This book demonstrates the rich and varied ways in which heavy metal music draws on the ancient Greek and Roman world. Contributors examine bands from across the globe, including: Blind Guardian ...(Germany), Therion (Sweden), Celtic Frost, Eluveitie (Switzerland), Ex Deo (Canada/Italy), Heimdall, Stormlord, Ade (Italy), Kawir (Greece), Theatre of Tragedy (Norway), Iron Maiden, Bal-Sagoth (UK), and Nile (US). These and other bands are shown to draw inspiration from Classical literature and mythology such as the Homeric Hymns, Vergil's Aeneid, and Caesar's Gallic Wars, historical figures from Rome and ancient Egypt, and even pagan and occult aspects of antiquity. These bands' engagements with Classical antiquity also speak to contemporary issues of nationalism, identity, sexuality, gender, and globalization. The contributors show how the genre of heavy metal brings its own perspectives to Classical reception, and demonstrate that this music-often dismissed as lowbrow-engages in sophisticated dialogue with ancient texts, myths, and historical figures. The authors reveal aspects of Classics' continued appeal while also arguing that the engagement with myth and history is a defining characteristic of heavy metal music, especially in countries that were once part of the Roman Empire.
Among heavy metal plants (the metallophytes), facultative species can live both in soils contaminated by an excess of heavy metals and in non-affected sites. In contrast, obligate metallophytes are ...restricted to polluted areas. Metallophytes offer a fascinating biology, due to the fact that species have developed different strategies to cope with the adverse conditions of heavy metal soils. The literature distinguishes between hyperaccumulating, accumulating, tolerant and excluding metallophytes, but the borderline between these categories is blurred. Due to the fact that heavy metal soils are dry, nutrient limited and are not uniform but have a patchy distribution in many instances, drought-tolerant or low nutrient demanding species are often regarded as metallophytes in the literature. In only a few cases, the concentrations of heavy metals in soils are so toxic that only a few specifically adapted plants, the genuine metallophytes, can cope with these adverse soil conditions.
Current molecular biological studies focus on the genetically amenable and hyperaccumulating Arabidopsis halleri and Noccaea (Thlaspi) caerulescens of the Brassicaceae. Armeria maritima ssp. halleri utilizes glands for the excretion of heavy metals and is, therefore, a heavy metal excluder. The two endemic zinc violets of Western Europe, Viola lutea ssp. calaminaria of the Aachen-Liège area and Viola lutea ssp. westfalica of the Pb-Cu-ditch of Blankenrode, Eastern Westphalia, as well as Viola tricolor ecotypes of Eastern Europe, keep their cells free of excess heavy metals by arbuscular mycorrhizal fungi which bind heavy metals. The Caryophyllaceae, Silene vulgaris f. humilis and Minuartia verna, apparently discard leaves when overloaded with heavy metals.
All Central European metallophytes have close relatives that grow in areas outside of heavy metal soils, mainly in the Alps, and have, therefore, been considered as relicts of the glacial epoch in the past. However, the current literature favours the idea that hyperaccumulation of heavy metals serves plants as deterrent against attack by feeding animals (termed elemental defense hypothesis). The capability to hyperaccumulate heavy metals in A. halleri and N. caerulescens is achieved by duplications and alterations of the cis-regulatory properties of genes coding for heavy metal transporting/excreting proteins. Several metallophytes have developed ecotypes with a varying content of such heavy metal transporters as an adaption to the specific toxicity of a heavy metal site.
Pollution by heavy metals (HM) represents a serious threat for both the environment and human health. Due to their elemental character, HM cannot be chemically degraded, and their detoxification in ...the environment mostly resides either in stabilization
or in their removal from the matrix, e.g., soil. For this purpose, phytoremediation, i.e., the application of plants for the restoration of a polluted environment, has been proposed as a promising green alternative to traditional physical and chemical methods. Among the phytoremediation techniques, phytoextraction refers to the removal of HM from the matrix through their uptake by a plant. It possesses considerable advantages over traditional techniques, especially due to its cost effectiveness, potential treatment of multiple HM simultaneously, no need for the excavation of contaminated soil, good acceptance by the public, the possibility of follow-up processing of the biomass produced, etc. In this review, we focused on three basic HM phytoextraction strategies that differ in the type of plant species being employed: natural hyperaccumulators, fast-growing plant species with high-biomass production and, potentially, plants genetically engineered toward a phenotype that favors efficient HM uptake and boosted HM tolerance. Considerable knowledge on the applicability of plants for HM phytoextraction has been gathered to date from both lab-scale studies performed under controlled model conditions and field trials using real environmental conditions. Based on this knowledge, many specific applications of plants for the remediation of HM-polluted soils have been proposed. Such studies often also include suggestions for the further processing of HM-contaminated biomass, therefore providing an added economical value. Based on the examples presented here, we recommend that intensive research be performed on the selection of appropriate plant taxa for various sets of conditions, environmental risk assessment, the fate of HM-enriched biomass, economical aspects of the process, etc.
▶ Hyperaccumulators concentrate heavy metals in leaves. ▶ Constitutive overexpressed genes are involved in heavy metal hyperaccumulation. ▶ Heavy metal hyperaccumulation can act as a defence ...mechanism from enemies. ▶ Hyperaccumulator traits may be exploited for phytoremediation and/or phytomining.
The term “hyperaccumulator” describes a number of plants that belong to distantly related families, but share the ability to grow on metalliferous soils and to accumulate extraordinarily high amounts of heavy metals in the aerial organs, far in excess of the levels found in the majority of species, without suffering phytotoxic effects. Three basic hallmarks distinguish hyperaccumulators from related non-hyperaccumulating taxa: a strongly enhanced rate of heavy metal uptake, a faster root-to-shoot translocation and a greater ability to detoxify and sequester heavy metals in leaves. An interesting breakthrough that has emerged from comparative physiological and molecular analyses of hyperaccumulators and related non-hyperaccumulators is that most key steps of hyperaccumulation rely on different regulation and expression of genes found in both kinds of plants. In particular, a determinant role in driving the uptake, translocation to leaves and, finally, sequestration in vacuoles or cell walls of great amounts of heavy metals, is played in hyperaccumulators by constitutive overexpression of genes encoding transmembrane transporters, such as members of ZIP, HMA, MATE, YSL and MTP families. Among the hypotheses proposed to explain the function of hyperaccumulation, most evidence has supported the “elemental defence” hypothesis, which states that plants hyperaccumulate heavy metals as a defence mechanism against natural enemies, such as herbivores. According to the more recent hypothesis of “joint effects”, heavy metals can operate in concert with organic defensive compounds leading to enhanced plant defence overall.
Heavy metal contaminated soils pose an increasing problem to human and animal health. Using plants that hyperaccumulate specific metals in cleanup efforts appeared over the last 20 years. Metal accumulating species can be used for phytoremediation (removal of contaminant from soils) or phytomining (growing plants to harvest the metals). In addition, as many of the metals that can be hyperaccumulated are also essential nutrients, food fortification and phytoremediation might be considered two sides of the same coin. An overview of literature discussing the phytoremediation capacity of hyperaccumulators to clean up soils contaminated with heavy metals and the possibility of using these plants in phytomining is presented.
The maintenance of ion homeostasis in plant cells is a fundamental physiological requirement for sustainable plant growth, development and production. Plants exposed to high concentrations of heavy ...metals must respond in order to avoid the deleterious effects of heavy metal toxicity at the structural, physiological and molecular levels. Plant strategies for coping with heavy metal toxicity are genotype-specific and, at least to some extent, modulated by environmental conditions. There is considerable interest in the mechanisms underpinning plant metal tolerance, a complex process that enables plants to survive metal ion stress and adapt to maintain growth and development without exhibiting symptoms of toxicity. This review briefly summarizes some recent cell biological, molecular and proteomic findings concerning the responses of plant roots to heavy metal ions in the rhizosphere, metal ion-induced reactions at the cell wall-plasma membrane interface, and various aspects of heavy metal ion uptake and transport in plants via membrane transporters. The molecular and genetic approaches that are discussed are analyzed in the context of their potential practical applications in biotechnological approaches for engineering increased heavy metal tolerance in crops and other useful plants.
Certain five heavy metals viz. arsenic (As), cadmium (Cd), chromium (Cr)(VI), mercury (Hg), and lead (Pb) are non-threshold toxins and can exert toxic effects at very low concentrations. These heavy ...metals are known as most problematic heavy metals and as toxic heavy metals (THMs). Several industrial activities and some natural processes are responsible for their high contamination in the environment. In recent years, high concentrations of heavy metals in different natural systems including atmosphere, pedosphere, hydrosphere, and biosphere have become a global issue. These THMs have severe deteriorating effects on various microorganisms, plants, and animals. Human exposure to the THMs may evoke serious health injuries and impairments in the body, and even certain extremities can cause death. In all these perspectives, this review provides a comprehensive account of the relative impact of the THMs As, Cd, Cr(VI), Hg, and Pb on our total environment.
With the recent growing interest of antibiotic resistance genes (ARGs) and their co-selection with heavy metal resistance genes (HMRGs), their relationship to heavy metals needs further analysis. ...This study examined the response of heavy metal resistant microorganisms (HMRMs) and antibiotic resistant microorganisms (ARMs) and their resistance genes (HMRGs and ARGs) to Cu and Cr stresses using metagenome. Results showed that Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, and Nitrospirae are the dominant HMRMs and ARMs, with majority of HMRMs taxa presenting changes similar to ARMs under heavy metal stresses. Types of HMRGs and ARGs changed (increased or decreased) under Cu and Cr stresses, and a significant relationship was noted between HMRGs and ARGs and their related microbe (p < 0.05). Network analysis revealed synergistic relationships between majority of HMRGs and ARGs; however, negative correlations were also noted between them. Co-occurrence of HMRGs and ARGs was mainly observed in chromosomes, and plasmids were found to provide limited opportunities for heavy metals to promote antibiotic resistance through co-selection. These findings imply that the response of HMRMs and ARMs is induced by heavy metals, and that the changes in these microbial communities are the main factor driving the diversity and abundance of HMRGs and ARGs.
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•Metagenomic analysis of Cu and Cr stresses on resistance gene and their related microbe.•Changes of HMRMs and ARMs are significantly induced by different heavy metals.•Significant relationship was noted between HMRGs and ARGs and their related microbial community.•Microbial communities are the main factor driving the diversity and abundance of HMRGs and ARGs.
In this study, 7 Pseudomonas strains were isolated from a wastewater treatment plant, and the alginate production of Pseudomonas strains under different environmental conditions was evaluated. ...Subsequently, alginate-biomass hydrogel beads were prepared using alginate and biomass of Pseudomonas, and their adsorption performances and mechanism to Pb2+ and Cd2+ were analyzed. The results show that weakly acidic pH and 37 °C is favorable for alginate synthesis of Pseudomonas strains, and P. alcaligenes YLS18 have the highest alginate yield (29.4 mg/g). The adsorption processes of Pb2+ and Cd2+ by hydrogel beads are well described by Langmuir model, indicating that the adsorption process is monolayer. Among the biomass of these strains, P. nitroreducens YLB32 shows the highest biosorption capacities, reaching 110.7 mg/g for Pb2+ and 54.3 mg/g for Cd2+ at pH 5. Alginate-biomass hydrogel beads obtain higher adsorption capacity to Pb2+ (184.0 mg/g) and Cd2+ (92.4 mg/g), and exhibit good reusability. The adsorption mechanism of Pb2+ and Cd2+ by hydrogel beads involves physical tapping of ions, electrostatic interactions, complexation, cation exchange and precipitation. These results provide strong support for promoting alginate recovery from activated sludge and for treating heavy metal wastewater.
•Weakly acidic condition and 37 °C were favorable for alginate synthesis.•Pseudomonas nitroreducens YLB32 have high adsorption capacity for Pb2+ and Cd2+.•Alginate-biomass hydrogel increased the adsorption capacity of strain biomass.•This study supports alginate recovery and heavy metal wastewater treatment.
The causes of neurodegenerative diseases are complex with likely contributions from genetic susceptibility and environmental exposures over an organism's lifetime. In this review, we examine the role ...that aquatic models, especially zebrafish, have played in the elucidation of mechanisms of heavy metal toxicity and nervous system function over the last decade. Focus is applied to cadmium, lead, and mercury as significant contributors to central nervous system morbidity, and the application of numerous transgenic zebrafish expressing fluorescent reporters in specific neuronal populations or brain regions enabling high-resolution neurodevelopmental and neurotoxicology research.
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•Electrodialysis can remove water and heavy metals in sludge simultaneously.•Citric acid can improve the removal rates of heavy metals.•Interrupted power supply has different effects ...on different heavy metals.•Acidic condition is more conducive to the transformation of heavy metals to dissolved speciation.
The heavy metals present in sludge are very harmful to the environment and the human body. It is necessary to remove them before sludge disposal. In this study, an ex situ method for removing heavy metals from sludge using electroosmosis was designed, and experiments were conducted to study the effects of electroosmosis voltages (30 V, 40 V and 50 V), citric acid concentrations (0.03 mol/kg, 0.06 mol/kg, 0.09 mol/kg and 0.12 mol/kg) and the power supply (continuous and interrupted) on the removal rate of heavy metals (Cu, Cr, Cd, Zn and Pb). The study found that the combination of the citric acid pretreatment and electroosmosis can effectively improve the removal rate of heavy metals. An appropriate increase in the voltage and citric acid concentration can improve the removal rate of heavy metals. The best combination was determined to be 40 V and 0.09 mol/kg. Under these conditions, the removal rates of Cu, Cr, Cd, Zn and Pb, were 14.39–41.28% (continuous power supply) and 21.78–42.36% (interrupted power supply). The interrupted power supply effectively improved the removal rates of Cd and Zn but reduced the removal rates of Cr and Pb. The power supply mode had no significant effect on the removal rate of Cu.
Heavy metal speciation was analyzed by the BCR method, and the relationship between the ratio of easily removed metal speciation and the removal rate was studied. The increase in the ratio of easily removed speciation was accompanied by an increase in the removal rate, indicating that citric acid and electroosmosis increased the removal rate by increasing the ratio of easily removed speciation. However, the high pH value around the cathode caused by the electrochemical reaction was not conducive to the removal of heavy metals.
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