• Journal of Environmental Science International
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• v.24 no.12
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• pp.1591-1600
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• 2015

The response of the freshwater microalga, Chlorella vulgaris, to heavy metal stress was examined based on chlorophyll fluorescence analysis to assess the toxic effects of heavy metals in freshwater ecosystems. When toxic effects were analyzed using regular chlorophyll fluorescence analysis, photosystem II activity($F_v/F_m$) decreased significantly when exposed to $Cu^{2+}$ and $Hg^{2+}$ for 12 h, and decreased in the order of $Hg^{2+}>Cu^{2+}>Cd^{2+}>Ni^{2+}$ when exposed for 24h. The effective photochemical quantum yield(${\phi}{\prime}_{PSII}$), chlorophyll fluorescence decrease ratio($R_{Fd}$), minimal fluorescence yield($F_o$), and non-photochemical quenching(NPQ), but not photochemical quenching(qP), responded sensitively to $Hg^{2+}$, $Cu^{2+}$, and $Cd^{2+}$. These results suggest that $F_v/F_m$, as well as ${\phi}{\prime}_{PSII}$, $R_{Fd}$, $F_o$, and NPQ could be used to assess the effects of heavy metal ions in freshwater ecosystems. However, because many types of heavy metal ions and toxic compounds co-occur under natural conditions, it is difficult to assess heavy metal toxicity in freshwater ecosystems. When Chlorella was exposed to heavy metal ions for 12 or 24h, $F_v/F_m$ and maximal fluorescence yield($F_m$) changed in response to $Hg^{2+}$ and $Cu^{2+}$ based on image analysis. However, assessing quantitatively the toxic effects of several heavy metal ions is challenging.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.175-182
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• 1993

Volatilization of toxic heavy metals, especially, metal chlorides at elevated temperatures in oxidation conditions was observed using a thermogravimetric furnace since such metal chlorides used to be a cause for the disease of industrial workers by their toxicity and high volatile extent. Most of tested metal chloride compounds were evaporated or decomposed into gas phase at elevated temperatures ranged from 200~90$0^{\circ}C$, while CrCl$_3$ and NiC1$_2$became stable with converting into oxide forms. A kinetic model for evaporation/condensation could predict maximum evaporation flux and the calculated values were compared with real evaporation flux. The ratio of two fluxes could be explained as the fraction of impinging gas molecules to the condensing surface( $\alpha$ ) and obtained in the range of 10$^{-3}$ ~10$^{-9}$ for the experimented toxic heavy metal chlorides. This ratio might be used to define the volatile extent or toxicity of such toxic metal compounds. The schemes to avoid volatilization of toxic heavy metals Into the atmosphere were suggested as follows ; 1 ) controlling the compositions of metals and Chlorine produced substances( such as PVC ) in the treated materials using a reverse estimation from regulatory limit and characteristics of a processing facility, 2) Installation of wet type devices such as a scrubber for condensing the metal compounds.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.556-562
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• 2017

Heavy metals in water systems are being managed on the concentration-based guidelines in Korea. However, various chemicals present in water can interact with heavy metals affecting their toxicity. Such interactions are not considered in the concentration-based guidelines. This study investigated the effect of hardness and coexisting heavy metals on heavy metal toxicity to emphasize the importance of having the effect-based guidelines together with the concentration-based guidelines in water management. The toxic effects of Cd, Zn, or mixtures of Cd and Zn were studied with Daphnia magna as a test species following the standard test method at different hardness conditions (100, 200, and $300mg\;L^{-1}$ as $CaCO_3$). The toxicities of single metal solutions and mixtures showed a decreasing trend with increasing hardness, and this can be attributed to the competition between heavy metals and cations such as calcium ions ($Ca^{2+}$) that cause hardness. The predicted toxicities of the heavy metal mixtures from the single metal toxicity deviated from the measured toxicities, and the predicted toxic effects tend to be greater than the measured toxic effects suggesting that Cd and Zn are in competition. This shows the limitations of using predicted toxic effects and the needs for further studies on mixture toxicities. Overall, this study shows that the management of heavy metals in waters needs to employ the effect-based guidelines together with the concentration-based guidelines.

• Journal of Applied Biological Chemistry
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• v.42 no.4
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• pp.169-174
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• 1999

Arabidopsis AHL gene contains 4 exons encoding a putative protein highly homologous to the yeast salt-sensitive enzyme HAL2, a 3'(2'),5'-bisphosphate nucleotidase involving in reductive sulfate assimilation. AHL cDNA complemented yeast met22 (hal2) mutant. AHL fusion protein expressed in E. coli exhibited $Mg^{2+}$-dependent, 3'-phosphoadenosine 5'-phosphate (PAP)-specific phosphatase activity. $Li^+,\;Na^+,\;K^+$ and $Ca^{2+}$ ions inhibit the enzyme activity by competing with $Mg^{2+}$ for the active site of the enzyme. The enzyme activity was also sensitive to ${\mu}M$ concentrations of toxic heavy metal ions such as $Cd^{2+},\;Cu^{2+}$ and $Zn^{2+}$, but was not recovered by addition of more $Mg^{2+}$ ions, suggesting that these ions inactivate the enzyme with a mechanism other than competition with $Mg^{2+}$ ions. Inhibition of the AHL enzyme activity may result in accumulation of PAP, which is highly toxic to the cell. Thus, the AHL enzyme could be one of the intial targets of heavy metal toxicity in plants.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.12-17
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• 2013

Heavy metal contamination of soil and water from industrial sources remains a worldwide environmental concern. Concentrations of toxic metals were measured in soil from banks of the Han and Anyang rivers. Pre-monsoon samples contained the highest heavy metal concentrations (Cu > As > Pb > Cd > $Cr^{6+}$; up to 57.80, 38.23, 25.43, 2.21, 0.32 mg/kg, respectively), but concentrations decreased at all sites during the monsoon and post-monsoon seasons. Higher heavy metal concentrations in pre-monsoon samples may be attributed to dust pollution, especially from roads near the river. A gradual reduction in heavy metal concentrations during the rainy season may be due to washing out. The high concentration of metals could cause health problems, especially in residential areas.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.3
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• pp.103-113
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• 2015

Objective : Five most generally adopting basic oriental prescriptions (yookmijihwangtang, ojeoksan, sipjeondaebotang, samultang, bojoongikgitang) samples were collected from 10 oriental hospitals nationwide and the transferring ratio to aqueous phase (TRAP) were calculated. Method : The samples are grounded evenly and the decocted at $120^{\circ}C$ for 12 min on hot plate and then filtered. The concentrations of As, Cd, Co, Cr and Pb in before and after decoction were measure by ICP/MS and the TRAPs were calculated. Results : The concentrations of As, Cr and Pb in the ground samples before decoction were all below criteria level, and TRAP values were also very low (<10%). For Cd, although some ground samples before decoction showed relatively high concentration level compare to the criteria level, because of their low TRAP (~3%), the actual concentrations in the decoction were quite low compare the criteria level. The Co's concentrations in the ground samples before decoction were all relatively low level. However, the TRAP of Co was astonishingly high value of around 40% average. Conclusion : The toxic heavy metal concentrations in the decoction were very low compare to the criteria level. The TRAPs are less than <10% except Co. The toxic heavy metals in the prescriptions are mainly remained in the residue and the only very small fraction may transferred to the decoctions. Therefore the toxicity of the oriental herbal medicine about the toxic heavy metal may be overstressed. The Co's TRAP turned out to be quite high value (40% average). Since the criteria level wes not established yet, the safety of decoctions according to Co was not fully confirmed.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.307-312
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• 2001

Adsorption capacities of toxic heavy metal ions using as-received carbon(AC), single and double surface-modified activated carbon(OAC and DSMC) in wide pH ranges are extensively evaluated. Physical and chemical properties of surface-modified activated carbons are evaluated through BET analysis, surface acidity and oxides measurements. Based oil tile adsorption isotherms of Pb, Cd and Cr ions by AC, OAC and DSMC, the adsorption amount on DSMC was obviously higher than that on the other carbons. Breakthrough behaviors of ternary metal ions in a column packed with three kinds of carbon were also characterized with respect to the variations of the influent pH and concentration. The adsorption capacity of DSMC in a fixed bed stood a favorable comparison with that of as-received carbon.

• ALGAE
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• v.21 no.4
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• pp.471-477
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• 2006

Amphora costata W. Smith 1853 is a down thrown diatom species and also known as metal corrosive ship-fouling organism. A. costata was isolated from Alang ship breaking yard, Alang and evaluated the toxicity tolerance and growth responses of the cultures exposed to different doses of toxic and relatively accessible heavy metals, such as Fe, Mn, Cd, Co, Cu, Zn, Ni, and Pb in the constantly monitored laboratory culture conditions. The strongest toxic effect was observed on A. costata exposed to Cd even at relatively low concentrations as compared to other metals. The following trend of decreasing order of toxicity i.e. Cd>Zn>Ni>Co>Pb>Cu>Fe was observed, when they were exposed to equal concentration and expose time.

• Toxicological Research
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• v.31 no.1
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• pp.1-9
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• 2015

Environmental toxicants such as toxic metals can alter epigenetic regulatory features such as DNA methylation, histone modification, and non-coding RNA expression. Heavy metals influence gene expression by epigenetic mechanisms and by directly binding to various metal response elements in the target gene promoters. Given the role of epigenetic alterations in regulating genes, there is potential for the integration of toxic metal-induced epigenetic alterations as informative factors in the risk assessment process. Here, we focus on recent advances in understanding epigenetic changes, gene expression, and biological effects induced by toxic metals.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.238-244
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• 2012

Toxic effects of heavy metal (Pb, Cr, As) were examined by the hatching rates of fertilized eggs in the oliver flounder, Paralichthys olivaceus. Eggs were exposed to Pb, Cr, As (0, 10, 100, 500, 1,000, 2,500, 5,000 ppb) and then normal hatching rates were investigated after 48 h. The normal hatching rates in the control condition (not including heavy metal) were greater than 80%, but suddenly decreased with increasing of heavy metal concentrations. Pb, Cr and As reduced the normal hatching rates in concentration-dependent way and a significant reduction occurred at concentration grater than 100, 100, 500 ppb, respectively. The ranking of heavy metal toxicity was Cr>As>Pb, with $EC_{50}$ values of 415, 518 and 1,029 ppb, respectively. The no-observed-effect-concentration (NOEC) and lowest-observed-effect-concentration (LOEC) show each 100 bbp and 500 ppb of normal hatching rates in exposed to Pb and As. The NOEC and LOEC of normal hatching rates in Cr were 10 ppb and 100 ppb, respectively. From these results, the normal hatching rates of P. olivaceus have toxic effect at greater than the 100 ppb concentrations in Pb, As and the 10 ppb concentrations in Cr in natural ecosystems. These results suggest that biological assay using the normal hatching rates of P. olivaceus are very useful test method for the toxicity assessment of a toxic substance as heavy metal in marine ecosystems.