High Toxic Metal Research Articles

Comment on "Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil"

Based on analysis of the reassociation kinetics of bacterial DNA in soil, Gans et al. (Reports, 26 August 2005, p. 1387) claimed that millions of microbe species existed in 10 grams of pristine soil and that 99.9% of the diversity was lost as a result of toxic metals. We show that the data do not support these startling conclusions unambiguously.

Response to Comment by Volkov et al . on "Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil"

Volkov et al . claim that significant conclusions about the total number of species ( S ) cannot be made because different abundance models cannot be distinguished and the sensitivity of the chi-square measure to changes in estimates of S is low. We point out that currently available data do not support these claims.

Comment on "Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil"

Gans et al. (Reports, 26 August 2005, p. 1387) provided an estimate of soil bacterial species richness two orders of magnitude greater than previously reported values. Using a re-derived mathematical model, we reanalyzed the data and found that the statistical error exceeds the estimate by a factor of 26. We also note two potential sources of error in the experimental data collection and measurement procedures.

High Toxic Metal Levels in Scalp Hair of Infants and Children

High Toxic Metal Levels in Scalp Hair of Infants and Children

Evaluación de la reactividad de sulfuros de hierro y residuos mineros: una metodología basada en la aplicación de la voltamperometría cíclica

The mining industry around the world produces an important amount of wastes, which by their high toxic metal and iron sulfide content present a serious environmental problem. Iron sulfide oxidation under weathering conditions provokes the main environmental problem of the mining industry, the generation of Acid Rock Drainage (ARD). Up to now the prediction methodologies do not allow the study of important factors that influence the generation of ARD, producing in some cases erroneous or uncertain conclusions. This paper shows the utilization of cyclic voltammetry using carbon paste electrodes (CPE-Mineral) as an alternative tool in the study of the oxidation capacity of iron sulfides and mining wastes. This electrochemical technique constitutes a novel methodology to establish and understand the factors involved during generation of ARD. Results of several studies including selected sulfide samples and sulfide mining wastes have been described in order to show the capacity of this methodology as a complementary tool in the prediction of the generation of ARD.

Copper tolerance of the thermoacidophilic archaeon Sulfolobus metallicus: possible role of polyphosphate metabolism

It has been postulated that inorganic polyphosphate (polyP) and transport of metal-phosphate complexes could participate in heavy metal tolerance in some bacteria. To study if such a system exists in archaea, the presence of polyP was determined by the electron energy loss spectroscopy (EELS) procedure and quantified by using specific enzymic methods in Sulfolobus acidocaldarius, Sulfolobus metallicus and Sulfolobus solfataricus. All three micro-organisms synthesized polyP during growth, but only S. metallicus greatly accumulated polyP granules. The differences in the capacity to accumulate polyP between these archaea may reflect adaptive responses to their natural environment. Thus, S. metallicus could grow in and tolerate up to 200 mM copper sulfate, with a concomitant decrease in its polyP levels with increasing copper concentrations. On the other hand, S. solfataricus could not grow in or tolerate more than 1-5 mM copper sulfate, most likely due to its low levels of polyP. Shifting S. metallicus cells to copper sulfate concentrations up to 100 mM led to a rapid increase in their exopolyphosphatase (PPX) activity which was concomitant in time with a decrease in their polyP levels and a stimulation of phosphate efflux. Furthermore, copper in the range of 10 microM greatly stimulated PPX activity in cell-free extracts from S. metallicus. The results strongly suggest that a metal tolerance mechanism mediated through polyP is functional in members of the genus Sulfolobus. This ability to accumulate and hydrolyse polyP may play an important role not only in the survival of these micro-organisms in sulfidic mineral environments containing high toxic metals concentrations, but also in their applications in biomining.

Mineral formation in an acid pit lake from a high-sulfidation ore deposit: Kirki, NE Greece

Open pit mining of base-metals from the high-sulfidation epithermal type deposit of Kirki (Thrace, NE Greece) resulted in the formation of an acid pit lake by infilling of the open cast by rain and draining waters after mine closure. The high toxic metals content of the ore, the limited buffering capacity of host rocks and the direct exposure of the ore zone to weathering result in an intense release of metals into the pit lake. The acidic and oxidative pit lake waters show high concentrations of trace metals. A mineral precipitate, covering the floor of the pit lake, comprises secondary anglesite, several species of the jarosite-group, rozenite, melanterite, wroewolfeite, gypsum, bukovskyite, beaverite, scorodite and minor goethite. The mineral precipitate presents a significant heavy metal content indicating effective removal of metals from the acid waters. Compared to other pit lakes in high-sulfidation type deposits it has a higher metal load, consistent with the mineralogy and grade of ore in pit walls.

Computational Improvements Reveal Great Bacterial Diversity and High Metal Toxicity in Soil

The complexity of soil bacterial communities has thus far confounded effective measurement. However, with improved analytical methods, we show that the abundance distribution and total diversity can be deciphered. Reanalysis of reassociation kinetics for bacterial community DNA from pristine and metal-polluted soils showed that a power law best described the abundance distributions. More than one million distinct genomes occurred in the pristine soil, exceeding previous estimates by two orders of magnitude. Metal pollution reduced diversity more than 99.9%, revealing the highly toxic effect of metal contamination, especially for rare taxa.

Source and health implications of high toxic metal concentrations in illicit tobacco products.

A significant flux of heavy metals, among other toxins, reaches the lungs through smoking. Consequently, contaminated soil is usually avoided for tobacco cultivation. Here we compare the heavy metal concentrations in tobacco from a sample of 47 counterfeit products, representative of the substantial market for these products in the U.K., with their genuine equivalents and find significantly higher concentrations of heavy metals in the counterfeits. Trace element patterns suggest that over-application of fertilizers (phosphate and/or nitrate) is the most likely cause. Nitrogen isotopes showed no significant enrichment in 15N (delta15N range from +1.1 to +4.6% in counterfeits and from +2.5 to +3.3% in genuine tobaccos) as might be expected from a sewage or manure source of nitrate, and a mineral phosphate source is considered the more likely source of metals. Stable carbon isotopes in the same tobaccos have a wide range (delta13C -18.3 to -26.4%), indicating the influence of multiple controls during cultivation and possibly post-harvesting. A review of the health effects of heavy metal transfer from tobacco via smoke to the lungs indicates that habitual smokers of counterfeits may be risking additional harm from high levels of cadmium and possibly other metals.

In Situ Processing of Ferroelectric Materials from Lead Waste Streams by Injection of Gas Phase Titanium Precursors: Laser Induced Fluorescence and X-ray Diffraction Measurements

Several industrial process exhaust gas streams contain enriched toxic metal species such as lead and cadmium. Gas phase sorbent precursor techniques have been developed to effectively capture these toxic metal species. This methodology is further extended to not only capture the toxic metal species, but produce useful materials. Injection of gas phase titanium precursors to reactively capture the lead species is proposed for the processing of ferroelectric lead titanatematerials in enriched lead exhaust streams. Conditions to produce lead titanate in high temperature systems are established. Diagnostic techniques such as X-ray diffraction and laser induced fluorescence spectroscopy are used to determine optimal conditions to not only capture the lead species but also produce perovskite structured lead titanate. Such approaches can be extended to real combustor exhaust streams with high toxic metal concentrations such as lead smelters for effective environmental control and production of novel materials.

Effects of Acidification on Bryophyte Communities in West Virginia Mountain Streams

AbstractBryophytes (mosses and liverworts) are often more responsive to water chemistry changes than are vascular plants. In this study, the relationships of bryophyte communities to stream pH and water chemistry were studied, using six streams on or near the Fernow Experimental Forest in Tucker County, West Virginia. Streams were surveyed with line transects using stratified random sampling. Bryophyte communities, based on species composition and structure, fell into three groups, corresponding to basic, moderately acidic, and very acidic stream water. For streams with sandstone beds, species diversity declined with decreasing pH, and no bryophytes were present at pH 3.15. The dominant species in moderately acidic to highly acidic streams is Scapania undulata, a species found to have exceptional tolerance to high acidity and toxic metal levels in Europe and Japan. Scapania undulata was transplanted from a stream with a pH of 5.97 to one with a pH of 3.15. In 3 mo, ultrastructural damage was observed. Acidity (pH) probably was not the only factor involved in controlling species composition and cell ultrastructure, since the two most acidic streams are subject to acid mine drainage and have very high concentrations of dissolved solids, particularly SO4 and Al. Other trace metals commonly associated with acidic surface waters also may have contributed to the differences in species composition.

The influence of cadmium and zinc on the cell size distribution of the alga Chlorella vulgaris

The mean cell size and the size distribution of a population of microbial cells are known to be influenced by the growth phase of the culture and the environment in which the cells are growing. Various studies have suggested that the presence of trace metals may seriously affect cellular functions (such as cell division and volume regulation). The work reported here is an investigation of the effect of cadmium and zinc ions (both singly and together), at various concentrations, on the mean cell size and the size distribution of the alga Chlorella vulgaris. It was found that algal cultures exposed to low levels of cadmium and zinc singly (from 1 × 10 −5 to 8 × 10 −5 M) generally showed the same response as the control, except that slightly larger cells resulted at the higher end of this range of concentration. While the presence of the metal ions singly at 2 × 10 −5 M did not significantly affect the mean cell size and the size distribution of the culture, equimolar concentrations of cadmium and zinc at this concentration resulted in size distribution profiles that were markedly different from the control. However, the giant aberrant cells reported by some authors to have arisen from high metal toxicity were clearly absent. A probit analysis of the size distribution of the cultures also showed that the size data from all the experiments could best be described as a log-normal distribution rather than as a normal distribution.

Characterization of arsenopyrite oxidizing Thiobacillus. Tolerance to arsenite, arsenate, ferrous and ferric iron

Two strains of Thiobacillus, T. ferrooxidans and T. thiooxidans, have been isolated from a bacterial inoculum cultivated during a one-year period in a 1001 continuous laboratory pilot for treatment of an arsenopyrite/pyrite concentrate. The optimum pH for the growth of both strains has been found to be between 1.7 and 2.5. Because of the high metal toxicity in bioleach pulps, the tolerance of T. ferrooxidans and T. thiooxidans with respect to iron and arsenic has been studied. The growth of both strains is inhibited with 10 g/l of ferric ion, 5 g/l of arsenite and 40 g/l of arsenate. 20 g/l of ferrous iron is toxic to T. ferrooxidans but 30 g/l is necessary to impede the growth of T. thiooxidans.