• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.201-206
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• 2009

It is generally accepted that organic materials are a significant factor on the soil aggregation formation but little information exists on how the formation and stabilization of aggregates in reclaimed tidelands. In this work, the effects of organic materials on the soil aggregate formation in reclaimed tidelands were determined. The soil was treated with 5 cm-size chopped fresh italian ryegrass residues (fresh organic material), commercial livestock compost with swine manure and sawdust (by product fertilizer), and fresh organic material + by product fertilizer (1 : 1 w/w) after ploughing at 20 cm soil depth. The three organic materials applied $2,000kg\;10a^{-1}$ every year. Water stable aggregate was estimated by wet-sieving method. Three years after the beginning of the experiment, water stable aggregate rate and MWD (mean weight diameter) were higher fresh organic material treatment than two other treatments. For improvement of physical property and structure of soil in reclaimed tidelands, fresh organic material treatment was more suitable than two other treatments.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.185-197
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• 2011

Sorption of chlorinated pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine onto natural clays (montmorillonite and zeolite) modified with cationic surfactant, hexadecyltrimethyl-ammonium (HDTMA) and a natural soil was investigated using batch adsorbers. The clays were transformed from hydrophilic to hydrophobic by the cation exchange between clay surface and HDTMA up to 100% of the cation exchange capacity (CEC). Physicochemical characteristics of the sorbents such as pH, PZC (point of zero charge), organic carbon content ($f_{oc}$), fourier transform infrared spectroscopy (FT-IR), differential thermogravimetric analysis (DTGA) and X-ray diffraction (XRD) were analyzed. Sorption isotherm models such as Freundlich and Langmuir were fitted to the experimental data, resulting Langmuir model ($R^2$ > 0.986) was fitted better than Freundlich model ($R^2$ > 0.973). Sorption capacity ($Q^0$) for 2,4-D and atrazine was in the order of HDTMA-montmorillonite > HDTMA-zeolite > natural soil corresponding to the increase in organic carbon content ($f_{oc}$). The sorption of the pesticides was also affected by pH. The sorption of 2,4-D decreased with the increase in pH, whereas that of atrazine was not changed. This indicated that the sorption capacity ($Q^0$) of 2,4-D and atrazine was not affected by the solution pH because they exist as anionic (deprotonated) forms at pH above pKa. The results indicate that organoclay has a promising potential to reduce chlorinated pesticides in the effluent from golf courses.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.545-556
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• 2003

Detailed interdisciplinary investigations demonstrate that the Yeongsan River estuarine-filled sediments clearly record important paleoenvironmental changes during the Last Glacial and Holocene. The sediments from 18.9 m(20.5∼l.6m in depth) long core MW-1 are differentiated by changes in sedimentary textures and palynomorph assemblages. Chronology was provided by AMS$^{14}$C dating and regional pollen correlation. Three paleoenvironrnental phases are recognized: (1) The Last Glacial deposits consist mainly of fluvial sediments and paleosols, experienced deposition alternating with pedogenesis. The appearance of the paleosols suggests that the paleoclimate might be cold and humid. (2) The early and middle Holocene phase started abruptly in response to the rapid global climatic warming. and is characterized by abundant marine palynomorphs. (3) The late Holocene is marked by more cool conditions. The paleoenvironmental changes recorded in the sediments coincide not only with local but also with broad-scale, probably global climate changes.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.299-307
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• 2004

Surfactant adsorption by two montmorillonite types with different interlayer cations of Ca and Na was characterized by examining the time dependence of surfactant behavior on the clay surfaces. Surfactants with different micelle concentration were conducted in our experiment to observe a nonequilibrium activity of cationic surfactant on the clay over reaction periods ranging from 0.1 min to 11 days. As compared with Ca-montmorillonite (SAz), a more active intrusion of surfactant molecules into the interlayers was found in Na-montmorillonite (SWy). During a short 'initiation' stage, the basal spacing of SWy montmorillonite increased rapidly with logarithmic time. For SAz montmorillonite, however, the abrupt basal spacing increase occurred at the later stage of the reaction. From the result, the difference in the adsorption behavior exhibited by the two montmorillonite types partly results from their intrinsic nature, that is, inorganic cations originally existing on the clay surfaces. Additionally, the micelle concentration of surfactants affects the development of organo-montmorillonite, especially, in the intercalant formation and stabilization under nonequilibrium.

• Journal of the Korean Geotechnical Society
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• v.22 no.9
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• pp.5-14
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• 2006

Generally, the sediments contain significant water, clay, colloidal fraction and contaminants, and can result in soft strata with high initial void, and its potential hazards in subsurface environments exist. Electrokinetic technique has been used in sedimentation for volume reduction of slurry tailing wastes and in remediation for extraction of contaminants from contaminated soils. In this research, the coupled effects of sedimentation and remediation of contaminated sediments are focused using electrokinetic sedimentation and remediation techniques from experimental aspects. A series of laboratory experiments including variable conditions such as initial solid content of the specimen, concentration level of the contaminant, and magnitude of applied voltage are performed with the contaminated sediment specimens mixed with ethylene glycol. Commercially available high specification Kaolin was used to simulate slurried sediment. From the test results, the settlement of specimen increases with increasing of applied voltage and decreasing of solid content and contamination level. The density of specimen increases due to settlement of specimen in the process of electrokinetic sedimentation and decreases due to extraction of organic contaminant in the process of electrokinetic remediation.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.241-247
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• 1991

Electric charge characteristics of volcanic ash soils in Cheju Island were investigated. For this study, soils of toposequence distributed along the sourthern slope of Mt. Halla, and the major soil groups such as dark brown soils, very dark brown soils, black soils, and brown forest soils were collected and analyzed for extratable acidity, KCl ext. Al, CEC, base saturation, permanent charge and variable charge, etc.. Weolpyeong and Yongheung soils developed on the lower elevations have high $NH_4OAc$ ext. bases, permanent charge and base saturation, and relatively low ext. acidity, CEC and variable charge. For other soils, whose colloidal fractions are dominated by allophane or Al-humus complexes, ext. acidity, CEC, variable charge, and variable charge ratio were very high, and $NH_4OAc$ ext. bases, permanent charge, and base saturation were very low. These trends were especially prominant in the surface. horizons of black soils and brown forest soils dominated by Al-humus complexes. Ext. acidity, CEC($NH_4OAc$), CEC(sum of cations), and variable charge strongly correlated with pyrophosphate ext. carbon. Very dark brown soils and cinder cone soils dominated by allophane showed low KCl ext. Al and relatively high pH, despite their very low base saturation.

• Industry Promotion Research
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• v.9 no.1
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• pp.31-38
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• 2024

In this study, evaluated the properties of layered silicate-based nanocomposite sensitive film. For the fabrication of nanocomposite materials, we selected organically modified layered silicate materials, specifically Cloisite^® and Bentone^®, which were treated with quaternary ammonium salts. The impedance of the humidity sensors containing organically modified montmorillonite/hectorite clay decreased with increasing relative humidity(RH%). In the case of the Cloisite^® humidity sensor exhibited slightly better impedance linearity and hysteresis compared to the Bentone^® 38 humidity sensor. Additionally the impedance of the sensor with Bentone^® 38 addition was the lowest when compared to the Cloisite^®-modified sensor. Comparing the Cloisite^®-modified sensors individually, we observed different moisture absorption characteristics based on the hydrophilic properties of the organic-treated materials. The response speed of Cloisite^® 93A tended to be slower due to differences in moisture evaporation rates influenced by the hydrophilic organic components. Based on these results, moisture barriers utilizing organically modified layered silicate materials may exhibit slightly lower moisture absorption properties compared to conventional polymer-based moisture barriers. However, their excellent stability, simple processing, and cost-effectiveness make them suitable for humidity sensor applications.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2132-2137
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• 2009

갈대(Phragmites communis Trin.)란 염분이 있는 곳에서 자라는 염생식물로서 우리나라 전역에 분포하고 있다. 지난 50년 동안 우리나라의 여러 습지에 걸쳐서 갈대는 우점종으로 자라왔고, 육지와 수중서식지에서 갈대의 확산범위는 증가하고 있다. 갈대의 확산은 다른 습지 식물의 서식지를 파괴하고, 갈대가 번식하면 동 식물들의 번식 자체가 어려울 뿐 아니라 갈대숲에 포식자가 늘어나 살아가기 어려운 환경으로 변하기때문에 갈대를 체계적으로 관리할 수 있는 방안이 마련되어야 한다. 본 연구는 우점종이 다른 두 습지에서 갈대군집의 성장률을 관찰하고, 토양의 화학적 분석과 식물의 생리적 분석을 통해 갈대군집 성장에 미치는 영양염류의 영향을 규명하였다. 연구 대상지는 한강하구에 위치한 장항습지와 성동습지로서 동일하게 갈대가 분포하며, 장항습지에는 줄 군락이 성동습지에는 새섬매자기 군락이 우점하고 있다. 분석 항목은 이화학적 항목을 비롯하여 용존유기탄소(DOC, dissolved organic carbon), 체외미생물효소활성도(Extracellular enzyme activities), 암모니아성 질소($NH_4^+$), 질산성 질소($NO_3^-$)을 분석하였다. 실험결과, 두 습지 갈대의 성장은 7월부터 9월에 증가하였고 성동습지의 토양성분이 점토질로 형성되어 높은 수분함량과 유기물함량을 유지하고 있기 때문에 갈대의 밀도가 높고 성장률이 활발한 것으로 나타났다. 또한 미생물활성과 환경인자간 양의 상관관계를 보아 환경인자들이 미생물 활성을 자극하고 미생물들은 식물의 성장을 촉진하여 영향을 주며, 반면 식물 뿌리는 enzyme을 생성하는 미생물에게 C 삼출물을 공급해 enzyme 활성에 영향을 미칠 것으로 사료된다.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.1-8
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• 2016

The purpose of this study is to examine the consolidation characteristics of waste landfill from sodium carbonate production. The waste lime is a byproduct from the production of soda ash. The consolidation settlement of waste lime landfill was determined for waste lime specimen which obtained from the field boring. The consolidation tests are conducted for determination of the primary and secondary consolidation settlements. The waste lime is classified as an organic soil with high plasticity. As a result of an organic content test, the contents of organic matter in waste lime is much higher than that of normal clay. Finally, the total consolidation settlement of waste lime landfill is calculated by using a theoretical method and computer program for the given initial void ratio, compression index, and embankment height.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.434-437
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• 2003

The fate and the behavior of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the environment are mainly controlled by their interactions with various components of soils and sediments. Due to their large surface area and abundance in many soils, smectites may greatly influence the fate and transport of the contaminants in the environment. In our experiment, PAH sorption by hexadecyltrimethylammonium (HDTMA)-modified smectite linearly increased in proportion to the amount of HDTMA added on the clay. However, trimethylammonium (TMA)-modified smectite did not show superiority in its sorption of PAH compared with the HDTMA-smectite or dodecyltrimethylammonium (DTMA)-smectite. Meanwhile, the smectites modified with the same cationic surfactants adsorbed Cd$^{2+}$ (heavy metal) significantly from water at low surfactant loading level, but the Cd$^{2+}$ adsorption linearly decreased as the loading of surfactant increased. The result shows that the sorption tendency of organoclays for organic or inorganic contaminants was significantly influenced by the amount and size of the surfactants added on the clay. It means that the stabilization and configuration of cationic surfactant formed on the clay interlayer according to the loading amount of each surfactant of different sizes may be an important factor in effectively sorbing environmental pollutants.nts.