanics and Engineering
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• v.18 no.5
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• pp.471-480
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• 2019

The constructions of engineering structures such as airports, highways and railway on clayey soils may create many problems. The economic losses and damages caused by these soils have led researchers to do many studies using different chemical additives for the stabilization of them. Lime is a popular additive used to stabilize the clayey soils. When the base course is stabilized by mixing with an additive, inevitable delays may occur during compaction due to reasons like insufficient workers, breakdown of compaction equipment, etc. The main purpose of this study is to research the effect of compaction delay time (7 days) on the strength, compaction, and dynamic properties of a clay soil stabilized with lime content of 0, 3, 6, 9, 12 and 15% by dry weight of soil. Compaction characteristics of these mixes were determined immediately after mixing, and after 7 days from the end of mixing process. Within this context, unconfined compressive strength (UCS) under the various curing periods (uncured, 7 and 28 days) and dynamic triaxial tests were performed on the compacted specimens. The results of UCS and dynamic triaxial tests showed that delayed compaction on the strength of the lime-stabilized clay soil were significantly effective. Especially with the lime content of 9%, the increase in the shear modulus (G) and UCS of 28 days curing were more prominent after 7 days mellowing period. Because of the complex forms of hysteresis loops caused by the lime additive, the damping ratio (D) values differed from the trends presented in the literature and showed a scattered relationship.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.548-558
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• 2013

In this work, laser induced breakdown spectroscopy (LIBS) is used to investigate soil samples collected from different desert areas of Riyadh city in Saudi Arabia. Both qualitative analysis and plasma parameters are studied via the observed LIBS spectra. These experiments have been done using a Spectrolaser-7000 system with 50 mJ fundamental wavelength of Nd:YAG laser and detection delay time of 1 microsecond. Many spectral lines are highly resolved for many elements like Al, Fe, Mg, Si, Mn, Na, Ca and K. The electron temperatures Te and electron densities Ne, for the constituent of generated LIBS plasma, are determined for all the collected samples. It is found that both Te and Ne vary from one desert area to other. This variation is due to the change of the elemental concentration in different desert areas that affects the sample's matrices. Time dependent measurements have also been performed on the soil samples. While the signal-to-base ratio (SBR) reached its optimal value at 1 microsecond, the plasma parameters Ne and Te reach values of $4{\times}10^{17}cm^{-3}$ and 9235 K, respectively, at 2.5 microsecond. The later indicate that the plasma cooling processes are slow in comparison to the previously observed results for metallic samples. The observed results show also that in the future it is possible to enhance the exploitation of LIBS in the remote on-line environmental monitoring application, by following up only the values of Ne and Te for one element of the soil desert sample using an optical fiber probe.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.277-285
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• 2014

The usage of efficient microorganism (EM) is increasing in concern for server purposes including odor removal during carcasses degradation. In this study, we have studied the type of soil and its effect on efficient microorganisms for the removal of odorous gases during buried carcasses degradation in lab-scale reactor. The carcasses are buried in the reactor with various soil types such as normal soil, 20% sandy and 20% clay soil with the efficient microorganism KEM. The efficient microorganisms KEM have the ability to stabilize the degradation of carcasses of the burial site. We have focused on the analysis of odorous gases such tri-methylamine (TMA), hydrogen sulfide ($H_2S$), methyl mercaptan (MM), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), carbon dioxide ($CO_2$), and methane ($CH_4$) along with the changes of microbial community changed during complete degradation of buried carcasses for a year. The results suggested that the 20% sandy soil contain lesser level of $H_2S$ and MM (0.09 and 0.35 mg) but 20% clay has higher nitrogen compound removing effect and leave only less amount of ammonia and TMA (0.31 and 2.06 mg). The 20% sandy soil also has the ability to breakdown the carcasses more quality compared with other types of soil. Based on the data obtained in this study suggesting that, the use of 20% sandy soil can effectively control sulfur compounds whereas 20% clay soil controls nitrogen compounds in the buried soil. Depending on the type of the soil, the dominant of microbial communities and the distribution was change.

• Korean Journal of Environmental Agriculture
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• v.42 no.3
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• pp.184-192
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• 2023

Microplastics are generated by the breakdown of plastic wastes in agricultural soil and residual pesticides in agricultural soil can adsorb on microplastics. In this study, the sorption characteristics of procymidone (PCM) and one of its metabolites, 3,5-dichloroaniline (DCA), on low-density polyethylene (LDPE) and polyvinyl chloride (PVC) microplastics were investigated. The sorption and desorption tests were carried out for 72 h using LDPE or PVC microplastic films to study the sorption isotherms of PCM and DCA and kinetics for sorption and desorption of PCM. The results show that the sorption data of PCM and DCA were better described by the Freundlich isotherm model (R²=0.7568-0.9915) than the Langmuir isotherm model (R²=0.0545-0.5889). The sorption potential of PVC for both PCM and DCA was greater than that of LDPE. The sorption data of PCM on PVC and LDPE were fitted better to the pseudo-second-order kinetic model than the pseudo-first-order kinetic model. The PCM sorption on LDPE was about three times faster than that on PVC. Both microplastic films released the sorbed PCM back to water, and more PCM was released from PVC than LDPE, but the desorption rate was faster with LDPE than PVC. Overall, the results show that different microplastics have different sorption characteristics for different chemicals. Also, the sorbed chemicals can be released back to environment suggesting the potential of contaminant spread by microplastics. Thus, the management practices of microplastics in agricultural soil need to consider their interaction with the chemical contaminants in soil.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1263-1263
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• 2001

The amounts of organic matter present in soil and the rate of soil organic matter (SOM) turnover are influenced by agricultural management practice, such as rotation, tillage, forage plow down direct seeding and manure application. The amount of nutrients released from SOM is highly dependent upon the state of the organic matter. If it contains a large proportion of light fractions (low-density) more nutrients will be available to the glowing crops. However, if it contains mostly heavy fractions (high-density) that are difficult to breakdown, then lesser amounts of nutrients will be available. The state of the SOM and subsequent release of nutrients into the soil can be predicted by NIRS as long as a robust regression equation is developed. The NIRS method is known for its rapidity, convenience, simplicity, accuracy and ability to analyze many constituents at the same time. Our hypothesis is that the NIRS technique allows researchers to investigate fully and in more detail each field for the status of SOM, available moisture and other soil properties in Alberta soils for precision farming in the near future. One hundred thirty one (131) Alberta soils with various levels (low 2-6%, medium 6-10%, and high >10%) of organic matter content and most of dry land soils, including some irrigated soils from Southern Alberta, under various management practices were collected throughout Northern, Central and Southern Alberta. Two depths (0- 15 cm and 15-30 cm) of soils from Northern Alberta were also collected. These air-dried soil samples were ground through 2 mm sieve and scanned using Foss NIR System 6500 with transport module and natural product cell. With particle size above 150 microns only, the “Ludox” method (Meijboom, Hassink and van Noorwijk, Soil Biol. Biochem.27: 1109-1111, 1995) which uses stable silica, was used to fractionate SOM into light, medium and heavy fractions with densities of <1.13, 1.13-1.37 and >1.37 respectively, The SOM fraction with the particle size below 150 microns was discarded because practically, this fraction with very fine particles can't be further separated by wet sieving based on density. Total organic matter content, mechanical texture, ash after 375$^{\circ}C$, and dry matter (DM) were also determined by “standard” soil analysis methods. The NIRS regression equations were developed using Infra-Soft-International (ISI) software, version 3.11.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.112-119
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• 1981

The persistence of preemergence herbicides, butachlor [2-chloro-2,6-diethyl-N(butoxymethyl) acetanilide] and nitrofen(2,4-dichlorophenyl-4-nitrophenyl ether), at 10 ppm level in different soil conditions amended with organic matter and lime was studied under flooded and field moisture capacity. The microbial breakdown played a major role in the dissipation of the herbicides in soil. Nitrofen degradation in flooded soil was greatly accelerated, while it was slowed down in field moisture capacity as compared with butachlor. Increased amendment of rice straw to the soil shortened the half-life of butachlor under flooded condition, however it prolonged that of butachlor when the amendment was exceeded over 1% on dry weight basis. Liming the soil stimulated decomposition of the herbicides in the soil systems, which ap pears to be pH independent.

• Proceedings of the KIEE Conference
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• 2005.11c
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• pp.53-55
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• 2005

Because of the continuous growth of energy consumption and also the tendency to site power lines and pipelines along the same route, the close proximity of power lines and buried metallic pipelines has become more and more frequent. The lightning strokes collected by an electric substation or power line tower might cause arcing through the soil to an adjacent gas pipeline. This paper gives the review of the breakdown mechanism and the standards of separation distance between lower and pipelines.

• Journal of Plant Biology
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• v.13 no.3
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• pp.20-24
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• 1970

In the moor of Mt. Dae-am, the following communities are seen in successive order ranging from the north to the south; the Sanguisorba Argutipens-Carex jaluensis community, the Carex jaluensis-Sanguisorba Argutipens-Sphagnum community, the Sphagnum cymbifolium-Carex jaluensis community, the Carex jaluensis-Sanguisorba Argutipens community and the Calamgrostis Langsdorfii-Ottelia alismoides community. The properties of the peats vary according to the community type, that is, nutrients such as organic matter, total nitrogen, exchangeable K and Mg in the soil tend to decrease as the plant communities shift from the north to the south. The pH range for eleven stations samples was 3.9 to 5.7, and the meadian is 4.6. The content of exchangeable Ca decreases from station to station successively towards the center which is poor in calcium. Presumably there appears to be a clear correlation of Sphagnum cymbifolium with the amount of exchangeable Ca and value of pH produced in bogs by the breakdown or organic residures. The nutrient content of the representative plants of the moor shows no definite relation with the station of their habitats.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.643-646
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• 2007

As increase of the land price at downtown area, it makes people more and more interested of improving the space utilization such as makes buildings bigger, deeper and higher. Therefore, the importance of the underground construction which is the basic principle has been increased. As constructors have to complete underground construction as soon as possible with the minimum costs, they concentrate on the whole process of underground structure. Although they makes every these efforts, construction failure still happen because of the uncertainty of the condition of soil and the unexpected danger of underground construction. To make matter worse, there are only some examples without detailed information like 'how much this breakdown damage to the construction?' so it is the anther problem that most of people doesn't recognize the economical negative impact of underground structure breakdown. This report would make people understood the importance and risk of the underground construction by showing some analysis which was assumed from the real accidents.