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PubMed2002

In vivo ingestion of heavy metal particles of Se, Hg and W by murine macrophages. A study using scanning electron microscopy coupled with X-ray microanalysis.

Several heavy metals that are currently employed in industry may become polluters of work and natural environments. As particulate matter, heavy metals are suitable for entering the human body through the respiratory and digestive systems. They often end up inside phagocytes; the size of the microscopic particles modulates both their phagocytosis, and the physiology of macrophages. Here we have adopted an experimental model to investigate the ingestion of particles of three industrial heavy metals (Se, Hg, W) by murine peritoneal macrophages in vivo. The phagocytes were studied by scanning electron microscopy coupled with X-ray elemental microanalysis (SEM-XRM), a method that allows specific identification of Se, W and Hg in cells at high resolution. We found that Hg that was taken up by macrophages was organized into small, round particles (0.31 +/- 0.14 microm). This was in contrast with the larger size of intracellular particles of Se (2.37 +/- 1.84 microm) or W (1.75 +/- 1.34 microm). Ingested particles of Se and W, but not Hg, often caused bulging of the cell surface of macrophages. We conclude that particulate matters of Se, W and Hg are organized in particles of different size inside macrophages. This size difference is likely to be associated with distinct phlogistic activities of these heavy metals, Se and W causing a milder inflammatory reaction than Hg.

Animals↗
PubMed1999

Metallothionein and heavy metals in brown trout (Salmo trutta) and European eel (Anguilla anguilla): a comparative study.

The levels and the cellular distribution of heavy metals, and the extent by which the metals binds to metallothionein (MT) in brown trout (Salmo trutta) and European eel (Anguilla anguilla), were analyzed in order to assess the natural conditions of MT and heavy metals in these two fish species. There were no differences in heavy metals and MT concentrations between males and females of brown trout in a nonreproductive status and between adult brown trout individuals. Brown trout presented higher Cu content than European eel. The cellular distribution of Cu was also different between the two fish species; while in brown trout most of the Cu was in the noncytosolic fraction, Cu was mainly located in the cytosol in European eel. However, the cellular distribution of Zn, Cd, and Pb was similar in the two fish species. There was also an important difference in the metal content of MT between both species. Whereas, in brown trout, Cu-binding MT represented 75% of total metal-binding MT, this value was 25% in European eel. The between-species differences found in this study are intrinsic characteristics not associated with environmental factors. These results establish the basis to use MT as a bioindicator.

Age Factors↗
PubMed1987

Excitable membranes--object for evaluating the effect of heavy metal pollution.

In acute experiments the interaction of heavy metals (CdCl2 and HgCl2) with neurotransmitters (ACh and 5HT) was studied on the excitable membrane of the identified neurons in the central nervous system of Helix pomatia L. (Gastropoda, Mollusca). It was shown that cadmium and mercury ions exert different influence on both resting and action potentials as well as on the responsiveness of the neural membranes to ACh and 5HT. The selective blocking effect of cadmium and mercury ions can be interpreted on the basis of specificity of postsynaptic receptor structures responsible for the transmitter action and of ion-channels involved in the excitatory processes. The heavy metal effect was not uniform for the different types of neurons, suggesting that pollutants can modify various functions to a different degree. The results show that testing on nerve cell membranes can serve as a useful method and model in investigating the effect of sublethal environmental contamination, as they may cause a profound modulation on the elements of the neural circuitry responsible for the regulation of the animal's behavior.

Action Potentials↗
PubMed2000

Heavy metal fluxes at the sediment-water interface of three coastal ecosystems from south-west of the Iberian Peninsula

Concentrations of the heavy metals Cr, Cu, Fe and Mn were measured in sediments and porewater samples collected in three coastal ecosystems southwest of the Iberian Peninsula: the Odiel and Barbate River Salt Marshes and the Bay of Cadiz. Both the sediment and the porewater metal concentrations in the Odiel River Salt Marshes are higher than the values found in the Bay of Cadiz and Barbate River Salt Marsh, particularly for copper, a metal associated with mining activity. In porewater, the profiles were not the same as those in the solid phase and reflect the different behaviours of the elements in relation to the redox conditions. The heavy metals Cr and Cu show a typical enrichment in the porewater of the oxic zone. The heavy metals Mn and Fe show an increase in the porewater at the depths where the maximum nitrate and phosphate concentrations occur, respectively. Significant differences between background levels for each heavy metal in the various studied zones exist. Iron and Cu showed larger background levels in the Odiel River Salt Marshes than those in the Cadiz Bay and the Barbate River Salt Marshes. In the Bay of Cadiz the background levels are also high, particularly for Cr. At the Odiel River Salt Marshes the diffusive flux of Cu is high (1.3-230.1 microg cm(-2) year(-1)), which suggests that the Odiel River Salt Marshes are subject to strong contamination by Cu, which is presumably introduced to the sediment in particulate form. In the Bay of Cadiz, Cr is the only metal with positive diffusive flux (2.15 microg cm(-2) year(-1)). It is higher than those obtained in other coastal ecosystems including the Odiel River Salt Marshes. The positive diffusive flux of Cr has been associated with the input of this metal by the naval industry and the manufacturing of car and aircraft components.

Journal Article↗
PubMed2001

Induction of micronuclei in eel (Anguilla anguilla L.) by heavy metals.

Micronucleus test was performed in situ on eels (Anguilla anguilla) from river sites with different levels of heavy metal pollution (cadmium and mercury). Cadmium content in eel liver but not micronuclei averages in kidney were associated with cadmium content in sediments. Mercury content in liver was not significantly associated with mercury content in sediments. Both cadmium and mercury induced micronuclei expression in eels when injected, the concentration tested being 1.7 mg metal/kg body weight and the micronuclei induction being 2.64 and 2.35 micronuclei per 1000 cells for cadmium and mercury respectively. It was concluded that these heavy metals are genotoxic for European eel, that eel liver metal content is a sensitive indicator for environmental monitoring of cadmium pollution, and that the micronuclei scores in eels are not a sensitive method to detect heavy metals pollution in freshwater ecosytems.

Animals↗
PubMed2005

Heavy metal pollution abatement using rock phosphate mineral.

The low-grade rock phosphate of Jhabua, Madhya Pradesh (India), was investigated for its possible application in the removal of lead, copper, zinc and cobalt ions from aqueous solutions. Effects of contact time, amount of adsorbent and initial concentration of metal ions were studied. Adsorption of heavy metal ions was found to follow the order: Pb2+ > Cu2+ > Zn2+ > Co2+. The probable mechanism of metal ions removal by rock phosphate was found to be by its dissolutions followed by subsequent precipitation.

Adsorption↗
PubMed2002

Leaf biochemical parameters in Avicennia marina (Forsk.) Vierh as potential biomarkers of heavy metal stress in estuarine ecosystems.

Sediment loadings and leaf accumulation of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) with accompanying changes in leaf chlorophylls' (a + b), carotenoids and the antioxidant enzyme peroxidase were examined in the grey mangrove Avicennia marina (Forsk.) Vierh, in order to determine the applicability of these parameters as biomarkers of heavy metal stress under field conditions. Copper was found to show limited accumulation to leaf tissue, following a linear relationship at lower sediment concentrations, with saturation at higher sediment Cu concentrations. Copper accumulation relationships to leaf tissue were maintained temporally, and increases in sediment Cu, salinity, and decreases in sediment pH and Zn contributed to the accumulation of Cu to leaf tissue. Lead showed a significant relationship between sediment and leaf Pb levels, but accumulation was minimal. Accumulation relationships for Pb were not maintained temporally, and high sediment Pb, low pH and organic content increased bioavailability and accumulation of Pb. Zinc was the most mobile of all metals and was accumulated to the greatest quantities in leaf tissue in a dose-dependant relationship. Some temporal variation in Zn accumulation occurred, and higher sediment pH, organic content Zn and Pb promoted leaf Zn accumulation. Leaf Cu and Zn showed the strongest relationship with peroxidase activity and to a lesser degree Pb. Zinc was the only accumulated metal to show relationship maintenance with peroxidase activity over time. It was found that peroxidase activity best reflects the total phytotoxic effect from the combined metal stress of all three accumulated leaf metals. The only significant photopigment relationship evidenced was that of leaf Zn with the chlorophyll a/b ratio, but was not maintained temporally. Peroxidase activity may be an appropriate biomarker for Zn or total metal accumulation in leaf tissue, and the chlorophyll a/b ratio a suitable biomarker of Zn accumulation though requires temporal monitoring under field conditions.

Avicennia↗
PubMed2006

Heavy metal sorption and desorption capacity of soils containing endogenous contaminants.

Soils on serpentinites in some regions of northwestern Spain have been the subject of agricultural management practices involving the use of fertilizers and various types of organic waste containing heavy metals. Although such practices have facilitated crop growth, they have also raised the natural contents in heavy metals of the soils. In this work, three ferralic Cambisols and another three mollic Leptosols with high Cr and Ni contents were used to study competitive sorption and desorption of six heavy metals via K(d100), which was employed as a measure of the ability of the soils to adsorb and retain each metal. Lead was found to be the metal sorbed and retained to the greatest extent, and Cd, Ni and Zn those sorbed and retained in the smallest amounts. Although the ferralic Cambisols were found to contain greater amounts of natural heavy metals, they exhibited an increased ability to adsorb and retain the body of metals relative to the mollic Leptosols by effect of their increased contents in clay and Fe, Mn and Al oxides, in addition to their higher ion-exchange capacity. Based on the results, Pb and Cu are strongly bound, and Zn, Cd and Ni weakly bound, to the soils. The ferralic Cambisols exhibited an increased capacity to adsorb and retain Cd, Ni, Zn and--especially--Cr than the mollic Leptosols; the latter, however, proved more effective in adsorbing and retaining Cu and Pb by virtue of their increased organic matter contents. Copper sorption and retention, and Pb retention, were found to be correlated with the content in organic matter and that in vermiculite--which was only present in the mollic Leptosols--in the clay fraction.

Adsorption↗
PubMed2006

Chloroplast targeting of phytochelatin synthase in Arabidopsis: effects on heavy metal tolerance and accumulation.

The enzymatically synthesized thiol peptide phytochelatin (PC) plays a central role in heavy metal tolerance and detoxification in plants. In response to heavy metal exposure, the constitutively expressed phytochelatin synthase enzyme (PCS) is activated leading to synthesis of PCs in the cytosol. Recent attempts to increase plant metal accumulation and tolerance reported that PCS over-expression in transgenic plants paradoxically induced cadmium hypersensitivity. In the present paper, we investigate the possibility of synthesizing PCs in plastids by over-expressing a plastid targeted phytochelatin synthase (PCS). Plastids represent a relatively important cellular volume and offer the advantage of containing glutathione, the precursor of PC synthesis. Using a constitutive CaMV 35S promoter and a RbcS transit peptide, we successfully addressed AtPCS1 to chloroplasts, significant PCS activity being measured in this compartment in two independent transgenic lines. A substantial increase in the PC content and a decrease in the glutathione pool were observed in response to cadmium exposure, when compared to wild-type plants. While over-expressing AtPCS1 in the cytosol importantly decreased cadmium tolerance, both cadmium tolerance and accumulation of plants expressing plastidial AtPCS1 were not significantly affected compared to wild-type. Interestingly, targeting AtPCS1 to chloroplasts induced a marked sensitivity to arsenic while plants over-expressing AtPCS1 in the cytoplasm were more tolerant to this metalloid. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications.

Aminoacyltransferases↗
PubMed2003

Epiphytic lichens as sentinels for heavy metal pollution at forest ecosystems (central Italy).

The results of a study using epiphytic lichens (Parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central Italy are reported. The woods investigated are characterized by holm oak (Quercus ilex), turkey oak (Quercus cerris) and beech (Fagus sylvatica) and represent the typical forest ecosystems of central Italy at low, medium and high elevations, respectively. The results showed that levels of heavy metals in lichens were relatively low and consequently no risk of heavy metal air pollution is expected for the six forest ecosystems investigated. However, for two of them there are indications of a potential risk: the beech forest of Vallombrosa showed signs of contamination by Pb as a consequence of vehicle traffic due to the rather high touristic pressure in the area, and the holm oak forest of Cala Violina showed transboundary pollution by Mn, Cr and Ni originating from the steel industry in Piombino. Epiphytic lichens proved to be very effective as an early warning system to detect signs of a changing environment at forest ecosystems.

Chromium↗
PubMed2003

Heavy metal contamination in the Taimyr Peninsula, Siberian Arctic.

The Taimyr Peninsula is directly north of the world's largest heavy metal smelting complex (Norilsk, Russia). Despite this proximity, there has been little research to examine the extent of contamination of the Taimyr Peninsula. We analyzed heavy metal concentrations in lichen (Cetraria cucullata), moss (Hylocomium splendens), soils, lake sediment, freshwater fish (Salvelinus alpinus, Lota lota and Coregonus spp.) and collared lemming (Dicrostonyx torquatus) from 13 sites between 30 and 300 km from Norilsk. Element concentrations were low in both C. cucullata and H. splendens, although concentrations of Al, Fe, Cu, Ni and Pb were significantly higher than those in Arctic Alaska, probably due to natural differences in the geochemical environments. Inorganic surface soils had significantly higher concentrations of Cd, Zn, Pb and Mg than inorganic soils at depth, although a lake sediment core from the eastern Taimyr Peninsula indicated no recent enrichment by atmospherically transported elements. Tissue concentrations of heavy metals in fish and lemming were not elevated relative to other Arctic sites. Our results show that the impact of the Norilsk smelting complex is primarily localized rather than regional, and does not extend northward beyond 100 km.

Animals↗
PubMed2004

Cellulose/chitin beads for adsorption of heavy metals in aqueous solution.

We successfully prepared the biodegradable cellulose/chitin beads by coagulating a blend of cellulose and chitin in 6 wt% NaOH/5 wt% thiourea aqueous solution with 5% H2SO4 as coagulant, and investigated the adsorption of heavy metals (Pb2+, Cd2+, Cu2+) from an aqueous solution on the beads by atomic absorption spectrophotometer. Batch adsorption experiments were carried out as a function of ion concentrations, initial pH, ionic strength, temperature, adsorption time and desorption time. The results revealed that the cellulose/chitin beads could adsorb effectively Pb2+, Cd2+ and Cu2+ ions, and the uptakes of Pb2+, Cd2+ and Cu2+ ions on cellulose/chitin beads were 0.33 mmol/g at pH0 4, 0.32 mmol/g at pH0 5 and 0.30 mmol/g at pH0 4, respectively. Experimental results also showed that the adsorption of these heavy metals was selective to be in the order of Pb2+ > Cd2+ > Cu2+ in a low ion concentration solution. The adsorption equilibrium time of these heavy metals on beads was 4-5 h, but the desorption time was 5-15 min. Moreover, these beads could be regenerated up to about 98% by treating with 1 mol/L HCl aqueous solution. The mechanisms for the removal of free heavy metal ions by cellulose/chitin beads was based on mainly complexation adsorption model, as well as a affinity of hydroxyl groups of the materials on metals. Therefore, we developed new environment-friendly beads prepared by a simple produce process for removal and recovery of heavy metals.

Adsorption↗
PubMed2002

Heavy metals in tributaries of Pampulha Reservoir, Minas Gerais.

A great amount of heavy metals enter Pampulha Reservoir via it's main tributaries (Sarandi and Ressaca). Although no water quality classification has been carried out for these tributaries, the reservoir is expected to be in class 2 of the CONAMA-86 system. As part of a monitoring scheme of the Pampulha Watershed, heavy metals (Zn, Pb, Cd, Ni, Cu, Cr, Mn and Fe) were investigated in the water at a control site (considered free from direct human influence) and at potential sites of toxicity and contamination during August (dry season) and November (wet season) of 1998. The results for the first sampling period showed relatively high concentrations of zinc (0.22 mg.L-1) in the upper portion of the reservoir. The highest values of nickel and chromium (0.19 and 0.89 mg.L-1, respectively) were found in the initial portion of the Sarandi Stream, while the highest concentrations of lead (0.05 mg.L-1), cadmium (0.014 mg.L-1), manganese (0.43 mg.L-1) and iron (15.25 mg.L-1) were detected in the Ressaca Stream by the landfill dump of Belo Horizonte. A relatively high concentration of cadmium was also detected at the confluence of the two streams. During the second sampling period, there was an increase in the concentrations of zinc at all sampling sites except the control, with values varying from 0.71 mg.L-1 (the Sarandi Stream) to 2.50 mg.L-1 (the Ressaca Stream). Lead, cadmium, nickel and chromium concentrations were also higher in the Ressaca Stream, but not detected at the other sampling sites. Copper values were higher than in the first period: 0.10 mg.L-1 at the control up to 0.38 mg.L-1 at the confluence of the streams. Similar results were found for manganese and iron, with values reaching up to 19.30 and 125 mg.L-1, respectively. Moreover, all values recorded in the second sampling period were much higher than recommended for class 2 waters. These results emphasize the need for such monitoring in relation to better water quality management of this reservoir.

Brazil↗
PubMed2003

The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed.

Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

Coal↗
PubMed2003

Activity and heavy metal resistance of non-specific esterases in leaf beetle Chrysomela lapponica from polluted and unpolluted habitats.

We compared the general activity and heavy metal resistance of non-specific esterases in two populations of the leaf beetle Chrysomela lapponica from habitats severely contaminated by heavy metals (mostly Ni and Cu) and two populations from unpolluted habitats. Concentrations of Ni and Cu in adult beetles from the most polluted site were 7.7 and 3.6 times higher that in beetles from unpolluted habitats. Larval esterases showed higher activity and lower susceptibility to heavy metals than esterases of adults. Larval esterase activity did not differ between populations from polluted and unpolluted sites, but adult beetles from polluted localities had lower esterase activity than beetles from unpolluted habitats. Both Cu and Ni sulfates in millimolar concentrations in vitro suppressed esterase activity of larvae from unpolluted habitats, but caused no negative effect on esterases of larvae from polluted sites. Similarly, inhibition of adult esterase activity by Ni was stronger in beetles from unpolluted localities than in beetles from polluted localities. This indicates that resistance of non-specific esterases to heavy metals is higher in leaf beetle populations from contaminated environment.

Analysis of Variance↗
PubMed1999

Rapid method for detection and detoxification of heavy metal ions in water environments using phytochelation.

Phytochelatins (PCs, (gammaGlu-Cys)n-Gly (n = 2-11)) are produced by higher plants, algae, and some fungi in response to heavy metal ion exposure. A rapid and convenient method for quantifying heavy metal ion concentrations in water environments was developed using a chemically synthesized PC as a mediator. The chelating ability of the PC and quantification of the thiol group were utilized to measure heavy metal ions at low concentrations. The method requires only ten minutes for measurement and only 1 ml of a liquid sample. A range of homogeneous PCs (n = 4-7) were chemically synthesized using a peptide synthesizer. These, especially PC7, exhibited higher sensitivity and consistency of measurement than the native PC from Silene cucubalus, which produced a mixture of PC2, PC3, and PC4. Detoxification of heavy metal ions in vitro by PC was also investigated. Using the paper disc method, the cell growth inhibition zone caused by cadmium ion against Salmonella typhimurium TA1538 was significantly decreased by addition of PC. Furthermore, at the minimum inhibitory concentration of cadmium ion (200 microM) in a nutrient broth culture of S. typhimurium, cell growth was almost completely recovered by addition of PC to the medium.

Journal Article↗
PubMed2004

Heavy metals in airborne particulate matter of urban Coimbatore.

Exposures to airborne metals are known to cause physiological responses in organisms and wide-ranging health effects in humans. Hence determination of metals in particulate matter is important from a toxicological perspective. In the current study heavy metals associated with respirable (RSPM) and nonrespirable (NRSPM) fractions of suspended particulate matter were estimated in air samples from six stations in Coimbatore, India, during March 1999 to February 2001. The mean quantity of heavy metals in RSPM was in the order Zn > Cu > Pb > Ni > Cr > Cd. Concentrations of these heavy metals were in the range of BDL (below detectable level) to 2,147 ng/m3 in RSPM. The highest level of lead (2,147 ng/m(3)) was recorded at an industrial station. The station also had the highest mean value (481 +/- 544.3 ng/m(3)), suggesting the importance of industrial operations in determining the ambient concentrations of lead. Significant positive correlation among metals excepting lead and copper suggests that they originate mostly from a common source. Air samples of urban and industrial areas showed higher concentrations than residential (Urban) and suburban areas.

Air Pollutants↗