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PubMed1998

Effect of heavy metals on Aedes aegypti (Diptera: Culicidae) larvae.

Studies were conducted to determine the biological effects of heavy metals on the development of Aedes aegypti. Embryos immersed in 32 ppm Cu or 5 ppm Cd did not hatch. The arrest of hatching was in part reversible by removal of the heavy metals. The mortality rate of third-instar larvae exposed to heavy metals for 24 h was metal and dose dependent; the 50% lethal concentration (LC50) endpoints were 3.1, 16.5, and 33 ppm for Hg, Cd, and Cu, respectively. Interestingly, a proportion of Aedes aegypti third-instar larvae exposed to either Cu or Cd for 24 h failed to produce a dissectable peritrophic matrix. This failure to produce a dissectable peritrophic matrix also was metal and dose dependent. These results are discussed in the context of Aedes aegypti as a model system for investigating the molecular biological effects of heavy metals in aquatic insects.

Aedes↗

PubMed1990

[Changes in biological activity of turf-podzolic soil of different mechanical composition contaminated with heavy metals].

It has been shown that soil pollution with heavy metals (copper, nickel) lead to negative changes in parameters characterizing potential biological activity of soil (nitrogen-fixation, breath, invertase activity, bacteria and fungi count). More profound changes were observed in sandy soil compared to loamy soil. A direct relationship of these effects with the content of mobile forms of heavy metals in soil has been established. For the comparative and prognostic investigation of the danger of soil pollution with heavy metals it has been suggested to use a coefficient of differences in the content of mobile forms and a coefficient of biological effect.

Bacteria↗

PubMed2003

Toxicity of heavy metals for microorganisms isolated from slow sand filter schmutzdecke.

This paper describes the susceptibility of three species of environmental bacteria isolated from the schmutzdecke of biologically active slow sand filters to cadmium, chromium and lead. The microorganisms, all identified as members of the genus Pseudomonas, were grown in tryptic soy broth with various concentrations of the selected heavy metals. The mean generation times (MGT) of the bacteria were compared to evaluate the toxic effects of the heavy metals. All three species tolerated high doses of heavy metals and the MGTs increased exponentially as the heavy metal concentrations increased; 12 mg l(-1) was the highest dose tested and the bacteria continued to grow albeit at very slow rates. In dilute media, the toxic effects of heavy metals were enhanced, illustrating the protection effect of organic matter and heavy metal complex formation. Growth studies of the isolated microorganisms on half-strength tryptic soy agar containing 6 mg l(-1) heavy metals also proved useful in determining toxicity.

Bacteria↗

PubMed2002

Study of the content of heavy metals related to environmental load in urban areas in Slovakia.

UNLABELLED: It is natural for the man to take care of his environment so the negative influences of intensification of industrial and agricultural production and the entire process of pollution are kept at minimum or eliminated as early as possible. However, they must first be identified. BACKGROUND: companion animals, for example dogs, are a very good indicator of the pollution load on the environment. They inhabit the same space as humans and are exposed to the action of the same pollutants. The most important role in contamination of the environment with heavy metals is played by emissions of different origin. For that reason it is appropriate and advantageous to evaluate the load on the man by parallel evaluation of the heavy metal load on dogs, particularly in large town agglomerations. MAIN PURPOSE: the aim of the study was to compare and evaluate the content of three heavy metals, cadmium, arsenic and lead, in the hair of dogs from two largest town agglomerations of Slovakia, Bratislava and Kosice. In addition to that, an effort was made to compare the environmental load in Bratislava and Kosice by using the dog as a bioindicator of environmental pollution with heavy metals and to quantify the content of heavy metals in dog' hair. METHODS: The generally low level of heavy metals in biological material makes it impossible to use common analytical methods. In our study the samples of dog hair were analysed using the method of atomic absorption spectrometry. The measurements were carried out on a Perkin-Elmer spectrometer, model 5000, using the following wavelengths: 228.8 nm for Cd, 193.7 nm for As and 283.3 nm for Pb. The results of analyses are presented as means. The concentrations of Cd, As and Pb are expressed in microg/kg dog hair. Statistical evaluation of results was carried out by means of Student's t-test. RESULTS: The mean values of heavy metals in the set of dogs from Bratislava reached the following levels: 38.09 microg/kg for Cd, 111.07 microg/kg for As, and 729.59 microg/kg for Pb. The set of dogs from Kosice allowed us to detect the following mean values: 22.21 microg/kg for Cd, 79.87 microg/kg for As, and 542.49 microg/kg for Pb. The mean values for the entire Slovak territory reached 27.39 microg/kg for Cd, 90.06 microg/kg for As, and 601.96 microg/kg for Pb. The comparison of the first two experimental sets of data with the Slovak mean values showed highly significant differences in arithmetic means (p < 0.01) for Cd and significant (p < 0.05) for As with the Bratislava set reaching higher values. No statistically significant differences were observed with regard to Pb. CONCLUSION: The study confirms the need for further research in this area with the dog as a bioindicator involving also other environmental loads not only that resulting from heavy metals. It indicates the importance of risk assessment in relation to environmental pollution. As the studies on animals are applicable also to the human population it appears very appropriate to use also this indirect way to point out to the negative impact of the polluted environment. Lead, cadmium and arsenic are the heavy metals that raise particular concern because of their wide-spectrum negative influences on live organisms. (Tab. 4, Fig. 5, Ref 28.)

Animals↗

PubMed1981

[Geomicrobiological studies. XIV. Heavy metal tolerance of desulfurizing bacteria under various ecological conditions].

Tolerance and adaptation to heavy metals of Desulfovibrio- and Desulfotomaculum-strains of different origin have been investigated in enrichment cultures under different conditions of sulphate supply. Three groups of low, medium, and high toxicity were found with As, V, and Mo in the first, Ni, Sb, Co, and Hg in the second, and Cd, Zn, U, and Cu in the third group. If the SO"4-supply was restricted to heavy metal sulphates with a relation of 1:1 of heavy metal- and SO"4 -ions (2:3 with Sb2(SO4)3) the tolerance was somewhat lowered. Adaptation to higher concentrations of heavy metals was possible, if the strains had not yet been exposed and adapted to higher concentration levels at their natural habitats. The tolerance range of desulfurizers has been compared with the tolerance range of different biochemical types of microorganisms.

Bacillaceae↗

PubMed2005

Comparison of EDTA and EDDS as potential soil amendments for enhanced phytoextraction of heavy metals.

Phytoextraction has been proposed as an alternative remediation technology for soils polluted with heavy metals or radionuclides, but is generally conceived as too slow working. Enhancing the accumulation of trace pollutants in harvestable plant tissues is a prerequisite for the technology to be practically applicable. The chelating aminopolycarboxylic acid, ethylene diamine tetraacetate (EDTA), has been found to enhance shoot accumulation of heavy metals. However, the use of EDTA in phytoextraction may not be suitable due to its high environmental persistence, which may lead to groundwater contamination. This paper aims to assess whether ethylene diamine disuccinate (EDDS), a biodegradable chelator, can be used for enhanced phytoextraction purposes. A laboratory experiment was conducted to examine mobilisation of Cd, Cu, Cr, Ni, Pb and Zn into the soil solution upon application of EDTA or EDDS. The longevity of the induced mobilisation was monitored for a period of 40 days after application. Estimated effect half lives ranged between 3.8 and 7.5 days for EDDS, depending on the applied dose. The minimum observed effect half life of EDTA was 36 days, while for the highest applied dose no decrease was observed throughout the 40 day period of the mobilisation experiment. Performance of EDTA and EDDS for phytoextraction was evaluated by application to Helianthus annuus. Two other potential chelators, known for their biodegradability in comparison to EDTA, were tested in the plant experiment: nitrilo acetic acid (NTA) and citric acid. Uptake of heavy metals was higher in EDDS-treated pots than in EDTA-treated pots. The effects were still considered insufficiently high to consider efficient remediation. This may be partly due to the choice of timing for application of the soil amendment. Fixing the time of application at an earlier point before harvest may yield better results. NTA and citric acid induced no significant effects on heavy metal uptake.

Biodegradation, Environmental↗

PubMed2000

Mechanism of heavy metal ion activation of phytochelatin (PC) synthase: blocked thiols are sufficient for PC synthase-catalyzed transpeptidation of glutathione and related thiol peptides.

The dependence of phytochelatin synthase (gamma-glutamylcysteine dipeptidyltranspeptidase (PCS), EC ) on heavy metals for activity has invariably been interpreted in terms of direct metal binding to the enzyme. Here we show, through analyses of immunopurified, recombinant PCS1 from Arabidopsis thaliana (AtPCS1), that free metal ions are not essential for catalysis. Although AtPCS1 appears to be primarily activated posttranslationally in the intact plant and purified AtPCS1 is able to bind heavy metals directly, metal binding per se is not responsible for catalytic activation. As exemplified by Cd(2+)- and Zn(2+)-dependent AtPCS1-mediated catalysis, the kinetics of PC synthesis approximate a substituted enzyme mechanism in which micromolar heavy metal glutathione thiolate (e.g. Cd.GS(2) or Zn.GS(2)) and free glutathione act as gamma-Glu-Cys acceptor and donor. Further, as demonstrated by the facility of AtPCS1 for the net synthesis of S-alkyl-PCs from S-alkylglutathiones with biphasic kinetics, consistent with the sufficiency of S-alkylglutathiones as both gamma-Glu-Cys donors and acceptors in media devoid of metals, even heavy metal thiolates are dispensable. It is concluded that the dependence of AtPCS1 on the provision of heavy metal ions for activity in media containing glutathione and other thiol peptides is a reflection of this enzyme's requirement for glutathione-like peptides containing blocked thiol groups for activity.

Amino Acids↗

PubMed2002

Heavy metals in agricultural soils of the Pearl River Delta, South China.

There is a growing public concern over the potential accumulation of heavy metals in agricultural soils in China owing to rapid urban and industrial development and increasing reliance on agrochemicals in the last several decades. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but elevated heavy metal uptake by crops may also affect food quality and safety. The present study is aimed at studying heavy metal concentrations of crop, paddy and natural soils in the Pearl River Delta, one of the most developed regions in China. In addition, some selected soil samples were analyzed for chemical partitioning of Co, Cu, Pb and Zn. The Pb isotopic composition of the extracted solutions was also determined. The analytical results indicated that the crop, paddy and natural soils in many sampling sites were enriched with Cd and Pb. Furthermore, heavy metal enrichment was most significant in the crop soils, which might be attributed to the use of agrochemicals. Flooding of the paddy soils and subsequent dissolution of Mn oxides may cause the loss of Cd and Co through leaching and percolation, resulting in low Cd and Co concentrations of the paddy soils. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the Fe-Mn oxide and residual fractions, while Zn was predominantly found in the residual phase. A significant percent fraction of Cu was bound in the organic/sulphide and residual phases. Based on the 206Pb/207Pb ratios of the five fractions, it was evident that some of the soils were enriched with anthropogenic Pb, such as industrial and automobile Pb. The strong associations between anthropogenic Pb and the Fe-Mn oxide and organic/sulphide phases suggested that anthropogenic Pb was relatively stable after deposition in soils.

Agriculture↗

PubMed2006

Spatial characterization and prioritization of heavy metal contaminated soil-water resources in peri-urban areas of National Capital Territory (NCT), Delhi.

Due to rapid industrialization and urbanization during last two decades, contamination of soils by heavy metals is on an increase globally. Lands under peri-urban agriculture are the worst affected. In NCT, Delhi about 14.4% of land area is chemically degraded. In order to take care of this problem, recently the Supreme Court of India ordered to shift various non-confirming (about 39,000 units) industries to regions outside NCT, Delhi. However in spite of this, there have been several reports and parliamentary debates on the phyto-toxicity and extensive accumulation of heavy metals in the region. Literature review revealed that the basis of these debates is a few studies on some point locations in/around Delhi. It was further observed that information on the distribution and extent of heavy metal pollution problem in the region was completely missing. The present study was thus basically aimed at assessing the spatial distribution/extent and type of heavy metal pollution in the study area, for enabling future designing of appropriate site-specific management measures by the decision makers. For this, detailed spatial information on bio-available heavy metal concentrations in the soils and surface/sub-surface waters of NCT (Delhi) was generated through actual soil/water surveys, standard laboratory methods and GIS techniques. The study showed that concentration of all micronutrients (viz. Zn: 0.05-0.18 ppm; Cu: in traces; Fe: 0-0.5 ppm; and Mn: 0-1.2 ppm) and most heavy metals (viz. Ni: 0-0.7 ppm; Pb: 0-0.15 ppm and Cd: in traces) in the surface/sub-surface irrigation waters were well within permissible limits. However Cr concentrations in irrigation waters of Alipur and Shahdara blocks were far above their maximum permissible limit of 1 ppm. It was further observed that Ni and Cr concentrations in the drinking waters of almost entire test area were far above maximum permissible levels of 0.02 and 0.01 ppm, respectively. Bio-available concentrations of several heavy metals (viz. Pb: 0.1-2 ppm; Cd: traces; Ni: 0.05-2 ppm and Cr: 0-0.4 ppm) in the study area soils were also observed to be well within the maximum permissible limits. However there were point Cu contaminations (5-10 ppm) in the sewage-sludge amended soils of vegetable growing areas near south Shahdara block. This was attributed to increased Cu availability due to oxidized acidic conditions generated by over-irrigation of agricultural lands. Available Mn concentrations in Kanjhawala, western Najafgarh and Alipur soils were also observed to be above maximum permissible limit of 10 ppm. This was observed to be mainly due to the geology (i.e. presence of Mn rich sedimentary rocks) and prevalence of reduced acidic conditions, due to paddy cultivation, in these areas. It was further observed that there is acute zinc (Zn) deficiency (< 0.6 ppm) in paddy growing soils of north Kanjhawala, Alipur and some parts of Najafgarh and Shahdara blocks due to extensive leaching of available Zn fractions to lower soil horizons. Similar available Zn deficiencies in high pH (8.5) soils of areas around Bamnoli village in E-Najafgarh block were also observed.

Agriculture↗

PubMed2005

Species-specific heavy metal accumulation patterns of earthworms on a floodplain in Japan.

We identified all earthworm species found on a floodplain contaminated by heavy metals (Cu, Zn, Cd, and Pb) from an old mine in central Japan and compared their abundance, biomass, and heavy metal concentrations in tissue. There were six species belonging to three families: Megascolecidae, Moniligastridae, and Lumbricidae. Earthworm community structure seemed to be influenced mostly by soil properties, especially pH and clay fraction. Despite the same endogeic characteristics, species-specific patterns of heavy metal accumulation were observed: species in Megascolecidae and Lumbricidae had relatively lower concentrations compared to those in Moniligastridae. Within Moniligastridae, Drawida sp. accumulated Cu and Pb markedly higher than Drawida japonica. Based on heavy metal concentrations in extracts of CaCl(2) and diethylenetriaminepentaacetic acid, the aging caused remarkably low concentrations in pore water, indicating low availability by dermal uptake. Therefore the different patterns of heavy metal accumulation among species would partly result from species-specific gut process.

Animals↗

PubMed2006

Effect of temperature on heavy metal toxicity to juvenile crayfish, Orconectes immunis (Hagen).

The acute toxicity of four selected heavy metals to juvenile crayfish Orconectes immunis (Hagen) (1-2 g wet body wt. each) at room temperature increased in the following order: cadmium (x3) < copper (x10) < zinc (x2) < lead. The toxicity of these metals to crayfish acclimated at 17, 20, 23/24, and 27 degrees C increased with temperature (by 7-20% between 20 and 24 degrees C and 14-26% between 20 and 27 degrees C) as judged by the lowering of LT(50) (time to kill 50% of test animals at a fixed concentration) values. A 4 degrees C rise in temperature (from 20 to 24 degrees C), which increased the toxicity of copper by about 7%, increased the rate of oxygen consumption by about 34%. Heavy metals inhibited the rate of oxygen consumption at all temperatures. In 20 degrees C-acclimated crayfish, copper caused about 17% inhibition of oxygen consumption compared to about 7-12% by other metals including the most toxic cadmium. A 3-4 degrees C rise in temperature tripled the inhibitory effect of copper (20%), cadmium and zinc (26 and 18%, respectively), but not of lead, on oxygen consumption. A 7 degrees C-rise in temperature (from 20 to 27 degrees C) increased the inhibitory effect of heavy metals, including lead, on oxygen consumption by up to 54% in the case of copper. The data indicate that rising global temperatures (currently 0.60 degrees C) associated with climate change can have the potential to increase the sensitivity of aquatic animals to heavy metals in their environment.

Animals↗

PubMedDate not supplied

[Estimation of the levels of heavy metals in the water courses and drinking water in the south of the Issyk-Kul Region].

The levels of heavy metals were determined in the river and drinking waters of the localities of the Ton and Jety-Oguz Districts of the Issyk-Kul Region. The quality of water was tested for the content of 11 heavy metals (Be, Pb, Cd, Ni, Co, Cr6+, Zn, Ba, Sr, TI, Sn) by emission spectral analysis in 1990-2000. The analysis of the findings indicated that the water levels of the heavy metals, met the sanitary requirements for drinking water, except for those of chromium whose content in the Barskoon and Chon-Kyzyl-Suu rivers in the cold period of 1999 was 2-3 times higher than the allowable levels. There were seasonal variations in the concentrations of heavy metals in the river waters. In most cases, the concentrations of most metals increase in the warm period of a year. The concentrations of heavy metals tended to increase in the river water in 2000 versus 1999.

Humans↗

PubMed1990

The stimulatory effect of heavy metal cations on proliferation of aortic smooth muscle cells.

Heavy metal cations Cd2+, Pb2+, and Hg2+ were added to substitute for Ca2+ in culture media to study their effect on the relationship between CaM and the proliferation of cultured rabbit aortic smooth muscle cells (ASMC). It was found that all the heavy metal cations studied stimulated the proliferation of ASMC in varying degrees, increased the CaM content in cells at late G1 stage and decreased the activity of cAMP PDE. These results suggest that the adverse effect of heavy metals may be related to the pathogenesis of atherosclerosis and hypertensive disease.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2001

Formation of heavy metal species during PVC-containing simulated MSW incineration.

The effect of PVC-derived chlorine on heavy metal emissions in MSW incineration was investigated using a tubular furnace and simulated MSW spiked with PVCs and heavy metals (Cd, Cr, Cu, and Zn). The molar ratio of the chlorine content to that of the heavy metal (Cl/M ratio) was varied from 3-200 as one parameter. The results indicated that the major species found in the fly ash were chlorides of alkaline and alkali-earth metals, whereas those identified in the bottom ash were MgSiO3, SiO2 and some complex aluminates and silicates. The emission of heavy metals and/or their compounds, with extreme and medium volatility, tended to be enhanced within the lower Cl/M range, whereas those with a refractory volatility were likely to be affected within the higher Cl/M range. However, those with an extremely refractory volatility were less affected by an increase of the Cl/M ratio. The variation of speciation and partitioning in MSW combustion as affected by the Cl/M ratio are discussed.

Environmental Monitoring↗

PubMed2004

Fungi ingestion as an important factor influencing heavy metal intake in roe deer: evidence from faeces.

In nature, animals have to cope with the fluctuating bioavailable metal pool in their habitat, which results in a seasonal variability of heavy metal levels in the animal body. Indeed, a pronounced summer-autumnal peak of heavy metals in roe deer (Capreolus capreolus L.) kidney was recently found in Slovenia. Considering the well-known hyperaccumulative ability of fungi, their ingestion was hypothesised to be one of the main reasons for the peak. Although fungi as a group are known to be a seasonally important food source for roe deer, data on their composition in the nutrition of the species have been lacking. To ascertain the importance of fungi ingestion on heavy metal intake in roe deer, we simultaneously studied fungal spores (by microscopic determination) and heavy metal levels (by inductively coupled plasma mass spectrometry and atomic absorption spectrometry) in roe deer faeces, collected in the period July-November 2001 at Veliki Vrh, the Salek Valley, Slovenia. Irrespective of species, fungal spores were present in 89% of faeces; the following genera were found to be consumed by roe deer: Lycoperdon, Calvatia, Hypholoma, Coprinus, Russula, Elaphomyces, Xerocomus, Enteloma, Amanita, Cortinarius, Agaricus, Inocybe, Boletus, Macrolepiota, Suillus and Pluteus. While the importance of fungi ingestion on the seasonal variability of other metals is less clear, it doubtless influences Hg intake in roe deer, which is confirmed by: (a) the high frequency of fungi in roe deer nutrition; (b) their hyperaccumulative ability; (c) the temporal distribution of Hg in roe deer faeces; (d) differences among three classes of faeces established on the basis of the frequency of spores present; (e) the correlation between the number of fungal genera present and Hg levels in faeces. Therefore, the influence of fungi ingestion has to be taken into consideration in assessing the hazard due to the accumulation of mercury along the food-chain.

Animals↗

PubMed2003

[Physiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccumulators].

In comparison with normal plants, hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil, without suffering from detrimental effects. With the help of molecular technologies, the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress. A number of trace element transporters have been cloned by functional complementation with yeast mutants defective in metal absorption. The relations between glutathione, phytochelatins metallothioneins, organic acids and heavy metals have been studied by molecular technologies. This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.

Absorption↗

PubMed2004

Mediterranean Talitrus saltator (Crustacea, Amphipoda) as a biomonitor of heavy metals contamination.

The use of sandhoppers and beachfleas as biomonitors of heavy metals contamination is relatively recent. Using adult individuals of Talitrus saltator from nine localities on the northern Mediterranean Sea, we studied the concentrations of eight trace elements: Al, Cd, Cr, Fe, Hg, Pb, Cu, Zn, both in the substratum and in the individuals. We also carried out a preliminary investigation of the correspondence between the sandhoppers' genetic variability and heavy metal contamination at the sampling sites. T. saltator accumulated Cd, Cu, Zn and Hg (at higher concentrations than in the sand) and also Al and Fe (at lower concentrations than in the sand). It seems that Mediterranean sandhoppers do not accumulate Pb and Cr. An intraspecific comparison between northern European (Baltic) and Mediterranean populations of T. saltator was made. Finally, we observed a tendency to a positive correlation between the sandhoppers' genetic variability and heavy metals contamination.

Amphipoda↗

PubMed2004

Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France).

The Lot-Garonne fluvial system is known for its historic heavy metal pollution resulting from mining and smelting activities since the late 19th century. Here, we report 137Cs activities and heavy metal (Cd, Zn, Cu, Pb and V) concentration-depth profiles from sediment cores retrieved in 2001 from three reservoirs in the Lot River. High mean sedimentation rates of 2.4-2.8 cm a(-1) are indicated by 137Cs dating. The reservoir sediments have recorded the heavy metal deposition and thus allow establishing a connection between the temporal evolution of the heavy metal pollution and historical changes in smelting and waste-treatment proceedings. Based on heavy metal concentrations in sediments upstream of the anthropogenic inputs and bottom-sediments of the furthest downstream core (interpreted as old soil or riverbed), concentrations of approximately 17, approximately 82, approximately 0.33 and approximately 28 mg kg(-1) for Cu, Zn, Cd and Pb, respectively, are proposed as natural background values for the Lot fluvial system. The geoaccumulation index (Igeo [Müller, G., 1979. Schwermetalle in den Sedimenten des Rheins-Veränderungen seit. Umschav 79, 133-149.]) revealed that the Lot River sediments must be considered as "severely polluted" in Cd and Zn. Moreover, despite remediation efforts undertaken in the former smelting site, the Lot River is still "severely" (Igeo approximately 4) and "moderately to severely" (Igeo>2) impacted by Cd and Zn inputs, respectively.

Cadmium↗