• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.81-84
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• 1999

The aqueous geochemical characteristics of Cr(III) and Cr(Ⅵ) in environmental systems are very different from one another: Cr(Ⅵ) is highly soluble, mobile and toxic relative to Cr(III) Reduction of Cr(Ⅵ) to Cr(III) are beneficial in aquatic systems because of the transformation of a highly mobile and toxic species to one having a low solubility in water, thus simultaneously decreasing chromium mobility and toxicity. Fe(II) species are excellent reductants for transforming Cr(Ⅵ) to Cr(III), and in addition, keeping Cr(III) concentrations below the drinking water standard of 52 ppb at pH values between 5 and 11. Investigations of the effects of NOM on Cr(Ⅵ) reduction are for examining the feasibility of using ferrous iron to reduce hexavalent chromium in subsurface environments. Experiments in the presence of soils, however, showed that the solid phase consumes some of the reducing capacity of Fe(II) and makes the overall reduction kinetics slower. The soil components bring about consumption of the ferrous iron reductant. Particular attention is devoted to the complexation of Fe(II) by NOM and the subsequent effect on Cr(Ⅵ) reduction. Cr(Ⅵ) reduction rate by Fe(II) was affected by the presence of NOM (humic acid), The effects of humic acid was different from the solution pH values and the concentration of humic acid. It was probably due to the reactions between humic acid and Cr(Ⅵ), humic acid and Fe(II), and between Cr(Ⅵ) and Fe(II), at each pH.

• Environmental Analysis Health and Toxicology
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• v.13 no.1_2
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• pp.1-9
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• 1998

The ROS-producing potency of chromium compounds of several oxidation states were determined in the H4 cells. $K_2Cr_2O_7$ as Cr (VI), synthetic Cr (V) compounds and Cr (III) as TPP produced high level of ROS. However, ROS values of Cr-picolinate as Cr (III), CrCl$_2$, CrCI$_2$, were almost equal to the control. The effects of physiological antioxidants compounds which react with free radicals were examined for their effects on chromate-induced production of reactive oxygen species (ROS) in A549 cells after the addition of $K_2Cr_2O_7$. The compounds used were vitamin C (ascorbate), vitamin E ($\alpha$-tocopherol), superoxide dismutase (SOD) and catalase. The preincubation of ascorbate (200uM) with A549 cells for 20hr resulted in a significant reduction of hexavalent chromate(100uM) induced ROS. However, there is no effects of preincubation of the cells with vitamin E succinate (10 and 20uM, 20hr) on the ROS production. Also, the effects of Cr (VI) on the cell cycle of A549 cells was measured by adding the DNA intercalating agent, propidium iodide. S phase of the cell cycle was increased by the chromium (VI) compounds up to 20uM indicating toxicity or possible mitogenic action of the cell. The shoulder in Go/G1 phase at 20uM Cr (VI) with 24 hr treatment indicates apoptosis.

• Korean Journal of Environmental Biology
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• v.31 no.2
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• pp.69-77
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• 2013

Toxic effects of arsenic (As) and chromium (Cr) has been investigated using the sea urchin (Hemicentrotus pulcherrimus) germ cell and pluteus-larvae. The gametotoxic and embryotoxic effects of As and Cr on H. plucherrimus were each investigated at 6.25, 12.5, 25, 50, 100. Spawning was induced by 0.5 M KCl solution and the normal fertilization and embryogenesis rates were performed for 10 min and 64 hrs after fertilization, respectively. The normal fertilization and embryogenesis rates in the control condition (not including As and Cr) were greater than 94% and 93%, respectively. The fertilization rate was not significantly changed compared with control but embryogenesis rate was significantly decreased with concentration-dependent manner. As and Cr reduced normal embryogenesis rates and a significant reduction occurred at concentration greater than 6.25 ppb (P<0.01) and 25 ppb (P<0.05), respectively. The lowest-observedeffect- concentration (LOEC) of normal embryogenesis rate in As and Cr were each 6.25 and 25 ppb, respectively. From these results, normal embryogenesis rate of H. pulcherrimus have toxic effect at greater than the 6.25 ppb concentration of As and 25 ppb concentration of Cr in marine ecosystems. These results suggest that the normal embryogenesis rates of H. pulcherrimus are very useful test method for the toxicity assessment of heavy metal as As and Cr in marine ecosystems.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.2
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• pp.170-176
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• 2018

This study examined the antioxidative effects of Cornis fructus (CF) extract on cultured C6 glioma cells. For this purpose, cytotoxicity analysis of chromium trioxide ($CrO_3$) was performed and the protective effects of the CF extract on $CrO_3$-induced cytotoxicity was examined after the C6 glioma cells were cultured for 48 hours. The antioxidative effects, such as electron donating activity (EDA) and lactate dehydrogenase (LDH) activity were also analyzed. In this study, $CrO_3$ decreased the cell viability in a dose dependent manner. The $XTT_{50}$ value was determined to be $33{\mu}M$ after the cells were treated for 48 hours at a concentrations of $20{\sim}40{\mu}M$ $CrO_3$. The catalase (CAT) antioxidant increased significantly the cell viability that had been decreased by $CrO_3$-induced cytotoxicity. Regarding the protective effect of the CF extract, the cell viability of the CF extract was increased significantly compared to that of $CrO_3$ only. In addition, the CF extract showed antioxidative effects, such as EDA and an inhibitory effect on the LDH activity. These findings suggest that the cytotoxicity of $CrO_3$ is correlated with oxidative stress, and the CF extract effectively prevented $CrO_3$-induced cytotoxicity through the antioxidative effects. In conclusion, natural products, such as the CF extract may be a useful therapeutic agent for the prevention or treatment of toxicity induced by heavy metals via oxidative stress.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.357-368
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• 2017

To establish new metal groundwater standard, 5 metals such as aluminum, chromium, iron, manganese, and selenium were evaluated by Chemical Ranking Of groundWater pollutaNts (CROWN) including possibility of exposure, toxicity, interest factor, connection standard for other media, and data reliability. 430 groundwater samples in 2013 and 2014 were collected semiannually from 110 groundwater wells and they were analyzed for selenium, manganese, iron, chromium, and aluminum. For this study, 430 groundwater samples were categorized into 3 geological distribution features, such as igneous, metamorphic, and sedimentary rock region and geological background levels were divided by pre-selection methods. For the results, the average concentrations of aluminum, chromium, iron, manganese, and selenium in 430 groundwater samples were $0.0008mg\;L^{-1}$, $0.0001mg\;L^{-1}$, $0.174mg\;L^{-1}$, $0.083mg\;L^{-1}$, and $0.0004mg\;L^{-1}$, respectively. In addition, among various geologies, average concentration of selenium was the highest in igneous rock region, average concentrations of chromium, manganese and aluminum were the greatest in sedimentary rock region, and average concentration of iron was the most high in metamorphic rock region. As a result of the geological background concentration with pre-selection method, background concentrations of selenium and aluminum in groundwater samples were the highest from sedimentary rock as $0.0010mg\;L^{-1}$ and $0.0029mg\;L^{-1}$ and background concentrations of manganese and iron in groundwater samples were the greatest from metamorphic rock as $0.460mg\;L^{-1}$ and $1.574mg\;L^{-1}$, and no chromium background concentration in groundwater samples was found from all geology.

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.165-172
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• 2020

Heavy metals are common pollutants in the freshwater environment and have toxicological effect in habitat organisms. The heavy metals highly accumulated in sediment and organism, and observed various physiological responses. In this study, we investigated the molecular response to heavy metal toxicity (Al, Aluminum; Cr, Chromium; Cu, copper; Mn, Manganese; Zn, Zinc) through expression of heat shock protein 40, 70, 90 (HSP40, 70, 90), cytochrome 450 (CYP450), Glutathione S-transferase (GST) and Serine-type endopeptidase (SP). HSPs showed up-regulation in Cu and Zn exposures. Furthermore, HSPs expression in treated groups tended to be higher than the control group. The tendency of CYP450 and GST mRNA expression was higher for Cr and Cu than for other exposure group. The expression of SP gene was low at Al exposure and other group were measured to be similar to control. These results suggest that heavy metal toxicity in freshwater ecosystem may affect physiological and molecular process. Also, the comprehensive gene expression in the aquatic midge Chironomus riparius give useful information to potential molecular biomarkers for assessing heavy metal toxicity.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.287-306
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• 2012

Amphibian population declines globally. Environmental contamination by heavy metals has been suspected to the one of the reason for distinction of amphibian which has obligate aquatic life style during larval period. Amphibians have been widely accepted as animal model for the study of endocrine disruption in aquatic ecosystem at molecular as well as individual levels. There are increasing need for toxicological data in amphibians at multiple endpoints for management of contamination and development of safety guidelines. Here, we reviewed toxicological information about toxicity of heavy metals (arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc) on various end-point of amphibian.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1211-1216
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• 2004

A MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) induced chromium resistant strain ($Cr^{r}18$) of unicellular cyanobacterium Anacystis nidulans has been isolated and characterized. The resistant strain could grow (although restricted to $50\%$ of control) in chromium concentration (180${\mu}M$) lethal to the wild-type. Sublethal ($160{\mu}M$) concentration of $Cr^{6+}$ significantly reduced (13-$37.5$) all the photosynthetic pigments of A. nidulans with maximum reduction in phycoerythrin followed by ChI $\alpha$. Pigments of A. nidulans were drastically decreased in lethal concentration of Cr^{6+} with maximum reduction in phycoerythrin ($75\%$) and allophycocyanin ($67.5\%$). Resistant strain $Cr^{r}18$ resisted toxic effects of sublethal and lethal concentrations of $Cr^{6+}$ on photosynthetic pigments as revealed by less decrease in pigments as compared to A. nidulans. Effect of $Cr^{6+}$ stress was also studied on nitrogen assimilation and phosphate uptake. Sublethal concentration of $Cr^{6+}$ drastically reduced ($71.5\%$) nitrate uptake by A. nidulans while a decrease of $29\%$ was observed in strain $Cr^{r}18$. Short (2 day) exposure of A. nidulans and its resistant strain $Cr^{r}18\;to\;Cr^{6+}$ did not affect nitrate reductase and glutamine synthetase (transferase), whereas longer (10 day) exposure to $Cr^{6+}$ lowered activities of both enzymes in A. nidulans but not significantly in the strain $Cr^{r}18$. Ammonium uptake by both strains was not affected by $Cr^{6+}$. Thus, $Cr^{6+}$ affected photosynthetic pigments, nitrogen assimilation, and phosphate uptake of A. nidulans, while strain $Cr^{r}18$ was able to resist toxic effects of the metal. Advantages of using strain $Cr^{r}18$ for bioremediation purposes have been evaluated by studying $Cr^{6+}$ removal from the solution. Resistant strain $Cr^{r}18$ was able to remove $33\%$ more $Cr^{6+}$ than A. nidulans and thus it can prove to be a good candidate for bioremediation of $Cr^{6+}$ from polluted waters.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.131-138
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• 1997

In this study, the effect of the various operating conditions on the removal of $Cr^{6+}$ from $Cr^{6+}$ containing wastewater which has strong toxicity by using electrolysis with iron electrode as anode and aluminum electrode as cathode was investigated. The removal efficiency of $Cr^{6+}$ was increased as the pH was decreased, as the distance of electrode was decreased and the voltage was increased. The reaction temperature slightly affected the removal efficiency. The optimum conditions for the treatment of $Cr^{6+}$ containing wastewater were initial pH 3, 5 volt and the distance of electrode was 1cm. The feasibility of the electrochemical treatment to the $Cr^{6+}$ containing industrial wastewater was verified from this study.

• Corrosion Science and Technology
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• v.6 no.2
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• pp.68-73
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• 2007

The toxicity of chromium that is used to impart corrosion resistance to galvanized steel created environmental and health-related concerns and generated a great deal of interest in developing chrome-free treatment coatings. In the present work, organic-inorganic composite coatings were used to coat electrogalvanized steel (EG) sheets for corrosion protection without degrading its weldability property. The new coatings composed of specially modified polyurethane dispersion hybridized with silicate and unique inorganic-organic inhibitors were developed during this work. It was found that about $1{\mu}m$ thickness of coating layer is secure enough in corrosion resistance of flat and formed part even after alkaline degreasing. Overall chemical resistances including fingerprint resistance and paint adhesion property were satisfied with the test specification of Sony technical standard of SS-00260-2002. Therefore, it is concluded that the newly developed chrome-free product can replace the conventional chromated product.