• Economic and Environmental Geology
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• v.36 no.3
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• pp.171-176
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• 2003

The fate and 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 our experiment, PAH sorption by hexadecyltimethylammonium(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. This reveals that the stabilization and configuration of cationic surfactant formed on the clay interlayer of different sizes may be an important factor in controlling the sorptive capacity of each pollutant in the environment.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.121-135
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• 2012

Soil dispersion and heavy metal leaching with two heavy metal-contaminated soils were studied to derive the optimal dispersion condition in the course of developing the remedial technology using magnetic separation. The dispersion solutions of pyrophosphate, hexametaphosphate, orthophosphate and sodium dodecylsulfate (SDS) at 1 - 200 mM and the pH of solutions was adjusted to be 9 - 12 with NaOH. The clay content of suspension as an indicator of dispersion rate and the heavy metal concentration of the solution were tested at the different pHs and concentrations of the dispersion solution during the experiment. The dispersion rate increased with increasing the pH and dispersion agent concentration of the solution. The dispersion efficiency of the agents showed as follows: pyrophosphate > hexametaphosphate > SDS > orthophosphate. Arsenic leaching was sharply increased at 50 mM of phosphates and 100 mM of SDS. The adsorption of $OH^-$, phosphates and dodecysulfate on the surface of Fe- and Mn-oxides and soil organic matter and the broken edge of clay mineral might decrease the surface charge and might increase the repulsion force among soil particles. The competition between arsenic and $OH^-$, phosphates and dodecylsulfate for the adsorption site of soil particles might induce the arsenic leaching. The dispersion and heavy metal leaching data indicate that pH 11 and 10 mM pyrophosphate is the optimum dispersion solution for maximizing dispersion and minimizing heavy metal leaching.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.83-88
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• 2019

BACKGROUND: In recent years, studies on microplastics have focused on their decomposition in the ocean. However, no studies have been reported on the interaction between microplastics and metal ions in aqueous solutions. Therefore, this study was conducted to evaluate the adsorption capacity of cadmium(Cd) by polypropylene (PP) in aqueous solution. METHODS AND RESULTS: Cadmium adsorption characteristics of PP in aqueous solution were evaluated through various conditions including initial Cd concentration(1.25-25 mg/L), contact time(0.5-24 h), initial pH(2-6) and temperature($20-50^{\circ}C$). Cadmium adsorption fit on PP was well described by Freundlich isotherm model with adsorption capacity(K) of 0.028. The adsorption amount of Cd by PP increased with increasing contact time, indicating that adsorption of PP by Cd was dominantly influenced by contact time. Especially, the removal efficiency of Cd by PP was highest at high temperature. However, the surface functional groups of PP before and after adsorption of Cd were similar, suggesting that adsorption of Cd by PP is not related to surface functional groups. CONCLUSION: Our study suggests that PP affects the behavior of Cd in aqueous solution. However, in order to clarify the specific relationship between microplastics and metal ions, mechanism research should be carried out.

• The Korean Journal of Pesticide Science
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• v.17 no.3
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• pp.168-177
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• 2013

This experiment was carried out to estimate leaching potential of thirteen endocrine disruptor-suspected pesticides in upland soils using soil columns (5 cm I.D. ${\times}$ 35 cm H.) packed with soil A (sandy loam) and soil B (loam). When 12.6 mL of water, average precipitation in Cheongju area during the period from June to August, 2001-2010, was percolated through soil column packed with soil A every day for 21 days, no pesticides were detected from leachate, with the exception of metribuzin which was detected with negligible. Also, when 2 L of water was percolated consecutively five times through soil columns packed with soil A and B, irrespective of soil types, cypermethrin, endosulfan, fenvalerate, parathion and trifluralin, which were very low water solubilities and high soil $K_{oc}s$, were not detected from leachate and were distributed mostly in the depth of 0-5 cm, representing that water solubility and soil $K_{oc}$ are major contributing factors to their leaching behavior. Despite high average leaching rates in carbaryl and methomyl, actual possibilities of ground water contamination in the agricultural environment by them would be very low, considering that the negligible amount of pesticide was percolated through a lysimeter with an undisturbed soil core simulating the field conditions, while most of pesticide was percolated through a soil column with the disturbed soil profile.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.25-33
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• 1997

To investigate the effects of cow manure compost(CMC) on soil and water environment as non-point source, the elution patterns of anions were determined in muti-layered soil columns which were consisted of one top and one bottom in combination. The top soil columns were uniformly packed with Ap horizon soils amended with air-dried CMC at different ratios(0, 2, 4, 6%, wt/wt), the bottom ones were packed with of B horizon soils of 15, 30, and 45cm in length. After saturating the each soil column, the leachate were collected from the bottom of the column while the double-ionized water was applied from the surface of the column by constant head method. From the hydraulic conductivity and anion eluted were measured in the leachate. Each saturated hydraulic conductivities for top and the bottom soils were 3$\times$$10^{-4}$sec and 1.6$\times$$10^{-3}$cm/sec. Most of water soluble chloride and sulfate, having non-specific adsorption characteristics onto the soil particles, were eluted within 1 PV, showing that there was no apparent retardation of anion movement with increasing CMC contents in the top soils. The effect of soil depths on anion movement were similar to the results of CMC contents. Sulfate of having both of non-specific and specific adsorption characteristics was also recovered in the effluent within 1 PV, while the elution curves were slightly skewed to the right showing that the CMC affected the movement of sulfate. Phosphate of specific adsorption characteristics was hardly eluted within 5 PV.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.21-28
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• 2006

We investigated the mobilization of Cd, Pb, and Cr in two different soils in response to sorption capacities and competition for available sorption site while they moved under saturated water conditions. Two soil samples that were clay and sandy clay loam were collected within 20 cm from the upland surface. To do this, we used three different systems of heavy metal combinations such as single, binary, and ternary as solution phase. And then we observed the breakthrough curve (BTC) and elution as a function of pore volume by applying heavy metal solution and displacing K solution until these curves reached to maximum and minimum. The results showed that BTC and elution curves were not symmetric and it required more pore volumes with increasing species of heavy metals in solution phase, as well as longer tailings. Compared the areas over and under BTC and elution curve, relatively small amount of heavy metal was displaced by K even though there were differences in electronegativity among heavy metals. Conclusively, we assumed that heavy metals transport in soil could be influenced by soil physical nonequilibrium and chemical equilibrium in solution as far as there were more than two species of heavy metals existed.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.334-341
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• 1997

In the laboratory experiment, concentration and rate of runoff of 7 pesticides were measured under the simulated rainfall. Total runoff rate of metolachlor, alachlor, chlorothalonil, chlorpyrifos, EPN, phorate and captafol were 57.0, 14.2, 13.2, 7.9, 7.2, 7.1 and 2.8%, respectively, and the average runoff concentrations were 940, 399, 55, 7.0, 9.3, 151 and 7.0 ppb, respectively. Significant relationship was observed between the runoff rate and water solubility in the laboratory experiment(r=0.923). Even though not very high, relatively significant results were obtained in other experimental conditions. Based on the results, runoff rate prediction$[Y=0.2812{\times}10exp(0.261logWS-0.366)+0.3594{\times}10exp(-0.545logKoc+1.747)+0.3594{\times}10exp(-0.362log\;Kow+1.105]$ and conversion equations were calculated to investigate the possibility of estimating runoff rate in the field by natural rain. Calculated runoff rate by conversion equation was similar to experimental result with captafol in the field while 6 times higher result was obtained by the prediction equation. Therefore, those prediction and conversion equations derived from the laboratory experiment data and physicochemical properties of the pesticides could be used for the prediction of field runoff rate of pesticides by natural rainfall.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.272-278
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• 2006

Movement of pesticides applied for crop protection to the non-target environmental compartments has increasingly concerned in recent. A special review on groundwater leaching potential of pesticides registered in Korea was done by using the data submitted on half-life and adsorption of the pesticides in/on soil. Groundwater ubiquity score(GUS) of pesticides as a leaching potential was calculated by using domestic trial data on pesticide half-life in paddy or upland soils and Koc data bases of Oregon State University (OSU), British Pesticide Safety Directorate and Sweden. Of total 382 pesticides reviewed, domestic half-lives of 107 pesticides were for paddy soil and 297 pesticides for upland soil. And total 317 Koc values were collected 148 pesticides from OSU DB and 276 pesticides from UK/Sweden DB. Very highly leachable pesticides were 18 and highly leachable pesticides were 44 among 313 pesticides classified by GUS.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.178-181
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• 2005

토양세척 공정 시 오염물질을 제거하기 위해 사용한 계면활성제를 재사용하기 위해 활성탄을 사용하였으며 이때 계면활성제와 HOC (Hydrophobic Organic Chemical)의 분배를 예측 할 수 있는 모델을 개발하였다. 계면활성제로는 Triton X-100, HOC는 phenanthrene을 활성탄으로는 Darco 20-40 mesh를 사용하였다. 개발된 모델로 계면활성제 주입량, 활성탄 주입량에 따른 계면활성제와 HOC의 분배결과를 각각 전산 모사를 통하여 얻었다. 그 결과 활성탄이 포함된 계 내에서의 계면활성제와 HOC의 분배가 미셀이 형성되는 농도를 전후로 서로 다른 분배 양상을 보였다. 또한 전산모사 결과는 실제 실험결과를 비교적 정확하게 반영함을 알 수 있다.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.81-85
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• 1999

Concentration change of soil-applied pretilachlor (2-chloro-2',6'-diethyl- N-2-propoxyethyl)-actanilide) was investigated under upland condition with various soil moisture contents ranging from 50 to 80%(water content by weight). Following pretilachlor from each soil solution was extracted by centrifugation using double tubes, its concentration was determined by HPLC. Pretilachlor concentration in the soil solutions were almost the same under various soil moisture conditions. However, the total amount of pretilachlor increased as the soil moisture content increased. With increasing soil moisture content, the bioactivity of soil-applied pretilachlor on inhibiting the growth of Echinochloa ultilis Ohwi et Yabuno and the absorption of $^{14}C$-pretilachlor in its plants were also enhanced. Our results demonstrate that the absorption of pretilachlor in plants varies with soil moisture content and thus the bioactivity of soil-applied pretilachlor on inhibiting plant growth is different under various soil moisture conditions at the same dosage based on air-dried weight.