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Results for “Metals, Heavy”

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At least 559 records · Page 31Linked to original sources

PubMed2000

Chromosomal responses of blowfly Lucilia cuprina to heat and heavy metal stress.

Chromosomal responses to heat and heavy metal shocks were studied in the pupal trichogen polytene chromosomes of Lucilia cuprina. Heat shock induced seven distinct puffs on different chromosomes at the following loci: 1C2, 21A1, 21C, 23B, 24B, 42A and 95B3. Arsenate and mercury, two of the most common toxic environmental chemical pollutants also, induced almost the same set of puffs except 20B2, which appeared to be induced by metals only and 95B3, which was not induced by arsenate. The findings suggest that a common set of gene loci encoding the heat shock proteins is responsive to these diverse environmental stresses.

Animals↗

PubMed2006

[Application of ICP-AES to the chemical speciation of heavy metals in flyash].

Chemical speciation of seven heavy metals of flyashes in incinerator was quantitatively tested using ICP-AES. Results showed that ICP-AES procedure could carry out quick, exact and high precision experiments. RSD ratio for most detected metals was lower than 3% while few metals present a comparatively high RSD when whose content was near the detection limits. The recovery ratio was 85.7%-100.63% flyashes were found to have high content of Zn, Pb. Cd, Cu, Mn, Pb and Zn existed mostly as carbonates and were leachable, while Cr and Ni were combined to metal oxides substrates and present immobilization characteristics.

Cadmium↗

PubMed1996

[The effect of heavy metals on neutrophils].

The influences of some heavy metals i.e. of mercury, zinc, copper, manganese, nickel and cobalt on metabolic activity and functional states of human neutrophils were presented. Simultaneously the pathomechanisms of the observed disturbances were described.

Cell Adhesion↗

PubMed2000

Heavy metals in Egyptian spices and medicinal plants and the effect of processing on their levels.

To determine the contamination of Egyptian spices and medicinal plants with heavy metals, a total of 303 samples, which represent 20 different types of spices and medicinal plants that were collected from areas of exportation in Egypt, were analyzed for heavy metals. Some of them have different growing seasons, and each has its own agricultural practices and several shipments. The results revealed that heavy metal contents in spice and medicinal plants depend on the plant species. The maximum levels of heavy metals in the analyzed samples were 14.4, 2.44, 33.75, 2.85, 0.10, 68.80, 343.0, 11.40, and 1046.25 microg/g for Pb, Cd, Cr, Ni, Sn, Zn, Mn, Cu, and Fe, respectively. Cobalt was not detected in any of the various samples under investigation. The levels of heavy metals determined in the analyzed samples were found to exceed the maximum allowable levels of Zentrale Erfassungs und Bewertungsstelle für Umweltchemikalien. The investigated medicinal plants were also processed by two different methods to determine the behavior of their metal contents during processing. It has been found that boiling the plant in water leads to the extraction of higher amounts of the metal from the plant than immersing it in the hot water. The achieved results were tabulated.

Egypt↗

PubMed2006

[Variation of particulate heavy metals in coastal water over the course of tidal cycle in estuary].

Variation characteristics and its mechanism of particulate heavy metals in coastal water over the course of tidal cycle on the eastern coast of Chongming Island in Yangtze Estuary were studied. Concentrations of Cu, Pb, Fe, Mn, Zn, Cr and Al in suspended particles in bottom water were respectively 184%, 99%, 56%, 62%, 147%, 50% and 45% higher than those in surface sediments influenced by particle size. The concentrations of the reducible Cu, Pb, Fe, Mn, Zn and Al in suspended particles of bottom water were also two to three times of those in surface sediments, but percentages of the reducible fraction of the above-mentioned elements in total metal concentrations in suspended particles were similar to those in surface sediments. High concentrations of particulate heavy metals occurred at the beginning of the food-tide, around the slack water and latter of the ebb tide over the course of five tidal cycles, which was mainly caused by the hydrodynamic conditions. When current velocity increased, the particulate heavy metals resuspended from bottom sediments diluted the perpetual suspended particles in water to a large extent. Environmental factors such as salt, dissolved oxygen and pH in water have little influence on the variations of particulate heavy metals over the course of tidal cycle.

China↗

PubMed2004

Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient.

We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level.

Air Pollutants↗

PubMed2006

The role of aryl hydrocarbon receptor and the reactive oxygen species in the modulation of glutathione transferase by heavy metals in murine hepatoma cell lines.

Glutathione transferase (GST) is a phase II detoxifying enzyme that plays a protective mechanism against oxidizing substances and toxic contaminants. Among these contaminants, heavy metals and polycyclic and halogenated aromatic hydrocarbons (PHAHs) have been shown to exert their toxic effects through the modulation of detoxifying enzymes, including the GSTs. Recently, we showed that heavy metals particularly Hg2+, Pb2+, and Cu2+ modulate the expression of phase II detoxifying enzymes such as NAD(P)H:quinone oxidoreductase 1 and Gsta1 in a concentration- and time-dependent manner. However, the effect of heavy metals and their potential interactions with aryl hydrocarbon receptor (AhR) ligands, PHAHs, on total Gst activity is still unknown. In the current study, we have investigated the effects of Hg2+, Pb2+, and Cu2+ in the absence and presence of four AhR ligands on the total Gst activity and reactive oxygen species (ROS) production in wild-type and AhR-deficient Hepa 1c1c7 cells. Our results showed that Hg2+ and Cu2+, but not Pb2+, significantly induced Gst activity in wild-type cells, whereas all metals induced the Gst activity in AhR-deficient cells. The induction of Gst activity by heavy metals was strongly correlated with an increase in the ROS production in wild-type, but not in AhR-deficient cells. Co-administration of heavy metals with AhR ligands differentially modulated Gst activity, in that co-exposure to Hg2+ plus AhR ligands could be beneficial in protecting against cytotoxicity as demonstrated by the increase in Gst activity with a proportional decrease in ROS production. Whereas co-exposure to Cu2+ plus AhR ligands was more toxic in that a decrease in Gst activity and an increase in oxidative stress of the cell were observed. We concluded that heavy metals differentially modulate the Gst activity through oxidative stress- and AhR-mediated mechanisms.

Animals↗

PubMed1976

Heavy metal levels and delta-amino-levulinic acid dehydrase levels in peripheral polyneuropathy.

On the basis of assay of heavy metals in whole blood (lead, cadimum, chromium, copper, nickel and manganese) and delta-amino-levulinic-acid dehydrase (ALA-D) and ALA in urine in a normal Danish population, the levels of these clinco-chemical factors were assayed in 23 patients with peripheral neuropathy of unknown etiology. All patients studied showed electro-physiological sign of denervation and/or reduced motor or sensoric nerve conduction velocity. Cadmium and manganese were never found to be increased. In all but four patients, an increase of one or more heavy metals was found. Ten patients showed raised levels of two or more metals, the dominant metal being lead (10 cases), nine patients showed increased in chromium. A significant corrleation was found between increasing lead levels and decreasing ALA-D activity. Although normal concentrations of manganese were found, correlation analysis revealed a significant correlation between increased manganese and decreased ALA-D. The raised values of heavy metals could not be traced to occupational or other exposure to heavy metals and the increased values were not related to tobacco consumption. The findings are discussed in relation to known data on neuropathy and the results seem to indicate a multifactorial patholgenesis of the disease. Among factors contributing to the precipitation of the syndrome may be raised levels of heavy metals.

Adult↗

PubMed1998

Heavy metals in dolphins stranded on the French Atlantic coast.

Heavy metal concentrations (total and organic Hg, Ti, Cr, Cu, Zn, Cd and Pb) were determined in the muscle, liver and kidney of 36 dolphins stranded on the French Atlantic coast between 1977 and 1990: 29 common dolphins Delphinus delphis, five bottlenose dolphins Tursiops truncatus and two striped dolphins Stenella coeruleoalba. Total Hg concentration in the liver increased with age, while relative methylmercury concentration decreased, reflecting the existence of a slow demethylation process. To a lower extent, a similar pattern was observed in the kidney and muscle. No age-related increase was found for other heavy metals, although the highest levels for Cd and Cr were always found in adults. No difference in contamination could be detected between the 1977-1980 and 1984-1990 periods.

Animals↗

PubMed2005

Assessment of heavy metal pollution in surface soils of urban parks in Beijing, China.

Assessing the concentration of potentially harmful heavy metals in the soil of urban parks is imperative in order to evaluate the potential risks to residents and tourists. To date, little research on soil pollution in China's urban parks has been conducted. To identify the concentrations and sources of heavy metals, and to assess the soil environmental quality, samples were collected from 30 urban parks located in the city of Beijing. Subsequently, the concentrations of Cu, Ni, Pb and Zn in the samples were analyzed. The investigation revealed that the accumulations of Cu and Pb were readily apparent in the soils. The integrated pollution index (IPI) of these four metals ranged from 0.97 to 9.21, with the highest IPI in the densely populated historic center district (HCD). Using multivariate statistic approaches (principal components analysis and hierarchical cluster analysis), two factors controlling the heavy metal variability were obtained, which accounted for nearly 80% of the total variance. Nickel and Zn levels were controlled by parent material in the soils, whereas Cu, Pb and, in part, Zn were accounted for mainly by anthropogenic activities. The findings presented here indicate that the location and the age of the park are important factors in determining the extent of heavy metal, particularly Cu and Pb, pollution. In addition, the accumulation of Zn did not appear to reach pollution levels, and no obvious pollution by Ni was observed in the soils of the parks in Beijing.

China↗

PubMedDate not supplied

Risk assessment of heavy metal contamination in shrimp farming in Mai Po Nature Reserve, Hong Kong.

An ecological survey was carried out to determine the sediment concentrations of nutrients and heavy metals and bioaccumulation of heavy metals in fish and shrimp including tilapia (Oreochromis mossambicus x O. nilotica), grey mullet (Mugil cephalus), gei wai shrimp (Metapenaeus ensis) and caridean shrimp (Macrobrachium nipponensis) in the traditional tidal shrimp ponds (gei wais) of Mai Po Nature Reserve, Hong Kong. The sediments collected from the landward sites contained higher nutrient contents, as well as zinc (Zn), chromium (Cr), copper (Cu), nickel (Ni) and cadmium (Cd) than those collected from the seaward sites, but vice versa for lead (Pb) and mercury (Hg). However, the concentrations of all metals were exceptionally high in the two sites located outside the reserve, suggesting that waters from Deep Bay might be the possible source of metal contamination affecting the reserve. All metals studied seemed to accumulate in the viscera of fish. Body size was the determining factor for the accumulation of heavy metals in caridean shrimp and gei wai shrimp but not fish. Concentrations of the metals studied in tissues of grey mullet and gei wai shrimp were found to be safe for human consumption. Concentrations of Cr in tilapia whole body (0.68-1.10 mg kg(-1) wet weight) were close to or over the guideline value of 1 mg kg(-1) set by the Food Adulteration (Metallic Contamination) Regulations of Hong Kong. Tilapia flesh and small caridean shrimp collected from gei wais were contaminated by Cr and Pb but still fit for human consumption. Caution is required if large caridean shrimp is to be consumed in large amounts continuously because the concentration of Pb exceeded the maximum permitted concentration (6 mg kg(-1)). The rather high Cr concentrations in tilapia whole body should not be overlooked as the fish will serve as a food source for migratory birds visiting the site.

Animals↗

PubMed2006

Relationship between testate amoeba (protist) communities and atmospheric heavy metals accumulated in Barbula indica (bryophyta) in Vietnam.

We studied the relationships between testate amoeba communities and heavy metal (Pb, Cd, Zn, Ni, Cu, Mn, and Fe) concentrations in the moss Barbula indica sampled at 29 sites in and around the city of Hanoi (Vietnam). Our first approach was to compare the heavy metal concentrations and testate amoeba variables between the city (zone 1) and the surrounding (zone 2). Mean moss concentrations of Pb, Cd, Zn, Ni, and Cu were significantly higher and testate amoeba species richness and abundance were significantly lower in zone 1 and the abundance of eight taxa differed significantly between the two zones. We then studied the correlation between heavy metals and testate amoebae. Species richness and abundance were correlated negatively to Pb concentration. Shannon H' was negatively correlated to both Pb and Cd. The abundance of several species was negatively correlated with Pb, Cd, Zn, and Ni; however, at the community level, Pb emerged as the only significant variable in a redundancy analysis. Our results suggest that testate amoebae are sensitive to and may be good bioindicators for heavy metal pollution, especially lead. Further research is needed to understand the causal relationships underlying the observed patterns.

Air Pollutants↗

PubMed2005

[Evaluation of TTC and INT-electron transport system activity tests for heavy metal inhibition of activated sludge].

The effects of Cu2+, Zn2+, Cd2+, Hg2+, Ni2+, Pb2+ and Ag+ on TTC and INT-electron transport system activity are studied and the sensitivities of TTC and INT-electron transport system activity to seven tested heavy metals are compared to evaluate both the parameters for assessing heavy metal inhibition of activated sludge. The median inhibitory concentration (IC50) of seven tested heavy metals measured via TTC-electron transport system activity is less than that measured via INT-electron transport system activity, which indicates that the INT-electron transport system activity is less sensitive to heavy metals than the TTC-electron transport system activity. The ranking of tested heavy metals in order of decreasing toxicity based on TTC-electron transport system activity was Hg2+, Cd2+, Cu2+, Ag+, Zn2+, Ni2+ and Pb2+ , and the ranking based on INT-electron transport system activity was Hg2+, Ag+, Cu2+, Cd2+, Zn2+, Ni2+ and Pb2+.

Bacteria↗

PubMed2001

Stabilization of heavy metals in sewage sludge composting process.

This study investigated the stabilization of heavy metals in a sewage sludge composting process using kaoline addition. The results indicate that the temperature increased rapidly to the thermophilic phase (>55 degrees C) at day 1. The additives enhanced the rate of biodegradation and microbial activity during the co-composting process. The changes in pH (ranging from 8 to 8.5) and electrical conductivity (EC) (< or =3 mS/cm) were in compliance with the best conditions during the co-composting process. The C/N ratio was determined in each co-compost sample as an indicator of the co-compost maturity. From the end product of the co-compost experiment, changes in the ratios indicate that the additives promote the co-compost maturation rate. Based on the physicochemical characteristics of the co-compost, the potential use for sewage sludge resource recovery as manure is suggested. The total concentrations of Pb, Cd, Cr, Cu, and Zn in the co-compost product were far below the limit values for agricultural use. The leachability of Pb, Cu, and Cr decreased with increasing co-composting time. That is, the kaoline additive has an inhibitory capacity for leaching heavy metals. The Cd concentrations in the sludge compost were below the detection limits. Because the total concentration of Zn was high in the sludge compost and most soluble Zn was leachable, the leachability of Zn ranged from 25% to 29%. As a result of the physicochemical characteristics and heavy metal stabilization, the selected additive was shown to improve the sewage sludge compost quality and provide information for agricultural applications.

Agriculture↗

PubMed2000

Heavy metal cytotoxicity studied by electron probe X-ray microanalysis of cultured rat hepatocytes.

Cytotoxicity of the heavy metals gold, mercury, thallium and lead was studied by measuring the intracellular element distribution of cultured rat hepatocytes by energy dispersive electron probe X-ray microanalysis of freeze-dried cryosections in a scanning transmission electron microscope. Exposure of the cells to aqueous solutions containing heavy metal ions in concentrations reaching a critical concentration caused increase of intracellular sodium and chloride content accompanied or followed by decrease of intracellular potassium content. Thus, the intracellular potassium/sodium ratio drastically decreased from control values of approximately 10 to values below 1 before changes of cell morphology became visible. In experiments with gold or mercury the decrease of the potassium/sodium ratio was preceded by transient cytoplasmic increase of sulfur and phosphorus. Heavy metal concentrations exceeding the critical concentration also caused an increase of cytoplasmic calcium concentration and finally decay of the cell structure. Cytotoxicity of heavy metals was found to increase in the order Pb, Au, Tl, Hg. Cytotoxic effects by Au, Tl or Hg in moderate concentrations were reduced by simultaneous addition of Zn or Pb to the culture medium. The results obtained prove electron probe X-ray microanalysis of cryosections as a sensitive probe of cell viability.

Animals↗

PubMed2006

Effects of long-term heavy metal contamination on soil microbial characteristics.

In this study, total heavy metal content and its effects on soil microbiological characteristics were investigated in soil samples from an area with known long-term pollution problems. The total heavy metal concentrations of contaminated soil samples were 109 and 1,558 mg/kg for Hg and As, respectively. Key microbiological parameters measured included dehydrogenase activity, ATP content and number of culturable aerobic bacteria, actinomycetes, fungi and asymbiotic nitrogen-fixers. Quantitative analysis of soil microbial populations shows a marked decrease in total culturable numbers of the different microbial groups of the contaminated soil samples. Certain groups of soil microbes were particularly sensitive to long-term contamination (asymbiotic nitrogen-fixers and heterotrophic bacteria). Dehydrogenase activity was found to be a sensitive assay for determining the effect of heavy metals on physiologically active soil microbial biomass and sustains the high applicability of this parameter for soil ecotoxicological testing as reported by other authors.

Actinobacteria↗

PubMed1986

An x-ray fluorescence technique to measure in situ the heavy metal burdens of persons exposed to these elements in the workplace.

Assays of hair and body fluid concentrations may be valuable measurements of acute exposure to a heavy metal, but they do not provide insight into the total heavy metal intake when the intake is low and chronic. The use of an x-ray fluorescence technique (XRF) enables measurement of the long-term retention of various heavy metals in select tissues in vivo. XRF was used to measure the mercury content of head and bone tissue in 298 dentists with long-term exposure to mercury-containing amalgams. It was also used to evaluate the lead burden of persons suspected of having elevated lead exposure at the workplace, and to assay the lead levels in urban and rural children. These studies indicated that the x-ray fluorescence method of assaying heavy metals in vivo is noninvasive, safe, rapid, and sensitive to levels of many heavy metals that accumulate in human tissues.

Adult↗

PubMed2005

Localization of specific monosaccharides in cells of the brown alga Padina gymnospora and the relation to heavy-metal accumulation.

The brown alga Padina gymnospora has been studied due to their ecological significance and biochemical characteristics, including its high capability of heavy-metal accumulation. It has been suggested that the fucans are among the main polysaccharides related to metal binding and precipitation in cell walls. The main purpose of this work was to determine the localization of specific monosaccharides in P. gymnospora cells. In this way, the lectins Ulex europaeus agglutinin and Canavalia ensiformis concanavalin A with specificity to alpha-L-fucose and to terminal residues of alpha-D-glucosyl and alpha-D-mannosyl, respectively, were applied in young individuals. These revealed a preferential distribution of alpha-L-fucose at cell walls near the external surface in cortical cells and near the plasmalemma in cortical and medullar cells. The distribution of alpha-L-fucose in cell walls indicates the distribution of sulfated polysaccharides (sulfated fucans) that colocalize with the heavy-metal granules (Zn and Cd) described in previous works. Therefore, our results suggest that alpha-L-fucose participates in the nucleation and immobilization of heavy metals in P. gymnospora cell walls. An intense labeling of U. europaeus agglutinin and a weak labeling of concanavalin A was also observed in physodes. X-ray microanalysis revealed the presence of zinc, sulfur, and calcium in physodes of algae collected in a heavy-metal-contaminated area. Besides the affinity between polyphenolic compounds and heavy metals, it is suggested that the mechanism of metal binding by physodes could be related to the presence of sulfated fucans.

Cell Wall↗