• Economic and Environmental Geology
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• v.35 no.5
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• pp.421-428
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• 2002

Lab-scale experiments were conducted to evaluate the effect of surface tension reduction on the extension of the influence zone and the VOC removal efficiency of ground water sparging. A glass column packed with coarse sand was used for VOC removal test at two different surface tensions. A glass column without porous media was also used fer control purpose prior to sand-packed column test. A quasi-two-dimensional glass box model, packed with a sand, was used fer sparging zone tests at different water surface tensions. Surface tension of the aquoues solution used in this study was controlled using sodium dodecyl sulfate (SDS). For the glass, sand column experiments, total amount of air filled in the media increased as surface tension decreased. Toluene (used as VOC in this study) removal rate increased slightly with decreased surface tension f3r both free water column and sand-packed column. Air sparging zone extended up to 500% as the surface tension decreased. Combining the results from two different experiments, VOC removal efficiency is expected to increase significantly with surface tension reduction.

• Journal of the Korean earth science society
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• v.24 no.4
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• pp.290-302
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• 2003

This study was carried out to evaluate geochemical properties for stream sediments, surrounding soils, sludge collected in the drainage pipe of leachate and waters (stream water, groundwater, leachate) around the Pungam Landfill in Gwangju city. The stream sediments don't show any systematic trend of contents from upstream to downstream. The most enriched major element in the stream sediments is Fe (up to 7.08wt.% in GJ-23). Though stream sediment GJ-23 and GJ-34 were enriched by some heavy metals (eg. As, Cu, Zn), they do not constitute serious problems for environment consideration. The concentration of Fe (35.lwt.%) and As (38ppm) are significantly high in the GJ-8, which is soil specimen adjacent to leachate reservoir. The sludge (GJ-7) shows very high concentrations of As, Mn, Cr, Pb. In particular, the Cr content is 45.6 ppm, which exceeds the permitted level. The leachate is characterized by high TDS (2210-2470mg/L) and high electric conductivity (468, 530ms/cm), and enriched in both cation (Na, K) and anion (HCO$_3$). The leachate(PK-3) had a relatively high concentration of Cl, and is plotted in Na-Cl type on the Piper's diagram. The NO$_3$-N of the groundwater and stream water exceeded the permitted levels for drinking water.

• Analytical Science and Technology
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• v.17 no.2
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• pp.163-172
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• 2004

The molecular size distribution and fluorescence properties of soil fulvic acids (FA) were characterized by using gel filtration chromatography (GFC) and luminescence spectroscopy. The objectives of this work were to fractionate the FA extracted from a forest soil into different nominal molecular size using GFC system and to characterize the fluorescence properties (excitation, emission and synchronous) of these fractions using luminescence spectrometer. The GFC column was calibrated with polyethylene glycols, acetone and dextrane Blue. The total permeation volume of the GFC system was 404 mL and the void volume 130 mL. The GFC molecular weight of the soil FA was in the range of 190~8,900 Dalton and the molecular weight at the peak on the chromatogram was 930 Dalton. The fluorescence intensity ratio ($I_{498nm}/I_{390nm}$) was found to be increased with an increasing molecular weight. This results may suggest that the fulvic acid fractions with high molecular weight have large amount of the condensed aromatic compound.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.241-248
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• 1993

An experiment was conducted in 1990~1991 to study the effects of various soil amelioration on the soil productivity and machine workability at tidal land paddy field of Kyewhado Substation, Homam Crop Experiment Station. The soil, Munpo Series(fine sandy loam, Typic Fluvaquents) was treated with gipsum, rice straw, rice straw compost and foreign soil(at 20cm depth) after deep ploughing. The results are surmerized as follows. 1. Sand and clay were slightly increased, while silt was slightly decreased in the rice straw and compost plots. The soil texture was changed from loam to sand loam by the addition of foreign soil 2. Soil bulk density and porosity was decreased in the rice straw, compost and foreign soil addition plots. 3. Cone penetration resistance was $12.5kg/cm^2$ at 10cm of soil depth before experiment and $12.5kg/cm^2$ at 20cm of soil depth after experiment except control, and the root zone was expended down to 20cm. 4. Soil salt content before experiment was 0.46 and 0.48% for surface soil(10cm) and subsoil(20cm), respectively ; The salt content of ameliorated plot was 0.26~0.32% and 0.16~0.31%, respectively, indicating good leaching of soil salt by the soil improvements. 5. The yields of rice in different treatments were in the order of the foreign soil addition > compost > gypsum > rice straw > control.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.109-118
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• 1999

Recently, transport parameters of conservative solutes such as KCl in a porous medium have been successfully determined using time domain reflectometry (TDR) . This study was initiated to Investigate the applicability of TDR technique to monitoring the fate of a heavy metal ion in a sandy soil and the distribution of its concentration along travel distance with time. A column test was conducted in a laboratory that consists of monitoring both resident and flux concentrations of $ZnCl_2$in a sandy soil under a breakthrough condition. A tracer of $ZnCl_2$(10 g/L) was injected onto the top surface of the sample as pulse type as soon as a steady-state condition was achieved. Time-series measurements of resistance and electrical conductivity were performed at 10 cm and 20 cm of distances from the inlet boundary by horizontal-positioning of parallel TDR metallic rods and using an EC-meter for the effluent exiting the bottom boundary respectively. In addition. Zn ions of the effluent were analyzed by ICP-AES. Since the mode and position of concentration detected by TDR and effluent were different, comparison between ICP analysis and TDR-detected concentration was made by predicting flux concentration using CDE model accommodating a decay constant with the transport parameters obtained from the resident concentrations. The experimental results showed that the resident concentration resulted in earlier and higher peak than the flux concentration obtained by EC-meter, implying the homogeneity of the packed sandy soil. A close agreement was found between the predicted from the transport parameters obtained by TDR and the measured $ZnCl_2$concentration. This indicates that TDR technique can also be applied to monitoring heavy metal concentrations in the soil once that a decay constant is obtained for a given soil.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.525-534
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• 2014

Environmental problems typically occurring in abandoned mine lands (AML) include: contaminated and acidic surface water and groundwater; stockpiled waste rock and mill tailings; and ground subsidences due to mining operations. This study examines the effectiveness of various geophysical techniques for mapping potential hazard and contaminated zones. Four AML sites with sedimentation contamination problems, acid mine drainage (AMD) channels, ground subsidence, manmade liner leakage, and buried mine tailings, were selected to examine the applicability of various geophysical methods to the identification of the different types of mine hazards. Geophysical results were correlated to borehole data (core samples, well logs, tomographic profiles, etc.) and water sample data (pH, electrical conductivity (EC), and heavy metal contents). Zones of low electrical resistivity (ER) corresponded to areas contaminated by heavy metals, especially contamination by Cu, Pb, and Zn. The main pathways of AMD leachate were successfully mapped using ER methods (low anomaly peaks), self-potential (SP) curves (negative peaks), and ground penetrating radar (GPR) at shallow penetration depths. Mine cavities were well located based on composite interpretations of ER, seismic tomography, and well-log records; mine cavity locations were also observed in drill core data and using borehole image processing systems (BIPS). Damaged zones in buried manmade liners (used to block descending leachate) were precisely detected by ER mapping, and buried rock waste and tailings piles were characterized by low-velocity zones in seismic refraction data and high-resistivity zones in the ER data.

• Membrane Journal
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• v.7 no.3
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• pp.136-141
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• 1997

Humic acid has been extracted and purified from biologically nondegradable humic substances. Using the ion exchange capability of carboxylic acids which are the main component of the humic acids, a membrane was prepared with poly(viny1 alcohol). Its transport behavior of biologically active ions, $K^+$and $Na^+$, were investigated. The ion transport velocity increased with hydrogen ion concentration, especially, in the range of $10^-1$~$10^0$. The selectivity increased with increasing the concentrations of $K^{＋}$ and Na$^{＋}$, In particular, the transport velocity of $K^+$ increased twice compared to that of $Na^+$ at the 100 hydrogen ion concentration. In this regards, humic acid may be used as a new material for ion exchange membranes.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2033-2037
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• 2008

최근 들어 국지성호우와 장마, 태풍에 의한 자연재해는 모든 분야에서 심각한 영향을 미치고 있다. 자연재해로 발생한 토사는 하천, 농업용 저수지, 댐 및 하구를 메워 흐름을 방해하고 저서생태계에 미치는 영향은 매우 크다. 이러한 토사는 농업용 저수지와 홍수 조절용 구조물의 사용 수명을 단축시키고, 하상을 높여 흐름을 방해하거나 변화시켜 하천 범람을 발생하기도 한다. 한편 하천범람과 제방 붕괴 등은 농지 침수는 물론 작물의 성장을 방해하는 등 많은 경제적 손실을 가져오고 있다. 본 연구에서는 토사의 농도와 분광반사특성의 상호관계를 알아보기 위하여 분광복사계(Li-1800)를 이용하여 미리 제작한 수조 안의 토사(실트질, 모래질) 농도를 변화시켜 토사농도에 따른 분광반사 특성을 파악하고, 그 특징에 대해 검토, 고찰하였다. 연구결과 실트질의 체적반사율이 모래에 비해 약 40% 높게 나타났으며, 실트와 모래 모두 $554{\sim}588nm$영역에서 최대반사율을 나타내었다. 상관분석 결과 각 토사의 상관계수는 실트질이 $0.63{\sim}0.99$, 모래가 $0.73{\sim}0.96$의 값을 나타냈으며, 두 토양 모두 $550{\sim}900nm$영역에서 r>0.90의 높은 상관성을 보였다. 또한, 토사농도에 따른 반사특성은 실트질의 경우 토사 농도가 $0{\sim}60%$까지 $470{\sim}740nm$영역에서 큰 상승폭을 보인 반면, 모래의 경우 토사농도가 25%까지 크게 증가하였으나 30%이상의 농도에서는 변화 폭이 매우 적어지는 특징을 보였다. 토사농도의 변화에 따른 탁수의 분광 반사특성은 토사의 종류에 따라 크게 다르다는 것을 확인할 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.42-47
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• 2007

In this paper, influence of lossy ground and gap variation between lossy ground and UWB antenna on impulse propagation in time domain for impulse ground penetrating radar (GPR) is numerically and experimentally investigated. For this study, a novel planar UWB fat dipole antenna is developed. First, influence of lossy ground and gap variation between lossy ground and UWB antenna is simulated. For verification, a test field of sand and wet clay soil is built and using the developed dipole antenna, transmission behavior is investigated at the test field. With an aid of IDFT (inverse discrete Fourier transform), time domain impulse response for transmission coefficient measured and simulated in frequency domain is obtained. Measurement and simulation show that the frequency of maximum transmission coefficient and transmission coefficient are increased with higher dielectric constant and larger gap distance. In time domain, it is shown that for higher dielectric constant, the amplitude of the received signal in time domain is higher and reflected signals are seriously modified. Also, it is found that variation of gap between antenna and ground surface makes timing of peak value changed.

• Journal of Soil and Groundwater Environment
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• v.7 no.2
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• pp.73-81
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• 2002

In normal Fenton's reagent, the reductive mechanism of carbon tetrachloride (CT) with superoxide radical (${O_2}^-$.) was observed and the rate of ${O_2}^-$. production was investigated as a function of $H_2O$$_2$ concentration and pH. As pH was increased, the rate of 1-hexanol degradation was rapidly decreased from 90% (at pH 3) to 5% (at pH 11). On the other hand, more degradation of carbon tetrachloride was observed at higher pH regimes indicating Fenton's reaction is an oxidant-reductant co-existing system at neutral pHs. The rate of $O_2^{-}$ . production was observed at different $H_2$$O_2$ concentrations and at different pHs. The rate increased from (45.3$\pm$7.8) x $10^{-6}$ M/s to (151.0$\pm$26.2) x $10^{-6}$ M/s ($294mM H_2$$O_2$) at pH 11: the rate 3150 increased from (22.1$\pm$3.8) x $10^{-6}$ M/s at pH 7 to (151.0$\pm$26.2) x $^10{-6}$ M/s at pH 11 with 294mM $H_2$$O_2$, These results showed that Fenton's reagent could be applied at wide pH regimes. Especially, carbon tetrachloride, which can not be easily adsorbed to soils and then can be dissolved into groundwater causing a cancer, could be efficiently treated by Fenton's reagent.reagent.