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Results for “Metals, Heavy”

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PubMed2004

Heavy metal exposure affects the humoral immune response in a free-living small songbird, the great tit (Parus major).

Although many studies have investigated possible effects of heavy metal contamination on components of the immune system in captive birds, studies on the effects of chronic exposure to heavy metals on the immune system of free-living birds are rare. Therefore we studied the effect of heavy metal exposure on the humoral immune responsiveness in free-living great tit (Parus major) populations from four study sites along a pollution gradient near a metallurgic smelter. Although there were no differences in body condition or hematocrit values among great tits from the four study sites, the heavy metal exposure appeared to affect an individual's humoral immune responsiveness, as measured by antibody titers to sheep red blood cells. Great tits from the study site farthest away from the smelter complex had a significantly higher immune responsiveness than birds from the two areas closest to the metallurgic smelter. Further work is now necessary to establish a causal association between heavy metal contamination and immunosuppression.

Animals↗

PubMed2001

Monitoring of electrokinetic removal of heavy metals in tailing-soils using sequential extraction analysis.

This research focused on the monitoring of the electrokinetic removal of heavy metals from tailing-soils, and emphasizes the dependency of removal efficiencies upon their physico-chemical states, as demonstrated by the different extraction methods adopted, which included aqua regia and sequential extraction. The tailing-soils examined contained high concentrations of target metal contaminants (Cd=179mgkg(-1), Cu=207mgkg(-1), Pb=5175mgkg(-1), and Zn=7600mgkg(-1)). The removal efficiencies of the different metals were significantly influenced by their speciations, mobilities and affinities (adsorption capacities) in the soil matrix. The removal efficiencies of mobile and weakly bound fractions, such as the exchangeable fraction were more than 90% by electrokinetic treatment, but strongly bound fractions, such as the organically bound species and residual fraction were not significantly removed (less than 30% removal efficiencies). In accordance with the general sequence of mobilities of heavy metals in soils, the removal efficiencies of more mobile heavy metals (Cd, Cu, and Zn) were higher than that of less mobile heavy metal (Pb).

Electricity↗

PubMed2026

Heavy-metal stress shapes habitat-specific microbial survival strategies in estuarine environments.

Estuarine ecosystems face increasing heavy metal pollution from rapid urbanization and industrialization, yet the microbial adaptive strategies to multiple metal stressors across different habitats remain poorly understood. This study investigated the diversity and composition of bacterial and fungal communities across free-living (FL), particle-attached (PA), and sediment (SE) fractions from three estuaries with varying heavy metal contamination, and further investigated functional adaptations of bacterial communities. High-throughput amplicon sequencing revealed habitat-specific communities, with SE hosting the highest alpha diversity and enrichment of metal-resistant genera such as Woeseia and Sva1033. Environmental filtering, particularly by Zn, was the dominant driver shaping bacterial assemblages across all habitats, whereas fungal communities displayed greater stochastic assembly patterns. Analysis of 44 high-quality bacterial metagenome-assembled genomes (MAGs) revealed diverse metal resistance genes (cusA, znuB, and zntA), along with enriched metabolic pathways for carbon, nitrogen, and sulfur cycling. Notably, both active efflux/oxidative stress defense and indirect immobilization mechanisms were observed across all habitats, but their relative importance differed: FL and PA communities exhibited a greater reliance on active metal efflux (czcAB) and oxidative stress defense (trxAB) to maintain intracellular homeostasis, whereas SE communities displayed a stronger genomic potential for sulfate reduction (dsrAB) that may contribute to metal immobilization through sulfide precipitation. This metabolic partitioning highlights the complementary roles of different habitats in mediating metal toxicity and biogeochemical cycling, providing new insights into microbial resilience in polluted estuaries and underscoring the urgency of addressing heavy-metal contamination in these critical ecosystems.

Estuaries↗

PubMed2006

Prolonged deposition of heavy metals in infiltration facilities and its possible threat to groundwater contamination.

A field investigation of infiltration facilities, built two decades ago in Tokyo, was carried out and sediment samples were collected from 12 infiltration inlets of three different locations. Heavy metals contents in the inlet sediment, road dusts and soils samples were analysed and compared. The particle size distribution analysis showed its variation in depth as well as from inlet to inlet. The nature of organic substances present in sediment found changes in particle sizes as well as in depth. The heavy metals content in the sediment samples ranged from 6-143 (Cr), 1-84 (Ni), 49-331 (Cu), 210-2186 (Zn) and 2-332 (Pb) microg/g. The heavy metal content ranges were similar to road dust, which indicated road dust as a possible source for sediment for the infiltration inlets. The lower heavy metals content in many sediment samples than the soil indicated possible release/desorption of heavy metals under newly created environments such as an anaerobic environment. Among the heavy metals there was a relatively good relationship between Cu and Zn, indicating the existence of their common sources.

Drainage, Sanitary↗

PubMed2004

Volatilization of heavy metals during incineration of municipal solid wastes.

Incineration experiments with MSW, which had been impregnated with heavy metals, were presented to obtain information on the volatilization behavior of the elements cadmium(Cd), lead (Pb), and zinc (Zn) under different conditions. Experiments were carried out in a bubbling fluid bed system connected to a customized inductively coupled plasma optical emission spectroscopy (ICP-OES) for analyzing metals in the flue gas. The results indicated that the combustion temperature, the gas atmosphere, and the chlorine content in the flue gas could affect the volatilization behavior of heavy metals. In the fluidized bed combustion, a large surface area was provided by the bed sand particles, and they may act as absorbents for the gaseous ash-forming compound. Comparer with the metals Cd and Pb, the vaporization of Zn was low. The formation of stable compounds such as ZnO x Al2O3 could greatly decrease the metals volatilization. The presence of chlorine would enhance the volatilization of heavy metals by increasing the formation of metal chlorides. However, when the oxygen content was high, the chlorinating reaction was kinetically hindered, which heavy metals release would be delayed.

Air Pollutants↗

PubMed2003

Heavy metals in the dump of an abandoned mine in Galicia (NW Spain) and in the spontaneously occurring vegetation.

The concentrations of different forms of heavy metals (Fe, Mn, Zn, Cu, Cr, Ni, Cd and Pb) were determined in a mine dump material rich in chalcopyrite. The concentrations were compared with those of the natural vegetation colonising the dump. Samples taken from the dump are acid (pH(H(2)O) between 3.0 and 5.0), have carbon contents lower than 0.5%, N lower than 0.2%, effective cation exchange capacity between 0.74 and 4.96 cmol(+)kg(-1) and percent Al saturation in the exchange complex higher than 20% in 85% of the samples. Iron was the most abundant heavy metal, in both total and bioavailable forms, and the relative abundance of metals was: Fe>Cu>Mn>Zn>Cr. The total Fe concentrations ranged between 4315 and 31578 mg x kg(-1), the total Cu between 273 and 5241 mg x kg(-1), the total Mn between 294 and 2105 mg x kg(-1), the total Zn between 73 and 894 mg x kg(-1) and total Cr between 0.01 and 30 mg x kg(-1). Ni, Cd and Pb were below the analytical detection limits. The concentration of bioavailable Fe ranged between 40 and 1550 mg x kg(-1); Zn was the least abundant metal in this fraction (between 2 and 100 mg x kg(-1)). Copper was the most abundant heavy metal in the exchange complex and in the aqueous extracts, followed by Zn, Mn and Fe. Exchangeable Cu ranged between 17.7 and 1866 mg x kg(-1), whereas the maximum concentrations of exchangeable Zn, Mn and Fe did not exceed 140 mg x kg(-1). The Cu concentration in the aqueous extracts varied between 0.1 and 8.3 mg x l(-1) and the concentration of Fe was always less than 0.52 mg x l(-1). The heavy metal contents in the spontaneously occurring vegetation in the dump ranged between: 150 and 900 mg Fe x kg(-1), 84 and 2069 mg Mn x kg(-1), 20.5 and 106 mg Cu x kg(-1) and between 35 and 717 mg Zn x kg(-1), when considering all the plant samples analysed. Festuca sp. accumulated Fe, Salix atrocinerea accumulated Zn and Mn, and Frangula alnus and Quercus robur accumulated Mn. These native plant species may contribute to decrease the heavy metal contents in the dump material.

Environmental Monitoring↗

PubMed2000

Strategies of heavy metal uptake by three plant species growing near a metal smelter.

Some higher plant species have developed heavy metal tolerance strategies which enable them to survive and reproduce in highly metal-contaminated soils. We have investigated such heavy metal uptake and accumulation strategies of two absolute metallophyte species (Armeria maritima ssp. halleri and Cardaminopsis halleri) and one pseudometallophyte (Agrostis tenuis) growing near a former metal smelter. Samples of plant parts and soil were analysed for Zn, Cd, Pb, and Cu. In soil, there were two dominant types of metal concentration gradients with depth. Under the absolute metallophytes, extremely high metal contents were measured in the surficial Ah horizon, followed by a strong decrease in the underlying soil horizons (L(11) and L(12)). Under the pseudometallophyte, metal concentrations in the Ah horizon were much lower and fewer differences were observed in metal concentrations among the Ah, L(11), and L(12) horizons. The concentrations of Zn, Cd, Pb, and Cu in Agrostis tenuis roots were greater than concentrations in leaves, indicating significant metal immobilisation by the roots. For C. halleri, Zn and Cd concentrations in leaves were >20,000 and >100 mg kg(-1), respectively, indicating hyperaccumulation of these elements. Armeria maritima ssp. halleri exhibited root concentrations of Pb and Cu that were 20 and 88 times greater, respectively, than those in green leaves, suggesting an exclusion strategy by metal immobilisation in roots. However, Zn, Cd, Pb, and Cu concentrations in brown leaves of Armeria maritima ssp. halleri were 3-8 times greater than in green leaves, suggesting a second strategy, i.e. detoxification mechanism by leaf fall.

Journal Article↗

PubMed2004

Leaching of heavy metals from contaminated soils: an experimental and modeling study.

In this paper, we characterize the leaching of heavy metals (Ni, Cu, Zn, Cd, and Pb) from eight contaminated soils over a wide range of pH (pH 0.4-12) using an original approach based on batch pH-static leaching experiments in combination with selective chemical extractions and geochemical modeling. The leached concentrations of the heavy metals are generally much lower than the total concentrations and show a strong pH dependency, resulting in "V-shaped" leaching curves with orders of magnitude changes in solution concentrations. The "multisurface" model used incorporates adsorption to dissolved and solid organic matter (NICA-Donnan), iron/aluminum (hydr)oxide (generalized two-layer model) and clay (Donnan model). These models were applied without modifications, and only the standard set of binding constants and parameters was used (i.e., without any fitting). The model predictions of heavy metal leaching are generally adequate and sometimes excellent. Results from speciation calculations are consistent with the well-recognized importance of organic matter as the dominant reactive solid phase in soils. The observed differences between soils with respect to element speciation in the solid phase correspond to the relative amounts of the reactive surfaces present in the soils. In the solution phase, complexes with dissolved organic matter (DOM) are predominant over most of the pH range. Free metal ions (Me2+) are generally the dominant species below pH 4. The combination of the experimental and modeling approach as used in this study is shown to be promising because it leads to a more fundamental understanding of the pH-dependent leaching processes in soils. The "multisurface" modeling approach, with the selected sorption models, is shown to be able to adequately predict the leaching of heavy metals from contaminated soils over a wide range of conditions, without any fitting of parameters.

Hydrogen-Ion Concentration↗

PubMed2005

Evaluation of heavy metal availability prior to an in situ soil phytoremediation program.

Metal mobility and the fractionation of elements and thus the biological uptake of Zn, Pb and Cd by plants were investigated using a simplified analytical procedure for soluble and bioavailable metals using a four-step sequential extraction procedure. Results showed that there was a low proportion of immediately soluble metals, as well as a high proportion of metals that could be released and would so be available for plant uptake. In the sequential extraction procedure, considering the total partition, there was a large proportion of Pb, Cd and Zn extracted in a readily mobile form. In acidic soils the content of metals in ready mobile form (exchangeable-bound to carbonates as well as to Fe and Mn oxides) and bound to organic matter constitutes an important source of potentially available elements. The same pattern was observed in alkaline soils, where almost 80% of the metals could be remobilized and be potentially available to plants. Knowing the metal partitioning and mobility of heavy metals it is very important for evaluating the phytoremediation efficiency.

Biodegradation, Environmental↗

PubMed2006

Transcriptome response to heavy metal stress in Drosophila reveals a new zinc transporter that confers resistance to zinc.

All organisms are confronted with external variations in trace element abundance. To elucidate the mechanisms that maintain metal homeostasis and protect against heavy metal stress, we have determined the transcriptome responses in Drosophila to sublethal doses of cadmium, zinc, copper, as well as to copper depletion. Furthermore, we analyzed the transcriptome of a metal-responsive transcription factor (MTF-1) null mutant. The gene family encoding metallothioneins, and the ABC transporter CG10505 that encodes a homolog of 'yeast cadmium factor' were induced by all three metals. Zinc and cadmium responses have similar features: genes upregulated by both metals include those for glutathione S-transferases GstD2 and GstD5, and for zinc transporter-like proteins designated ZnT35C and ZnT63C. Several of the metal-induced genes that emerged in our study are regulated by the transcription factor MTF-1. mRNA studies in MTF-1 overexpressing or null mutant flies and in silico search for metal response elements (binding sites for MTF-1) confirmed novel MTF-1 regulated genes such as ferritins, the ABC transporter CG10505 and the zinc transporter ZnT35C. The latter was analyzed in most detail; biochemical and genetic approaches, including targeted mutation, indicate that ZnT35C is involved in cellular and organismal zinc efflux and plays a major role in zinc detoxification.

ATP-Binding Cassette Transporters↗

PubMed2005

The removal of heavy metals in urban runoff by sorption on mulch.

A series of adsorption experiments was conducted in order to assess the ability of three mulches to remove several of the heavy metal ions typically encountered in urban runoff. Three types of mulch, cypress bark (C), hardwood bark (H), and pine bark nugget (P), were selected as potential sorbents to capture heavy metals in urban runoff. The hardwood bark (H) mulch had the best physicochemical properties for adsorption of heavy metal ions. In addition, because of its fast removal rate and acceptably high capacity for all the heavy metal ions, it was concluded that the H mulch is the best of the three adsorbents for treatment of urban runoff containing trace amounts of heavy metals. In order to investigate the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The sorption of these metals on H mulch conformed to the linear form of the Langmuir adsorption equation. At pH 5 and 6, the Langmuir constants (S(m)) for each metal were found to be 0.324 and 0.359 mmol/g (Cu); 0.306 and 0.350 mmol/g (Pb); and 0.185 and 0.187 mmol/g (Zn) at 25 degrees C.

Biodegradation, Environmental↗

PubMed2001

Metal-binding proteins and peptides in bioremediation and phytoremediation of heavy metals.

The expression of metal-binding proteins or peptides in microorganisms and plants in order to enhance heavy metal accumulation and/or tolerance has great potential. Several different peptides and proteins have been explored. This review focuses on cadmium (Cd) because of the significant importance of this metal and because of its global presence in many food materials.

Metals, Heavy↗

PubMed2004

Heavy metals accumulation in soils irrigated by municipal and industrial effluent.

Four soil profiles have been exposed in municipal, industrial effluents and municipal wastes mixed with industrial wastes (mixed effluent) and tube well irrigated areas of Indore district of Madhya Pradesh. Soil samples were collected horizon wise and analyzed for pH, electrical conductivity (EC), organic carbon, CaCO3, clay content, cation exchange capacity (CEC), exchangeable sodium percentage (ESP) and heavy metals content viz. Fe, Mn, Zn, Cu, Cd, Cr, Co and Pb. Results showed all the heavy metals content decreased with increase in depth of soil profile. Municipal wastes / untreated sewage affected soil of Bhangarh village depicted highest content of heavy metals. The order of percentage availability of different heavy metals irrespective of the sources of irrigation is Pb>Co>Cr>Cd. However, continuous application of sewage indicated higher accumulation of heavy metals although the rate of accumulation was faster in case of industrial effluent within 2 years of irrigation. Organic carbon content had significant positive correlation with heavy metals except Cu and Zn, and negative correlation with pH and CaCO3. ESP had a negative correlation with all the metals. Zn, Mn, Cd and Co indicated significant negative correlation with the CEC of the soil. Inter-metallic correlation indicates a significant positive correlation in between Fe, Cu, Zn, Mn, Co, and Pb and among themselves.

Agriculture↗

PubMed1994

[Resistance to heavy metals in ruminal staphylococci].

Ruminal, coagulase-negative, urease and bacteriocin-like substances producing staphylococci were screened for their heavy metal ions and antibiotics resistance. All strains tested were resistant to disodium arsenate at a minimal inhibition concentration (MIC > 5 g/l) and cadmium sulphate (MIC > 4 g/l). MIC = 50-60 mg/l was determined in eight staphylococci screened in mercury chloride resistance test (Tab. I). Silver nitrate resistance was detected in seven of the bacteria used (MIC = 40-50 mg/l). All strains were novobiocin resistant. Staphylococcus cohnii subsp. urealyticum SCU 40 was found as a strain with resistance to all heavy metal ions and 5 antibiotics (Tab. II). In addition, this strain produced bacteriocin-like substance which inhibited growth of six indicators of different origin (Tab. II). The most of staphylococci were detected as heavy metal ion polyresistant strains and antibiotic polyresistant strains producing antimicrobial substances with inhibition effects against at least one indicator of different origin. These results represent the first information on heavy metal ion resistance in ruminal bacteria. They also show relation or coresistance between heavy metal ions and antibiotics. Resulting from this study, staphylococci can be used as a bioindicator model for animal environmental studies. In addition, it can be used for specific interactions studies within the framework of ruminal bacterial ecosystem and also mainly with regard to molecular genetic studies.

Animals↗

PubMed2000

Removal of heavy metals from aqueous solution by chelating resin in a multistage adsorption process.

Copper and zinc removal from aqueous solution by chelating resin was investigated theoretically and experimentally in the present study. A multistage process was proposed as an alternative for enhancement of the heavy removal of the single-stage process. Heavy metal mass balance equations with empirical Freundlich adsorption isotherm were developed to represent the multistage process and the theoretical model permits determination of the inter-stage heavy metal concentrations and the total amount of chelating resin required for achieving a desired level of heavy metal removal. Optimization of the linearized theoretical model shows that equal division of the total amount of chelating resin among all stages of the multistage process yields the best results in terms of saving of chelating resin for a given heavy metal removal or enhanced heavy metal removal for a given total amount of chelating resin. Experimental tests were also conducted to establish the equilibrium adsorption of heavy metal by the chelating resin and to empirically verify the advantages of the multistage adsorption process.

Adsorption↗

PubMed2005

Decomposition in soil microcosms of leaves of the metallophyte Arabidopsis halleri: effect of leaf-associated heavy metals on biodegradation.

More knowledge is needed concerning the disturbance of soil organic matter cycling due to heavy metal pollution. The present study deals with the impact of heavy metal pollution on litter breakdown. Our aim was to assess whether heavy metals initially present in the leaves of the metallophyte Arabidopsis halleri: (i) slow down the rate of C mineralization, in relation to metal toxicity towards microflora, and/or (ii) increase the amount of organic C resistant to biodegradation, in relation to an intrinsic resistance of metallophyte residues to biodegradation. We incubated uncontaminated soil samples with either metal-free or metal-rich plant material. Metal-free material was grown in a greenhouse, and metal-rich material was collected in situ. During the 2-month period of incubation, we measured evolved CO(2)-C and residual plant C in the coarse organic fraction. Our results of CO(2)-C evolution showed a similar mineralization from the microcosms amended with highly metal-rich leaves of A. halleri and the microcosms amended with the metal-free but otherwise similar plant material. Measuring residual plant C in its input size-fraction gave a more precise insight. Our results suggest that only the large pool of easily decomposable C mineralized similarly from metal-free and from metal-rich plant residues. The pool of less decomposable C seemed on the contrary to be preferentially preserved in the case of metal-rich material. These results support the hypothesis of an annual extra-accumulation in situ of such a slowly decomposable fraction of plant residues which could account to some extent for the observed accumulation of metallophyte litter on the surface of highly metal-polluted soils.

Arabidopsis↗

PubMed2002

[Eco-toxicological effects of heavy metals on the inhibition of seed germination and root elongation of Chinese cabbages in soils].

The Eco-toxicity effects of individual Cu, Zn, Pb and Cd on the inhibition of seed germination and root elongation of Chinese cabbages (Brassica pekimensis) were tested in four types of soils (red loam soils, meadow brown soils, chestnut soils and dark brown soils) and water solution. The combined effects of heavy metals pollution were determined with meadow brown soils. Results indicated that with same concentration, the inhibition rates of heavy metals on root elongation of Chinese cabbages are stronger than that on the seed germination. The inhibition effects of heavy metals on the root elongation of Chinese cabbages in soils are much lower than that in water, indicating that soils play an important role of buffering on heavy metals pollution. Inhibition rates of heavy metals on the root elongation (IRHMRE) of Chinese cabbages are significantly negative related with the contents of organic matter (OR) and Kjedahl-nitrogen (K-N) in soils, however, there is no significant related between IRHMRE and soil pH, so does the content of T-K. In the concentrations that result in the irritated effect in the single form of Cu, Zn, Pb and Cd pollution, synergic effects are produced significantly when four heavy metals are combined. As the results, the threshold values that result in the inhibition effects on root elongation in Chinese cabbages decrease markedly.

Brassica↗

PubMedDate not supplied

Cigarettes as a source of some trace and heavy metals and pesticides in man.

Trace and heavy metal and pesticide contents of different tobacco brands sold in Finland during 1920 to 1984 were determined by atomic absorption spectroscopy and gas chromatography-mass spectrometry with the purpose of investigating the variation in contents over time. In addition, the following were studied: the effect of commercial filters in cigarettes in preventing the inhalation of metals, the transfer of metals and pesticides to the mainstream smoke; and the correlation between the cadmium content of adipose tissue of smokers and their smoking habits. No differences were found in trace and heavy metal contents of different brands and packs from different decades. The pesticide residues in tobacco have followed the pattern of their use in the tobacco plantation. The dichlorodiphenyltrichloroethane (DDT) content of tobacco has decreased during the past 20 yr to about 1/200 of the peak value, i.e., from 34.5 to 0.17 micrograms/g. Cigarette filters significantly prevent the inhalation of cadmium, lead, magnesium, and iron. The mean content of cadmium in fat tissue of male smokers was four times that of non-smokers. The difference was statistically significant.

Adipose Tissue↗