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PubMed2006

Influence of initial pH on bioleaching of heavy metals from contaminated soil employing indigenous Acidithiobacillus thiooxidans.

Bioleaching of heavy metals from contaminated soil was carried out employing indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out to assess the influence of initial pH of the system on bioleaching of chromium, zinc, copper, lead and cadmium from metal contaminated soil. pH at the end of four weeks of bioleaching at different initial pH of 3-7 was between 0.9 and 1.3, ORP between 567 and 617mV and sulfate production was in the range of 6090-8418mgl(-1). Chromium, zinc, copper, lead and cadmium solubilization ranged from "59% to 98%" at different initial pH. A. thiooxidans was not affected by the increasing pH of the bioleaching system towards neutral and it was able to utilize elemental sulfur. The results of the present study are encouraging to develop the bioleaching process for decontamination of heavy metal contaminated soil.

Acidithiobacillus thiooxidans↗

PubMed2005

Comparison of the acid combinations in microwave-assisted digestion of marine sediments for heavy metal analyses.

Sediments as a tool for monitoring contamination by heavy metals in the environment has long been considered. It is therefore a necessity to produce reliable data for such purposes. Microwave-assisted acid dissolution has proved to be a suitable method for digesting complex matrices, such as sediments. However, due to the infancy of the technique, the procedures are numerous and varied in both the reagents used and microwave conditions. In this study, the efficiency of two recommended acid mixtures, a HNO3-HF mixture and an aqua regia-HF mixture, under the same microwave digestion conditions were compared using certified reference materials. It was observed that the HNO3-HF mixture showed better efficiency than the aqua regia-HF mixture in most of the heavy metals analyzed in all certified reference materials used.

Environmental Pollutants↗

PubMed2003

Treatment of waters polluted with crude oil and heavy metals by means of a natural wetland.

In the Dolni Dubnik oil deposit, Northern Bulgaria, waters polluted with crude oil and heavy metals (iron, manganese, zinc, cadmium, lead, copper) were treated by means of a natural wetland located in the deposit. The waters had a pH in the range of about 4.5-6.5 and contained about 1-5 mg/l oil. The concentrations of heavy metals usually were about 2-4 times higher than the relevant permissible levels for waters intended for use in the agriculture and industry. The watercourse through the wetland covered a distance of about 100 m and the water flow rate varied in the range of about 0.2-0.8 l/s. The wetland was characterized by an abundant water and emergent vegetation and a diverse microflora, including different oil-degrading bacteria and fungi. The treatment of the polluted waters by means of the above-mentioned wetland markedly depended on the temperature but was efficient during the different climatic seasons, even during the cold winter months at temperatures close to 0 degrees C. The oil content in the wetland effluents in most cases was decreased to less than 0.2 mg/l, and the concentrations of heavy metals were decreased below the relevant permissible levels. The removal of oil was connected with its microbial degradation. The removal of heavy metals was due to different processes but the microbial dissimilatory sulphate reduction and the sorption of metals on the organic matter and clay minerals present in the wetland played the main role.

Agriculture↗

PubMedDate not supplied

Intake of heavy metals from foods in Finland, West Germany and Japan.

Comparison of heavy metal intakes between Finland, West Germany and Japan suggests that the average oral exposure to lead and cadmium in Finland is 30-40% of that in the other two countries. Environmental contamination is the obvious cause of high heavy metal content of vegetables and liver in West Germany and Japan and this explains a part of the difference observed in the intake rates. For example cabbage and lettuce in West Germany contain on average over 10 times more lead than the corresponding Finnish products. On the other hand a part of the difference is explained by food consumption habits. For example there is a high consumption of fish and seaweed in Japan, and beer in West Germany, and these products also significantly contribute to intake of heavy metals. Since international comparisons of intakes of food contaminants are at present inaccurate and difficult to conduct, a co-ordinated international study should be implemented. The analytical work should be centralized or alternatively an intercalibration of participating laboratories could precede the actual study. The sampling should cover polluted areas in proportion to their yield of crops.

Cadmium↗

PubMed1994

Heavy metals in avian eggshells: another excretion method.

Birds can rid their bodies of heavy metals through both excretion and deposition in feathers, and females can also eliminate heavy metals in the contents of their eggs. In this paper the levels of heavy metals (lead, cadmium, mercury, selenium, manganese, chromium) in the contents and shells of eggs of roseate terns (Sterna dougallii) and herring gulls (Larus argentatus) nesting at Cedar Beach, Long Island, are reported. For both species, metal concentrations were significantly higher in the contents compared to the shells for lead, mercury, selenium, and chromium. For herring gulls, metal levels were higher in the shells for cadmium and manganese. Levels of cadmium, mercury, and selenium were significantly higher in roseate tern egg contents than for herring gulls. In eggshells, lead, cadmium, mercury, and selenium were significantly higher in roseate terns compared to herring gulls. For both species, eggshells account for about 7-8% of the egg by weight, but less than 1% of the egg burden for mercury, 1-5% for lead, selenium, and chromium, and 7-11% for manganese. For cadmium, shells account for only 5% of the egg burden for roseate terns, but 29% for herring gulls. These data suggest that, except for mercury, eggshells provide another method of excretion of metals in these two species of birds.

Animals↗

PubMed1997

Localization of enzymically enhanced heavy metal accumulation by Citrobacter sp. and metal accumulation in vitro by liposomes containing entrapped enzyme.

A heavy-metal-accumulating Citrobacter sp. has been used for the treatment of metal-laden industrial wastes. Metal uptake is mediated via a cell-bound phosphatase that liberates inorganic phosphate which precipitates with heavy metals as cell-bound metal phosphate. A phosphatase-efficient mutant accumulated little UO(2)2+, while a phosphatase-overproducing mutant accumulated correspondingly more metal, with a uranium loading equivalent to the bacterial dry weight achieved after 6 h exposure of resting cells to uranyl ion in the presence of phosphatase substrate (glycerol 2-phosphate). The phosphatase, visualized by immunogold labelling in the parent and overproducing strains, but not seen in the deficient mutant, was held within the periplasmic space with, in some cells, a higher concentration at the polar regions. Enzyme was also associated with the outer membrane and found extracellularly. Accumulated uranyl phosphate was visible as cell-surface- and polar-localized deposits, identified by energy-dispersive X-ray analysis (EDAX), proton-induced X-ray emission analysis (PIXE) and X-ray diffraction analysis (XRD) as polycrystalline HUO2PO4.4H2O. Nucleation sites for initiation of biocrystallization were identified at the cytoplasmic and outer membranes, prompting consideration of an in vitro biocatalytic system for metal waste remediation. Phosphatidylcholine-based liposomes with entrapped phosphatase released phosphate comparably to whole cells, as shown by 31P NMR spectroscopy in the presence of 'NMR-silent' 112Cd2+. Application of liposome-immobilized enzyme to the decontamination of uranyl solutions was, however, limited by rapid fouling of the biocatalyst by deposited uranyl phosphate. It is suggested that the architecture of the bacterial cell surface provides a means of access of uranyl ion to the inner and outer membranes and enzymically liberated phosphate in a way that minimizes fouling in whole cells.

Bacterial Proteins↗

PubMed2003

Heavy metal bioavailability in a soil affected by mineral sulphides contamination following the mine spillage at Aznalcóllar (Spain).

A field experiment, lasting 14 months, was carried out in order to assess the effect of organic amendment and lime addition on the bioavailability of heavy metals in contaminated soils. The experiment took place in a soil affected by acid, highly toxic pyritic waste from the Aznalcóllar mine (Seville, Spain) in April 1998. The following treatments were applied (3 plots per treatment): cow manure, a mature compost, lime (to plots having pH < 4), and control without amendment. During the study two crops of Brassica juncea were grown, with two additions of each organic amendment. Throughout the study, the evolution of soil pH, total and available (DTPA-extractable) heavy metals content (Zn, Cu, Mn, Fe, Pb and Cd), electrical conductivity (EC), soluble sulphates and plant growth and heavy metal uptake were followed. The study indicates that: (1) soil acidification, due to the oxidation of metallic sulphides in the soil, increased heavy metal bioavailability; (2) liming succeeded in controlling the soil acidification; and (3) the organic materials generally promoted fixation of heavy metals in non-available soil fractions, with Cu bioavailability being particularly affected by the organic treatments.

Biological Availability↗

PubMedDate not supplied

Organ heavy-metal accumulation during parenteral nutrition is associated with pathologic abnormalities in rats.

OBJECTIVES: Metabolic bone disease, hepatic abnormalities, splenic insufficiency, and nephropathy have been associated with long-term total parenteral nutrition (TPN). We determined the heavy-metal contamination in TPN solutions and investigated whether it was associated with organ deposition and pathologic organ damage. METHODS: Five representative TPN solutions (two adult standard solutions, one renal solution, and one standard pediatric solution to reflect clinical practice) and 28 TPN components were analyzed with inductively coupled plasma mass spectrometry. Twenty-six male Fisher 344 rats were assigned to two groups (chow/NaCl = 8 and TPN = 18). TPN or NaCl was infused at a rate of 50 mL/d. After 14 d, serum, femurs, spine, liver, kidneys, brain, spleen, and testes were analyzed for heavy-metal deposition by using inductively coupled plasma mass spectrometry. Tissues were fixed in formalin, sectioned, and stained with hematoxylin and eosin, periodic acid Schiff, and Masson's trichrome stain. Kidneys were fixed in gluteraldehyde for ultrastructural examination with scanning electron microscopy. RESULTS: The predominant sources of contaminants in TPN were amino acids (Al, As, Cr, Ge, Pb, Sn), dextrose (As, Ba, Cr, Sn), Ca gluconate (Al), K2PO4 (Al), lipid emulsion (As, Sn), and vitamins (As). Significant variations in the level of contamination depended on TPN formulation and brand of constituents. In the kidney, Pb, Cr, and Mn concentrations were greater than in controls, although there was no correlation with serum creatinine. Hepatic Cr and Pb concentrations were greater in TPN rats, although there was no correlation with serum aspartate aminotransferase or total bilirubin. Splenic Ba, Cr, Ge, Pb, Mn, and Sn concentrations were greater in TPN rats. Only serum Cr concentration was significantly correlated with splenic concentration (r = 0.46, P = 0.04). Brain and serum Ba concentrations were significantly correlated (r = 0.60, P = 0.007). No significant correlations were observed between any other metal in serum and that metal's respective organ concentration. No increase in heavy-metal accumulation was seen in the femur, spine, or testis. There were no significant depositions of As, Cd, Hg, St, or V in any of the organs examined. Serum Al and Cr concentrations were significantly increased in TPN rats, although there was no correlation with tissue concentrations. No significant increases in heavy-metal concentrations in tissue or plasma were observed for any of the other metals measurable by inductively coupled plasma mass spectrometry. Histologically in the TPN group, 50% of the rats had mild to moderate hepatic steatosis and 33% to 50% developed renal morphologic abnormalities; brains and spleens remained histologically normal. CONCLUSIONS: We found significant heavy-metal contamination of TPN solutions, and this contamination can lead to organ deposition and subsequent histologic abnormalities.

Animals↗

PubMed2006

[Enrichment and toxicity effect of heavy metals in soil ecosystem].

The study on the heavy metals-polluted soil of Qingshuitang District, Zhuzhou City showed that the main enriched heavy metals in the soil were Cd, Hg, As, Zn, Pb and Cu, among which, the former three had strong biotoxicity while the others had definite toxicity, with the average integrative pollution index being 6.40. The heavy metals enrichment in soil animals increased with increasing pollution degree. Especially for some species of Megascoiecidae, they had a high enrichment of Cd, with the enrichment index being 11.96. The species and quantity of soil animals decreased with increasing Cd concentration. Cd had an obvious biotoxic effect on Megsacoiecidae' s isozyme activity. The heavy metals enrichment in vegetables also increased with increasing pollution degree, but there existed obvious interspecies difference in Cd enrichment.

Arsenic↗

PubMed1981

Induction of metallothionein mRNA in HeLa cells by dexamethasone and by heavy metals.

Synthesis of metallothionein, a cysteine-rich heavy metal binding protein, is induced in cultured HeLa cells both by the heavy metals Cd2+, Zn2+ and Cu2+, and by the glucocorticoid hormone dexamethasone. The accumulation of [35S]cysteine-labeled metallothionein and the amount of translatable metallothionein mRNA show identical concentration dependences in response to dexamethasone treatment and in response to zinc exposure. Induction of translatable metallothionein mRNA is rapid in response to both the metal and glucocorticoid inducers. Increased synthesis and accumulation of metallothionein in response to either metal or glucocorticoid exposure is regulated by the level of translatable metallothionein mRNA in HeLa cells.

Cadmium↗

PubMedDate not supplied

Assessment of uncertainty and risk in modeling regional heavy-metal accumulation in agricultural soils.

Present agricultural land use and atmospheric deposition may lead to heavy-metal accumulation rates in soils that may violate soil quality standards in the future. To undertake suitable preventive measures against heavy-metal enrichment, flux balances in agroecosystems and their uncertainties have to be assessed. For this reason we developed an empirical stochastic model, PROTERRA-S, that considers heavy-metal inputs through agricultural management as well as outputs by crop removal and leaching on a regional scale. In this manuscript we describe application of PROTERRA-S to the Sundgau region in Switzerland. Considering uncertainty in informational and natural variability, large variations of the aggregated regional cadmium and zinc balances were found, with standard deviations that were of the same order of magnitude as their average values. Uncertainty in the simulated net zinc flux originated mainly from uncertainty in the zinc concentrations of manure and crops and from uncertainty in atmospheric deposition of zinc. For cadmium, the main contribution to the total uncertainty came from uncertainty in crop concentration, regression functions to estimate Freundlich parameters, atmospheric deposition, and from spatial variation of soil pH and cation exchange capacity (CEC). For both zinc and cadmium, informational uncertainty in input data were large, indicating that significant uncertainty reduction could be achieved by additional data collection campaigns. A monetary risk value for the regional zinc accumulation rate in Sundgau was calculated to be on the order of 22 million Euro.

Agriculture↗

PubMed1993

The differential induction of alpha 1-acid glycoprotein and serum amyloid A genes by heavy metals.

We have investigated the differential regulation of the mouse (Balb/c) acute phase reactants, alpha 1-acid glycoprotein and serum amyloid A by heavy metals (Hg, Cd, Pb, Cu, Ni and Zn). Mice have two distinct alpha 1-acid glycoprotein mRNAs encoded by alpha 1-acid glycoprotein gene-1, (AGP-1) and alpha 1-acid glycoprotein gene-2 (AGP-2) and 3 distinct serum amyloid A mRNAs encoded by serum amyloid A gene-1, (SAA-1), serum amyloid A gene-2 (SAA-2) and serum amyloid A gene-3 (SAA-3). Using specific oligonucleotides as probes we have demonstrated that the AGP-1 and AGP-2 genes, and the SAA-1 and SAA-2 genes are differentially induced by heavy metals in the liver. At the peak of induction, AGP-2 mRNA is 80-100-fold higher than the AGP-1 mRNA level; the SAA-1 mRNA level is approx. 40-fold higher than SAA-2, and SAA-3 mRNA is not detected. A similar differential pattern of expression is observed in bacterial lipopolysaccharide mediated inductions. However, low levels of SAA-3 are also seen in this treatment. Adrenalectomy has no effect on the inductions by heavy metals of AGP-2 and the SAAs, indicating that the glucocorticoid receptor pathway may not function in this regulation. However, AGP-1 induction is significantly delayed, indicating that glucocorticoid may be essential for a rapid response to Hg. The liver is the major site of heavy metal induction of AGP and SAA genes; Hg induces AGP-1 and 2, and SAA-1 and 2 only in the liver. Our studies clearly show that the AGP and SAA genes belong to a subgroup of acute-phase reactants that respond to heavy metals. CRP is another member of this family. Furthermore, our data suggest that the mechanism is not directly mediated by glucocorticoid or cytokine induction pathways.

Adrenalectomy↗

PubMed2003

Simple optical fibre biosensor based on immobilised enzyme for monitoring of trace heavy metal ions.

A simple optical fibre biosensor based on immobilised enzyme for monitoring of trace heavy metal ions has been developed. The biosensor recognition system was designed based on the inhibition of urease activity, where the urease is immobilised on ultrabind membrane. The studies of inhibition by the heavy metal ions Hg(II), Ag(I), Cu(II), Ni(II), Zn(II), Co(II) and Pb(II) were performed using a fibre-optic biosensor configuration, where the pH change resulting from the bio-catalytic hydrolysis of urea was monitored at the wavelength 615 nm spectroscopically, using commercial pH indicator strip before and after the exposure to the heavy metal ions. The immobilised urease was regenerated by l-cysteine. The linear response range between 1 x 10(-9)-1 x 10(-5) M and the limit of detection 1 x 10(-9 )M (0.2 microg/L) for Hg(II) ions was achieved by employing the flow method. The optimisation of experimental parameters, including flow method, is also discussed.

Biosensing Techniques↗

PubMed1992

[Environmental pollutants and fertility disorders. Heavy metals and minerals].

So far, the influence of lead, cadmium and mercury on human fertility has hardly been considered. First experiences by the authors with the chelating agent 2,3 dimercaptopropane-1-sulfonate (DMPS), which mobilizes heavy metals deposited in the body, seem to favour an association between the body load of heavy metals and complications during the menstrual cycle and during pregnancy. By means of an extensive survey of references, the importance of heavy metals for reproduction is demonstrated. In addition, the deficiency of particular minerals and their interaction with heavy metals are considered. Indications are given for diagnosis and therapy of the exposure to heavy metals. The practical procedure is demonstrated by means of three case studies.

Abnormalities, Drug-Induced↗

PubMed2006

Accumulation of nutrients and heavy metals in Phragmites australis (Cav.) Trin. ex Steudel and Bolboschoenus maritimus (L.) Palla in a constructed wetland of the Venice lagoon watershed.

A recently constructed wetland, located in the Venice lagoon watershed, was monitored to investigate growth dynamics, nutrient and heavy metal shoot accumulation of the two dominating macrophytes: Phragmites australis and Bolboschoenus maritimus. Investigations were conducted over a vegetative season at three locations with different distance to the inlet point to assess effects on vegetation. The distance from the inlet did not affect either shoot biomass or nutrients (N, P, K and Na) and heavy metals (Cr, Ni, Cu and Zn) shoot content. With the exception of Na, nutrient and heavy metal concentrations were higher in shoots of P. australis than in B. maritimus. Heavy metal concentration in the incoming water and in the soil was not correlated to the plant content of either species. Shoot heavy metal concentrations were similar to those reported in the current literature, but accumulation generally increased towards the end of the growing season.

Biodegradation, Environmental↗

PubMed2006

Toxicity of heavy metals on Scenedesmus quadricauda (Turp.) de Brébisson in batch cultures.

BACKGROUND: Aquatic environments are often exposed to various pollutants like heavy metals that are released from industrial, agricultural and domestic wastes. Emissions of heavy metals can then enter all ecosystems and bring about severe problems in plants, especially algae depending on the concentrations of a given element. The objective of the investigation presented is to detect toxic effects due to some heavy metals in the biomass of green alga Scenedesmus quadricauda. METHODS: All experiments were conducted with axenic cultures of the green alga Scenedesmus quadricauda (Turp.) de Brebisson (Chlorococcales, Chlorophyta). The cultures were grown in Chu-no.10 medium, and optimum physical and chemical growth conditions were provided to get higher growth rates and lower doubling times of cells. Growth of the micro algal cultures was measured on a daily schedule by counting cultures and determination of chlorophyll-a. The sterile-filtered heavy metal concentration solutions (Cd, Pb and Cu) were prepared and added as stock solutions of their salts (CdCl2*2.5 H2O, Pb(NO3)2*H2O and CuSO4*5 H2O). RESULTS AND DISCUSSION: The growth decreased gradually with the alga exposed to Cd at 0.05, 0.1, and 0.5 mg/L in comparison with the control whereas 1 mg/L Cd2+ had a clearly destructive effect. The growth was decreased with Pb at 15, 20 and 25 mg/L gradually, while at 30 mg/L the effect was more pronounced. When Cu was used, the growth was increased gradually at 0.5, 1 and 1.5 mg/L and vice versa at 2 mg/L. CONCLUSION: There were differences in toxic effects of the metals with different metal as well as their concentrations and the time of exposure.

Biomass↗

PubMed1983

Effect of heavy metals on human rheumatoid synovial cell proliferation and collagen synthesis.

The dose-dependent effects of heavy metals on cell proliferation, collagen synthesis, and non-collagen protein synthesis were studied in early passage cultures of human synovial cells exposed to 1-100 microM concentration of gold, silver, mercury, cadmium or lead for 5 days. The incorporation of [3H]thymidine into trichloroacetic acid insoluble material was inhibited 50% by each of the heavy metals at concentrations between 1 and 10 microM. Gold, lead and mercury (10 microM) decreased the DNA content of the cultures by less than 15%; silver (10 microM) and cadmium (10 microM) resulted in decreased DNA content, which was attributed to cytotoxicity. A dose-dependent inhibition of [3H]proline incorporation into bacterial collagenase resistant (non-collagen) protein was observed after incubation with 10 microM mercury, lead and silver. During incubations with 10 microM gold and cadmium, collagenase resistant protein accumulation increased. All the heavy metals except for gold inhibited collagen accumulation to a greater extent than non-collagen protein accumulation. Gold (10 microM) stimulated the amount of collagen produced per cell, and the percentage of collagen to total protein was increased 50%. The rate of collagen accumulation in medium decreased during incubation with 10 microM silver, mercury, cadmium and lead. The stimulation of collagen synthesis may be a unique property of gold related to the therapeutic indices of gold, compared to other heavy metals, in rheumatoid arthritis.

Arthritis, Rheumatoid↗

PubMed2006

Effect of heavy metal stress on antioxidative enzymes and lipid peroxidation in leaves and roots of two mangrove plant seedlings (Kandelia candel and Bruguiera gymnorrhiza).

The effects of multiple heavy metal stress on the activity of antioxidative enzymes and lipid peroxidation were studied in leaves and roots of two mangrove plants, Kandelia candel and Bruguiera gymnorrhiza, grown under control (10 per thousand NaCl nutrient solution) or five levels of multiple heavy metal stress (10 per thousand NaCl nutrient solution containing different concentration of Pb2+, Cd2+, and Hg2+). Leaves and roots of control and heavy metal-stressed plants were harvested after two months. In leaves of heavy metal-stressed plants superoxide dismutase (SOD) and peroxidase (POD) activities fluctuated in different stress levels compared to the control, while catalase (CAT) activity increased with stress levels in K. candel, but remained unchanged in leaves of B. gymnorrhiza. In comparison with the control, the dynamic tendency of SOD, CAT, and POD activities in roots of heavy metal-stressed plants all ascended, and then declined. The increase in enzyme activities demonstrated that K. candel is more tolerant to heavy metals than B. gymnorrhiza. Lipid peroxidation was enhanced only in leaves of heavy metal-stressed B. gymnorrhiza. These results indicate that in heavy-metal stress antioxidative activities may play an important role in K. candel and B. gymnorrhiza and that cell membrane in leaves and roots of K. candel have greater stability than those of B. gymnorrhiza. For pollution monitoring purposes, POD activity in roots and leaves maybe serve as a biomarker of heavy metal stress in K. candel, while lipid peroxidation maybe serve as biomarker in B. gymnorrhiza.

Cadmium↗