• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.68-74
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• 2005

This study was carried out to evaluate the feasibility of field-scale sequential soil washing process for remediation on Kyongsangnamdo D mine soils which was heavily contaminated by arsonic. Arsenic concentration of untreated soils was $321\pm32mg/kg$. By applying the basic operating condition which was proposed from several pilot-scale experiments, arsenic concentration of treated soils was reduced 2.04 mg/kg ($99\%$ removal efficiency). We optimized the basic operating condition (mainly on washing solution concentration, cut-off size, and mixing ratio) to improve efficiently and economically the field-scale sequential soil washing process. The resulting optimized conditions were that solution concentration is 0.2M HCl, 1.0M HCl, 1.0M NaOH, that the cut-off size is 0.15mm (seive $\sharp$100), and that the mixing ratio is 1 3. Also, the optimized pH value for soil washing effluent treatment was 6 (33 ppb), in which the precipitation disruption caused by supersaturation of the floe did not occur. Results of TCLP tests showed that arsenic concentration from the washed gravels was 1.043 mg/L, that from soils ND (not detected), and that from filter cakes 0.066 mg/L. Also, the water content as a percentage of dewatered sludges was low $(48\%)$ and so the dewatered sludges can be disposed by landfilling. Through these results, we can concluded that tile field-scale sequential soil washing process developed in this study is adopted for remediation of arsenic-contaminated soils.

• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.33-44
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• 2009

The objective of the study was to develop a hybrid technology integrating biological and physicochemical technologies to efficiently remediate arsenic contaminated lands such as abandoned mine area. The tailing soil samples contaminated with As at a high level were obtained from Songchon abandoned mine, and the content of arsenic and heavy metals as well as physicochemical properties and mineral composition were investigated. In addition, two sets of sequential extraction methods were applied to analyze chemical speciations of arsenic and heavy metals to expect their leachability and mobility in geoenvironment. Based on these geochemical data of arsenic and heavy metal contaminants, column-type experiments on the bioleaching of arsenic were undertaken. Subsequently, experiments on the hybrid process incorporating bioleaching and electrokinetics were accomplished and its removal efficiency of arsenic was compared with that of the individual electrokinetic process. With the results, finally, the feasibilty of the hybrid technnology was evaluated. The arsenic removal efficiencies of the individual electrokinetic process (44 days) and the hybrid process incorporating bioleaching (28 days) and electrokinetics (16 dyas) were measured 57.8% and 64.5%, respectively, when both two processes were operated in an identical condition. On the contrary, the arsenic removal efficiency during the bioleaching process (28 days) appeared relatively lower (11.8%), and the result indicates that the bioleaching process enhanced the efficacy of the electrokinetic process as a result of mobilization of arsenic rather than removed arsenic by itself. In particular, the arsenic removal rate of the electrokinetics integrated with bioleaching was observed over than 2 times larger than that obtained by the electrokinetics alone. From the results of the study, if the bioleaching which is considered a relatively economic process is applied sufficiently prior to electrokinetics, the removal efficiency and rate of arsenic can be significantly improved. Consequently, the study proves the feasibility of the hybrid process integrating both technologies.

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.349-351
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• 2007

• Korean Journal of Plant Resources
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• v.26 no.1
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• pp.68-74
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• 2013

This study was conducted to analyse the effectiveness of shading on growth and arsenic absorption of Pteris multifida, known as hyperaccumulator of arsenic, from paddy soils contaminated with heavy metals. Study was carried out in paddy soil polluted by arsenic near the former Janghang smelter. P. multifuda in the same growth stage was planted with $20{\times}20cm$ intervals in each experimental plot ($2{\times}2m$), and cultivated for 24 weeks. The growth of P. multifuda according to shading conditions was evaluated, the accumulated amount of arsenic in plants and arsenic variation in the soil was analyzed using ICP. In the result of this study, the growth of P. multifida cultivated under shading treatment was vigorous than non-shading. Accumulated amount of arsenic in aerial parts of P. multifida cultivated under non-shading ($169.8mg{\cdot}kg^{-1}$) was slightly higher than shading ($140.9mg{\cdot}kg^{-1}$), and those in underground part were almost the same. But the growth was great in 70% shading treatment. Therefore, arsenic contents absorbed from soils was much higher in shading treatment. Arsenic translocation rate (TR) of P. multifida was very high (0.87~0.89) regardless of shading conditions. So arsenic in soil could be efficiently eliminated by removal of aerial parts.

• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.344-353
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• 2014

This study was carried out to analyze the effect of arsenic types on growth and arsenic accumulation ability of Pteris multifida. Among arsenic pollution sources, Sodium arsenate, Calcium arsenate, Sodium arsenite and Potassium arsenite were treated in horticultural compost contaminated with $500mg{\cdot}kg^{-1}$. P. multifida was cultivated for 12 weeks. The results of study, Calcium arsenate treatment showed slightly decreased growth of P. multifida. But, growth of P. multifida cultivated in the remaining arsenic treatment was similar to untreated control plot. With only short-term cultivation of 4 weeks, aerial part of P. multifida in Sodium arsenate treatment showed high arsenic accumulation of $2,289.5mg{\cdot}kg^{-1}DW$. The arsenic accumulation ($2,956.0mg{\cdot}kg^{-1}DW$) was the highest at 12 week. On the other hand, underground part showed the highest arsenic accumulation in Potassium arsenite treatment ($2,470.2mg{\cdot}kg^{-1}DW$) and Calcium arsenate treatment accumulated $1,060.7mg{\cdot}kg^{-1}DW$ of arsenic. Regardless of arsenic types, aerial part of P. multifida was absorbed more than $1000mg{\cdot}kg^{-1}DW$ of arsenic. And removal of arsenic in soil was also higher. Therefore, Pteris multida is considered to be suitable phytoremediation meterial of various arsenic contaminated areas.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.52-59
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• 2008

Adsorption is a major process causing the accumulation of arsenic onto soil. Therefore, further understanding of the adsorption/desorption characteristics of arsenic species on soil is essential for predicting their fate and preparing appropriate remediation strategy to remove arsenic from soil. In this study, the column adsorption/desorption experiment has been performed with As(III) and As(V) on soil. Experiment with As(III) was conducted under reducing condition, whereas that with As(V) was under oxidizing condition. Most of As(III) was remained on the oxidation state during the experiment. The results showed that the adsorption/desorption rate of As(III) was higher than that of As(V). Adsorption and desorption of arsenic species were not completely reversible in the column experiment. It was also found that As(V) in the column experiment was adsorbed more rapidly on soil than in the batch experiment.

• 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.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.349-356
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• 2003

As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

• Ecology and Resilient Infrastructure
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• v.11 no.3
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• pp.65-77
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• 2024

A series of experiments were performed to select suitable plant species for phytoremediation of arsenic (As) contaminated sandy pine forest soil in Janghang. Native plant species could uptake and remove As and sustain growth under the allelopathy of the pine forest and half-shade environmental conditions. We transplanted a total of 11 species into the pine forest in a pot, cultured them in a greenhouse for 3 months, and then harvested these plants to measure As accumulation, fresh weight, bioconcentration factor (BCF), and the amount of As removal per plant. The BCF of Lampranthus spectabilis was 3.52 and the amount of As taken up in Pennisetum alopecuroides shoots was 111.95 mg/kg. Higher biomass plants Lampranthus spectabilis and Lonicera japonica took up 8.49 mg/kg and 2.87 mg/kg of As in the above-ground parts, respectively. We applied oxalaic acid of 10, 20, and 40 mmol/kg-soil in total (divided into 15-20 splits) to each pot over a period of one month to enhance As uptake. Results showed no significant changes in plant growth or soil dehydrogenase activity. However, a statistically significant increase (p<0.05) in As uptake in Pennisetum alopecuroides was observed when a higher amount of oxalic acid (40 mmol/kg-soil) was applied.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.101-107
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• 2010

In order to deal with the problem that phytoremediation takes long time in achieving the practical effect, the enhanced phytoremediation by Barnyard grass (Echinochloa crus-galli) was conducted. In addition, we examined the synergistic effect by adding PSM (phosphate -solubilizing microbes) and EDTA (ethylenediaminetetraacetic acid) to the arsenic contaminated soil in the vicinity of the abandoned mine. The removal efficiency of arsenic in the site with PSM application increased about 16% when compared to control site, which was due to increase of plant biomass. The EDTA has been successfully utilized in respect of enhanced mobility and solubility of arsenic in the soil. As a result, BF (bioaccumulation factor) significantly increased but the inhibition of plant growth resulted in 20% reduction of arsenic removal efficiency. The application of PSM and EDTA may enhance the efficiency of phytoremediation. However, the time and method of EDTA application should be further examined to reach the maximum removal efficiency.