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PubMed2005

Variations in heavy metal contamination of stream water and groundwater affected by an abandoned lead-zinc mine in Korea.

This study evaluated variations in heavy metal contamination of stream waters and groundwaters affected by an abandoned lead-zinc mine, where a rockfill dam for water storage will be built 11 km downstream. For these purposes, a total of 10 rounds of stream and groundwater samplings and subsequent chemical analyses were performed during 2002-2003. Results of an exploratory investigation of stream waters in 2000 indicated substantial contamination with heavy metals including zinc (Zn), iron (Fe) and arsenic (As) for at least 6 km downstream from the mine. Stream waters near the mine showed metal contamination as high as arsenic (As) 8,923 microg L(-1), copper (Cu) 616 microg L(-1), cadmium (Cd) 223 microg L(-1) and lead (Pb) 10,590 microg L(-1), which greatly exceeded the Korean stream water guidelines. Remediation focused on the mine tailing piles largely improved the stream water qualities. However, there have still been quality problems for the waters containing relatively high concentrations of As (6-174 microg L(-1)), Cd (1-46 microg L(-1)) and Pb (2-26 microg L(-1)). Rainfall infiltration into the mine tailing piles resulted in an increase of heavy metals in the stream waters due to direct discharge of waste effluent, while dilution of the contaminated stream waters improved the water quality due to mixing with metal free rain waters. Levels of As, Cu and chromium (Cr) largely decreased after heavy rain but that of Pb was rather elevated. The stream waters were characterized by high concentrations of calcium (Ca) and sulfate (SO(4)), which were derived from dissolution and leaching of carbonate and sulfide minerals. It was observed that the proportions of Ca and SO(4) increased while those of bicarbonate (HCO(3)) and sodium and potassium (Na+K) decreased after a light rainfall event. Most interestingly, the reverse was generally detected for the groundwaters. The zinc, being the metal mined, was the most dominant heavy metal in the groundwaters (1758-10,550 microg L(-1)) near the mine, which far exceeded the Korean standard of 1000 microg L(-1) for drinking water. The decreases in the heavy metals contents in the groundwaters associated with reduced rainfall were quite different from the increases observed for the stream waters, which is not clearly understood at this time and warrants further investigation.

Environmental Monitoring↗

PubMed2005

Application of chemometrics methods for the estimation of heavy metals contamination in river sediments.

The concentration and speciation of six heavy metals in sediments of eight sampling sites of Haihe River were investigated. The metals, namely Cd, Cu, Co, Ni, Mn and Pb were considered. By using sequential extraction (SE), the total metals were divided into five fractions: exchangeable, carbonate bound, iron/manganese oxide bound, sulfides and organic matter fraction and residual fraction. A multivariate statistical approach (principal component analysis, PCA) was used to evaluate the contamination of heavy metals by the total levels and chemical forms, respectively. The results showed that the total metals concentration (TMC) could not provide sufficient and accurate information because the mobility, bioavailability and toxicity of metals depend not only on their total concentration but also on the physicochemical form in which they occur.

China↗

PubMed2004

[Characteristic analysis of heavy metals' evaporation of MSWI fly ash].

In order to reduce the secondary pollution caused by municipal solid waste incineration (MSWI) fly ash, it must be treated soundly before final disposal, because the content of heavy metals in MSWI fly is high. In this paper, the evaporation of heavy metals (Pb, Cd, Cu, Zn) were studied between 600 degrees C-1100 degrees C, meanwhile the influence of CaCl2 on heavy metals' evaporation was studied. The result shown that without chlorination agent, the evaporation for Pb and Cd were as high as above 90%, about 80% for Cu, less than 40% for Zn. It was also found the evaporation of the heavy metals was enhanced when chlorination agent was added, and for Zn the evaporation increase was the most.

Calcium Chloride↗

PubMed2002

Accumulation of heavy metals in Caspian seals (Phoca caspica).

Concentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co, and Hg) were determined in the muscle, liver, and kidney of 42 Caspian seals and fishes collected from the Caspian Sea in 1993. Higher Mn and lower Fe and Cu concentrations were found in the liver in comparison with other marine pinnipeds. Lower Cu concentrations in the liver appear to be a common feature in small seals belonging to subgenus Pusa, which include ringed, Baikal, and Caspian seals. However, low Fe and high Mn in livers were specific to Caspian seal. Concentrations of toxic metals such as Hg and Cd were relatively low. Pinniped species can be divided into two groups, based on accumulations of Cd or Hg in the liver. Interestingly, it was found that Cd-accumulating groups feed on invertebrates, whereas the preferred diet of Hg accumulators is fish. Caspian seals seemed to belong to the Hg-accumulating group.Cd and Hg concentrations in the liver and kidney of young animals increased with age. Mercury concentrations in adult animals increased with age continuously, whereas Cd concentrations in adult animals decreased. This trend might be due to preferential feeding habits and shift in ratio of Hg and Cd in the diet ( i.e., invertebrates to fish).

Age Factors↗

PubMed2006

Control of heavy metals during incineration using activated carbon fibers.

Activated carbon fibers (ACFs) were applied to control heavy metals in incineration flue gas. Three heavy metal species (Cr, Cd and Pb), three ACFs, various adsorption temperatures (150, 250 and 300 degrees C) and weights of ACFs were experimentally determined. The results indicated that the effects of the type of ACF and the weight of the ACFs on the solid-state Cr removal were insignificant. The extent of solid-state Cd and Pb removal was related to the knitting structure of ACFs and the physical characteristic of the metals. The removal efficiencies of the solid-state and gaseous metals at various reaction temperature followed the order 250>150>300 degrees C and 300>250>150 degrees C, respectively.

Adsorption↗

PubMed2005

Structural and up-conversion luminescence properties in Tm3+/Yb3+-codoped heavy metal oxide-halide glasses.

Tm3+/Yb3+-codoped heavy metal oxide-halide glasses have been synthesized by conventional melting and quenching method. Structural properties were obtained based on the Raman spectra, indicating that halide ion has an important influence on the phonon density and maximum phonon energy of host glasses. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions 1G4-->3H6 and 1G4-->3H4, respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. With increasing halide content, the up-conversion luminescence intensity and blue luminescence lifetimes of Tm3+ ion increase notably. Our results show that with the substitution of halide ion for oxygen ion, the decrease of phonon density and maximum phonon energy of host glasses both contribute to the enhanced up-conversion emissions.

Fluorescence↗

PubMed2002

Complexation with dissolved organic matter and solubility control of heavy metals in a sandy soil.

The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The results show that the DOM-complexed species is generally more significant for Cu and Pb than for Cd, Zn, and Ni. The ability of two advanced models for ion binding to humic substances, e.g., model VI and NICA-Donnan, in the simulation of metal binding to natural DOM was assessed by comparing the model predictions with the measurements. Using the default parameters of fulvic and humic acid, the predicted concentrations of free metal ions from the solution speciation calculation using the two models are mostly within 1 order of magnitude difference from the measured concentrations, except for Ni and Pb in a few samples. Furthermore, the solid-solution partitioning of the metals was simulated using a multisurface model, in which metal binding to soil organic matter, dissolved organic matter, clay, and iron hydroxides was accounted for using adsorption and cation exchange models (NICA-Donnan, Donnan, DDL, CD-MUSIC). The model estimation of the dissolved concentration of the metals is mostly within 1 order of magnitude difference from those measured except for Ni in some samples and Pb. The solubility of the metals depends mainly on the metal loading over soil sorbents, pH, and the concentration of inorganic ligands and DOM in the soil solution.

Hydrogen-Ion Concentration↗

PubMed1986

Structure, organization, and regulation of human metallothionein IF gene: differential and cell-type-specific expression in response to heavy metals and glucocorticoids.

We describe a human genomic clone containing the metallothionein (MT) IF and MT IG genes. Southern blot analysis and partial DNA sequence determinations show that these genes are organized in a head-to-head fashion and are located approximately 7.0 kilobases apart from each other. Sequence analysis shows that the MT IF gene contains three exons separated by two introns. All of the intron-exon junctions are defined by the GT-AG rule. The 5' flanking region shows the presence of a duplicated metal regulatory element (TGCGC CCGGCCC) important in heavy-metal induction of this gene and a sequence for its basal level expression (GCGGGGCGGGTGCAAAG). The 5' flanking region is also highly G + C rich (approximately 75%) and contains several GC boxes (GGGCGG), probably important in the binding of transcription factors. The TATAA box and the AATAAA sequence are represented by their variants, the TATCAA box and the AATTAA sequence, respectively. This gene is functional and inducible by heavy metals but not by dexamethasone in mouse LMTK- cells after its transfer on a plasmid containing the herpes simplex virus thymidine kinase gene. Further studies on various human cell lines show that this gene is not expressed in a splenic lymphoblastoid cell line (WI-L2) but is expressed in two hepatoma cell lines (Hep 3B2 and Hep G2) in response to cadmium, zinc, and copper. Dexamethasone appears to have no significant effect on its expression. The studies suggest that the MT IF gene shows cell-type-specific expression and is differentially regulated by heavy metals and glucocorticoids.

Amino Acid Sequence↗

PubMed2003

Toxic effects caused by heavy metals in the yeast Saccharomyces cerevisiae: a comparative study.

The decreasing order of toxicity of select heavy metals on the yeast Saccharomyces cerevisiae, in 10 mM MES (2-(N-morpholino)ethanesulfonic acid) pH buffer at pH 6.0, was found to be copper, lead, and nickel. Heavy metal (200 microM) induced a decrease in the number of viable cells by about 50% in the first 5 min for copper and in 4 h for lead, while nickel was not toxic up to a 200 microM concentration over a period of 48 h. Glucose (25 mM) strongly enhanced the toxic effect of 50 microM copper but had little or no effect on the toxicity of 200 microM lead or nickel. Copper, lead, and nickel induced the leakage of UV260-absorbing compounds from cells with different kinetics. The addition of 0.5 mM calcium, before addition of 200 microM copper, showed a protective action against cell death and decreased the release of UV-absorbing compounds, while no effect was observed against lead or nickel toxic effects. Copper complexation capacities of the filtrates of cells exposed for 2 h in 200 microM copper and 24 h in 200 microM lead were 51 and 14 microM, respectively. The implication of the complexation shown by these soluble compounds in the bioavailability of heavy metals is discussed.

Calcium↗

PubMed2002

Heavy metals in water bodies purified by suspended substrate of rivers.

The equations, which are used to describe the relationships of adsorption quantity (s), adsorption percent (Pa), aqueous equilibrium concentration(c) of heavy metal on river suspended substrates and the ratio of adsorbent to water(j), are developed when heavy metal adsorption on river suspended substrate satisfies with linear adsorption equation. The results, according to the simulation from heavy metal adsorption on suspended substrates of several main Chinese rivers from a previous research report, indicated that these developed equations could describe the linear adsorption processes in practice very well, meanwhile, the adsorption equilibrium constant of adsorbent for heavy metal was an intensity factor regardless of ratio of suspended substrates to water but strongly depended on media's pH. Furthermore, the suspended substrates of Yellow River gave stronger purification ability for Pb than for Cd and Cu. When Cd was purified by different river suspended substrates, it exhibited that the order of their purification ability for Cd was that of Songhuajiang River > Zhujiang Pearl River > Yellow River, which was consistent with their contents of cation exchange capacity(CEC). In addition, we estimated and compared the purification ability of river suspended substrates for cadmium, and the resulting purification percent was 37.64%, 64.58% and 50.98% for Songhuajiang River, Yangtze River and Zhujiang River, respectively.

Adsorption↗

PubMed2002

Microwave extraction of heavy metals from wet rhizosphere soils and its application to evaluation of bioavailability.

Single microwave extraction of heavy metals Cr, Ni, Zn, Cu, Cd, and Pb by the extractants CaCl(2), EDTA, CH(3)COOH and HCl has been established. The experimental conditions were optimized. A microwave power of 60% and an extraction time of 25 min were adopted. Comparison of microwave extraction and conventional extraction methods revealed that results obtained by microwave techniques were generally in a good agreement with those obtained by use of extraction methods; use of the former resulted in substantial time saving and a better precision, however. Microwave extraction was used to evaluate the bioavailability of heavy metals in soils. Single correlation analysis was performed to establish the relationship between the concentrations of the extractable heavy metals in wet rhizosphere soils and their concentrations in wheat ( Troticum aestivum L.) grown on the soils under greenhouse conditions. The correlation coefficients between the extractable metals in soils and their concentrations in wheat roots were found to be 0.5398-0.7819, 0.6425-0.8073, 0.5568-0.8276, 0.5851-0.6087 for the extractants CaCl(2), EDTA, CH(3)COOH, and HCl, respectively.

Biological Availability↗

PubMed2006

Multivariate analysis of heavy metal contamination in urban dusts of Xi'an, Central China.

Though there are many studies of heavy metal contaminations of urban dusts in developed countries, little attention has been paid to this kind of study in developing countries, including China. Therefore, a series of investigations were performed to provide heavy metal signatures of urban dusts and to evaluate potential sources in Xi'an, Shaanxi Province. Sixty-five samples of urban dusts were collected in Xi'an. Then Ag, Cr, Cu, Mn, Pb and Zn concentrations were determined by using atomic absorption spectrophotometry, and As, Hg and Sb concentrations by atomic fluorescence spectroscopy. The results indicate that, in comparison with Chinese soil, urban dusts in Xi'an have elevated metal concentrations as a whole, except those of arsenic and manganese. These concentration levels are comparable to those in other studies. Correlation coefficient analysis, principal component analysis (PCA) and cluster analysis (CA) were performed and three main sources with corresponding cluster elements were identified: (1) Ag and Hg have commercial and domestic sources; (2) Cr, Cu, Pb, Sb and Zn are mainly derived from industrial sources, combined with traffic sources as well for Pb and Zn; (3) As and Mn come mainly from soil sources, and As also has an industrial source. Based on PCA and CA analyses, manganese was selected as the reference element, and heavy metal enrichment factors (Efs) were calculated, which in turn further confirms the source identification. Also, Efs give an insight of human influence degree of urban dusts.

Arsenic↗

PubMed2003

First step towards a quantitative model describing Czc-mediated heavy metal resistance in Ralstonia metallidurans.

Quantitative models were derived to explain heavy metal resistance in Ralstonia metallidurans. A deltaczcA deletion of the gene for the central component of the Co2+/Zn2+/Cd2+ efflux system CzcCBA combined with the expression level of czcCBA as studied with a phi(czcC-lacZ-czcBA) operon fusion demonstrated that CzcCBA was the only prerequisite for resistance to Co2+/Zn2+/Cd2+ at concentrations of 200 microM and above. The cellular content of the CzcA protein (resistance nodulation cell division protein family RND) determined by Western blot was used to model the CzcCBA expression level as the response to various metal concentrations. These data and experimentally determined uptake velocities were used to derive a flow equilibrium model that describes the cytoplasmic content c(i) of the cells as an interaction between cation uptake and CzcCBA-mediated efflux. Alternatively, binding of heavy metals to inactivated R. metallidurans cells was described with a modified Freundlich's equation. The metal content of growing R. metallidurans cells was determined and compared to the predictions of both models. High amounts of zinc precipitates. exclusively formed by living cells, prevented a model validation for zinc. An additional net efflux activity let to lower amounts of cell-bound Co2+ than predicted. The flow equilibrium model described cadmium resistance sufficiently for R. metallidurans growing in the presence of 0.2-1 mM Cd2+. Description of cadmium resistance in early stationary cells requires the binding model in addition to the flow equilibrium model. Thus, it was possible to simulate physiological events in growing cells by quantitative models that are derived from the biochemical data of the interacting transport proteins.

Algorithms↗

PubMed2005

Complexing of heavy metals with DNA and new bioaffinity method of their determination based on amperometric DNA-based biosensor.

The immobilized single-stranded DNA (ssIDNA) has been found to be a very effective biospecific analytical reagent when used in a newly developed bioaffinity method of the determination of heavy metals based on the amperometric DNA-based biosensor. This has been concluded from the comparative study of the complexing of heavy metals with double-stranded DNA, single-stranded DNA, and ssIDNA, using Fe(III) and Cu(II) as a model (metal/nucleotide ratio and stability constants are maximum for ssIDNA), from the study of adsorption of Fe(III), Cu(II), Pb(II), and Cd(II) on nitrocellulose membranes, containing single-stranded DNA, and from the determination of their binding constants with ssIDNA. According to these data, the chosen heavy metals can be lined up in a series of binding strengths with ssIDNA: Cu(II) > Pb(II) > Fe(III) > Cd(II). The method of the determination of heavy metals is based on biospecific preconcentration of metal ions on the biosensor followed by the destruction of DNA-metal complexes with ethylenediaminetetraacetate and voltammogram recording has been proposed. The lower detection limits are 4.0 x 10(-11), 1.0 x 10(-10), 1.0 x 10(-9), and 5.0 x 10(-9) M for Cu(II), Pb(II), Cd(II), and Fe(III), respectively. The heavy metals have been assayed in multicomponent environmental and biological systems such as natural and drinking water, milk, and blood serum samples.

Biosensing Techniques↗

PubMed2005

Heavy metal removal from aqueous solution in sequential fluidized-bed reactors.

In this study, the sequential fluidized bed reactors (FBRs), were used to remove heavy metals including, Cu, Pb, and Ni, from synthetic wastewater. Heavy metals were removed through crystallization of metal carbonate and hydroxide precipitates on the surface of sand grains. The results showed that the influent metal concentration limits in the sequential FBRs were higher than those in the vertical FBRs. The removal efficiency for Cu, Pb, and Ni reached 96%, 93%, and 98% when the influent concentrations were 250 mg l(-1), 130 mg l(-1) and 130 mg l(-1), respectively. The pH value in the effluent of the FBR ranged from 8.7 to 9.1. The amount of metal coated onto the sand surface was determined and it was found that most of the metal ions were collected in the first reactor. The mechanism of heavy metal removal in the sequential FBRs concluded crystallization and filtration.

Carbonates↗

PubMedDate not supplied

Hybrid process for heavy metal removal from wastewater sludge.

Bioleaching processes have been demonstrated to be effective technologies in removing heavy metals from wastewater sludge, but long hydraulic retention times are typically required to operate these bioprocesses. A hybrid process (coupling biological and chemical processes) has been explored in laboratory pilot-scale experiments for heavy metals (cadmium [Cd], copper [Cu], chromium [Cr], and zinc [Zn]) removal from three types of sludge (primary sludge, secondary activated sludge, and a mixture of primary and secondary sludge). The hybrid process consisted of producing a concentrate ferric ion solution followed by chemical treatment of sludges. Ferric iron solution was produced biologically via oxidation of ferrous iron by A. ferrooxidans in a continuous-flow stirred tank (5.2 L) reactor (CSTR). Wastewater sludge filtrate (WSF) containing nutrients (phosphorus and nitrogen) has been used as culture media to support the growth and activity of indigenous iron-oxidizing bacteria. Results showed that total organic carbon (TOC) concentrations of the culture media in excess of 235 mg/L were found to be inhibitory to bacterial growth. The oxidation rate increased as ferrous iron concentrations ranged from 10 to 40 g Fe2+/L. The percentage of ferrous iron (Fe2+) oxidized to ferric iron (Fe3+) increased as the hydraulic retention time (HRT) increased from 12 to 48 h. Successful and complete Fe2+ oxidation was recorded at a HRT of 48 h using 10 g Fe2+/L. Subsequently, ferric ion solution produced by A. ferrooxidans in sludge filtrate was used to solubilize heavy metals contained in wastewater sludge. The best solubilization was obtained with a mixture of primary and secondary sludge, demonstrating a removal efficiency of 63, 71, 49, and 80% for Cd, Cu, Cr, and Zn, respectively.

Acidithiobacillus↗

PubMed2000

Concentrations of some heavy metals in water, sediment and fish species from the Atatürk Dam Lake (Euphrates), Turkey.

Concentrations of heavy metals (Cd, Co, Cu, Fe, Hg, Mn, Mo, Ni, Pb and Zn) were measured in the water, sediment and fish species (Acanthobrama marmid, Chalcalburnus mossulensis, Chondrostoma regium, Carasobarbus luteus, Capoetta trutta and Cyprinus carpio) from the Atatürk Dam Lake, Turkey. Among the heavy metals studied Cd, Co, Hg, Mo and Pb were not detected in water, sediments and fish samples, while Ni was undetectable levels in fish samples. Levels of Cu, Fe, Mn and Zn varied depending on different tissues. The results of this study indicated that a general absence of serious pollution in the dam lake is due to heavy metals, where as the concentrations of elements found could mainly be attributed to geological sources.

Animals↗

PubMed2001

The capture of heavy metals from incineration using a spray dryer integrated with a fabric filter using various additives.

This study investigated the effects of feedstock additives [polyvinyl chloride (PVC) and NaCl] and spray dryer additives (SiO2, CaCl2, NaHCO3) on heavy metal and fly ash removal efficiencies, and on particle size distribution of heavy metals. A spray dryer with an integrated fabric filter was used as an air pollution control device (APCD). Removal efficiencies for fly ash and heavy metals were greater than 95 and 90%, respectively. When additives of PVC or NaCl were used, the concentration of heavy metals distributed in fly ash apparently varied when the particle diameter was <1 microm. Although the effects of the additives SiO2, CaCl2, and NaHCO3 on the elemental size distribution of Cr were insignificant, these additives did slightly increase concentrations of Cd, Zn, and Pb partitioning in coarser particles (>1 microm).

Air Pollutants↗