SEARCH · PubMed Health

Results for “Metals, Heavy”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources

PubMed2004

[Influence of liquid ceramic additive on binding of heavy metal during the vitrification of fly ash from municipal solid waste incinerator].

Vitrification process can effectively control the leachability of heavy metals in fly ash generated from municipal solid waste incinerator (MWSI). The use of liquid ceramic (LC) additive as a heavy metal chemical stabilization agent was evaluated for MSWI fly ash. The residuals of chromium, lead and zinc in slag increase by different degree with liquid ceramic additive at 1400 degrees C, while those of cadmium and copper decreases. The migrating characteristic of nickel is hardly affected by the additive less than 10%. The volatilization of Cr and Zn occurs after 61 minute with 10% addition of LC, and the binding efficiency of Cr decreases with increasing of melting temperature. The results indicate that the binding efficiency of heavy metals was affected greatly by LC additive and showed significant differences according to type of heavy metal during melting process. The short melting time (no longer than 33 min) is useful to obtain high binding efficiency of heavy metals.

Carbon↗

PubMed2002

Mobility of heavy metals associated with the natural weathering of coal mine spoils.

Knowledge of chemical mobility of heavy metals is fundamental to understanding their toxicity, bioavailability, and geochemical behavior. In this paper, two different methods, i.e. mineralogical means and sequential extractions, were employed to analyze the total contents, existing states, and chemical forms of heavy metals in coal mine spoils. The results demonstrate that the mobility of heavy metals in coal mine spoils depends not only on their existing states and the stability of their host minerals but also on the properties of the coal mine spoils. In the process of coal mine spoils-water interaction, sulfides that contain heavy metals first break down and release metals, which are then adsorbed and complexed by the iron oxyhydroxide colloid resulting from pyrite oxidization and organic matter. During the natural weathering of coal mine spoils, only a small fraction of these metals are released to the environment, and most of them still remains in the residual material.

Biological Availability↗

PubMed2000

Can excrement and feathers of nestling songbirds be used as biomonitors for heavy metal pollution?

Although birds have been frequently used as indicators of heavy metal pollution, few studies have examined pollutant levels in nestling passerines. In this paper we determined the levels of two essential (zinc and copper) and three nonessential heavy metals (lead, cadmium, and arsenic) in the excrement and feathers of great (Parus major) and blue tit (Parus caeruleus) nestlings at a polluted site (near a metallurgic factory) and a reference site (4 km farther east). The excrement of both great and blue tit nestlings contained significantly higher concentrations of arsenic, cadmium, copper, and lead at the polluted site. Zinc concentrations did not differ significantly between sites for both species. The feathers of great and blue tit nestlings accumulated significantly higher concentrations of lead at the polluted site than at the reference site. Zinc levels in the feathers of great tit nestlings were significantly higher at the reference site than at the polluted site. For all other elements considered, concentrations did not differ significantly between the two sites. There were no interspecific differences in metal levels between great and blue tits in both excrement and feathers. There was a significant positive correlation between the lead concentration in the excrement and feathers for both great and blue tits. We therefore conclude that excrement of great and blue tit nestlings can be used as a biomonitor for heavy metals (lead, cadmium, arsenic, and copper), whereas feathers appear only to be suitable as a biomonitor for lead pollution.

Animals↗

PubMed2003

Effects of soil amendments at a heavy loading rate associated with cover crops as green manures on the leaching of nutrients and heavy metals from a calcareous soil.

The potential risk of groundwater contamination by the excessive leaching of N, P and heavy metals from soils amended at heavy loading rates of biosolids, coal ash, N-viro soil (1:1 mixture of coal ash and biosolids), yard waste compost and co-compost (3:7 mixture of biosolids to yard wastes), and by soil incorporation of green manures of sunn hemp (Crotalaria juncea) and sorghum sudangrass (Sorghum bicolor x S. bicolor var. sudanense) was studied by collecting and analyzing leachates from pots of Krome very gravelly loam soil subjected to these treatments. The control consisted of Krome soil without any amendment. The loading rate was 205 g pot(-1) for each amendment (equivalent to 50 t ha(-1) of the dry weight), and the amounts of the cover crops incorporated into the soil in the pot were those that had been grown in it. A subtropical vegetable crop, okra (Abelmoschus esculentus L.), was grown after the soil amendments or cover crops had been incorporated into the soil. The results showed that the concentration of NO3-N in leachate from biosolids was significantly higher than in leachate from other treatments. The levels of heavy metals found in the leachates from all amended soils were so low, as to suggest these amendments may be used without risk of leaching dangerous amounts of these toxic elements. Nevertheless the level of heavy metals in leachate from coal ash amended soil was substantially greater than in leachates from the other treatments. The leguminous cover crop, sunn hemp, returned into the soil, increased the leachate NO3-N and inorganic P concentration significantly compared with the non-legume, sorghum sudangrass. The results suggest that at heavy loading rates of soil amendments, leaching of NO3- could be a significant concern by application of biosolids. Leaching of inorganic P can be increased significantly by both co-compost and biosolids, but decreased by coal ash and N-viro soil by virtue of improved adsorption. The leguminous cover crop, sunn hemp, when incorporated into the soil, can cause the concentration of NO3-N to increase by about 7 fold, and that of inorganic P by about 23% over the non-legume. Regarding the metals, biosolids, N-viro soil and coal ash significantly increased Ca and Mg concentrations in leachates. Copper concentration in leachate was increased by application of biosolids, while Fe concentration in leachates was increased by biosolids, coal ash and co-compost. The concentrations of Zn, Mo and Co in leachate were increased by application of coal ash. The concentrations of heavy metals in leachates were very low and unlikely to be harmful, although they were increased significantly by coal ash application.

Abelmoschus↗

PubMed2002

Heavy metal concentrations and enzyme activities in soil from a contaminated Korean shooting range.

Soil enzyme activities and heavy metal concentrations (Cd, Zn, Cu and Pb) were measured at a general shooting range in South Korea. Total heavy metal concentrations varied with pH, and were negatively correlated with moisture content and organic matter. Most enzyme activities (dehydrogenase, acid phosphatase and beta-glucosidase) and ATP values (measure of biomass) were lower in polluted soils, especially in bald spots contaminated by heavy metals and TNT (2,4,6-trinitrotoluene). These data indicate that concentrated shooting activity inhibits enzyme activity and microbial growth. Soil enzyme activities in richly vegetated spots around the general shooting range were higher (2- to 3-fold) than in bald spots, but lower in areas of heavy metal contamination. Our results demonstrate that the dominant plant species in richly vegetated spots accumulated heavy metals from soils, and suggest certain plants may be useful for decontaminating polluted soil.

Journal Article↗

PubMed1996

Endogenous heavy metal ions perturb fura-2 measurements of basal and hormone-evoked Ca2+ signals.

Using the membrane-permeant chelator of heavy metal ions, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylene diamine (TPEN), we demonstrate that in pancreatic acinar cells, hepatocytes, and a variety of mammalian cell lines, endogenous heavy metal ions bind to cytosolic fura-2 causing basal cytosolic free [Ca2+] ([Ca2+]i) to be overestimated. TPEN had most effect in cells lightly loaded with fura-2, suggesting the presence of a limited pool of heavy metal ions (> or = 12 microM in pancreatic acinar cells) that does not rapidly exchange across the plasma membrane. In fura-2-loaded hepatocytes, vasopressin failed to evoke a detectable change in fluorescence, but after preincubation of cells with TPEN, it caused fluorescence changes characteristic of an increase in [Ca2+]i. We conclude that in many mammalian cells, a slowly exchanging mixture of cytosolic heavy metal ions binds to fura-2 both to quench its fluorescence and to mimic the effects of Ca2+ binding, thereby causing basal [Ca2+]i to be overestimated. By chelating endogenous heavy metal ions, TPEN allows basal [Ca2+]i to be accurately measured and, by preventing competition between heavy metal ions and Ca2+ for binding to fura-2, unmasks the full effect of agonists in increasing [Ca2+]i.

Animals↗

PubMedDate not supplied

[Concentration of heavy metals (Pb, Cd, Hg) in maternal blood].

BACKGROUND: It was the aim of these investigations to find out, whether or not pregnancy risks result from the heavy metal concentrations of the mother's blood (Pb, Cd, Hg). MATERIALS AND METHODS: The control group is composed of 125 women in child bed. Women with hypertonia during the pregnancy (n = 11), women after premature delivery (n = 25) and after a miscarriage (n = 21) are the risk collective. Blood: The investigations were carried out in EDTA-blood. Questionnaire: Place of residence, profession, nourishment and tooth amalgam surface. From this we received information about risk factors for a heavy metal burden. METHODS: The Cd- and Pb-concentrations were measured by "Graphitrohr-AAS with Zeemancorrection" and the Hg-concentration by "Cold-Vapour-AAS". RESULTS: 1. Women in child bed in the Jena area have a heavy metal concentration of Pb, Cd and Hg in the lower reference range. 2. At the risk pregnancies (hypertonia during the pregnancy, premature delivery and miscarriage) no increased heavy metal burden was found. 3. There was a significant correlation between the blood mercury level of women in child bed and the number of tooth amalgam fillings. DISCUSSION: In the Jena area women in child bed have a heavy metal concentration in the lower reference range. Environmental heavy metal burden producing frequent miscarriage, premature delivery and hypertonias in the pregnancy could not be shown. The tooth amalgam filling significantly increased the Hg-burden. Environmental stress and eating habits may also play a role. CONCLUSION: At the risk pregnancies (hypertonia during the pregnancy, premature delivery and miscarriage) no increased heavy metal burden was found.

Adult↗

PubMed2003

Heavy metals in livers of waterbirds from Spain.

Wetlands tend to accumulate heavy metals from local sources, such as Pb shot used for waterfowl hunting, and from regional sources, such as atmospheric deposition and riverine or marine inputs. We determined concentrations of six heavy metals (Cr, Mn, Cu, Zn, Cd, and Pb) in livers of waterbirds shot by hunters in five Spanish wetlands to study the different factors that can contribute to the accumulation of these metals (sex, age, diet, grit, and Pb shot ingestion). Differences among wetlands were observed only for Cr, Cu, and Cd. Differences among species were observed for all the metals, and Cu was notably higher in pochards (Aythya and Netta genus) than in other waterfowl. Cu, Zn, and Cd concentrations increased with age, and only Pb showed differences related to sex, with males having higher concentrations than females. Most metals other than Pb were correlated with each other. Lead was dependent on Pb shot ingestion. Grit ingestion positively correlated with concentrations of Cr and to a lesser extent with Mn, Zn, and Cd. Ingestion of grit or shot may obscure relationships between metals and diet. Herbivorous species, which had more grit in the gizzard, had higher Cr, Zn, and Cd concentrations. Granivorous birds, which have the highest rates of Pb shot ingestion, had the highest concentrations of Pb. Grit and Pb shot ingestion are both important sources of heavy metals for waterbirds. Lead was the single metal studied whose concentrations exceeded toxicity thresholds.

Aging↗

PubMed1988

[Sewer sediments--for the detection of the heavy metal containing waste water flow into sewer systems].

Increased heavy metal content often prevents agricultural application of sewage sludge. The identification of a singular pollutant requires time-consuming and cost intensive investigations. A gridlike investigation of sewer sediments offers an effective tool for the identification of heavy metal pollutants--even if the discharge of sewage occurs by batch processes. For the sewer sediments enrich the heavy metals during longer periods. By means of this methodology we succeeded in lowering the cadmium concentration of the sewage sludge within 3 months from 40 to 5 mg/kg DS and to enable its agricultural application.

Cadmium↗

PubMed2003

Cocoa shells for heavy metal removal from acidic solutions.

The development of economic and efficient processes for the removal of heavy metals present in acidic effluents from industrial sources or decontamination technologies has become a priority. The purpose of this work was to study the efficiency with which cocoa shells remove heavy metals from acidic solutions (pH 2) and to investigate how the composition of these solutions influences heavy metal uptake efficiency. Adsorption tests were conducted in agitated flasks with single-metal solutions (0.25 mM Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), multi-metal solution (comprised of 0.25 mM of each of the cations above) and an effluent obtained from chemical leaching of metal-contaminated soil, in the presence of different cocoa shell concentrations (5-40 g/l). Results from the single-metal solution assays indicated that the fixation capacity of heavy metals by cocoa shells followed a specific order: Pb>Cr>Cd=Cu=Fe>Zn=Co>Mn=Ni=Al. Cocoa shells are particularly efficient in the removal of lead from very acidic solutions (q(max)=6.2 mg Pb/g, pH(i)=2.0 and T=22 degrees C). The presence of other metals and cations in solution did not seem to affect the recovery of lead. It was also observed that the maximum metal uptake was reached in less than 2 h. This research has also demonstrated that the removal of metals caused a decline in solution proton concentration (pH increase) and release of calcium, magnesium, potassium and sodium from the cocoa shells.

Cacao↗

PubMed1976

Electromyographic changes in automechanics with increased heavy metal levels.

Twenty automechanics possessing increased whole blood values of one or more of the following heavy metals; chromium, copper, lead, manganese and nickel, were studied for peripheral nerve affection by means of electromyography (both sensoric and motoric nerve potentials were recorded). The heavy metal contents were related to the findings of denervation, distal motor latency, distal sensory latency, motoric and sensoric conduction velocities. Apart from two workers, in whom only lead was assayed, the remaining group of 18 were assayed for all heavy metals under study. Six workers showed increased distal motor and/or sensory latency and seven decreased nerve conduction velocity (four motoric and three sensoric affections). Of the workers with nerve affection, three showed increased levels of lead (nickel and chromium also raised). Four workers showed increased lead, nickel and chromium and one of lead, chromium and manganese. All in all, 10 out of 20 workers (50 percent) with elevated lead levels showed definite signs of peripheral neuropathy and seven out of 14 with raised nickel values showed these signs but they could all be accounted for by the increased lead levels. All except seven workers with raised lead levels in the whole group showed values above the critical limit of 80.0 mug/100 ml in whole blood. The data argue for the highly toxic effect of lead and other heavy metals on the peripheral nervous system and stress the diverse toxic exposure which automechanics undergo during their work. The possibility of there being a synergistic action between heavy metals and components of mineral oil and petroleum is discussed.

Action Potentials↗

PubMed2001

Phytochelatin production in freshwater algae Stigeoclonium in response to heavy metals contained in mining water; effects of some environmental factors.

Production of phytochelatins (PC) in two freshwater, filamentous green algae of the genus Stigeoclonium, in response to heavy metals contained in mining water was studied. Stigeoclonium sp. grown abundantly in ditches with the mining water (southern Poland) accumulated high amounts of heavy metals. The other studied alga Stigeoclonium tenue Kütz. was isolated from unpolluted lake water in the Netherlands. Both algae exposed to the heavy metal mixture (17 microM; mainly zinc) contained in the hard, alkaline (pH 8.2) mining water produced similar amounts of phytochelatins (PC2 and PC3): 500-600 nmol SH g(-1) dry weight. After water acidification to pH 6.8, a > 2-fold increase of the total phytochelatin level as well as the appearance of longer chain peptide PC4 in the cells of both algae was observed. The concentration of labile forms of zinc in the acidified mining water was four times as high as that in the alkaline water. The heavy metal mixture (17 microM) in non-complexing solution of pH 6.8 caused a comparable phytochelatin production in both Stigeoclonium strains as the same mixture present in the acidified mining water. However, in the non-complexing solution of pH 8.2, the metal mixture induced in algae more PCs than at pH 6.8. A positive effect of bicarbonate enrichment in the solution on the PC production in S. tenue was also observed. Stigeoclonium sp. exposed to high concentrations (10 microM) of individual metals (Zn, Pb and Cd available as free cations) synthesised much higher amounts of phytochelatins (PC2-PC4) than in response to the metal mixture contained in the mining water. The order of PC induction by the studied metals in the Stigeoclonium sp. was Cd > Pb > Zn. Addition of suspended solid matter to the heavy metal solution resulted in essential quantitative changes in phytochelatins in algal cells; a considerable decrease of PC2, PC3 and PC4 levels was observed. The PC production in algae of the genus Stigeoclonium exposed to the heavy metal mixture is discussed in the context of various metal bioavailability and the algal adaptation to complex aquatic environment.

Bicarbonates↗

PubMed2003

Comparison of decision support systems for an optimised application of compost and sewage sludge on agricultural land based on heavy metal accumulation in soil.

Two different decision support systems (DSS) for the application of organic wastes on agricultural land were developed. Both DSS calculate the maximum application period of organic waste considering exhaustion of the uptake potential of soils for heavy metals. The definition of the uptake potential differs between the DSS alternatives. In the first DSS (DSS-AR), the uptake potential is derived from the difference of actual total heavy metal concentration in soil (according to aqua regia digestion) and the respective statutory limit value. The other DSS (DSS-SI) calculates the remaining sorption capacity of the soil for a heavy metal, i.e. the difference between the predefined maximum and the actual heavy metal concentration at the sorbent. The concentration of sorbed heavy metal is derived from pedotransfer functions (general purpose Freundlich isotherms) using predefined limit concentrations in soil solution (WHO drinking water quality standards) or the actual concentration of soluble heavy metal (according to neutral salt extraction), respectively. For evaluation of their individual characteristics, both DSS were tested in model scenarios using soil data (basic physicochemical properties; Cd, Pb, and Zn concentrations) from various agricultural regions and German guidelines for organic waste application. The DSS-SI showed a better performance than the DSS-AR in this context. The capacity of the soil for heavy metal uptake was used with higher efficiency, i.e. the potential was maximised while environmental limit values were still complied with. Furthermore, the DSS-SI offered a better approximation of the natural variability of soil conditions using an extended set of soil properties in comparison to the DSS-AR. Despite these indications of good DSS-SI performance, the approach requires improvement with regard to the pedotransfer functions implemented in order to consolidate and extend the range of predictions. Furthermore, it should be noted that assessment of the DSS-SI is influenced by the availability of data and is only valid under the current environmental and statutory framework at the regional scale observed. For this reason, transfer of the results of this study into regions with other administrative structures and/or environmental conditions is critical. Individual testing of the DSS-SI and the DSS-AR is required prior to the intended transfer, i.e. implementation of the approaches in the decision support process.

Adsorption↗

PubMed2006

Trapping heavy metals by using calcium hydroxyapatite and dielectrophoresis.

We propose a novel technique for the removal of heavy metal waste from contaminated water. Our method consists in using dielectrophoresis (DEP) to trap hydroxyapatite (HAP) particles of 1 microm size in water after they have adsorbed heavy metal (Pb, Zn, Cu, Co and Cr). Although HAP can adsorb heavy metals in water and as such offers great promise as a waste-cleaning tool , one of the current challenges is the efficient removal of the HAP particles once they have adsorbed the heavy metals. We show in this paper that DEP can be used to concentrate such particles in certain regions, thus rendering the rest of the solution volume nearly free of contaminated particles. We present here both experimental and numerical results for suspensions at low concentrations.

Durapatite↗

PubMed2006

Precipitation of heavy metals in produced water: influence on contaminant transport and toxicity.

Produced water undergoes changes in its physical chemistry including precipitation of heavy metals after being discharged and mixed with ambient seawater. Potential impacts of the precipitation of heavy metals on their transport and toxicity were studied using samples from offshore oil production sites on the Scotian Shelf off eastern Canada. Concentrations of aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel and zinc were measured in total, particulate and dissolved fractions together with Microtox tests for assessment of toxicity. Heavy metals in produced water were transformed from dissolved to particulate phase in a period of hours under oxygenated conditions, and aggregated to larger particles that settle rapidly (>100 m/day) over a few days. In addition, there was production of buoyant particles comprised of heavy metal precipitates sequestered onto oil droplets that were transported to the surface. The particulate fraction was generally more toxic than the dissolved fraction. This was evident at the mixing interface between produced water and seawater where elevated particulate and toxicity levels were observed. Laboratory studies suggest an increase in the toxicity of discharged produced water over time. Time-series experiments showed a sustained toxic response for more than a week following the oxidation of freshly discharged produced water that initially elicited little or no toxic response in the Microtox test. Chemical processes identified in this study, namely precipitation of heavy metals and consequent settling and rising fluxes of particles, will influence the toxicity, the fate and the transport of potential contaminants in the produced water. Therefore, these processes need to be considered in assessment of the environmental impact associated with offshore oil and gas operations.

Chemical Precipitation↗

PubMed1983

[Concentration of heavy metals in brook trout in comparison to aquatic plants and sediments].

From 1974 to 1977 the heavy metal content of river water, fishes (Salmo trutta fario), three aquatic plants (Cladophora glomerata, Potamogeton pectinatus, Zannichellia palustris), one river-bank plant (Phalaris arundinacea), and sediments (clay fraction) taken from the River Leine, up and downstream of Göttingen, were determined. Galvanic-bath sewage containing heavy metals caused an increase (11-60%) in the concentration of nine elements in the water. The average level of heavy metals in the river water corresponded to that of the Ems, Elbe and Weser, but was lower than that of the Neckar, Rhine and Danube. It was also below the European Community Guidelines (1975) on the quality of water used for the artificial recharging of ground water. River water upstream of the city has been used for this recharging for many years. There is a good correlation between the metal content in the investigated samples and in the water. In the muscles, only Cd, Co and Mn, in the liver Cd, Co, Cr. Hg, Mn and Zn, and in the total fish Cd, Co, Cr, Cu and Zn had increased significantly. In contrast to all other elements, Cr shows the highest concentration in the muscles. A previous accumulation of Cr in the liver is not a prerequisite for the accumulation in the muscles. Mercury shows the highest accumulation in the muscles, apparently because of the high retention rate of this element. Muscles also are a good monitor for this element. The impact of heavy metals on the Leine water was reflected in aquatic plants, which showed an increase in concentration up to 95-fold (according to metal or plant) - but not in river-bank plants. C. glomerata has the remarkable capability of accumulating all ten elements. Since P. arundinacea cannot reflect the different load of heavy metals it is therefore less suitable as a biological monitor for these metals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2005

Comparison of leaching characteristics of heavy metals from bottom and fly ashes in Korea and Japan.

The objective of this research was to compare the leaching characteristics of heavy metals such as cadmium, chromium, copper, nickel, lead, etc., in Korean and Japanese municipal solid waste incineration (MSWI) ash. The rate of leaching of heavy metal was measured by KSLT and JTL-13, and the amount of heavy metals leached was compared with the metal content in each waste component. Finally, bio-availability testing was performed to assess the risks associated with heavy metals leached from bottom ash and fly ash. From the results, the value of neutralization ability in Japanese fly ash was four times higher than that in Korean fly ash. The reason was the difference in the content of Ca(OH)(2) in fly ash. The amount of lead leached exceeded the regulatory level in both Japanese and Korean fly ash. The rate of leaching was relatively low in ash with a pH in the range of 6-10. The bio-availability test in fly ash demonstrated that the amount of heavy metals leached was Pb>Cd>Cr, but the order was changed to Pb>Cr>Cd in the bottom ash. The leaching concentration of lead exceeded the Japanese risk level in all fly ashes from the two countries, but the leaching concentration of cadmium exceeded the regulatory level in Korean fly ash only.

Biological Availability↗

PubMed2003

Effect of temperature on removal of heavy metals from contaminated river sediments via bioleaching.

The aim of this study was to determine the effect of temperature on the solubilization of heavy metals from contaminated river sediment by sulfur oxidizing bacteria taken from Ell-Ren River sediment. Of three temperatures tested (25 degrees C, 37 degrees C and 55 degrees C), pH decrease was greatest at 37 degrees C, indicating that, after acclimation, bacterial oxidizing activity is greatest at this temperature. At 55 degrees C, pH change was similar to that which occurred with no inoculum added. The increase in sulfates and high pH at 55 degrees C indicate that the indirect mechanism was not initiated at this temperature. Solubilization efficiency of total extractable Ni, Zn, Cu and Cr was high (>90%) at 37 degrees C, whilst that of Pb was only 60.4%. Except for Pb, the optimal temperature for solubilization of total extractable heavy metal was 37 degrees C. The order of average solubilization efficiency of total extractable heavy metals was Ni, Zn, Cu>Cr>Co, Pb. The solubilization efficiency of Pb and Co was markedly less than that of other heavy metals. Transfer of heavy metals between binding fractions was most apparent at 55 degrees C before and after bioleaching.

Geologic Sediments↗