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At least 613 records · Page 34Linked to original sources

PubMed2003

Investigation on the emission factors and removal efficiencies of heavy metals from MSW incinerators in Taiwan.

Two large-scale municipal waste incinerators (MWIs) equipped with different air pollution control devices (APCDs) were selected for conducting flue gas sampling and determination of heavy metals emissions including lead, zinc, cadmium, chromium, copper and mercury. In addition, the emission characteristics and removal efficiencies of heavy metals were evaluated via simultaneous sampling of flue gas upstream and downstream of APCDs. The average removal efficiency of particulate matter was 99.47%, and the removal efficiency of heavy metals could reach 95% or higher (except for Hg) for MWI-A. Preliminary results indicated that the average removal efficiency of particulate matter was 99.94%, and the removal efficiency of heavy metals could reach 98% or higher (except for Hg) for MWI-B. The average removal efficiencies of Hg for MWI-A and MWI-B were 47% and 30% respectively. The removal efficiencies achieved with existing APCDs were close to that reported in the US EPA document (AP-42) for MWIs. The average concentrations of heavy metals and particulate matter emitted from stack could meet current emission standards in Taiwan for both MWIs, but particulate matter, Pb and Cd concentrations of MWI-A were higher than the current emission regulations in Germany and the Netherlands.

Air Pollutants↗

PubMed2001

Studying the evaporation behavior of heavy metals by thermo-desorption spectrometry.

"Thermal desorption experiments" were carried out during which heavy metal evaporation was studied by on-line monitoring. This could be achieved by the use of a tubular furnace connected to a heavy metal detector, i.e. an ICP-OES (inductively coupled plasma optical emission spectrometer), by a specially designed and patented interface. The spectrograms typically had a time resolution of four different elements per minute using a conventional (sequentially operating) ICP-OES. This study shows how thermo-desorption spectrometry (TDS) can be applied to study the evaporation of high boiling substances, such as heavy metal and alkali metal compounds. The future scope of the method is discussed.

Incineration↗

PubMed2001

Honeybees and their products as potential bioindicators of heavy metals contamination.

The concentrations of three representative heavy metals (cadmium, chromium and lead) were measured by atomic absorption spectroscopy in honeybees and in apiary's products (honey, pollen, propolis, and wax). Samples were collected from five different sampling points: four from areas surrounding the city of Rome, and the fifth in the city center which receives intense vehicular traffic. All apiaries employed for this study were specifically constructed without any metal part in order to avoid the risk of contamination of the assayed materials. Sample collection was conducted over a 3-month period (6 samplings for honey and pollen, 3 sampling for propolis and wax, 2 samplings for honeybees, all of which were collected in duplicate). Experimental data revealed, in general, statistically significant differences between the background levels of heavy metals recorded from the reference sites and the levels measured in the site located in the center of the city of Rome. These results indicate that honeybees and, to a lesser extent, some of their products (pollen, propolis, wax, but not honey), can be considered representative bioindicators of environmental pollution.

Animals↗

PubMed2006

Shortened lifespan of nematode Caenorhabditis elegans after prolonged exposure to heavy metals and detergents.

The acute toxicities of heavy metals and detergents have been well examined with respect to several endpoints, such as mortality, for application to toxicity tests for environmental assessments. However, chronic influences of these agents on multicellular organisms still need to be determined. Here we studied long-term effects on the lifespan of a free-living nematode, Caenorhabditis elegans, resulting from prolonged exposure to heavy metals or detergents, as well as short-term inhibitory effects on reproduction and growth. These agents inhibited growth of hatched larvae and reproductive capacity in a concentration-dependent manner. They also effectively shortened the lifespan of the adult nematode over the same concentration range. Since toxic effects on both growth and lifespan were observed over similar concentration ranges, where acute toxicities in various endpoints are detected, the shortening of the lifespan can be used as a new endpoint for the assessment of various ecotoxic agents.

Animals↗

PubMed2002

Mannosomes: a molluscan intracellular tubular membrane system related to heavy metal stress?

Amongst animals, several hydrogen peroxide-generating oxidases are apparently restricted to molluscs. One of these, D-mannitol oxidase, is concentrated in the alimentary system, where it is associated with its own subcellular membrane system of unique tubular morphology, most likely representing a structural modification of the ER. These structures can be purified by subcellular fractionation and have been termed 'mannosomes'. Little is known about the functions of mannitol oxidase or of mannosomes, but the previously reported molluscicide-induced increase in mannosomes implies their involvement in a general stress reaction. In this study, we examined the effects of heavy metal stress in the terrestrial gastropod Arion lusitanicus. The activity of mannitol oxidase and mannosome abundance were monitored, together with metal effects on heat-shock protein level, and these parameters were compared to heavy metal accumulation in the digestive gland. We found that mannitol oxidase is inhibited by heavy metals more than other oxidases. On the other hand, hsp70 levels and mannosomal protein were increased with enhanced heavy metal stress, the latter indicating a probable increase in the number of mannosome organelles. Thus, stress protein (hsp70) and mannosomal protein were positively correlated with heavy metal accumulation, whereas the enzyme activity showed a negative correlation with increasing heavy metal content of the slugs.

Administration, Oral↗

PubMed2005

Health risks of heavy metals to the general public in Tianjin, China via consumption of vegetables and fish.

Consumption of vegetables and fish contaminated with the heavy metals Cu, Zn, Pb, Cd, Hg, and Cr is the most likely route for human exposure in Tianjin, China. Health risks associated with these heavy metals were assessed based on the target hazard quotients (THQs), which can be derived from concentrations of heavy metals in vegetables and fish consumed in four districts (Dong Li, Xi Qing, Jin Nan, and Bei Chen) and the urban area of Tianjin, China. Individual metal THQ (<1) values indicate the relative absence of health risks associated with intake of a single heavy metal through consumption of either contaminated vegetables or fish only. However, consumption of both vegetables and fish would lead to potential health risks especially for children, since individual THQs for vegetables and fish would sum up to almost 1. If individual THQs resulting from crops consumption are considered, the health risks would be greater for children since the THQ values will always be >1. Risk contribution from Cr is minimal compared to the other elements. Hg is the major risk contributor for children in Bei Chen since the THQ contribution amounts to about 45% of the total THQ values due to vegetables and fish consumption. The health risk to adults in Ding Li is ascribed mainly to the intake of Cd by vegetables and fish consumption, which contributes a substantial fraction to the total THQ (about 51%).

Adult↗

PubMed1997

Heavy metals input with phosphate fertilizers used in Argentina.

Sustainability of conventional agriculture is based upon a high input of agrochemicals, such as phosphate fertilizers. Conventional inorganic phosphorus fertilizers may cause an inadvertent addition of heavy metals, which are contained as impurities. Fertilizers commonly used in Argentina were analyzed to determine concentrations of chromium, cadmium, copper, zinc, nickel and lead. Rock phosphate contained the highest levels of cadmium and zinc, chromium was enhanced in diammonium phosphate and copper and lead were high in one superphosphate sample. Urea-phosphate contained the lowest levels of heavy metals. Concentrations of heavy metals varied considerably and the levels of Cd and Pb in some analyzed materials were significant relative to those naturally present in soils. Continuous fertilization of soils could increase the heavy metal contents exceeding natural abundances in soils, and transfer of these metals to the human food chain must not be overlooked.

Argentina↗

PubMed2005

Heavy metal interference with growth hormone signalling in trout hepatoma cells RTH-149.

We have studied the effects of heavy metals (Hg2+, Cu2+, Cd2+) on growth hormone (GH) activation of tyrosine kinase and Ca2+ signaling in the trout (Oncorhynchus mykiss) hepatoma cell line RTH-149. Molecular cloning techniques using primer designed on Oncorhynchus spp. growth hormone receptor (GHR) genes allowed to isolate a highly homologous cDNA fragment from RTH-149 mRNA. Thereafter, cells were analysed by Western blotting or, alternatively, with Ca2+ imaging using fura-2/AM. Exposure of cells to ovine GH alone produced a stimulation of the JAK2/STAT5 pathway and intracellular free Ca2+ variations similar to what has been observed in mammalian models. Cell pre-exposure to Cu2+, Hg2+ or Cd2+ affected cell response to GH by enhancing (Cu2+) or inhibiting (Cd2+) the phosphorylation of JAK2 and STAT5. Heavy metals induced the activation of the MAP kinase p38, and pre-exposure to Hg2+ or Cu2+ followed by GH enhanced the effect of metal alone. Image analysis of fura2-loaded cells indicated that pre-treatment with Hg2+ prior to GH produced a considerable increase of the [Ca2+]i variation produced by either element, while using Cu2+ or Cd2+ the result was similar but much weaker. Data suggest that heavy metals interfere with GH as follows: Hg2+ is nearly ineffective on JAK/STAT and strongly synergistic on Ca2+ signaling; Cu2+ is activatory on JAK/STAT and slightly activatory on Ca2+; Cd2+ is strongly inhibitory on JAK/STAT and slightly activatory on Ca2+; heavy metals could partially activate STAT via p38 independently from GH interaction.

Amino Acid Sequence↗

PubMed1982

Constraints in cropping heavy-metal contaminated fluvial sediments.

Growth and heavy-metal uptake of various food crops and grass cultivated on harbour dredge spoils were studied, and health aspects in consuming the marketable products were discussed. Vegetables (potato, carrot, radish, endive, lettuce) and grass (English ryegrass) performed well on dredge spoils, but small grains (wheat, barley) were affected by manganese deficiency. As compared with crops grown on uncontaminated reference soils, there was a net accumulation of As and heavy metals, especially so Cd, Zn and Cu, and a reduced uptake of Mn. Mainly because of the elevated Cd concentrations of the edible parts, exceeding the guideline of 0.1 mg/kg in fresh matter, the harbour dredge spoils investigated are considered unfit for the production of food crops, but may be used as grassland for dairy cattle. Highest Cd concentrations were attained in leafy vegetables and wheat (grain) and lowest in potato (tuber).

Edible Grain↗

PubMed2006

Leachability of heavy metals and arsenic from slags of metal extraction industry at Angleur (eastern Belgium).

At Angleur (eastern Belgium), a 53,000 m3 dump site, related to former Zn extraction, contains high concentrations of heavy metals and arsenic associated with minerals such as arsenopyrite (FeAsS), franklinite (ZnFe2O4) and willemite (Zn2SiO4). Eight representative samples were investigated by means of a modified availability test, which pointed towards a considerable availability of Cd, Pb and Zn. In addition a detailed analysis of leaching behaviour as a function of pH was performed by means of a pH(stat) leaching test. The results of this test were supported by modelling predictions with MINTEQA2. pH(stat) titration results also allowed determination of the acid neutralising capacity, making it possible to predict heavy metal release upon acidification, assuming a worst-case scenario. On a short- to medium-long term (+/-100 years) a release of 900 mg/kg Zn has to be expected upon assumed natural acidification. However, a leaching test performed at the natural pH (i.e. pH 8 for the sample studied) indicates that heavy metal release is very limited and far below the European limit values for slag material on dumps category 1. Therefore, despite the elevated total heavy metal and As concentrations on the site, leaching is relatively low under present environmental conditions. Moreover, the slag material has a rather elevated pH (6.5-8) and no acid mine drainage is produced. Glass phases seem very important in controlling heavy metal mobility since potential reactive minerals that are locked up in a silicate matrix are protected against leaching.

Arsenic↗

PubMed2004

Phytoextraction of heavy metals by canola (Brassica napus) and radish (Raphanus sativus) grown on multicontaminated soil.

Phytoextraction can provide an effective in situ technique for removing heavy metals from polluted soils. The experiment reported in this paper was undertaken to study the basic potential of phytoextraction of Brassica napus (canola) and Raphanus sativus (radish) grown on a multi-metal contaminated soil in the framework of a pot-experiment. Chlorophyll contents and gas exchanges were measured during the experiment; the heavy metal phytoextraction efficiency of canola and radish were also determined and the phytoextraction coefficient for each metal calculated. Data indicated that both species are moderately tolerant to heavy metals and that radish is more so than canola. These species showed relatively low phytoremediation potential of multicontaminated soils. They could possibly be used with success in marginally polluted soils where their growth would not be impaired and the extraction of heavy metals could be maintained at satisfying levels.

Brassica napus↗

PubMed1998

Identification of heavy metal induced changes in the expression patterns of the translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus1.

Heavy metal contaminated soils are assessed for specific human health and ecological risk by governmental regulatory agencies utilizing the abundant soil invertebrate, the earthworm, in a biomonitoring process. Fingerprinting the molecular genetic responses resulting from heavy metal exposure facilitates the identification of biomarkers for assessing the impact of such pollution on individual organisms. This paper reports the identification of a novel translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus. In addition to the standard molecular biological technique of differential Southern blotting, a fully quantitative approach (fluorescent microvolume PCR) was performed to assess the specific expression profiles of TCTP in earthworms exposed to different heavy metal regimes. After normalizing with actin as an invariant control, the results showed that TCTP was upregulated by at least a factor of 4 in the population originating from a Pb/Zn/Cd polluted mine, compared to an unpolluted control population. An even more pronounced increase was identified in earthworms native to a Cu polluted mine, where TCTP increased 335-fold. TCTP copies in earthworms exposed to artificial soil with a single stressor (Cd) were 14 times higher than in the appropriate control earthworms (maintained on artificial soil without Cd). The data presented are novel in two ways: first, they provide evidence for an upregulation that is induced by heavy metals (especially copper); second, they show that TCTP can also be under transcriptional control, therefore upregulation is not limited to translational modifications as TCTP's nomenclature suggests.

Amino Acid Sequence↗

PubMed1999

Capsella bursa-pastoris (L.) Medic. as a biomonitor of heavy metals.

Capsella bursa-pastoris (L.) Medic. (shepherd's purse) has been tested as a possible biomonitor of heavy metals in the city of Bradford, UK and compared with Poa annua L. (annual meadow-grass), a species with a similar ecology that had previously been studied for biomonitoring potential. Forty-two sites (urban roadside, urban, urban park, suburban and rural) in and around Bradford were investigated. Concentrations of Pb, Cd, Zn and Cu have been determined in soils and in washed and unwashed plant leaves. Differences between the washed and unwashed samples, reflecting airborne and soil entry routes, respectively, varied according to the metal pollutant. There were significant relationships between the heavy metal concentration in samples of surface soil (depth 0-10 cm) and washed leaves, the concentrations being greater with progressively increased urbanisation of the sites. Capsella bursa-pastoris has been found to be a useful biomonitor of the four heavy metals studied, and it may be a particularly useful species since it could monitor short-term changes in pollution in urban areas.

Cadmium↗

PubMed1993

Resistance to heavy metals by some Nigerian yeast strains.

The heavy metal resistance of yeasts isolated from sugary substrates such as orange, palm wine and pineapple and identified as Saccharomyces carlsbergensis and S. cerevisiae was studied. The yeast isolates were tested against different concentrations of cadmium, copper, manganese, silver and zinc salts ranging from 1 to 20 mmol/L. Local yeasts showed resistance to 3-15 mmol/L cadmium, 18-20 copper, 16-20 manganese, 1-9 silver and 16-19 for zinc. The significance of the results is discussed in relation to the effects of heavy metals on growth of microorganisms and selection of yeasts for the brewing industry in Nigeria.

Cadmium↗

PubMed2005

Comparative study on the accumulation of heavy metals in different organs of tench (Tinca tinca L. 1758) and plerocercoids of its endoparasite Ligula intestinalis.

Concentrations of heavy metals (Cu, Fe, Zn, Mn, Cr, Pb and Cd) in some organs of tench and tissues of its parasite found in Kovada Lake (Turkey) were analyzed using atomic absorption spectrophotometry and subsequently compared with the data from sediments and water. Only Cu, Fe, Zn and Mn were detected in water, sediment, plerocercoids of Ligula intestinalis and fish samples, while levels of Cr, Pb and Cd were below the detection limits. Four elements were found at higher concentrations in the plerocercoid than in different fish tissues (muscle, liver and gill), being 1.6-37.4 times higher than that measured in muscle, liver and gill. Significant positive (for Cu) and negative (for Fe, Zn and Mn) correlations were found between the quantity of heavy metals in water and tissues of L. intestinalis plerocercoids while there were significant positive (for Cu and Zn) and negative (for Fe and Mn) correlations between the quantity of heavy metals in bottom sediment and tissues of L. intestinalis plerocercoids. Cestodes were found suitable to reflect the amount heavy metals in sediments, providing more reliable information about the actual pollution of the reservoirs.

Animals↗

PubMed1992

Influence of demetallization of hydrogenated sunflower oil on changes in the forms of heavy metals and their pro-oxidative effects.

The effect of removing heavy metals from hydrogenated sunflower oil using a method based on changes in the contents of the various forms of the heavy metals copper, iron, zinc and nickel and their respective pro-oxidative effects was studied. A high degree of removal of dissociated and bounded ions was observed for hydrogenated oil, while there was no change in the contents of the co-ordination form. The pro-oxidative effect of the dissociated ions and of the bound metal ions in hydrogenated oil decreased nine-fold and seven-fold, respectively, compared with that of the non-hydrogenated oil, as a result of which the oxidation stability of hydrogenated oil increased two-fold. Comparative studies confirmed as appropriate the use of wash waters and auxiliary solutions that do not contain heavy metals for the processing of the hydrogenate after the classical technology.

Copper↗

PubMed2006

Degradation of organic matter from black shales and charcoal by the wood-rotting fungus Schizophyllum commune and release of DOC and heavy metals in the aqueous phase.

We investigated the degradation of refractory organic matter (OM) by the basidiomycete fungus Schizophyllum commune to understand the release of dissolved organic compounds, heavy metals and sulfur. The investigated OM consisted of: charcoal, the short time end product of high temperature wood alteration in the absence of oxygen and composed mainly of pure OM; and black shales composed of clay minerals, quartz, sulfides and OM formed geogenically in an abiotic long-term process. In both cases, the OM fraction contains mainly polyaromatic hydrocarbons. We investigated the degradation of these fractions by a wood-rotting basidiomycete, which is able to produce exoenzymes like peroxidases and laccases. These enzymes can perform radical reactions to oxidize OM (like lignin) and therefore hypothetically are able to degrade OM from charcoal and/or low grade metamorphic black shales. Release of new components into dissolved organic carbon (DOC) could be detected in both cases. The attack on OM in the case of black shales coincided with the release of the heavy metals Fe, Mn and Ni. By following sulfur concentrations throughout the experiment, it was shown that heavy metal release is not due to pyrite oxidation. Ground black shale and charcoal samples were inoculated with S. commune in a diluted minimal medium containing aspartic acid and glucose. The aqueous and solid phases were sampled after 1, 7, 28 and 84 days. DOC was measured as non purgeable carbon and characterized by size exclusion chromatography and UV detection. Carbon concentrations of the solid phase were determined by element analyses. After initial decrease of the DOC concentrations due to the degradation of the carbon source provided with the medium, DOC increased up to 80 mg/l after 84 days. Carbon decreased in the solid fraction confirming that this carbon was released as DOC by the fungus. The newly generated DOC formed larger agglomerations than the DOC of the growth medium. The investigation proved that the degradation of persistent carbon sources, such as charcoal and black shale, is accelerated by fungal activity. Consequently, the associated release of heavy metals is also accelerated by the fungus. Main products of the biological degradation processes were organic heavy metal complexes which can enter the environment.

Biodegradation, Environmental↗

PubMed2003

Effects of heavy metal exposure on aggressive behavior in a small territorial songbird.

Several studies have shown that elevated levels of certain heavy metals may affect the behavior of birds and mammals. However, most of these studies were carried out under controlled laboratory conditions; results from free-living populations are scarce. In this study we examined the possible effects of exposure to high heavy metal concentrations on the aggressive behavior of resident great tit (Parus major) males by means of simulated territorial intrusion experiments during the egg-laying and incubation period at a highly polluted and a reference site. We also examined the effects of heavy metal exposure on the breeding performance of the tested couples, and we examined the plasma testosterone concentrations of great tit males in both study sites. We found no significant differences in the aggressive behavior between great tits at the polluted and the reference site during the egg-laying period. During the incubation period, responding male great tits at the polluted site performed significantly more aggressive flights around the decoy than did males at the reference site. During this period, there was also a tendency that more responding males were out of sight of the observer for some time during the experiment at the reference site than at the polluted site and this also for a longer period of time. Other behavioral parameters did not differ significantly between the two sites. Although plasma testosterone levels were higher at the polluted site, they did not differ significantly between the two sites. The tested couples at the polluted site interrupted their laying sequence significantly more and hatching success was significantly reduced compared to the tested birds at the reference site. We found no significant difference in clutch size, the length of the laying interruptions, fledging success, and fledgling age between the two sites. Although our results showed only minor alterations in the territorial aggressive behavior of male great tits exposed to heavy metal pollution, these small changes may have an important influence on the breeding and survival of these birds.

Aggression↗