• Journal of Ecology and Environment
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• v.29 no.6
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• pp.559-563
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• 2006

This work was investigated the effects of the elevated $CO_2$ and Pb contamination on the growth of Pinus densiflora. Two-years pine trees were planted in Pb-contaminated soils (500 mg/kg-soil) and uncontaminated soils, and cultivated for 3 months in the growth chamber where $CO_2$ concentration was controlled at 380 or 760 ppmv. The growth of P. densiflora were comparatively analyzed in 4 kinds of soil samples (CA : $CO_2$ 380 ppmv + Pb 0 mg/kg, CB : $CO_2$ 380 ppmv + Pb 500 mg/kg, EA : $CO_2$ 760 PPmv + Pb 0 mg/kg, EB : $CO_2$ 760 ppmv + Pb 500 mg/kg). It was measured the growth changes of the p. densiflora caused by $CO_2$ concentration and Pb contamination. The growth of P. densiflora was remarkably inhibited in the Pb-contaminated soil, although the biomass and the root elongations were not significantly affected by the elevated $CO_2$. These results suggested that the growth of p. densiflora was sensitively influenced by Pb contamination rather than $CO_2$ concentration. Compared to the initial soil, total Pb concentration in the soil samples was decreased at 760 ppmv $CO_2$ as well as at 380 ppmv $CO_2$ after 3 months. The accumulation of Pb in the roots at 760 ppmv $CO_2$ was two-fold of that at 380 ppmv $CO_2$, indicating that Pb bioavailability in the root of p. densiflora might be affected by the elevated $CO_2$.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.123-136
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• 2010

In order to remediate heavy metal contaminated Nong island, Maehyang-ri shooting range soils through the batch reactor scale washing were evaluated. The experiment texture soil of N3 in the Nong island at north side incline was (g)mS containing 12.9% gravel, 47.0% sand, 35.1% silt and 5.0% clay. And the N3 soil area was contaminated with Cd($22.5\pm1.9$ ppm), Cu($35.5\pm4.0$ ppm), Pb($1,279.0\pm5.1$ ppm) and Zn($403.4\pm9.8$ ppm). The EDTA(ethylene diamine tetra acetic acid, $C_{10}H_{16}N_2O_8$) in the N3 soil was observed as most effective extractants among the 5 extractants(citric acid, EDTA, phosphoric acid, potassium phosphate and oxalic acid) tested. And chemical partitioning of heavy metals after washing N3 soil with EDTA was evaluated. Removal efficiency of residual fractions was higher than that of non-residual fractions. To choose EDTA extractant which is the most effective in soil washing technology using batch reactor process cleaning Pb and Zn contaminated sits; Pb and Zn removal rates were investigated 92.4%, 94.0% removal(1,000 mM, soil:solution=5, $20^{\circ}C$, 24 hour shaking, pH=2, 200 RPM), respectively. The results of the batch test showed that the removal efficiency curve was logarithmic in soil was removal. Thus, EDTA washing process can be applied to remediate the Pb and Zn contaminated soil used in this study.

• Journal of Environmental Science International
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• v.19 no.5
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• pp.585-590
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• 2010

This study attempted to facilitate various groundcover plants, related to phytoremediation material, and advance shade plants with a heavy metal tolerance to contaminated soil in an urban shade space. Saxifraga stolonifera, which has commonly been used a landscape shade plants, was evaluated to determine its heavy metal tolerance to different concentrations(Control, $100mg{\cdot}kg^{-1}$, $250mg{\cdot}kg^{-1}$ and $500mg{\cdot}kg^{-1}$ treatment) of Cd, Pb and Zn in soil. The growth of Saxifraga stolonifera showed no significant tendency after the initial transplantation, but showed distinct changes with the respective treatment heavy metal types and concentrations over time. Especially, severe chlorosis, with more yellowish green leaves, was observed, with inhibition at Cd concentrations greater than $100mg{\cdot}kg^{-1}$. Conversely, no external symptoms or growth retardation were observed with Pb and Zn concentrations less than $500mg{\cdot}kg^{-1}$. Therefore, Saxifraga stolonifera can be applied as a long term phytoremediation species in soil contaminated with low concentrations of heavy metal in urban shade spaces.

• Journal of Soil and Groundwater Environment
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• v.27 no.5
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• pp.10-17
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• 2022

Inorganic acids such as HCl, HNO₃, and H₂SO₄ have been commonly applied to soil washing of heavy metals-contaminated soil due to their cost-effectiveness. However, implementing the 'Chemical Substance Control Act' requires off-site risk assessment of the chemicals used in the soil washing. Therefore, in this study, organic acids or Fe(III)-based washing agents were evaluated to replace commonly used inorganic acids. Ferric removed heavy metals via H⁺ generated by hydrolysis, which is similar to the HCl used in the control group. Oxalic acid and citric acid were effective to remove Cu, Zn, and Cd from soil. Organic acids could not remove Pb because they could form Pb-organic acid complexes with low solubility. Furthermore, Pb could be adsorbed onto the iron-organic acid complex on the soil surface. Ferric could remove exchangeable-carbonate, Fe-Mn hydroxide, and organic matter and sulfides bound heavy metals (F1, F2, and F3). Organic acids could remove the exchangeable-carbonate and Fe-Mn hydroxide bound metals (F1&F2). Therefore, this research shows that the fractionation of heavy metals in the soil and the properties of washing agents should be considered in the selection of agents in the process design.

• Journal of Soil and Groundwater Environment
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• v.22 no.2
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• pp.33-40
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• 2017

In typical remediation practices, separate washing systems have to be applied to clean up the soils contaminated with both oil and heavy metals. In this study, we evaluated the efficiency of successive two-stage soil washing in removal of mixed-contaminants from soil matrix. Two-stage soil washing experiments were conducted using different combinations of chemical agent: 1) persulfate oxidation, followed by organic acid washing, and 2) Fenton oxidation, followed by inorganic acid washing. Persulfate oxidation-organic acid washing efficiently removed both organic and inorganic contaminants to meet the regulatory soil quality standard. The average removal rates of total petroleum hydrocarbons (TPH), Cu, Pb, and Zn were 88.9%, 82.2%, 77.5%, and 66.3% respectively, (S/L 1:10, reaction time 1 h, persulfate 0.5 M, persulfate:activator 3:1, citric acid 2 M). Fenton oxidation-inorganic acid washing also gave satisfactory performances to give 89%, 80.9%, 87.1%, and 67.7% removal of TPH, Cu, Pb, and Zn, respectively (S/L 1:10, reaction time 1 hr, hydrogen peroxide 0.3 M, hydrogen peroxide:activator 5:1, inorganic acid 1 M).

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.90-96
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• 2011

Simultaneous removal of heavy metals (Cd, Pb) and diesel-fuel from a soil column was evaluated by respectively flushing with sodium dodecyl sulfate (SDS) solution, mixture of SDS and sodium iodide (SDS + NaI), and surfactant foam (SDS + NaI foam). First, this study evaluated these flushing methods to the heavy metals only-contaminated soil for removal of heavy metals from the heavy-metal only contaminated soil column. After 7 pore volume flushing of the soil column, Cd removal efficiencies from the soil were 40% by SDS solution, 50% by SDS + NaI mixture, and 60% by surfactant foam. The flushing results implied that anionic surfactant and ligand can be efficiently applied to extraction of Cd from the heavy metal contaminated soil. Furthermore, surfactant foam flushing showed an increased flushing efficiency with enhancing the contact between surfactant solution and soil. However, Pb removal efficiency by these flushing methods did not show any difference unlike those of Cd. Second, this study eventually evaluated flushing methods for simultaneous removal of heavy metals and diesel-fuel from the soil column with 7 pore volume flushing. Diesel-fuel removal efficiencies were 50% by SDS + NaI flushing and 90% by SDS + NaI foam flushing. Cd removal efficiency by the foam flushing reached to 80% which was higher than the result of the previous heavy metals onlycontaminated soil experiment. This result implied that diesel-fuel could act as a metal-solvent while it contacted to heavy metals present in the soil. This study clearly showed that surfactant foam flushing simultaneously removed heavy metals and diesel fuel from the soil column.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.11-14
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• 2001

In this study, the relationship between metals (Cu, Cr, Cd, Zn. Pb, and Fe) 5 fractions and toxicity of soil samples from various contaminated sites in Korea were investigated. Metal toxicity of soils was tested using MetPLATE$^{TM}$ test kit, which is known as metal sensitive and organic insensitive. Significant amount of Fe was found in soils, and metal contents were in the order of Fe>Zn>Pb>Cu>Cr>Cd. Metal levels in organic fraction were rather high for all metals except Fe, and quite high percentages (35~79%) for residual fraction were observed for all metals. There were no significant relationships between the content of each metal fraction and toxicity which showed regression $R^2$in the range of 0.0003~0.414. However, correlation between toxicity and total metal contents showed regression coefficient $R^2$= 0.72. These results showed that the risk evaluation of metals in contaminated sites should be difficult to assess only by the contents of metal distribution because of the complexity of mixture of various metals.s.

• Economic and Environmental Geology
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• v.54 no.3
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• pp.399-408
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• 2021

Natural soil was artificially contaminated with heavy metals (Cd, Pb, and Zn), and the movement of earthworm was characterized in real time using the ViSSET system composed of vibration sensor and the other components. The manifestation mechanism of ecological toxicity of heavy metals was interpreted based on the accumulative frequency of earthworm movement obtained from the real-time monitoring as well as the conventional indices of earthworm behavior, such as the change in body weight before and after tests and biocumulative concentrations of each contaminant. The results showed the difference in the earthworm movement according to the species of heavy metal contaminants. In the case of Cd, the earthworm movement was decreased with increasing its concentration and then tended to be increased. The activity of earthworm was severely increased with increasing Pb concentration, but the movement of earthworm was gradually decreased with increasing Zn concentration. The body weight of earthworm was proved to be greatly decreased in the Zn-contaminated soil, but it was similarly decreased in Cd- and Pb-contaminated soils. The bioaccumulation factor (BAF) was higher in the sequence of Cd > Zn > Pb, and particularly the biocumulative concentration of Pb did not show a clear tendency according to the Pb concentrations in soil. It was speculated that Cd is accumulated as a metallothionein-bound form in the interior of earthworm for a long time. In particular, Cd has a bad influence on the earthworm through the critical effect at its higher concentrations. Pb was likely to reveal its ecotoxicity via skin irritation or injury of sensory organs rather than ingestion pathway. The ecotoxicity of Zn seemed to be manifested by damaging the cell membranes of digestive organs or inordinately activating metabolism. Based on the results of real-time monitoring of earthworm movement, the half maximal effective concentration (EC50) of Pb was estimated to be 751.2 mg/kg, and it was similar to previously-reported ones. The study confirmed that if the conventional indices of earthworm behavior are combined with the results of newly-proposed method, the mechanism of toxicity manifestation of heavy metal contaminants in soils is more clearly interpreted.

• Journal of Soil and Groundwater Environment
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• v.22 no.1
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• pp.18-26
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• 2017

In a previous study, we assessed the feasibility of ferric chloride ($FeCl_3$) as a washing agent in bench-scale in-situ soil washing to remove Pb from agricultural paddy soil. Herein is a subsequent study to evaluate variations in soil properties after $FeCl_3$ soil washing in terms of fractionation and bioavailability of Pb and chemical properties of the soil. After soil washing, the soil pH decreased from 4.8 to 2.6 and the exchangeable fractions of Pb in the soil increased from 12 mg/kg to 15 mg/kg. Variations in the Pb fractionation of the soil increased Pb bioavailability by almost three-fold; however,the base saturation decreased by 75%. The concentrations of total nitrogen and available phosphate were similar before and after soil washing. The available silicate concentration significantly increased after soil washing but was two times lower than that of soil washed with HCl, which is widely used as a washing agent. This indicates that $FeCl_3$ can be an acceptable washing agent that protects the soil clay structure. The results suggest that soil amendment, such as liming, is needed to recover soil pH, reduce mobility of Pb, and provide exchangeable bases of Ca, Mg, and K as essential elements for the healthy growth of rice plants in reused soil that has been washed.

• Journal of Environmental Science International
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• v.26 no.6
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• pp.797-802
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• 2017

This study aimed to remove organic matter and heavy metals that could affect the recycling of soils contaminated by heavy metals, by means of electrolysis, carried out simultaneously with the leaching of the soil. To ensure better experimental equipment, a soil electrolysis apparatus, equipped with spiral paddles, was used to agitate the heavy-metal-contaminated soil effectively. The heavy-metal-contaminated soil was electrolyzed by varying the voltage to 5 V(Condition 1), 15 V(Condition 2), and 20 V(Condition 3), under the optimal operating conditions of the electrolysis apparatus, as determined through previous studies. The results showed that the pH of the electrolyte solution and the heavy-metal-contaminated soil, after electrolysis, tended to decrease with an increase in voltage. The highest removal efficiencies of TOC and $COD_{Cr}$ were 18.8% and 29.1%, 38.8% and 4.2%, and 33.3% and 50.0%, under conditions 1, 2 and 3, respectively. Heavy metals such as Cd and As were not detected in this experiment. The removal efficiencies of Cu, Pb and Cr were 4.7%, 8.3% and 2.1%, respectively, under Condition 1, while they were 42.9%, 15.2% and 22.1%, respectively, under Condition 2, and 4.7%, 23.0%, and 24.9%, respectively, under Condition 3. These results suggest that varying the voltage with the soil electrolysis apparatus for removing contaminants for the recycling of heavy-metal-contaminated soil allows the selective removal of contaminants. Therefore, the results of this study can be valuable as basic data for future studies on soil remediation.