Alkylation of metals and the activity of metal‐alkyls†

The biochemical basis for resistance to metal ion toxicity is emerging though it is complicated by the different resistance mechanisms. Several strategies for resistance to toxic metal ions have been identified:

1. The development of energy driven efflux pumps which keep toxic element levels low in the interior of the cell. Such mechanisms have been described for Cd(II) and As(V).

2. Oxidation (e.g. AsO^2‐ to AsO₄ ^3‐) or reduction (e.g. Hg²⁺ to Hg⁰) can enzymatically and intracellularly convert a more toxic form of an element to a less toxic form.

3. The biosynthesis of intracellular polymers which serve as traps for the removal of metal ions from solution such as traps have been described for cadmium, calcium, nickel and copper.

4. The binding of metal ions to cell surfaces.

5. The precipitation of insoluble metal complexes (e.g. metal sulfides and metal oxides) at cell surfaces.

6. Biomethylation and transport through cell‐membranes by diffusion controlled processes.

In this short review I shall discuss the implications of biomethylation as a detoxification mechanism for microorganisms as well as for certain higher organisms.     

Aerogels and metal–organic frameworks for environmental remediation and energy production

Environmental pollution and climate change are requiring new methods to clean pollutants and produce sustainable energy. Aerogels and metal organic frameworks are emerging as advanced porous materials with higher functionality, high surface area, high porosity and flexible chemistry. Aerogels are dried gels prepared using the sol–gel procedure, whereas metal organic frameworks are networks of organic ligands and metal ions connected by coordination bonds. Applications of aerogels include the removal of heavy metals, CO₂ capture and reduction, photodegradation of pollutants, air cleanup and water splitting. This article reviews the synthesis and types of aerogels and metal organic frameworks, and the application to pollutant removal, energy production including hydrogen, methane reforming, CO₂ conversion and NOx removal.     

Genetic toxicology of metal compounds: An examination of appropriate cellular models †

Bacterial systems have not had success predicting metal carcinogenicity. Hypotheses explaining this failure are examined. Using a broad genetic endpoint, λ prophage induction, under sub‐toxic growing conditions, genotoxicity is seen for compounds of chromium, manganese, lead, molybdenum and tungsten. Copper, manganese, arsenic and molybdenum compounds enhanced UV mutagenesis in E. coli WP2.

The toxicity of metal compounds to cultured mammalian cells correlates well with rat oral LD₅₀ values. Whereas insolubility can present problems in bacterial studies, concentrations of metal compounds toxic to mammalian cells can be determined even in the presence of precipitate, and sometimes [Pb(NO₃)₂, BaCl₂ and BeCl₂] occurs only in its presence. PbS and MnS, which are insoluble, are much more toxic than the more soluble compounds Pb(NO₃)₂ and MnCl₂. These results demonstrate the importance of cellular phagocytosis of insoluble metal compounds as a factor in studying the toxicity and genotoxicity of metal compounds.     

Continuous monitoring of ambient polycyclic aromatic hydrocarbons near open‐air burning of metal scraps

Airborne concentrations of PAH in the vicinity of the source region with open‐air burning of metal scraps were measured between February, 1992 and November, 1993. The activity of open‐air burning decreased significantly since 1993 due to prohibition regulation. Both gaseous phase and particle‐bound PAH were measured at five sampling sites, which included one reference sampling site far away from the source region. Both values of gaseous and particle‐bound PAH concentrations, which were measured in the vicinity of source region, decreased clearly during the two years monitoring period. It shows that the uncontrolled open‐air burning of metal scraps was a significant emission source of airborne PAH in the study area. The profiles of various species of PAH were also compared. A large decrease in benzo(a)pyrene was observed in the source region.     

Background metal levels determination in bivalves – quality assessment of the European Water Framework Directive

Background levels of metals (Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn) in biomonitors (Mytilus galloprovincialis mussels and Crassostrea gigas oysters), in estuarine waters within the Basque Country (south-east Bay of Biscay) are estimated using non-parametric statistical tools and data are presented graphically, with the aim of being used in assessing the ecological status, within the European Water Framework Directive (WFD). The basis for this study was the statistical analysis of data compiled from monitoring programmes undertaken along the Basque coast, between 1990 and 2008. For this analysis, a heuristic method was adapted and used. Results showed different metal background ranges throughout the year for both mussels and oysters. Values corresponding to the upper limit of the background range (i.e. value of the upper whisker of the box-plot) are proposed as the ‘high/good’ status boundary, according to the WFD.     

Heavy metal analysis in fish‐kill cases in rivers in Guipuzcoa (Spain)∗

Some fish‐kills in Basque rivers were studied by gill tissue analysis: Samples were wet digested and the solution was analyzed by atomic absorption spectroscopy. In three cases, the cause was linked to the effluents of an aluminium anodizing factory, cyanide caused one kill and copper wastes were related with another. Three cases were attributed to natural reasons and one of the kills was of unknown origin.     

Heavy metal characteristics in Ko?ani Field plant system (Republic of Macedonia)

Heavy metal contamination of soils is widespread and induces a long-term risk to ecosystem health. This research focuses on the heavy metal contamination, transfer values and risk assessment in the Ko?ani Field plant system (Republic of Macedonia). To identify the heavy metal concentrations in Ko?ani crops (rice and maize), the geochemical analysis was performed by inductive coupled plasma mass spectrometer and thereupon the transfer factor (TF) and estimated daily intake amount values were calculated. The highest As, Cd, Mo, Pb and Zn values were determined in the rice samples grown in the paddy fields near the Zletovska River. The highest Pb and Mo concentrations measured in the maize samples were from the maize fields near the Zletovska River and Ciflik city. High TF values for Mo, Zn, Cd and Cu revealed a strong accumulation of Mo, Zn and Cd by rice and Mo and Zn by maize crops. The results of the estimated daily intake showed that the regular consumption of rice and maize crops containing the highest Cd, Mo, Pb and Zn concentrations could pose a serious threat to human health, because the daily intake of Cd, Mo, Pb and Zn for crops grown in the fields around the Zletovska River exceeded the recommended provisional tolerable daily intake values. Taking into account the results, the area around Zletovska River is considered as the most anthropogenically impacted part of Ko?ani Field.     

Toxicity models of metal mixtures established on the basis of “additivity” and “interactions”

Observed effects of metal mixtures on animals and plants often differ from the estimates, which are commonly calculated by adding up the biological responses of individual metals. This difference from additivity is commonly referred to as being a consequence of specific interactions between metals. The science of how to quantify metal interactions and whether to include them in risk assessment models is in its infancy. This review summarizes the existing predictive tools for evaluating the combined toxicity of metals present in mixtures and indicates the advantages and disadvantages of each method. We intend to provide eco-toxicologists with background information on how to make good use of the tools and how to advance the methods for assessing toxicity of metal mixtures. It is concluded that statistically significant deviations from additivity are not necessarily biologically relevant. Incorporation of interactions between metals in a model does not on forehand mean that the model is more accurate than a model developed based on additivity only. It is recommended to first use a relatively simple method for effect prediction of uninvestigated metal mixtures. To improve the reliability of toxicity modeling for metal mixtures, further efforts should focus on balancing the relationship between the significance of statistics and the biological meaning, and unraveling the toxicity mechanisms of metals and their mixtures.

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Fate of organo‐heavy metal complexes of sludges from domestic wastes in soils: A simplified modelization

Simplified models provided information on the binding ability of organic acids with trace elements, the distribution of the formed organo‐heavy metal complexes at different pH, and the biological stability (biodegradation ability) of these complexes.     

Endeavors on the development of efficient and sustainable supported metal catalysts for chemical synthesis on solid–liquid interfaces

Supported metal catalysts, particularly for precious metals, have gained increasing attention in green synthetic chemistry. They can make metal-catalyzed organic synthesis more sustainable and economical due to easy separation of product with less metal residue, as well as reusability of the high-cost catalysts. Although great effort has been spent, the precise catalytic mechanism of supported metal-catalyzed reactions has not been clearly elucidated and the development of efficient and stable r...     

Variations in heavy metal contamination of stream water and groundwater affected by an abandoned lead–zinc mine in Korea

This study evaluated variations in heavy metal contamination of stream waters and groundwaters affected by an abandoned lead–zinc mine, where a rockfill dam for water storage will be built 11 km downstream. For these purposes, a total of 10 rounds of stream and groundwater samplings and subsequent chemical analyses were performed during 2002–2003. Results of an exploratory investigation of stream waters in 2000 indicated substantial contamination with heavy metals including zinc (Zn), iron (Fe) and arsenic (As) for at least 6 km downstream from the mine. Stream waters near the mine showed metal contamination as high as arsenic (As) 8,923 μg L⁻¹, copper (Cu) 616 μg L⁻¹, cadmium (Cd) 223 μg L⁻¹ and lead (Pb) 10,590 μg L⁻¹, which greatly exceeded the Korean stream water guidelines. Remediation focused on the mine tailing piles largely improved the stream water qualities. However, there have still been quality problems for the waters containing relatively high concentrations of As (6–174 μg L⁻¹), Cd (1–46 μg L⁻¹) and Pb (2–26 μg L⁻¹). Rainfall infiltration into the mine tailing piles resulted in an increase of heavy metals in the stream waters due to direct discharge of waste effluent, while dilution of the contaminated stream waters improved the water quality due to mixing with metal free rain waters. Levels of As, Cu and chromium (Cr) largely decreased after heavy rain but that of Pb was rather elevated. The stream waters were characterized by high concentrations of calcium (Ca) and sulfate (SO₄), which were derived from dissolution and leaching of carbonate and sulfide minerals. It was observed that the proportions of Ca and SO₄ increased while those of bicarbonate (HCO₃) and sodium and potassium (Na+K) decreased after a light rainfall event. Most interestingly, the reverse was generally detected for the groundwaters. The zinc, being the metal mined, was the most dominant heavy metal in the groundwaters (1758–10,550 μg L⁻¹) near the mine, which far exceeded the Korean standard of 1000 μg L⁻¹ for drinking water. The decreases in the heavy metals contents in the groundwaters associated with reduced rainfall were quite different from the increases observed for the stream waters, which is not clearly understood at this time and warrants further investigation.     

Is the economic dimension inducing the other sustainability dimensions,or is it the reverse? Perceptions from the Portuguese metal industry

ABSTRACT

In organizational sustainability, the economic dimension is recognized as having a very important role. However, the discussion regarding whether it is exclusively the economic dimension that has the power to induce the other sustainability dimensions is far from agreement. The purpose of the present paper is to analyze the perceptions regarding the existence of mutual influences between the economic dimension of sustainability and the other sustainability dimensions – environmental, social and cultural – in a relevant Portuguese economic sector: the metal industry. The analysis and statistical tests performed with the 211 collected answers led to the conclusion that the influence exerted by the economic dimension on the other sustainability dimensions is perceived as dominant, both in present and future perspectives. The results also show the perception that the economic dimension is equally influenced by the environmental and social dimensions, and in a less extent, by the cultural dimension, and that all these mutual influences are perceived to increase in the future. The existence of organizational management systems has a positive effect on the perceptions regarding the existence of mutual influences between sustainability dimensions, but only for those companies with more than one certified management system. These results confirm that organizational management systems are connected to higher degrees of awareness regarding sustainability issues. Given that the great majority of the sampled industries are SMEs, the results obtained in this research demonstrate that the existence of mutual influences between sustainability dimensions is recognized even in small-sized industries.     

Spatial distribution and risk assessment of soil heavy metal contamination along roadsides of the northwestern Sichuan Plateau,China北大核心CSCD

Traffic activities in roadways are the major source of heavy metal contamination on the northwestern Sichuan Plateau, China. To characterize the spatial pattern of heavy metal distribution, we collected soil samples and measured the concentrations of five heavy metals (Cd, Cu, Ni, Pb, and Zn) from nine sites in Hongyuan County, Sichuan Province, including three transects that reflected typical gradients of traffic density. Each transect consisted of three levels of traffic density sites. We calculated single pollution index, Nemerow multi-factor index, and potential ecological risk index, to assess the ecological risk of the heavy metal contamination. Results showed that the soils were contaminated by Cd and Zn, with higher concentrations than that of the natural soil background values in all sampling sites. Moreover, Cd and Zn concentrations increased with increasing traffic density, suggesting that traffic activities were potentially responsible for the metal contaminations. The single pollution index indicated that the study sites were heavily contaminated by Cd and slightly polluted by Ni, Pb, and Zn, and the Nemerow multi-factor and potential ecological risk indexes indicated moderate potential ecological risks at the study sites. Specifically, the sites with high traffic density were moderately contaminated and the sites with low traffic density were mildly contaminated. In general, Cd and Zn were highly accumulated in soils of the study region; therefore focus should be on the high ecological hazard associated with soil heavy metal contamination, even in undeveloped regions. © 2018 Science Press. All rights reserved.     

Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

Quaternary phosphonium cationic ionic liquid/porous metal–organic framework as an efficient catalytic system for cycloaddition of carbon dioxide into cyclic carbonates

Environmental Chemistry Letters - Global warming and climate change concerns are triggering worldwide interest for sustainable transformation of CO2 into useful chemicals. Here, a new and efficient...     

Geochemical fractionation and spectroscopic fingerprinting for evaluation of the environmental transformation of potentially toxic metal(oid)s in surface–subsurface soils

Environmental Geochemistry and Health - The contamination of soil by toxic metal(oid)s has emerged as a major concern worldwide, particularly in developing countries. A metals behavior in the soil...     

Does the metal content in soil around a pregnant woman’s home increase the risk of low birth weight for her infant?

Low birth weight (LBW) is associated with a number of maternal environmental exposures during pregnancy. This study explored the association between soil metal concentrations around the home where the mother lived during pregnancy and the outcome of LBW. We used a retrospective cohort of 9,920 mother–child pairs who were insured by Medicaid during pregnancy and lived in ten residential areas, where we conducted soil sampling. We used a grid that overlaid the residential areas and collected soil samples at the grid intersections. The soil was analyzed for the concentration of eight metals [arsenic (As), barium (Ba), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), and mercury (Hg)], and we then used Bayesian Kriging to estimate the concentration at the actual maternal addresses, since we had the GIS coordinates of the homes. We used generalized additive modeling, because the metal concentrations had nonlinear associations with LBW, to develop the best fitting multivariable model for estimating the risk of LBW. The final model showed significant associations for female infants, maternal smoking during pregnancy, non-white mothers, Cu, and As with LBW. The As variable was nonlinear in relation to LBW, and the association between higher concentrations of As with LBW was strong (p = 0.002). We identified a statistically significant association between soil concentrations of arsenic around the home of pregnant women and an increased risk of LBW for her infant.     

Observations on metal trends in soil and vegetation samples collected in the vicinity of a hazardous waste incinerator under construction (1996–1998)

The temporal variation in metal concentrations in soil and vegetation samples collected in an area of Catalonia (Spain), which will be under the potential influence of a new hazardous waste incinerator was determined. In 1996 and again in 1998, As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl and V were measured in 40 soil and 40 herbage samples collected at 250–4000 m from the facility at the same sampling points. Data of both surveys and the percentages of variation are here presented for all metals. Results are shown according to the main wind directions in the area, as well as distances from the new facility. During the period 1996–1998, a general decrease was noted for most metals. Only the levels of Hg were significantly increased during this period. The present results will be useful for future surveys aimed to evaluate the environmental impact of metals derived from emissions of the new plant.     

Nanoconfinement engineering for enchanced adsorption of carbon materials,metal–organic frameworks,mesoporous silica,MXenes and porous organic polymers: a review

In material synthesis, nanoconfinement acts both as a physical reactor to tune the shape and size of nanomaterials, and as a chemical microenvironment for the nucleation and growth of nanoconfined substances, resulting in unique material properties. This nanoconfinement effect has been extensively applied to synthesize materials for hydrogen storage, catalysis and separation for environmental protection. Here, we review methods to construct nanoconfined space in carbon materials, metal–organic frameworks, mesoporous silica, porous organic polymers and MXenes, a class of two-dimensional inorganic compounds. We discuss nanoconfinement for enhanced adsorption with focus on covering size and dispersion, crystallization and stability, confined water and coordination.