• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.111-116
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• 2010

The treatment of heavy metal, in the waste ash from incinerator and mine solid waste, by using alkali-soluble acrylic copolymer emulsion, that is effective in the absorption of heavy metal has been studied. It seemed that alkali soluble acrylic copolymer emulsion was very effective in the absorption of Hg, Pb, Cd and Cu in this test. Also, eco-friendly thixotropic grout, using alkali soluble acrylic copolymer emulsion, that is effective in the absorption of heavy metal, for the recycling of waste ash from incinerator and mine solid waste has been tested. It was observed that waste ash could be used as a raw material of eco-friendly thixotropic grout mortar due to the effectiveness of alkali soluble acrylic copolymer emulsion in the fixation of heavy metals including $Cr^{6+}$ from waste ash in this test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.448-452
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• 2006

This study was performed to evaluate the long-term teachability of the stabilized hexavalent chromium contaminated soils treated with chromium reducing agent and soluble phosphate. The study shows that $Cr^{6+}$ in the leachate was little detected and the remaining $PO_4-P$ concentration kept below 0.1 mg/L due to the formation of geochemically stable hexavalent chromium phosphate minerals from the reactions of labile soil $Cr^{6+}$ forms with the added soluble phosphate salt and chromium reducing agent. The results provide evidence for the potential use of the immobilization technique for the hexavalent chromium contaminated soil remediation in the near future.

• Journal of Soil and Groundwater Environment
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• v.14 no.3
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• pp.32-39
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• 2009

This study was conducted in order to get the scientific background for soil pollution criteria. The 92 soil samples derived from various geological units were taken and analyzed to survey natural heavy metal background levels using aqua regia digestion method and 0.1N HCl extraction method. From these results, the average natural contents of metals were 0.287 mg/kg for Cd, 15.26 mg/kg for Cu, 18.43 mg/kg for Pb, 25.36 mg/kg for Cr, 54.27 mg/kg for Zn, 17.68 mg/kg for Ni, 6.83 mg/kg for As by the aqua regia method, and 0.040 mg/kg for Cd, 0.48 mg/kg for Cu, 3.06 mg/kg for Pb, 0.09 mg/kg for Cr, 1.54 mg/kg for Zn, 0.27 mg/kg for Ni, 0.089 mg/kg for As by the 0.1N HCl extraction method. Ratios of soluble contents and total contents were Cd 0.14, Cu 0.03, Pb 0.17, Cr 0.004, Zn 0.03, Ni 0.02, As 0.013 and the correlation coefficients of soluble contents and total contents were 0.24(As), 0.88(Cd), 0.43(Cr), 0.65(Cu), 0.70(Pb), 0.61(Ni), 0.24(Zn). The correlation factor decreased in the order of Cd > Pb > Cu > Ni > Cr > Zn $\approx$ As.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.727-733
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• 2011

A new Korean standard for the determination of Cr(VI) in soils has been officially published as ES 07408.1 in 2009. This analytical method is based on the hot alkaline digestion and colorimetric detection prescribed by U.S. EPA method 3060A and 7196A. The hot alkaline digestion accomplished using 0.28 M $Na_2CO_3$ and 0.5 M NaOH solution (pH 13.4) at $90{\sim}95^{\circ}C$ determines total Cr(VI) in soils extracting all forms of Cr(VI), including water-soluble, adsorbed, precipitated, and mineral-bound chromates. This aggressive alkaline digestion, however, proved to be problematic for certain soils which contain large amounts of soluble humic substances or active manganese oxides. Cr(III) could be oxidized to Cr(VI) by manganese oxides during the strong alkaline extraction, resulting in overestimation (positive error) of Cr(VI). In contrast, Cr(VI) reduction by dissolved humic matter or Fe(II) could occur during the neutralization and acidic colorimetric detection procedure, resulting in underestimation (negative error) of Cr(VI). Futhermore, dissolved humic matter hampered the colorimetric detection of Cr(VI) using UV/Vis spectrophotometer due to the strong coloration of the filtrate, resulting in overestimation (positive error) of Cr(VI). Without understanding the mechanisms of Cr(VI) and Cr(III) transformation during the analysis it could be difficult to operate the experiment in laboratory and to evaluate the Cr(VI) results. For this reason, in this paper we described the theoretical principles and limitations of Cr(VI) analysis and provided useful guidelines for laboratory work and Cr(VI) data analysis.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.580-586
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• 2000

A soluble Cr(VI) reductase was purified from the Cr(VI) reducing strain Escherichia coli ATCC33456 by ammonium sulfate fractionation, and chromatographies on Q-Sepharose FF, Cibacron blue 3GA dye affinity, Mono-Q 5/5, and Superdex 200 HR 10/30 columns. The estimated molecular mass of the purified enzyme was 27 kDa on SDS-polyacrylamide gel electrophoresis and 54 kDa on gel filtration, thus indicating a dimeric structure. The isoelectric point of the enzyme was pH 4.85. The optimum reaction pH and storage pH were both 7.0, the optimum reaction temperature was $37^{\circ}C$, and the storage temperature was $4^{\circ}C$. NADH and NADPH both served as electron donors for the reductase, with $V_{max}$ of 68.3 ${\mu}M$ Cr(VI)/min/mg protein and Km of 7.6 $\mu$M using HADH, and Vmax of 42.3 ${\mu}M$ Cr(VI)/min/mg protein and Km of 14.6 $\muM$ using NADPH. When 1 mM EDTA was added, the Cr(VI) reducing activity increased 4-fold.

• Journal of Korean Society for Atmospheric Environment
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• v.4 no.1
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• pp.1-12
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• 1988

This study was carried out to measure the contents of soluble sulfur and heavy metals in the leaves of roadside tree at 34 sampling sites of Seoul area from the Sep. 1 to Sep. 30 during 1985 and 1986. The results were as follows; 1. Average contents of soluble sulfur at all sampling sites were; Plantanus orientalis 0.474%, Ginkgobioloba 0.562%, and Salix pseudolasiogyne 0.566%. 2. Correlation between sulfur dioxide concentration in the air and soluble sulfur in the leaves by area were; Green belt area R = 0.985, Residential area R = 0.856, Commercial area R = 0.668, Industrial area R = 0.886. Correlation by species were ; Platanus orientalis R = 0.817, Ginkgobiloba R = 0.771, Salix pseudo-lasiogyne R = 0.824. 3. Correlation between $SO_X$ concentration in the air and sulfur contents in the leaves showed positive significance. 4. Contents of soluble sulfur in the heavy traffic area were higher than that of light traffic area. 5. Heavy metal contents of 1986 were higher than that of 1985; Fe> Mn > Zn > Pb > Cu > Cd > Cr. 6. Lead contents in the leaves of 1986 were; Platanus orientalis 16, 701 ppm, Gingobiloba 21,729ppm, Salix Pseudo-lasiogyne 12.418 ppm.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.657-662
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• 2005

Extractions fro fertilizer and soil samples were performed to yield the operationally defined fractions 'soluble' chromate (extractable with $NH_4NO_3$), 'exchangeable' chromate (extractable with phosphate buffer pH 7.2), and these results were compared with the data obtained by extractions with ammonium sulfate, borate buffer pH 7.2, saturated borax pH 9.6, and polyphosphate (Graham's salt). In order to maintain the pH of extractant solution about constant, the concentration of extractant buffer had to be raised to at least 0.5 M. The results strongly depended on the kind of extractant, and the solid: liquid ratio. For most of the samples investigated, the extraction efficiency increased in the order borate-sulfate-nitrate-phosphate. Whereas the recovery of $K_2CrO_4\;and\;CaCrO_4$ added to the samples of basic slags prior to the extraction was about complete, the recovery of added $PbCrO_4$ was highly variable. In soil extracts, the color reaction was interfered from co-extracted humics, which react with the chromate in weak acid solution during the time period necessary for color reaction (1 hour). However, this problem can be overcome by standard addition and subtraction of the color of the extractant solution. In soil extract of about pH < 7, organic material reduced chromate during the extraction period also, and standard addition of soluble chromate is recommended to prove recovery and the stability of chromate in the samples. In admixtures of soils and basic slags, results for hexavalent chromium were lower than from the mere basic slags. This effect was more pronounced in phosphate than in nitrate extracts. As a proficiency test, samples low in organic carbon from contaminated sites in Hungary were tested. The results from $NH_4NO_3$ extracts satisfactorily matched the results of the Hungarian labs obtained from $CalCl_2$ extractants.

• Advances in environmental research
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• v.6 no.4
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• pp.281-299
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• 2017

Single (0.005 M DTPA), sequential (six-step) and kinetic (0.05 M EDTA) extractions were performed to assess Cd, Cr, Cu, Ni, Pb, and Zn mobilization and their potential ecological risks in Abuja (Nigeria) water (WTS) and wastewater (WWTS) treatment sludges. Total metal levels (mg/kg) in WTS and WWTS, respectively were: Cd(3.67 and 5.03), Cr(5.70 and 9.03), Cu(183.59 and 231.53), Ni(1.33 and 3.23), Pb(13.43 and 17.87), Zn(243.45 and 421.29). DTPA furnished metal extraction yields (%) in WTS and WWTS, respectively as: Cd(11 and 6), Cr (15 and 7), Cu(17 and 13), Ni(23 and 3), Pb(11 and 12), and Zn(37 and 33). The metals were associated with the soluble/exchangeable, carbonate, Mn/Fe-oxide, organic matter and residual forms to varying degrees. Kinetic extractions cumulatively leached metal concentrations akin to the mobilizable fractions extracted sequentially and the leaching data fitted well into the Elovich model. Metal mobilities were concordant for the three leaching procedures and varied in the order:WTS>WWTS. Calculated ecological risk indices suggested moderate and considerable metal toxicity in WTS and WWTS, respectively with Cd as the worst culprit. The findings may be useful in predicting heavy metals bioavailability and risks in the sludges to guide their disposal and use in land applications.

• Economic and Environmental Geology
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• v.40 no.4
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• pp.403-418
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• 2007

The objective of this research was to characterize the fate and transport of Cr(VI) contaminated groundwater in the Daejeon industrial area. Five subsidiary monitoring wells were newly installed and two existing wells were utilized for the investigation and the reduction process of Cr(VI) contaminated groundwater of the Daejeon(Mun-pyeong) national groundwater monitoring station. The Cr(VI) concentrations at the shallow aquifer well of the station were in the range of 3.2-4.5 mg/L indicating continuous contamination. However, Cr was not detected at the deep bedrock well and the other monitoring wells except MPH-1 and 3. The Cr(VI) concentrations of MPH-1 and MPH-3 were below the drinking water guideline value (0.05 mg/L). Therefore, the plume of the Cr(VI) contaminated groundwater was predicted to be confined within the narrow boundary around the station. The soluble/exchangeable Cr(VI) concentrations were below the detection limit in all core and slime samples taken from the five newly installed wells. Although the exact source of contamination was not directly detected in the study area, the spatial Cr(VI) distribution in groundwater and characteristics of the core samples indicated that the source and the dispersion range were confined within the 100 m area from the monitoring station. The contamination might be induced from the unlined landfill of industrial wastes which was observed during the installation of an subsidiary monitoring well. For the evaluation of the natural attenuation of Cr(VI), available reduction capacities of Cr(VI) with an initial concentration of 5 mg/L were measured in soil and aquifer materials. Dark-gray clay layer samples have high capacities of Cr(VI) reduction ranging from 58 to 64%, which is obviously related to organic carbon contents of the samples. The analysis of reduction capacities implied that the soil and aquifer materials controlled the dispersion of Cr(VI) contamination in this area. However, some possibilities of dispersion by the preferential flow cannot be excluded due to the limited numbers of monitoring wells. We suggest the removal of Cr(VI) contaminated groundwater by periodical pumping, and the continuous groundwater quality monitoring for evaluation of the Cr(VI) dispersion should be followed in the study area.

• Journal of Environmental Science International
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• v.15 no.6
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• pp.503-511
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• 2006

Airborne particles collected from a heavily industrialized site were analyzed by chemical speciation of seven trace metals: Pb, Cd, Cr, Cu, Ni, Zn, and As. The average concentrations were as follows: $Zn,\;502.0{\pm}230.7;\;Pb,\;176.5{\pm}310.9;\;Cu,\;111.9{\pm}82.7;\;As,\;38.0{\pm}31.0;\;Cr,\;21.5{\pm}24.4;\;Cd,\;20.8{\pm}17.4;\;and\;Ni,\;11.4{\pm}8.4\;ng/m^3$. The median enrichment factor (EF) values of Cd (7,280), As (1,030), Cu (215), Zn (214), and Pb (143), with respect to iron, were much larger than 100. We observed that Cd was found in the soluble and exchange- able form (56.9%), and that Pb and Cr were found in carbonates, oxides and the reducible form (69.8% and 61.1%, respectively). These two forms, which are the most easily absorbed into human body tissue, predominated in most of the trace metals investigated in this study.