• Economic and Environmental Geology
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• v.36 no.6
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• pp.481-490
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• 2003

The objectives of this study are (1) to determine the extent and degree of As contamination of the water and sediments influenced by mining activity of the abandoned Au-Ag mines, (2) to examine As speciation In contaminated water, (3) to monitor variation of As contamination in water system throughout the dry and wet seasons, and (4) to investigate the As chemical form in the sediments through the sequential extraction analyses. Natural water(mine water, surface water and groundwater) and sediments were collected in six abandoned Au-Ag mine(Au-bearing quartz veins) areas. The contamination level of As in mine water of the Dongil(524${\mu}m$/L) is more higher than the tolerance level(500 ${\mu}m$/L) for waste water of mine area in Korea. Elevated levels of As in stream water were also found in the Dongil(range of 63.7∼117.6 ${\mu}m$/L.) and Gubong(range of 56.1∼62.9 ${\mu}m$/L) mine areas. Arsenic contamination levels in groundwater used by drinking water were more significant in the Dongil(11.3∼63.5 ${\mu}m$/L), Okdong(0.2∼68.9 ${\mu}m$/L) and Gubong(2.0∼101.0${\mu}m$/L) mine areas. Arsenate[As(V), $H_2AsO_4^-$] is more dominant than arsenite[As(III), $H_3AsO_3$] in water system of the most mine areas. The concentration ratios of As(III) to As(total), however, extend to the 95% in stream water of the Okdong mine area and 70∼82% in groundwater of the Okdong and Dongjung mine areas. As a study of seasonal variation in the water system, relatively high levels of As from the dongil mine area were found in April rather than in September. Sequential extraction analysis showed that As was predominantly present as coprecipitated with Fe hydroxides from sediment samples of the Dongjung and Gubong mine(35.9∼40.5%), which indicates its possibility of re-extraction and inducing elevated contamination of As in the reductive condition. In sediments from the Dongil, Okdong and Hwachon mine area, high percentage(55.2∼83.4%) of As sulfide form was found.

• Ocean and Polar Research
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• v.33 no.4
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• pp.435-445
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• 2011

We investigated geochemical properties, and microbial sulfate- and iron(III) reduction in sediment influenced by the aquaculture of abalone in the Nohwa-do, southern coastal sea in Korea. Concentrations of ammonium, phosphate, and sulfide in the pore-water were higher at farm sites than at control sites. The differences between the 2 types of sites were most apparent in terms of the weights of abalone and the temperature increase during September. Accordingly, the rates of sulfate reduction at the farm sites during September (61 mmol S $m^{-2}d{-1}$) were 3-fold higher than the sulfate reduction during May (20 mmol S $m^{-2}d{-1}$). In contrast, Fe(III) reduction rates were highest at the control sites in May, but its significance was relatively decreased at farm sites during September when sulfate reduction rates were highest. During September, benthic ammonium flux was 3-fold greater at the farm sites (35 mmol N $m^{-2}d{-1}$) than at the control sites (12 mmol N $m^{-2}d{-1}$), and phosphate flux was 8-fold higher at the farm sites (0.018 mmol P $m^{-2}d{-1}$) than at control sites (0.003 mmol P $m^{-2}d{-1}$). Overall results indicated that the inappropriate operation of a large-scale aquaculture farm may result in excess input of biodeposits and high nutrient fluxes from the sediment, thereby decreasing diversity of the benthic ecosystem and deepening eutrophication in coastal waters.

• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.275-282
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• 1981

A simple semiquantitative procedure was developed for the determination of sub-ppm level of chromium(VI) in aquatic samples by using an analytical micro-column packed with diphenylcarbazide(DPC) gel beads. DPC gel beads were prepared by swelling XAD-2 resin(115∼150 mesh in dry condition) in ethanol for 10min, packing into a glass column(1.5 mm bore, 65nm length) and adsorbing 1ml of ethanol solution of $2{\times}10^{-3}M$ DPC for 20min at room temperature. When 0.5ml of ethanol solution containing chromium(VI) was passed through the DPC gel column for 40min, the original white color of the reagent gel turned to red-violet from the up-stream of the column. As the length of colored band was proportional to the total amount of chromium(VI) in the sample solution passed through the column, the concentration of chromium(VI) could be determined from the calibration line which had been prepared by using the standard solution. Chromium(VI) ion as small as from 0.1 to 0.8 ppm could be determined with ${\pm}5{\sim}{\pm}15{\%}$ relative errors. Since other interfering cations were few, 100-fold excess of Fe(III), 50-fold excess of Cu(II) could be masked with EDTA. This method was successfully applied to the analysis of chromium(VI) in industrial effluents.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.311-317
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• 1983

These studies were carried out to investigate the effects of rice straw on the leaching of chemical constituents in paddy soil. Rice plants were cultured in paddy soil to which rice straw was applied and then chemical properties of percolated water were analysed. The results were as follows. The leaching of calcium and magnesium was affected by rice straw application in the early stages of plant growth and by rice root activity in the late stages. The application of the straw promoted the reduction of the soil followed by increasing the leaching of iron and manganese. The leaching of potassium, ammonium-nitrogen and chloride was not due to the application of rice straw and the leaching of carbon dioxide increased with the application of rice straw, at the same time chemical properties seemed to be affected by rice root activity. Generally, cation and anion leached in the percolated water were equivalent. Calcium, magnesium, Fe as cation and $HCO_3$, $SO_4{^{-2}}$ as anion were important constituents in the percolated water from paddy soil.

• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.129-138
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• 2009

The XRF core scanner was used, to analyze high resolution chemical elements in deep sea sediment cores from Clarion-Clipperton fracture zone of the northeastern Pacific. Comparison of data estimated by the XRF core scanner with ICP-AES showed relatively weak correlation coefficients between elements (especially Ba, Pb, Sr, Zr) except for Mn contents ($r^2$ > 0.89). However down-core variations of most elements seemed to be well matched each other and furthermore, XRF core scanner data reflected changes of sedimentary facies characterized by sediment colors. Mn/Al ratio dramatically changed at boundaries of facies in BC08-02-05 and BC08-02-13 but progressive changes occured in BC08-02-02, BC08-02-09 and BC08-02-10 where the sediments have been affected by bioturbations. The difference of Mn/Al ratio in each facies (Facies I, Facies II, Facies III) has been caused by redox condition of depositional environment. Vertical change of Mn/Al ratio were divided into two types probably affected by activities of benthic organisms in the study area.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.203-209
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• 2005

Objective of this research was to assess the effectiveness of the different sources of the zero-valent irons (ZVIs) on the reduction of the toxic Cr(VI) to the nonhazardous Cr(III) in an aqueous solution. The physical and chemical properties of the six ZVIs were determined. Particle size and specific surface area of the ZVIs were in the ranges of $85.55{\sim}196.46{\mu}m\;and\;0.055{\sim}0.091m^2/g$, respectively. Most of the ZVIs contained Fe greater than 98% except for J (93%) and PU (88%). Reduction efficiencies of the ZVI for Cr(VI) reduction were varied with kinds of ZVIs. The J and PU ZVIs reduced 100% and 98% of Cr(VI) in the aqueous solution, respectively, within 3 hrs of reaction. However, PA, F, Sand J1 reduced 74, 65, 29 and 11% of Cr(VI), respectively, after 48 hrs. The pH of the reacting solution was rapidly increased from 3 to $4.34{\sim}9.04$ within 3 hrs. The oxidation-reduction potential (Eh) of the reacting solution was dropped from 600 to 319 mV within 3 hrs following addition of ZVIs to the Cr(VI) contaminated water. The capability of ZVIs for Cr(VI) reduction was the orders of PU > J > PA > F > S > J1, which coincided with the capacities to increase the pH and decrease the redox potentials. Results suggested that the reduction of Cr(VI) to Cr(III) was derived from the oxidation of the ZVI in the aqueous solution.

• 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 Life Science
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• v.27 no.1
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• pp.72-77
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• 2017

Inorganic iron is essential for various metabolic processes, including RNA synthesis, electron transport, and oxygen detoxification in microorganisms. Many bacterial pathogens compete for iron acquisition in diverse environmental condition such as host. Salmonella Typhimurium SL1344 also requires inorganic iron as a cofactor for growth. When a M9 minimal liquid medium was supplemented with ethylenediamine di-o-hydroxyphenylactic acid (EDDA) which acts as an iron-chelating agent, growth of Salmonella Typhimurium SL1344 in the supplemented medium was completely arrested by deficient of useful iron under iron-depleted condition. However, a number of siderophores, which are small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria and fungi, were produced for utilization of restricted iron under iron-depleted condition. A M9 minimal liquid medium complemented with human transferrin (hTf)-iron complex turned completely off production of siderophores, but growth of Salmonella Typhimurium SL1344 maintained level similar to compare one complemented with iron (III) chloride (FeCl3). This means that human transferrin (hTf)-bound iron can utilize via directly interaction with Salmonella Typhimurium SL1344 without productions of siderophores. Through construction and analysis of negative mutant for utilization of human transferrin (hTf)-bound iron, we confirm that the bacterium can directly use human transferrin (hTf)-bound iron without extracellularly intermediated carriers such as siderophores.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.65-69
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• 1998

In order to evaluate the utility of bituminous coal fly ash, gypsum, oyster shell as soil amendments, aadic clayloam paddy soils with low calaum content were amended in the upper 15㎝ with amendments, and then Chinese cabbage was cultivated under plastic film house. Amendments treated were, in metric tons per hectare, i) none(Check) ; ii) 80 fly ash(FA) ; iii) 4 shell(SH) ; iv) 56 fly ash+24 gypsum (FG) ; v) 40 fly ash+24 gypsum+0.8 shell(FGS). On the whole, soil chemical properties were improved by amendments treatments. Amongst treatments, FA prominently neutralized soil pH and increased contents of Av. $P_2O_5$, Ex. K, and Av. B in soils. Besides, it showed the highest ratio in bacteria/fungi and (bacteria+actinomycetes)/fungi. FGS also affected the neutralization of soil pH and the increment of Ex. Mg. Amendments plants appeared alkaline damages only at early growing stage, but showed positive responses in fresh weight yields : 23% for FGS : 21% for FG : 19 18% for SH. At harvesting, leaves both of FA and FGS plants had higher values in contents of N, P, K, Ca, Mg, Fe, Mn, Zn, B, reduang-sugar, and vitamin-C than of others. In especial, Check plants appeared the heart rot symptoms owing to calaum defiaency differently from amendments plants. Taken together, FGS was an effective combination enable to maximize the utility of fly ash, gypsum, shell as soil amendments, espeaally in cabbage yield and quality.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.497-508
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• 2017

This study was carried out to document and diagnose the conditions of the seated stone statue of Buddhist Master Seungga in Seunggasa temple immediately after its conservation treatment, which was found to be long covered in surface of white materials. The stone Halo was researched along with the Statue, and basic data was secured through precisely examination and nondestructive diagnosis. The result from the surface deterioration evaluation shows that both the Statue and Halo had a little bit of physical deterioration, although their level of chemical deterioration was proportionally higher due to discoloration. The physical property diagnosis using ultrasonic measurements on the Statue and Halo showed that the average ultrasonic velocity was found to be 3,570 m/s and 3,373 m/s, respectively, which corresponds to grade III, an indication of a favorable physical property. The surface covered materials were detected to be Ca, Ti, Pb, Fe, Al and Si, emanating from Hobun (Oster shell powder; $CaCO_3$) or lime ($CaO{\cdot}Ca(OH)_2$) and silicate minerals. Furthermore, Ti and Pb seems to be the component of the white coloring pigments, titanium white ($TiO_2$) and white lead ($2PbCO_2{\cdot}Pb(OH)_2$). Therefore, the seated stone statue of Buddhist Master Seungga is presumed to be painted with Hobun or lime and thereafter painted over with titanium white and white lead.