• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.59-70
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• 2012

In this study, to select the best stabilizer for the heavy metals-contaminated soil from a smelter area during phytoremediation, a plant uptake experiment and a soil stabilization were simultaneously applied using Pteris multifida Poir. and five pre-screened stabilizers(zeolite, Mn dioxide, slag, Ca oxide, and magnetite). The extracted heavy metal was measured and compared using a 3 step sequential extraction for the soil samples. The growth rate of the plant was also evaluated. The stabilizers stabilized heavy metals in soil and reduced the extraction rate. Magnetite and calcium oxide showed better results than other stabilizers. The stabilizers enhanced the growth of the plant. All the heavy metals except for arsenic were concentrated in roots while arsenic was concentrated in leaves of the plant. It is concluded that the stabilizers can minimize the heavy metal release from the contaminated soil during phytoremediation and stimulated the growth of plant. These effects of stabilizers could compensate for some weak points of phytoremediation such as reaching of heavy metals by rainwater.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1156-1167
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• 2018

The aim of this study was to isolate and characterize lead (Pb)-solubilizing bacteria from heavy metal-contaminated mine soils and to evaluate their inoculation effects on the growth and Pb absorption of Brassica juncea. The isolates were also evaluated for their plant growth-promoting characteristics as well as heavy metal and salt tolerance. A total of 171 Pb-tolerant isolates were identified, of which only 15 bacterial strains were able to produce clear haloes in solid medium containing PbO or $PbCO_3$, indicating Pb solubilization. All of these 15 strains were also able to dissolve the Pb minerals in a liquid medium, which was accompanied by significant decreases in pH values of the medium. Based on 16S rRNA gene sequence analysis, the Pb-solubilizing strains belonged to genera Bacillus, Paenibacillus, Brevibacterium, and Staphylococcus. A majority of the Pb-solubilizing strains were able to produce indole acetic acid and siderophores to different extents. Two of the Pb-solubilizing isolates were able to solubilize inorganic phosphate as well. Some of the strains displayed tolerance to different heavy metals and to salt stress and were able to grow in a wide pH range. Inoculation with two selected Pb-solubilizing and plant growth-promoting strains, (i.e., Brevibacterium frigoritolerans YSP40 and Bacillus paralicheniformis YSP151) and their consortium enhanced the growth and Pb uptake of B. juncea plants grown in a metal-contaminated soil. The bacterial strains isolated in this study are promising candidates to develop novel microbe-assisted phytoremediation strategies for metal-contaminated soils.

• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1298-1307
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• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.47-54
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• 1999

SRB(Sulfate Reducing Bacteria) converts sulfate into sulfide using an organic carbon source as the electron donor. The sulfide formed precipitates the various metals present in the AMD (Acid Mine Drainage). This study is the fundamental research on heavy metal removal from AMD using SRB. Two completely mixed anaerobic reactors were operated for cultivation of SRB at the temperature of $30^{\circ}C$ and anaerobic batch reactors were used to evaluate the effects of carbon source, COD/sulfate($SO_4^=$) ratio and alkalinity on sulfate reduction rate and heavy metal removal efficiency. AMD used in this study was characterized by low pH 3.0 and 1000mg/l of sulfate and dissolved high concentration of heavy metals such as iron, cadmium, copper, zinc and lead. It was found that glucose was an organic carbon source better than acetate as the electron donor of SRB for sulfate reduction in AMD. Amount of sulfate reduction maximized at the COD(glucose)/sulfate ratio of 0.5 in the influent and then removal efficiencies of heavy metals were 97.5% of Cu, 100% of Pb, 100% of Cr, 49% of Mn, 98% of Zn, 100% Cd and 92.4% of Fe. Although sulfate reduction results in an increase in the alkalinity of the reactor, alkalinity of 1000mg/1 (as $CaCo_3$) should be should be added continuously to the anaerobic reactor in order to remove heavy metals from AMD.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.137-142
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• 2011

This study was conducted to establish the optimal electrolyte and bismuth concentrations using bismuth film electrode in laboratory and to confirm the possibilities of using this operational condition for heavy metals monitoring in field. In lab test, heavy metal measurement was not accurate more than 600 ppb when heavy metal (Pb, Cd, Zn) range 100~1,000 ppb was measured with bismuth 2,000 ppb. So, bismuth and heavy metal was reacted about 1:1 with ASV method. In electrolyte test, 0.1 M acetate buffer (pH 4.5), 0.1 M chloroacetate buffer (pH 2.0), 0.1 M HCl (pH 2.0), 0.1 M $HNO_3$ (pH 2.0) was tested. As a results, 0.1 M acetate buffer was most suitable in ASV measurement with bismuth film electrode. In field application, Pb, Cd and Zn was measured respectively 36~45 ppb, 84~91 ppb, 90~98 ppb when heavy metal (Pb, Cd, Zn) 100 ppb was spiked in field sample. These results were identified of matrix effect in field sample, So relationship between heavy metal measurement and matrix effects will be studied.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.397-403
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• 2015

Heavy metals reduce the photosynthetic efficiency and disrupt metabolic reactions in a concentration-dependent manner. Moreover, by replacing the metal ions in metalloproteins that use essential metal ions, such as Cu, Zn, Mn, and Fe, as co-factors, heavy metals ultimately lead to the formation of reactive oxygen species (ROS). These, in turn, cause destruction of the cell membrane through lipid peroxidation, and eventually cause the plant to necrosis. Given the aforementioned factors, this study was aimed to understand the physiological responses of rice to cadmium (Cd) and arsenic (As) toxicity and the effect of essential metal ions on homeostasis. In order to confirm the level of physiological inhibition caused by heavy metal toxicity, hydroponically grown rice (Oryza sativa L. cv. Dongjin) plants were exposed with $0-50{\mu}M$ cadmium (Cd, $CdCl_2$) and arsenic (As, $NaAsO_2$) at 3-leaf stage, and then investigated malondialdehyde (MDA) contents after 7 days of the treatment. With increasing concentrations of Cd and As, the MDA content in leaf blade and root increased with a consistent trend. At 14 days after treatment with $30{\mu}M$ Cd and As, plant height showed no significant difference between Cd and As, with an identical reduction. However, As caused a greater decline than Cd for shoot fresh weight, dry weight, and water content. The largest amounts of Cd and As were found in the roots and also observed a large amount of transport to the leaf sheath. Interestingly, in terms of Cd transfer to the shoot parts of the plant, it was only transported to upper leaf blades, and we did not detect any Cd in lower leaf blades. However, As was transferred to a greater level in lower leaf blades than in upper leaf blades. In the roots, Cd inhibited Zn absorption, while As inhibited Cu uptake. Furthermore, in the leaf sheath, while Cd and As treatments caused no change in Cu homeostasis, they had an antagonist effect on the absorption of Zn. Finally, in both upper and lower leaf blades, Cd and As toxicity was found to inhibit absorption of both Cu and Zn. Based on these results, it would be considered that heavy metal toxicity causes an increase in lipid peroxidation. This, in turn, leads to damage to the conductive tissue connecting the roots, leaf sheath, and leaf blades, which results in a reduction in water content and causes several physiological alterations. Furthermore, by disrupting homeostasis of the essential metal ions, Cu and Zn, this causes complete heavy metal toxicity.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.559-567
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• 2020

The abnomal responseses on growth and morphology of attached diatoms by various heavy metals were studied. Ulnaria ulna (Nitzsch) Compère was employed as experimental species and exposed to the five heavy metals such as Cu, Zn, Pb, Cd, and As with four concentrations (0, 0.01, 0.1, and 2 mg L-1), respectively. The samples of Ulnaria ulna were examined on the changes of cell growth and teratological forms on the 7th, 14th, 21th, and 28th day, respectively, after exposure to the heavy metals. The samples exposed to the highest concentration, 2.0 mg L-1, of all the heavy metals showed the most obvious decreases of growth. The samples exposed to Cd (μ=0.049day-1) and As (μ=0.048day-1) showed the highest decreasing rate of growth (p=0.021(Cd), p=0.002(As)) and the highest morphological changes of diatom valves were also samples exposed to Cd (10.41%) and As (10.13%) (p=0.009 (Cd), p=0.005(As)). In contrast, Pb induced the lowest decreasing rate (μ=0.090 day-1) and the least change in valve morphology (3.31%). The Cd and As showed relatively stronger effects on growth rates compared to Cu, Zn, and Pb. For the percentage of emergence of morphological species by the type, the highest percentage were observed in sampled exposed to type 1 (43.4%) and followed by type 2 (29.1%). The type 2 and 4 were most abundant in samples exposed to Zn and Pb while the type 3 was most abundant in Cd and As. The Cu induced only type 1, suggesting that the frequency of emergence of each type varied among hevay metals. This research suggests that the degrees of abnomal changes on growth rate and valve morphology of Ulnaria ulna can be used as a bioindicater species for heavy metal contamination in freshwater.

• Journal of Soil and Groundwater Environment
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• v.12 no.3
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• pp.44-52
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• 2007

Contaminated sediments more than 30 million/$m^3$ is generated from dredging work for harbours and coastal maintenance in Korea. Approximately 300 million/$m^3$ of sediments is dredged to deepen harbours and shipping lanes in US and of which $3{\sim}12million/m^3$ is highly contaminated. Although much is known about technologies for the remediation of heavy metal contaminated soil, much less is known about the treatment of contaminated sediment. In general, negatively charged fine particles will migrate towards positively charged system of electrodes under the influence of electrophoresis. However, the electrically induced migration of colloidal particles contaminated with heavy metals may be hindered by the positively charged heavy metal contaminants adsorbed onto the soil surfaces depending on the contamination level. This paper demonstrates settling behaviour of clayey soil by comparison with electrophoretic particle movement under the effects of heavy metal contamination, applied electric field strength, and its polarity changed by the electrode configuration.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.241-248
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• 2009

A farming area located near an abandoned copper mine in GuPo-ri, Choongchung province is heavily contaminated with heavy metals such as As, Pb, Cd, Cu and Zn of which concentrations are higher than the values typically detected in Korean soil environment. In this work, laboratory and field studies were conducted to examine feasibility of using Ca-citrate-phosphate solution in stabilizing heavy metals in the polluted soils. In laboratory batch experiments with field soil, the addition of Ca-citrate-phosphate solution resulted in decrease of aqueous phase concentration of phosphate and improvement of heavy metal stabilization, compared to those for sterilized soil samples. This indicates that microbial uptake of phosphate may have provided positive effects on availability of phosphate toward heavy metal stabilization. According to microbial community analysis for the field experiment, the use of Ca-citrate-phosphate led to increased diversity of microbial populations, and strict anaerobic microorganisms such as Anaerofilum and Treponema became the most dominant populations in the solution-amended field experiments. These findings suggest that, when Ca-citrate-phosphate is used for heavy metal stabilization in soils, microbial processes may have important roles in improving the stabilization of heavy metals by providing reducing conditions to the treatment locations or/and by making phosphate available to heavy metal stabilization.

• Journal of Environmental Science International
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• v.12 no.5
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• pp.559-564
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• 2003

The specific ion effects are observed in the alumina-metal EDTA(Ethylene Diamine Tetraacetic Acid) system. These effects seem to be associated with the fluidity of the metal ion in the complex. A consideration of the order of adsorption of the complexes on alumina indicates that a specific ion effect also affects the stability of the system. It is clear that EDTA and its heavy metal complexes have a significant effect on the dewaterability of alumina. These effects are not well represented by zeta potential measurements, especially for EDTA alone. With the nonspeciating complexes, though, the maximum permeability is predicted by the pH$\_$zpc/ from zeta potential measurements. At other pH value, the refiltration rate is better predicted by the state of coagulation as measured by log W.