Heavy Metals

Nonlinear Behavior of Heavy Metals in Soils Mobility and Bioavailability

The dynamics of heavy metals and their transport in the soil profile play a significant role in their bioavailability and leaching losses beyond the root-zone . The primary emphasis in this chapter is on different approaches that describe the dynamics of heavy metals in the soil system. Such knowledge is necessary because these approaches provide direct information on the concentration of heavy metals in the soil solution and thus on their dynamics and bioavailability in soils . Moreover, such predictive capability requires knowledge of the physical, chemical, as well as biological processes influencing heavy metal behavior in the soil environment To quantify the transport of heavy metals in the soil, models that include reactivity or retention and release reactions of the various heavy metal species with the soil matrix are needed Retention and release reactions in soils include ion exchange, adsorption-desorption, precipitation-dissolution, and other mechanisms such as chemical or...

Sources and Origins of Heavy Metals

There are different sources for heavy metals in the environment. These sources can be both of natural or anthropogenic origin. This chapter gives a general introduction into the different heavy metal sources such as mag-matic, sedimentary, and metamorphic rocks, weathering and soil formation, the rock cycle, the origin of heavy metals in surface and groundwater as well as in the atmosphere, and anthropogenic sources stemming from human activities such as industrial production and agriculture 1,2 .

The Origin of Heavy Metals in Soil 121 Geochemical Origins of Heavy Metals

Sedimentary rocks comprise approximately 75 of the rocks outcropping at the earth's surface and are therefore more important than igneous as soil parent materials. They are formed by the lithification of sediments comprising rock fragments or resistant primary minerals, secondary minerals such as clays, or chemical precipitates such as CaCO3. In general, clays and shales tend to have relatively high concentrations of many elements due to their ability to adsorb metal ions. Black (or bituminous) shales contain high concentrations of several metals and metalloids, including Ag, As, Cd, Cu, Pb, Mo, U, V, and Zn. The sediments from which they are formed act both as an adsorbent for heavy metals and as a substrate for microorganisms. The latter catalyzes the development of reducing conditions, which lead to further heavy metal accumulation through the precipitation of metal sulfides.

Heavy Metals In Rocks And Soils

Rocks and soils are the principal natural sources of heavy metals in the environment. The primary rocks, which are called magmatic or igneous rocks, crystallize from magma upon cooling down. Magma is defined as molten rock material originating from the earth's mantle, which can be transported to the surface by several geological processes such as volcan-ism or plate tectonics 3 , Magma contains a large variety of different chemical elements. Heavy metals are incorporated as trace elements into the crystal lattice of the primary minerals, which form during the cooling of the magma. This process is called isomorphic substitution, as the heavy metals substitute other atoms during the crystallization. The amount of isomorphic substitution is determined by the ion radius, the ion charge, and the electronegativity of the main element and of the substituting element. The trace elements occurring in the most common rock forming minerals are given in Table 1.

Soil Plant Relationships of Heavy Metals 131 Soil Plant System

The major interrelationships affecting the dynamics of heavy metals between the soil and the plant are shown in Fig. 1.1. The soil-plant system is an open system subject to inputs, such as contaminants, fertilizers, and pesticides, and to losses, such as the removal of metals in harvested plant material, leaching, erosion, and vitalization. Fig. 1.1 The soil-plant system showing the key components concerned with the dynamics of heavy metals (modified from Peterson and Alloway 1979) Fig. 1.1 The soil-plant system showing the key components concerned with the dynamics of heavy metals (modified from Peterson and Alloway 1979)

Toxicity of Heavy Metals in Biological Systems

Before we can describe the toxic effects of heavy metals (given the definition provided in the first part of this chapter), it is necessary to recall two well-known facts. First, a heavy metal is not toxic per se it is only toxic when its concentration in the plant exceeds a certain threshold ( it is the dose that makes the effect ). This is especially important to the second fact that some elements, called micronutri-ents, have essential functions in plant cells. This has been shown for Co, Cu, Fe, Mn, Mo, Ni and Zn. Only when the internal concentration exceeds a certain threshold do they demonstrate toxic effects, and then they are commonly termed heavy metals . As far as we know, all of these plant micronutrients are transition elements. No lead-group elements or rare earth elements have been found to be essential for higher plants. Micronutrients are essential for biosynthesis, growth, nucleic acids, growth substances, chlorophyll and secondary metabolites, carbohydrates and...

Primary Targets of Heavy Metal Toxicity

Many of the toxic responses induced by heavy metals that have been identified to date have to be classified as being general stress responses, rather than ones that are specific to heavy metals. The question then arises as to whether a specific metal ion actually induces a sensing mechanism in the plant cells for the presence of the toxin at all, or whether it just the damage caused by a heavy metal that induces a signal. According to Clemens (2006), the data that are available to answer this question are rudimentary at best . To give an example, proline accumulates under Cd2+ stress. However, the accumulation does not occur directly in response to the presence of Cd2+ but because of the disturbance to the water balance caused by the excess of Cd2+. One way to investigate the specificity of the stress caused by an excess of a heavy metal ion is to apply the microarray strategy to mRNA-related cDNAs in order to compare the effects of different heavy metals with those of other stress...

Heavy Metals In Water And Groundwater

For example, water flowing over limestone (CaCOs) will develop a pH of about 8, while water flowing through granite, which consists mainly of quartz (Si02) and feldspars, will develop a more acid pH of about 6. If pyrite (FeS2) is present, oxidation of the mineral will cause the generation of acid waters, which can affect heavy metal solubility and may lead to an increased mobility of those metals 23 . A drop of pH to 5 or lower is reported to cause serious problems for the aquatic ecosystems 24 , The mobilized heavy metals are dispersed downstream and immobilized by adsorption onto clay minerals and Fe and Mn oxyhydroxides or absorbed onto algae at a lower trophic level in the food web. These heavy metals may accumulate to critical levels in the food web and will cause damages to organisms on a higher trophic level 1 .

Effects of Heavy Metals on the Soil Microbial Mass

Several authors have shown that high concentrations of various heavy metals in soils had inhibitory effects on microbial activity. Tyler et al. (1989) reported that the normal decomposition of conifer litter and recycling of plant nutrients were inhibited in the forest surrounding a brass foundry which had emitted large amounts of Cu, Zn, and other metals as aerosols over many years. The reason for the inhibition of microbial activity was that the growth of trees in the area was retarded due to deficiencies in plant macronutrients. However, other authors, such as Olson and Thornton (1982), have reported that soils from severely metal contaminated sites, such as Shipham in Somerset, contained bacteria that showed tolerance to Cd relative to bacteria in uncontaminated soils. Doelman and Haanstra (1979) showed that Pb inhibited both microbial respiration and dehydrogenase activity in polluted soils. Although tolerant populations of microorganisms were found in polluted soils, there was a...

Heavy Metals In The Atmosphere

Heavy metals are carried in the atmosphere as gases, aerosols, and particulates. Sources of heavy metals are mineral dusts, sea salt particles, extraterrestrial matter, volcanic aerosols, forest fires, and industrial sources such as emissions from transportation, coal combustion, and fugitive particulate emissions 26 . There are two major types of aerosols. Primary aerosols are directly emitted into the atmosphere from the earth's surface, while secondary aerosols are formed by chemical reactions in the atmosphere, which involve gases, pre-existing aerosols, and water vapour 27 . Table 5 lists estimated emissions of Cd, Pb, Cu, and Zn into the atmosphere. Ref. 28 provides a comprehensive study on origin and chronological development of atmospheric global emissions and the global cycles of heavy metals. Fig. 5. Transport mechanisms of heavy metals in soil and groundwater (modified after Ref. 2). Fig. 5. Transport mechanisms of heavy metals in soil and groundwater (modified after Ref....

Localization and Distribution of Heavy Metals and Their Transport in the Plants

On the basis of accumulation of heavy metals, plants are divided into three main types Generally the heavy metal content in various plant organs decreases in the following sequence root leaves stems inflorescence seed. However, this order sometimes varies with plant species. Roots usually manifest the maximum content of heavy metals. Leaves vary with age in their ability to accumulate heavy metals, some heavy metals accumulated preferable in the youngest leaves of plant. Whereas in other maximum content is found in senescing leaves. The seed coat presents the first barrier for heavy metal absorption by germinating seeds. Obroucheva et al. (1998) has reported that some heavy metals enter the seed coat and are mainly found in the cell wall of seed coat. Heavy metals did not enter the embryos, even at lethal concentrations. When roots absorb heavy metals, they accumulate primarily in rhizodermis and cortex (Table 2.2) with few exceptions, where accumulation occurs in the endodermis cell...

Bioavailability of Toxic Heavy Metals

Soil rhizobacteria can also directly influence metal solubility by changing the heavy metal speciation in the rhizosphere. Studies of the roles of mycorrhizae in metal bioavailability in the rhizosphere and their ability to increase host plant tolerance of excessive levels of heavy metals in soil showed that there were different availabilities of Cu, Zn, and Pb in the rhizospheres of AM (arbuscular mycorrhiza)-infected and uninfected maize in comparison to bulk soil. The results may indicate that the mycorrhiza can protect its host plant from the phytotoxicity of excessive copper, zinc and lead by changing them from bioavailable forms into forms that are not bioavailable. The fact that copper and zinc accumulations in the roots and shoots of mycorrhiza-infected plants were significantly lower than those in the

Impact of Heavy Metals on Bacterial Community Structure and Microbial Processes

The deleterious effects of heavy metals on microbe-mediated processes have been discussed in detail by several researchers (Baath 1989 Giller et al. 1998). Generally, decreases in carbon mineralization and fixation, nitrogen transformation, soil enzyme activities, and litter decomposition can be observed. Other typical effects of heavy metal contamination are a decrease in the number of microbes (CFU), microbial biomass, or an increase in the frequency of heavy metal resistant bacteria (Pennanen et al. 1996 M ller et al. 2001). However, measuring these parameters is not a suitable approach for determining changes in the entire structures of soil communities exposed to pollutants. Since many of the microbiological and biochemical techniques used to study the effects of heavy metals on soil bacteria are cultivation dependent, they do not provide detailed information on noncultivable bacteria, thus neglecting the major part of the soil microbial community. Consequently, soil microbial...

Strategies Employed by the Metallophytes to Cope with High Concentrations of Heavy Metals at the Whole Plant Level

Heavy metal tolerance has been developed by plants of totally unrelated taxonomic affinities. It is frequent in Brassicaceae, and also seen in Caryophyllaceae, Plumbaginaceae, Violaceae, Asteraceae, Poaceae, and others. Over 34 different plant families have developed heavy metal tolerant species (Verbruggen et al. 2009). Heavy metal tolerance is thus one of the clear-cut examples of convergence in biology. Therefore, it is not surprising that the strategies to cope with the excess of heavy metals differ from one plant taxon to the next. Similarities in the mechanisms exist between metallophytes and halophytes. Armeria maritima can thrive both in coastal salt marshes with a high NaCl content (ssp. maritima) and on heavy metal heaps (ssp. halleri). This plant has special glands, developed from stomata, which apparently serve to excrete excess NaCl (Luttge 1975 Rozema et al. 1981). Similar glands might also be used to transfer the surplus of heavy metals to the outside by the...

Toxicity of the Heavy Metals in Cells and Responses of the Plant Cells

Heavy metals can have multiple effects in the plant cytoplasm (a) Formation of Siderophores These are large, complex molecules that are excreted from the plant cells into the soil. These chelators bind heavy metals to form a large complex which is not taken up by the cells. Thus the surplus of heavy metals would not reach the cell cytoplasm. Such a role of siderophores is not accepted by all investigators working in the field. (b) Synthesis of small molecules such as the carboxylic acids malate, citrate, or oxaloacetate that bind heavy metals with their acid groups. These carboxylic acids may bind heavy metals outside the roots or in the root apoplasm which may prevent uptake of heavy metals. The root symplasm of plants excretes up to 20 of the organic carbon containing such organic acids. Root exudation may change the pH-value in soils and thereby may alter the accessibility and uptake rate of heavy metals into plant roots (Alford et al. 2010). Alternatively, such simple organic...

Heavy Metals and Their Toxicities

Heavy metals are defined as elements with a mass of 5.0 g cm-3. Physiologically, they can be subdivided in those I. Sherameti and A. Varma (eds.), Soil Heavy Metals, Soil Biology, Vol 19, DOI 10.1007 978-3-642-02436-8_5, Springer-Verlag Berlin Heidelberg 2010 At a certain threshold concentration, any heavy metal will become toxic to the organism containing it. This threshold value is species specific and varies with the heavy metal. The toxicity of a heavy metal may even vary between individuals of a given species or cultivar. Thus there is no general tolerance of plants to heavy metals. However, a plant species can be more adapted to one heavy metal than another, and so is more tolerant to Ni, for example, than the next species. Another plant species may be more tolerant to Cu than a counterpart. Figure 5.1 illustrates these impacts of metals on plants in a simplified way. In classical plant physiology, organisms are tolerant when they can endure a high concentration range of a heavy...

Ecotoxicological Effects Of Heavy Metals

Ecotoxicology developed from the traditional fields of toxicology and environmental chemistry and can be defined as the study and effect of toxic agents in ecosystems 206 . Ecotoxicology is an interdisciplinary science, which deals with the interactions among organisms, toxic agents (here heavy metals), and the environment, and integrates disciplines such as environmental biogeochemistry, toxicology, and ecology. The vast majority of ecotoxicological studies have been performed at the individual level, yet investigations including studies of toxic effects at the cellular, individual, and population level have been performed 207 . In the following chapter, the pathways of heavy metals into ecosystems and living organisms, their bioavailability, bioaccumulation, and general health effects are discussed. As for the health effects of individual heavy metals, the reader is referred to subchapter 4 Individual behaviour of selected heavy metals .

Microbial Adaptation to Heavy Metals

Mechanisms allows these microorganisms to function metabolically in environment polluted by metals. These mechanisms could be constitutive or inducible. The bacterial resistance mechanisms are encoded generally on plasmids and transposons, and it is probably by gene transfer or spontaneous mutation that bacteria acquire their resistance to heavy metals. For example, in gram-negative bacteria (e.g., Ralstonia eutropha), the czc system is responsible for the resistance to cadmium, zinc, and cobalt. The czc-genes encode for a cation-proton antiporter (CzcABC), which exports these metals (Nies 1999). A similar mechanism, called ncc system, has been found in Alcaligenes xylosoxidans, which provides resistant against nickel, cadmium, and cobalt. On the contrary, the cadmium resistance mechanism in gram-positive bacteria (e.g., Staphylococcus, Bacillus, or Listeria) is through Cd-efflux ATPase. Plasmid-encoded energy-dependent metal efflux systems involving ATPases and chemios-motic ion...

Understanding the Inhibition of Soil Enzymes by Heavy Metals

Heavy metals exert inhibitory effects on soil enzymes, but these effects depend on many factors in the soil. Khan et al. (2007) investigated soil enzyme activities (catalase, alkaline phosphatase, and dehydrogenase) when various levels of Cd and or Pb were applied to the soil. This work thus provides a good example of the combined effects of heavy metals on soil enzyme activities (see Table 11.5). Strong inhibition was observed at high heavy metal concentrations in both the single-metal and dual-metal systems however, the inhibition was greater in the dual-metal system than the single-metal systems in other words, a synergistic effect was observed. However, some combinations of metals exhibit this synergism while others do not. Wyszkowska et al. (2006) concluded that treatment with copper alone was more inhibitory towards soil enzyme activity than copper applied in conjunction with other heavy metals (Cu with Zn, Ni, Pb, Cd, and Cr). Table 11.4 ED5n values for evaluating soil enzyme...

Plants Response towards Metal Toxicity

Mechanisms of tolerance vary considerably according to the metal accumulated and of course the plant species. There is much contention in the literature over the possible mechanisms of metal tolerance in plants. This reflects the complex nature of higher plant responses to metal toxicity 12 . There are a number of strategies that plants could possibly employ to combat high external metal concentrations, these can be classified into two basic main categories exclusion and accumulation 12,14 . Plants that restrict uptake or transport of metals through the roots by either precipitating metal by increasing the pH of the rhizosphere or by excreting anions such as phosphate which complex metals in the root environment, are known as excluders 1,14 .

Effects of Heavy Metals on Soil Fungal Communities

Although different groups of microbes may show different sensitivities to heavy metals in the environment, the total microbial biomass is usually decreased in heavy metal contaminated sites this is also true in many cases for the total fungal biomass. In oak litter polluted with Fe, Zn, Cu, Cr, Ni, and Pb, the amount of fungal biomass decreased with increasing metal content (Cotrufo et al. 1995). On the other hand, after the addition of sewage sludge containing Cu, Ni, and Zn, fungal biomass increased despite a decrease in the total microbial biomass (Khan and Scullion 2000). Soils containing more carbon are usually less affected than carbon-poor sandy soils. Several studies have shown that microbial communities respond to toxic metals by exhibiting changes in the relative abundances of bacteria and fungi. The results of these studies are summarized in Table 12.1. These findings, however, have to be treated with care while the experimental addition of metal to soils Table 12.1 Effect...

Mechanisms to Prevent Cells from Heavy Metal Toxicity

Extracellular and intracellular mechanisms are involved in heavy metal tolerance for fungi. Mostly such mechanisms have not explicitly been studied in mycorrhizal fungi, but it appears likely that data from non-mycorrhizal basidiomycetes (or ascomycetes) can be translated to ECM since they use the same mechanisms (Fig. 10.2). Extracellular chelation by excreted ligands, such as citrate and oxalate, as well as cell-wall binding or an enhanced efflux reduce the amount of heavy metals in the cell. Intracellular chelation by metallothioneins phytochelatins or

In Understanding Heavy Metal Detoxification Mechanisms

The analysis of total soluble protein in response to heavy metal stress provides valuable information about cytosolic soluble proteins related to the toxicity response to particular heavy metals. However, such an approach does not allow for exploration of the mechanisms and proteins associated with heavy metal transport, sequestration, and deposition detoxification processes. It is therefore necessary to investigate the responses of specific tissues and subcellular compartments that are directly involved in heavy metals translocation, transformation, extrusion, and sequestration within cells, such as the xylem, cell wall, plasma membrane, vacuole, and apoplast (Hall 2002). To understand the function of organelles in heavy metal detoxification processes, it is important to analyze the subcellular proteome with advanced proteomic technologies.

Heavy Metals and Their Long Term Behaviour in Aquatic Sediment Profiles

Heavy metals are among others the best characterised anthropogenic contaminants used for monitoring histories. Exemplary for their overall discharge, accumulation, sequestration and persistance, in particular input trends of lead and mercury into the archives of lake sediments are chosen for documentation. Based on appropriate natural accumulation, conditions of sediment trapping and deposition as well

Heavy Metals as a Soil Pollution Agent

Heavy metals are defined as elements with metallic characteristics and an atomic number 20 (Jing et al. 2007). Heavy metals can be classified into two categories essential (Cu, Zn, Fe, Mn, Ni, and Co) and nonessential (Cd, Hg, Ag, and Pb) elements (Williams et al. 2000 Gadd 1990). Metals are natural parts of soils (Jing et al. 2007). Heavy metal ions are main component of a variety of enzymes, transcription factors, and other proteins (Williams et al. 2000). However, excessive concentrations of both essential and nonessential heavy metals in soil can cause toxicity symptoms and inhibition of plant growth (Hall 2002). Heavy metal pollution both limits plant establishment and causes declines in numbers of soil microorganisms and their activity (Shetty et al. 1994). Also, accumulation of metals in plant organs in excessive level can limit physiological processes such as photosynthesis and synthesis of chlorophyll pigments (Wani et al. 2007b). Influences of heavy metals on the microbial...

Phytoremediation Of Heavy Metals Iih Bradl

In the past several years, the use of plants for the removal of heavy metals in various media such as water, groundwater, industrial wastewaters, soils, sediments, and sludges has attracted the interest of the environmental engineering community as a potentially useful remediation tool 159j. This chapter introduces various aspects of phytoremediation, beginning with basic physiological aspects, which allow plants to contain, sequester, or remove heavy metals, explains several mechanisms of phytoremediation such as phytoextraction, phyto rhizofiltration, phytovolatilization, and phy-tostabilization, and finally assesses advantages and disadvantages of phytoremediation including the economical aspects in comparison to other remediation techniques available at the market.

Introduction What are Heavy Metals

There are approximately sixty-five elements that may be termed heavy metals, as they exhibit metallic properties and having atomic weights of between 63.54 and 200.59. Generally, heavy metals have densities above 5 g cm-3 (Hawkes 1997), and cannot be degraded or destroyed, meaning that they persist in all compartments of the environment. However, some heavy metals known as trace metals (e.g., Cu, Zn, Fe, Ni, Mo, Co) are essential for the growth and metabolism of organisms at low concentrations, and microorganisms possess mechanisms of varying specificity for their intracellular accumulation from the external environment. In contrast, many other heavy metals have no essential biological function (e.g., Pb, Sn, Cd, Al, Hg) but can still be accumulated in biomass and are freely transferred from one organism to another through the food chain.

Heavy Metals in Soils and Sludge

HM levels in agricultural soils have been found to be increasing this is attributed to phosphate fertilizer, agrochemicals application, and atmospheric deposition (Jones, 1991 Billet, Fitzpatrick, and Cresser, 1991 Hovmand, Tjell, and Mosbaek, 1983) This, in turn, has led to the increased uptake of HMs by plants, as reported for the pea, radish, and lettuce crops, which were found with increased levels of Cd due to the phosphate fertilizers used (Reuss et al ., 1978) In agricultural soils within Europe, it is estimated that there has been a 10 to 15 increase in the concentration of the heavy metals Cd, Pb, and Hg during the twentieth century, due to factors such as those mentioned previously (McBride, 1995) This increase, however, is very small as compared with the increase in HMs observed after the application of biosolids in agricultural lands and resulting in increased uptake of heavy metals by plants, as indicated by the large number of publications found in the literature...

Forms of Heavy Metals in Biosolids

Anaerobically digested sludge is a complex of certain minerals and organic matter, with remnants of bacteria and colloidal inorganic and organic materials . After digestion, the sludge is subjected to rapid oxidation and alterations in microbial activity. Thus, the chemical forms of HMs are the result of a balance between the solids precipitated, the complexes and hydrated ions in the solution, and the same ions that are held in the organic materials, in the bacterial residues, and on the surfaces and interstices of the minerals (Lake, Kirk, and Lester, 1984) . The interactions of all these are so complicated that the distribution of the HMs among the different phases mentioned above can only be described through quantitative models that require accurate values of equilibrium constants for all the reactions of precipitation, complex formation, and redox processes that occur (Fletcher and Beckett, 1987a) . These later researchers, studying the formation of Cu complexes with DOM...

Heavy Metal Toxicity in Plants

Abstract Although many metal elements are essential for the growth of plants in low concentrations, their excessive amounts in soil above threshold values can result in toxicity. This detrimental effect varies with the nature of an element as well as plant species. Heavy metal toxicity in plants depends on the bioavailabil-ity of these elements in soil solution, which is a function of pH, organic matter and cation exchange capacity of the soil. Nonessential metals metalloids such as Hg, Cd, Cr, Pb, As, and Sb are toxic both in their chemically combined or elemental forms, and plants responses to these elements vary across a broad spectrum from tolerance to toxicity. For example, the bioaccumulation of heavy metals in excessive concentrations may replace essential metals in pigments or enzymes disrupting their function and causing oxidative stress. Heavy metal toxicity hinders the growth process of the underground and aboveground plant parts and the activity of the photosynthetic...

Proteomic Studies in Response to Heavy Metal Toxicity

Currently, many studies seeking to identify heavy metal toxicity-induced differentially expressed proteins or heavy metal stress-responsive proteins in plants rely on a classical gel-based proteomic approach. This approach typically involves two-dimensional polyacrylamide gel electrophoresis (2-DE) coupled with Edman sequencing, Matrix-Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry (MS), or nanoscale liquid chromatography (nano-LC) electrospray ionization (ESI)-MS MS analysis (Ahsan et al. 2009). However, advanced proteomic techniques are still limited with regard to their application to the analysis of heavy metal-responsive proteins in plants. Thus far, only a few reports describing quantitative shotgun proteomic approaches for identification of metal toxicity-induced proteins in plants have been published (Patterson et al. 2007 Alvarez et al. 2009 Schneider et al. 2009). Using the iTRAQ approach, Patterson et al. (2007) analyzed boron...

Earthworm Heavy Metal Relationships and Accumulation and Detoxification of Heavy Metals by Earthworms

Although heavy metals exist lithologically in the ground, their concentrations in soil increase through various industrial emissions (Cemek and Kizilkaya 2006), commercial fertilizers, (Karaca et al. 2002) and sewage sludges (Kizilkaya and Bayrakl 2005). Depending on soil characteristics, heavy metals accumulated in food chain and this affects soil life and especially biological-biochemical reactions negatively (Kizilkaya and Askin 2002 Kizilkaya et al. 2004 Karaca et al. 2010b). The earthworms are used as a cursor when assessing the effects of heavy metals on various ecosystems. Heavy metals influence earthworm life by killing (Fitzpatrick et al. 1996 Neuhauser et al. 1985 Spurgeon and Hopkin 1995 Kizilkaya et al. 2009,) or inhibiting their growth (Khalil et al. 1996 Van Gestel et al. 1991), cocoon production (Ma 1988 Spurgeon and Hopkin 1996), and activity (Siekierska and Urbanska-Jasik 2002). In ecosystem risk assessments, concentrations of mobile or available heavy metals are more...

Effects of Heavy Metals on Fungal Physiology

Growth reduction is a typical response of fungi to the toxicity of heavy metals (Baldrian 2003). It has been demonstrated that this reduction is dependent on nutrient availability, and that higher nutrient content can alleviate metal toxicity (Gadd et al. 2001). The growth of cord-forming saprotrophic basidiomycetes in the soil environment represents the colonization of nutrient-poor space in the search for nutrients. This growth is supported from the colonized bulky substrate, e.g., wood pieces or litter patches. This type of colonization of nutrient-limited soil regions was significantly reduced for Pleurotus ostreatus in the presence of Cd or Hg (Baldrian et al. 2000), and Pb exhibited the same effect on several litter-decomposing fungi (Tuomela et al. 2005 Kahkonen et al. 2008). The morphological changes induced by heavy metals are common among all groups of fungi (Baldrian 2003). Changes in mycelial morphology were observed in Mucor rouxii in the presence of a high copper...

Heavy Metal Detoxification and Tolerance in Higher Plants

Hyperaccumulator or accumulator plants and their related PGPR are main topic in metal detoxification. PGPR and arbuscular mycorrhizal fungi (AMF) develop plant growth and development in heavy metal polluted soil via helping root growth and branching. PGPR and AMF are able to lessen the toxicity of heavy metals either by declining the bioavailability of toxic heavy metals or raising bioavailability of nontoxic heavy metals. PGPR and AMF can alter chemical properties in the rhizosphere and stimulate metal accumulation (Denton 2007). Mycorrhizal plant metal uptake depends on several factors such as soil physi-cochemical properties (fertility level, pH), host plants, fungi involved, and the concentration of metal in soil (Diaz et al. 1996). Heggo et al. (1990) found that the influence of VAM fungi on heavy metal uptake is dependent upon initial soil metal concentration. Weissenhorn et al. (1994) found that heavy metals completely eliminate Arbuscular mycorrhizal (AM) colonization of plant...

Aspects of the Use of Metallophytes to Remediate Soils Polluted by Heavy Metals

Phytoremediation has been reviewed (Salt et al. 1998 Pilon-Smits 2005) Maerques et al. 2009 Muthukumar and Bagyaraj 2010). It comprises stabilization of soils devoid of plants due to heavy metal toxicity and extraction of heavy metals by plants. Volatilization and degradations have a role in the removal of other pollutants but not in the case of heavy metals. However, Hg and the toxic metalloids As and Se may be chemically converted to more readily extractable or volatile compounds. It is sometimes stated that metallophytes are often slow growing and are not productive enough to stabilize heavy metal soils against erosion, leaching, or runoff (Pilon-Smits 2005). This is, indeed, the case for most metallophytes. However, Thlaspi goesingense (Fig. 2.1) of South-Eastern European serpentine soils is fairly productive and offers good promises to achieve this goal. Edaphic factors of the soils to be stabilized play an important role in any attempt. It is in most cases not sufficient to sow...

Molecular Mechanisms and Genetic Basis of Heavy Metal Toxicity and Tolerance in Plants

Abstract Heavy metal pollutants are mainly derived from growing number of anthropogenic sources. As the environmental pollution with heavy metals increases, some new technologies are being developed, one of these being phytoremediation. Hyperaccumulator plant varieties can be achieved by using methods of genetic engineering. An uptake of excessive amounts of heavy metals by plants from soil solution leads to range of interactions at cellular level which produce toxic effects on cell metabolism in terms of enzyme activity, protein structure, mineral nutrition, water balance, respiration and ATP content, photosynthesis, growth and morphogenesis and formation of reactive oxygen species (ROS).On the basis of accumulation of heavy metals plants are divided into three main types (i) the accumulator plants, (ii) the indicator plants, and (iii) the excluder plants. Generally, the accumulation of heavy metals in plant organ is in series root leaves stem inflorescence seed. Most of plants...

Heavy Metals Biosorption by Vermicomposts

Humic Acid Metal Complexation

At present there are only a few studies regarding the treatment of wastewaters containing heavy metals by vermicompost. The efficiency of vermicompost for removing heavy metals from aqueous solutions or industrial effluents has not been studied in detail except to mention a few and namely Jordao et al. (2002), Pereira and Arruda (2003), Carrasquero Duran et al. (2006), Jadia and Fulekar (2008), Urdaneta et al. (2008) and Jordao et al. (2009). Those researchers found that metal concentrations in the purified effluents were below the maximum values established for waste discharges by the prevalent local standards. They also reported that the vermicompost residues obtained from the metal retention process could be applied as a fertilizer to agricultural lands. In their review of vermicomposting and vermicompost, Sharma et al. (2005) have given a comprehensive description of vermicompost, and the main their main conclusions are discussed in the following section. Vermicompost has been...

Biosorption of Heavy Metals

Heavy Metal Biosorptionthrough Biomass

Pollutants such as heavy metals, volatile organic compounds and dissolved solids are found in wastewaters. Heavy metal remediation of aqueous streams is of special concern due to recalcitrant and persistency of heavy metals in environment (Sud et al. 2008). They are removed on adsorbents such as activated carbon, clay and sediments in riverbeds and in suspension. Over the years, the role of adsorption in water waste-water treatment has been critically investigated (Oke et al. 2008). Adsorption of heavy metals onto suspended particles had been studied as a model of transportation of metals in rivers and sea. The effects of chemical composition and particle size on adsorption by suspended particles had also been studied. Attention had mostly been on carbon as adsorption materials and indeed Erhan et al. (2004) had documented about 37 sources of carbon, which had been studied as adsorbents for the removal of water pollutants. Three problems associated with the use of carbon for the...

Nonequilibrium Transport of Heavy Metals in Soils Physical and Chemical Processes

Soil contamination of heavy metals from mining, industrial, agricultural, and geological sources poses serious environmental risk around the world because of its high toxicity to human health as well as the ecosystem . The transport of toxic metals in the vadose zone and aquifers may lead to the further contamination of surface and groundwaters (NRC, 2003) . The widespread contamination caused by Cd, Cu, Hg, Pb, Ni, Zn, As, and Cr has elevated these heavy metals to the top of the priority pollutants list (Cameron, 1992) . Because of the heterogeneity in the physical and chemical soil properties at scales ranging from molecular to watershed, nonequilibrium conditions are found to be prevalent in both laboratory and field studies of heavy metal transport. A wide range of research in the fields of hydrology, geochemistry, biogeochemistry, soil physics, and environmental engineering has demonstrated that rate-limited processes play a dominant role in the transport of heavy metals in soils...

Speciation and the Toxicity of Heavy Metals

Although mercury vapor is highly toxic, the heavy metals Hg, Pb, Cd, Cr, and As are not particularly toxic as the condensed free elements. However, all are dangerous in the form of their cations and most are also highly toxic when bonded to short chains of carbon atoms. Biochemically, the mechanism of the toxic action usually arises from the strong affinity of the cations for sulfur. Thus, sulfhydryl groups, SH, which occur commonly in the enzymes that control the speed of critical metabolic reactions in the human body, readily A common medicinal treatment for acute heavy-metal poisoning is the administration of a compound that binds to the metal even more strongly than does the enzyme subsequently the metal-compound combination is sol-ubilized and excreted from the body. One compound used to treat mercury and lead poisoning is British Anti-Lewisite (BAL) its molecules contain two SH groups that together capture the metal. Also useful for this purpose is the calcium salt of...

Critical Limits for Heavy Metals in Soil

Both effect-based steady-state and standstill critical load approaches have been used to calculate and map heavy metal critical loads. In brief, an effect-based methodology identifies atmospheric depositions (critical loads) that will not lead to concentrations of heavy metals above critical limits in defined compartments at steady state. The standstill critical load is the atmospheric deposition that will not lead to any further accumulation of heavy metals in the soil. Standstill critical loads should also include inputs other than atmospheric deposition.

Soil Pollution and Heavy Metals

The primary sources of metal pollution are the burning of fossil fuels, mining and smelting of metalliferous ores, downwash from power lines, municipal wastes, fertilizers, pesticides and sewage 8 . The danger of heavy metals is aggravated by their almost indefinite persistence in the environment. Although some metals are essential for life (i.e., they provide essential cofactors for metalloproteins and enzymes), at high concentrations they can act in a deleterious manner by blocking essential functional groups, displacing other metal ions, or modifying the active conformation of biological molecules 9 . In addition, they are toxic for both plants and microorganisms. In fact, many metals affect directly various physiological and biochemical processes causing reduction in growth, inhibition of photosynthesis and respiration, and degeneration of main cell organelles 10 . Some metals are accumulated in roots (especially Pb), probably due to some physiological barriers against metal...

Anthropogenic Sources Of Heavy Metals

Heavy metals are released into the environment by many human activities. They are also used in a large variety of industrial products, which in the long term have to be deposited as waste. Heavy metal release into the environment occurs at the beginning of the production chain, whenever ores are mined, during the use of products containing them, and also at the end of the production chain. Table 6 gives an overview on the multiple uses and products, which contain heavy metals. The natural sources are dominated by parent rocks and metallic minerals, while the main anthropogenic sources are agricultural activities, where fertilizers, animal manures, and pesticides containing heavy metals are widely used, metallurgical activities, which include mining, smelting, metal finishing, and others, energy production and transportation, microelectronic products, and finally waste disposal. Heavy metals can be released into the environment in gaseous, particulate, aqueous, or solid form and...

Biomonitoring Studies in India 7421 Heavy Metals

Lichen morphology and physiology enable it to be a good reservoir of metals. Various heavy metals such as Pb, Zn, Ni, Cu, Hg, and Cr considered as toxic for many other living organisms, may be accumulated simultaneously in lichen thallus (Garty 1993) . Accumulation of metals by lichen thalli is one of the extensively studied aspects in lichen biomonitoring (Nieboer et al. 1978).Vehicular activity is reported to be the main source of atmospheric Cr, Cu and Pb (Loppi et al. 1998 Tuba and Csintalan 1993). In India, air quality of major cities in the country has been evaluated with the help of lichens. Vehicular pollution contributes major input of wide range of pollutants in the atmosphere including heavy metals (Chauhan et al. 2010). Biomonitoring studies are mainly concentrated on bioaccumulation of metallic content since in the urban centers vehicular and anthropogenic activity is the main contributing source of pollution. The negative correlation of concentration of Pb with the...

Mobility of Heavy Metals in Tropical Land

Heavy metals exist in two forms in nature. As stated above, microbes can convert contaminants to less harmful products however, they can also immobilize contaminants (National Research Council 2003). Metal immobility is primarily achieved through reactions that cause the metal to precipitate or that keep the metal in a solid phase (Evanko Cynthia and Dzombak 1997). Chemical and physical properties affect the mobility of metals in soils and groundwater. Under acidic conditions (pH between 4.0 and 8.5) metal cations are mobile while anions tend to bind into oxide minerals. At high pH values, cations are adsorbed onto mineral surfaces and metal anions are mobilized. Hydrous metal oxides of iron, aluminum, and manganese can affect metal concentrations because these minerals can remove cations and anions.

Contamination of Land by Heavy Metals

In nature, heavy metals are concentrated in the Earth's core. The Earth has a three-layered structure that can be compared to hard-boiled egg, with the yolk surrounded by the white and then by the shell. Deep inside the Earth is a heavy metallic sphere called the core. The Earth's core is divided into two parts, the outer core and the inner core. Lighter elements such as aluminum and silicon float to the outer core while heavier molten materials, such as the elements iron and nickel, settle in the inner core. Due to geological activity, these metals are redistributed from the core to the Earth's crust (its outer layer) and thus its surface. However, humans affect the I. Sherameti and A. Varma (eds.), Soil Heavy Metals, Soil Biology, Vol 19, DOI 10.1007 978-3-642-02436-8_19, Springer-Verlag Berlin Heidelberg 2010 natural geological and biological distributions of heavy metals by polluting the air, water, and soil. The primary anthropogenic sources of heavy metals are point sources,...

Bioaccumulation of Heavy Metals

Recall from Chapter 10 that some substances display the phenomenon of biomagnification Their concentrations increase progressively along an ecological food chain. The only one of the five heavy metals under consideration that is indisputably capable of doing this is mercury. Many aquatic organisms do, however, bioconcentrate (but do not biomagnify) heavy metals. For example, oysters and mussels can contain levels of mercury and cadmium that are 100,000 times greater than those in the water in which they live. The concentrations of most heavy metals in drinking water are usually small and cause no acute health problems however, exceptions do occur and will be discussed later. As is the case with toxic organic chemicals, the amounts of metals that are ingested through our food supply are usually of much greater concern than is the intake attributable to drinking water. Paradoxically, the heavy metals in the fish that we ingest usually originate in fresh water.

Characteristics of Plants Used for Phytoremediation of Heavy Metals

Plants suitable for phytoremediation should possess a series of characteristics (1) ability to accumulate metals preferably in the aboveground parts, (2) tolerance to metal concentration accumulated, (3) fast growth and high biomass, (4) widespread highly branched root system, (5) easy harvestability, and (6) non consumable by humans and animals (Arthur et al., 2005). However, plant species just can partially fulfill these conditions. For example, those few plants that can accumulate metals to exceptionally high concentrations in their shoots, with no adverse effects on their growth (hyperaccumulators), are both small and slow growing, and often they are rare species of limited population size and very restricted distributions (Pollard et al., 2002). On the other hand, high biomass producing species, such as trees and agricultural crops tend to take up relatively smaller amounts of heavy metals than hyperaccumulators. Comparing with agricultural species, trees have some advantages as...

Heavy Metals Toxicity and Removal by Biosorption

10.2 Biosorption of Heavy 10.2.2 Heavy Metals Biosorption by 10.4 Heavy Metals Abstract Industrialization, urbanization and various anthropogenic activities such as mining and agriculture have increased releases of toxic heavy metals into the natural environment such as soils, lakes, rivers, groundwaters and oceans. The release of heavy metals in biologically available forms alter both natural and man-made ecosystems. Although some heavy metal ions are essential micronutrients for plant metabolism, they become highly toxic when they occur at high concentrations in soils, groundwaters and waste streams. Moreover, heavy metals are not biodegradable and persist in the environment. Conventional methods for the removal of the heavy metals ions from contaminated wasters and wastewaters include chemical precipitation, electroflotation, ion exchange, reverse osmosis and adsorption onto activated carbon. Recently, pioneering research on biosorption of heavy metals has led to the identification...

Forms of Heavy Metals in Soils

Mean Concentrations of Heavy Metals of Major Rock Types Mean Concentrations of Heavy Metals of Major Rock Types Source Adapted from Alloway, B .J . 1995. The origins of heavy metals in soils . In B .J . AHoway (Ed.) Heavy metals in soils, second edition. Blackie Academic & Professional, London. a Mean values for ultramafic, mafic, and granitic rocks Source Adapted from Alloway, B .J . 1995. The origins of heavy metals in soils . In B .J . AHoway (Ed.) Heavy metals in soils, second edition. Blackie Academic & Professional, London. a Mean values for ultramafic, mafic, and granitic rocks heavy metals of interest in this chapter according to the main rock types are shown . Anthropogenic sources contributing significantly to the input of heavy metals in soils are fertilizers, pesticides and lime, sewage sludge, animal waste, coal residues, mining and milling wastes, etc . Heavy metals in soils exist in various chemical forms that show different availability to plants . These various forms...

Remediation of Heavy Metals From Soils

Heavy metals can not be destroyed biologically since there is a lack of degradation or change in the nuclear structure of the element. Such metals can only be transformed from one oxidation state or organic complex to another (Garbisu et al. 2002). As such, the remediation of heavy metal contamination in soils is more difficult. Phytoremediation is best applied at sites with shallow contamination of organic, nutrient or metal pollutants that are amenable to one of several applications namely phytoextraction, rhizofiltration, phytostabilization, phytovolatilization, etc. (Schnoor 1997). In phytoextraction, the plants are used to concentrate metals from soil into their roots and shoots in rhizofiltration, plant roots are used to absorb, concentrate or precipitate metals from effluents in phytostabilization, plants are used to reduce the mobility or bioavailability of heavy metals through their absorption and precipitation whereas in phytovolatilization, the absorbed volatile materials...

Heavy Metals Toxicity

The term heavy metals refers to metals and metalloids having densities greater than 5 g cm-3 and is usually associated with pollution and toxicity although some of these elements (essential metals) are required by organisms at low concentrations (Adriano 2001) . Heavy metals toxicity and the danger of their bioaccumulation in the food chain represent one of the major environmental and health problems of our modern society. Primary sources of pollution is from the burning of fossil fuels, mining and melting of metallic ferrous ores, municipal wastes, fertilizers, pesticides, and sewage sludge (Peng et al. 2006) . The most common heavy metals contaminants are cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn). Metal-bearing effluents generally emanate from metallurgical industries, electroplating and metal finishing industries and hazardous waste sites (Elouear et al. 2008) . For example, cadmium (Cd(+) is a non-essential and a non-biodegradable metal ion...

Bioremediation of Heavy Metals

Aimages Advantages Bioremediation

Bioremediation can be defined as any process that uses microorganisms or their enzymes to return an environment altered by contaminants to its original condition. There are a number of advantages to bioremediation, which can be employed in areas that cannot be reached easily without excavation. It is well documented that the presence of metals in the soil impacts both the physiology and the ecology of microorganisms by inhibiting a broad range of microbial processes, including methane metabolism, growth, and nitrogen and sulfur conversion. It is known that toxic metal cations can substitute for essential physiological cations within enzymes in organisms, rendering them nonfunctional. Metals also tend to impose oxidative stresses on microorganisms. The extent in which metals tend to inhibit the biodegradation of organic compounds is directly related to the metal speciation - the physical or chemical form of the metal species in the soil, which also governs its toxicity to...

Accumulation of Heavy Metals by Fungi

Elevated concentrations of toxic metals can occur in the fruitbodies of basidiomy-cetes in polluted environments, and soil saprotrophic and mycorrhizal fungi have been frequently proposed as suitable biomonitors of metal pollution (Kalac and Svoboda 2000 Collin-Hansen et al. 2002 Baldrian 2003). The extent of accumulation of individual metals is species or strain specific, with the high levels of metal enrichment in fungal fruitbodies serving as evidence of the high metal tolerance of fungi. Also, several soil saprotrophic basidiomycetes (e.g., the members of the genera Agaricus, Coprinus, Lepista, Lycoperdon, Marasmius, or Mycena) have been found to be accumulators of heavy metals (Mejstrik and Lepsova 1993 Svoboda et al. 2006). Fruitbodies of Armillaria mellea, collected from metal-polluted soils near motorways, contained several parts per million of Cd and Pb and tens of parts per million of Zn. Cd accumulated with a concentration factor of 32, while Zn and Pb were excluded, with...

Environmental Importance of Heavy Metals

Heavy metals are a group of elements with a density greater than 5 g cm3. Fifty three of the ninety naturally occurring elements are HMs (Schutzendubel and Polle, 2002). Metals, such as Cd, Cu and Zn, are primarily of geogenic origin in soils, but anthropogenic activities such as, mining, smelting, metal-working industries, combustion of fossil fuels, phosphate fertilization, addition of sludge to soils, etc., lead to the emission of HMs and their accumulation in ecosystems. Contamination of soils by HMs is a critical environmental concern due to their potential adverse ecological effects. Heavy metals are potential threats for human health and the environment, through their accumulation in the soil, water and in the food-chain (Yadav, 2009). Heavy metals can enter in the human diet and accumulate gradually in the human body. It can result several adverse health effects (e.g. kidney damage or osteoporosis) (Wu et al., 2010). The regulatory limits of Cd, Cu and Zn in agricultural soils...

Interactions of Fungi with Heavy Metals in the Soil Environment

Fungi are able to restrict the entry of toxic metal species into cells by (1) extracellular metal sequestration - binding the metal to siderophores or other fungi-derived metabolites (2) binding it to the cell wall and wall-associated components, and (3) reducing its uptake by intracellular chelation or sequestration. The above defense mechanisms act simultaneously the mycorrhizal fungus Paxillus involutus is able to produce oxalate that binds some extracellular metals. The heavy metals that are not bound come into contact with mycelium and are localized in or near the cell wall, in the vacuoles, and in the cytoplasm. For Cd, its distribution among the three biomass components listed above was 50 , 20 , and 30 , respectively (Blaudez et al. 2000). Similar detoxification systems may act both intra- and extra-cellularly in the case of nickel immobilized by Aspergillus niger, Ni oxalate crystals have been documented in the extracellular fraction as well as in the cell wall and cytoplasm...

Mobilization and Immobilization of Heavy Metals

Malic acid excretion by saprotrophic and mycorrhizal fungi. Ectomycorrhizal fungi can form micropores (3-10 mm) in weatherable minerals, and hyphal tips are able to excrete micro- to millimolar concentrations of these organic acids (Jongmans et al. 1997). Heavy metals can be mobilized during this process as well as during fungal weathering of limestone, sandstone, marble or other minerals (Gadd 2007). The ability to solubilize metals from metal oxides is frequently present among soil micromycetes (e.g., Aspergillus and Penicillium spp.). One-third of 56 soil isolates were able to solubilize either ZnO, Zn3(PO4)2, or Co3(PO4)2, and five strains solubilized all of the compounds (Sayer et al. 1995). In addition, pyromorphite (Pb5(PO4)3Cl) can be solubilized by several organic acid-producing fungi (Sayer et al. 1999). While acidification seems to be the most frequent mechanism of metal solubilization, there are also other mechanisms that involve metal chelation, such as MnO and Zn...

Fungi and Heavy Metals

Most of the results already obtained derive from laboratory and pot experiments, with metal salts used as the source of heavy metals, which are not very representative of natural field conditions, where metals usually accumulate in a less-available chemical form. Heavy metals can delay, reduce, and even completely eliminate AM colonization and AMF spore germination in the field, and a negative correlation between Zn concentrations and AM colonization has been reported in soil treated with urban industrial sludge. In other studies, however, the addition of metal-containing sludge did not significantly affect AM development under field conditions, probably because different AMF ecotypes can exhibit different degrees of metal tolerance. Thus, a relatively high rate of mycorrhizal colonization can be found in plants growing in highly polluted soils. A higher tolerance of Cu, Zn, Cd, and Pb of indigenous fungi from sludge-polluted sites was observed in comparison to those from unpolluted...

Sufficient and Phytotoxic Levels of Heavy Metals in Plants

Heavy metals present in the soil are absorbed by the plants growing in it to either sufficient or phytotoxic levels (Dhillon and Dhillon 1996) (Table 16.2). Table 16.2 Sufficient and phytotoxic levels (mg kg ') of heavy metals in plants (from Dhillon and Dhillon 1996) Table 16.2 Sufficient and phytotoxic levels (mg kg ') of heavy metals in plants (from Dhillon and Dhillon 1996) reduced biomass production. The cultivation of sugarcane adjacent to industrial activity and metal-polluted landfills, and the application of municipal wastes to the soil along with the indiscriminate use of phosphatic fertilizers and pesticides can enhance the levels of toxic heavy metals in the soil, and thus in sugarcane. Therefore, the present chapter describes the effects of heavy metal pollution of the soil on the growth and juice quality of sugarcane.

The Relationship Between Heavy Metals and Earthworms

Over the last few decades, various human agricultural activities (i.e., intensive use of chemical fertilizers and sewage sludges Karaca et al. 2002 Kizilkaya and Bayrakli 2005) as well as industrialization (Cemek and Kizilkaya 2006) have resulted in increased levels of heavy metals in many soils, although heavy metals can also occur lithogenically in unpolluted soils ( zdemir et al. 2007 Tarakcioglu et al. 2006). In most cases, these heavy metals are natural components of the Earth's crust ( zdemir et al. 2007 Tarakcioglu et al. 2006). Whether they have anthropogenic or lithogenic origins, heavy metals can accumulate in the food chain and can be accumulated by soil organisms, thus affecting their biological and biochemical activities, which leads to many environmental problems (Kizilkaya and Askin 2002 Kizilkaya et al. 2004). Since they are a major representative of soil life, earthworms are also negatively influenced by heavy metals, but in contrast to most other members of the soil...

Heavy Metals

In the fundamental review paper written by Duffus (2002), 13 different works were cited that used lower limits on the density of a heavy metal ranging from 3.5 to 7 g cm-3. The author stated that the threshold varied depending on the author, and that it is impossible to come up with a consensus . Moreover, he concluded that any idea of defining heavy metals on the basis of density must be abandoned as yielding nothing but confusion . However, this is beside the point although half of the works cited suggested similar lower limits of 4.5 or 5 g cm-3, plants do not have the ability to detect the density of a metal. Thus, heavy metal remains an obscure term in the life sciences. It should also be noted that the review paper of Duffus (2002) was commissioned by the International Union of Pure and Applied Chemistry, and certainly represents a chemical point of view that is often neglected by biologists. Apart from the specific weight, the atomic weight, the atomic number, specific chemical...

Heavy Metal Toxicity

Differences in toxicity within the body of living organisms (Stohs and Bagchi 1995). Plants are organisms exposed to different kinds of stresses, such as air pollution, drought, temperature, light, heavy metals, salinity, freezing, UV radiation and nutritional limitation. Hall (2002) reported that the toxicity symptoms observed in plants in the presence of excessive amounts of heavy metals may be due to range of interactions at cellular level. The toxic effects may be direct or indirect and appear as metal-induced toxic effect on cell metabolism in terms of enzyme activity, protein structure, mineral nutrition, water balance, respiration and ATP content, photosynthesis, growth and morphogenesis, and formation of reactive oxygen species. Inhibition of plant growth is often used in the environmental tests for toxic heavy metals. Growth inhibition by heavy metals results from metabolic disorders and direct effects on growth, e.g., due to the interactions with cell wall polysaccharides...

Metal Toxicity

The relative toxicity of a heavy metal depends on its availability, which is determined by the properties of the soil and the plant species of interest. Once taken up by the plant, heavy metals interact with different cell components and result in disturbances to the normal metabolic processes. This can cause cell injuries and in some cases the death of the organism (Shaw et al. 2004). The heavy metals with the highest toxicity are those included in class B of Nieboer and Richardson's system (those that bind to ligands containing sulfur and nitrogen). They also exhibit a wide spectrum of toxic mechanisms. No class B metal has ever been found to occur naturally in any enzyme. These metals bond most effectively with SH groups such as cysteine, and with nitrogen-containing groups such as lysine and the active centres of enzymes (Shaw et al. 2004).

Soil Health and Need for Biological Remediation

Contaminated soils around the world have limited value for farming purposes. Affected soil that are excessively polluted become relatively sterile to maximum life forms. Many technologies are currently used to clean up heavy metal contaminated soils. The most commonly used ones are soil removal and land filling stabilization solidification, physico-chemical extraction, soil washing, flushing, bioremediation and phytoremediation. None of above mentioned techniques are completely accepted as best treatment option because either they offer a temporary solution, or simply immobilize the contaminant or are costly when applied to large areas (Jeyasingh and Philips 2005). Productivity of conventional agricultural systems largely depends on the functional process of soil microbial communities. The structure and diversity of microbial communities are influenced by the soil structure and spatial distribution, as well as by the relationship between abiotic and biotic factors of the microbial...

Possible Role of Heavy Metal Tolerant Plants in Remediation

A metallophyte is a plant that can tolerate high levels of heavy metals such as lead, zinc and others. Plants that do well on heavy metal enriched soils can be used in the phytoremediation of polluted areas. The ability of metallophytes to tolerate extreme metal concentrations commends them as the perfect option for ecological restoration of metal-contaminated sites. Metallophyte can be used to stabilize soils against the erosion of the surface soil by wind and rainfall, and they can colonize disturbed areas. Metallophytes can be used to extract heavy metals (Bothe et al. 2010). As discussed above AM Fungi might contribute to metal tolerance. Plant species belonging to plant families Chenopodiaceae, Cruciferaceae, Plumbaginaceae, Juncaceae, Juncaginaceae, Amaranthaceae and few members of Fabaceae are believed not to form a symbiosis with AM fungi (Khan 2005). A detailed review on the role of soil microbes in the rhizospheres of plants growing on trace metal contaminated soils in...

Stocks of Metals and Their Internal Heterogeneity

Key points in the evaluation of stocks are the correct estimation of the volumes of material and of the internal heterogeneity of metals distribution in the volume of interest. This internal heterogeneity is directly correlated with the mineralogy of the material. Geophysical characterization of waste stacks allows the development of structural and then hydrogeological models needed for the evaluation of metals export (part 4). The surface heterogeneity in terms of heavy metals distribution and availability is essential for devising appropriate phytostabilization methods (part 6). Additional information for mining areas comes from the observation that in many cases (although not usually in mining dumps and tailing dams) heavy metals are associated with minerals having strong magnetic properties because of their common genesis, weather of mining or industrial origin (see Hunt et al. 1995, for a review of the magnetic properties of rocks and minerals). Petrovsky et al. (2001) analyzed...

Assessing the Mobility of Metals in Solid Wastes and Contaminated Soils

Metallic oxides, hydroxides, amorphous aluminum silicates, and organic matter (Neagoe et al. 2012) possess reactive surfaces on which heavy metals tend to be selectively adsorbed. To quantify the concentration of heavy metals in this form, it is necessary to use an extractant able to form particularly stable bonds with these elements. Salomons (1995) relates metal speciation to potential relative mobility with the following distinctions exchangeable cations - high mobility metals associated with iron and manganese oxyhydroxides - medium mobility metals bound fixed inside organic substances - medium mobility metals bound fixed inside mineral particles - low mobility metals associated with sulfidic phase -strongly dependent on environmental conditions metals associated with silicate phase - unlikely to be release under the normal weathering conditions.

Microbiological Conditions

A recent review of the mineral-microbe interactions was done by Dong (2010). Also recently, Bini (2010) reviewed the Archaeal transformations of metals in the environment. The relationships between the geomicrobiology of metals and their use for bioremediation were reviewed by Gadd (2010), and the same author had extensively screened the biogeochemical transformations of rocks, minerals, and metals by fungi (Gadd 2007). The ecological relevance of mineral weathering by bacteria in the larger context of soil ecology was done by Uroz et al. (2009). An extensive description of the coupled hydrobiogeochemical processes (where the bio refers strictly to microorganisms) in groundwater for several heavy metals and radionuclides was done recently by Jardine (2008). We refer the reader to these syntheses for details about these processes. In this part of the chapter, we want only to underline the small scale of the ecosystems supported by microorganisms and its consequences for the internal...

Mobilization of Metals by Surface Water Fluxes

Table 3.3 Mineral and phases associated with heavy metals in river sediments (literature compilation reproduced from Hudson-Edwards 2003 with permission) Table 3.3 Mineral and phases associated with heavy metals in river sediments (literature compilation reproduced from Hudson-Edwards 2003 with permission) Although the institutional perspective on heavy metals concentrations and mobility in contaminated river sediments recently prevail as a result of pressure from the implementation of Water Framework Directive (WFD, e.g., Byrne et al. 2010, but for a general methodological approach, see Macklin et al. 2006, or Bird et al. 2010), we believe that this view is far too limiting for understanding the real (not necessarily already regulated) consequences of metals presence mining catchments. Actually even within the WFD context, a more integrated approach for water quality as depending on all sources of metallic substances at catchment levels (not limited to mining areas) is promoted (Chon...

Abundance of REE in the Environment 421 REE in Solids

REE contents in soils are, like the contents of other heavy metals, the result of a variety of processes, including sorption, surface complexation, precipitation, coprecipitation or dissolution, depending on physico-chemical parameters like pH and Eh, on the parent material, fertilization schemes, or input via groundwater (Laveuf and Cornu 2009). For 30 Swedish top soil samples, REE concentrations in the range of 32-183 mg g were measured (Tyler and Olsson 2002). Liang et al. (2005) reported higher concentrations for Chinese soils (85-523 mg g). Astrom et al. (2010) worked on acidic sulfate-rich soils of a boreal landscape and found a total REE content of 197 mg g, whereas Grawunder et al. (2009) reported for

Cation Exchange Capacity

The density of negative charges on the surfaces of soil colloids defines the cation exchange capacity of soil This capacity is governed by the type of clay and the amount of organic colloids present in the soil . Montmorillonitic-type clays have a higher net electrical charge than kaolinitic-type clays consequently, they have a higher cation exchange capacity. Soils containing a high percentage of organic matter also tend to have high cation exchange capacities The surface negative charges may be pH dependent or permanent and to maintain electroneutrality, they are reversibly balanced by equal amounts of cations from the soil solution Weak electrostatic bonds link cations to soil surfaces, and heavy metals can easily substitute alkaline cations on these surfaces by exchange reactions Moreover, specific adsorption promotes the retention of heavy metals, also by partially cova-lent bonds, although major alkaline cations are present in soil solutions at much greater concentrations

Iron and Manganese Oxides

Hydrous Fe and Mn oxides are particularly effective in influencing metal solubility in relatively oxidizing conditions They are important in reducing metal concentrations in soil solutions by both specific adsorption reactions and precipitation Although Mn oxides are typically less abundant in soils than Fe oxides, they are particularly involved in sorption reactions with heavy metals Mn oxides also adsorb heavy metals more strongly, thus reducing their mobility This action is particularly important in contaminated soils The specific adsorption of metals by hydrous oxides follows the preferential order Pb Cu Zn Cd .

Conclusions and Outlook

The bacterial mobilization of heavy metals and radionuclide are poorly understood processes (Ruggiero et al. 2005). Microorganisms may, in principle, be advantageous and biotechnologically beneficial when occurring in the rhizosphere of metal-tolerant plants (special hyperaccumulator plants), thereby facilitating phytoremediation processes (Vassilev et al. 2004 Yang et al. 2005). Interaction of metal ions with biological matter is essential as well as important for various biological processes for all organisms (Sigel and Sigel 1996), and in related fields (biogeochemistry, bioremediation and phytoremediation, biomining, biotechnology of metal extraction, sorption and recovery, etc.). It can hardly be overemphasized that lack of understanding of molecular mechanisms underlying the effects of soil microorganisms and plant-root exudates on the state of metal compounds in the rhizosphere is a serious impediment in use of phyto-bioremediation technology for cleaning heavy soils...

Estimating Elements Loss by Runoff

Nutrients such as N, K, P, and other agricultural chemicals are released from a thin layer of surface soil that interacts with rainfall and runoff. In chemical transport models, the thickness of the interaction zone is determined by model calibration with experimental data, with depths ranging between 2 0 and 6.0 mm (Donigian et al ., 1977) . Frere et al. (1980), however, suggested an interaction zone of 10 mm, assuming that only a fraction of the chemical present in this depth interacts with rainfall water In previous studies in this laboratory, Elrashidi et al (2003, 2004, 2005a,b, 2007a,b, 2008, 2009) successfully used a fixed soil thickness of 10 mm to estimate the loss of nutrients and heavy metals by runoff from agricultural land

Streptomycetes in Soil

The oxidation of pyrite is accelerated by orders of magnitude due to the action of iron or sulfide oxidizing bacteria, e.g., Acidithiobacillusferrooxidans, Leptospirillium ferrooxidans and Ferroplasma acidiphilum or F. acidarmanus (Banks et al. 1997 Rawlings 2002). The resulting acid and sulfate production, as well as the release of rare earth elements, heavy metals and arsenic, are characterizing acid mine drainage (Fig. 9.2) and acid rock drainage (Banks et al. 1997 Kothe et al. 2005 Liang and Thomson 2009).

Heavy Metal Resistant Streptomycetes in Soil

Microorganisms developed both intracellular and extracellular defense mechanisms to cope with heavy metals in the environment (Fig. 9.4). One strategy is the adsorption of metals to extracellular surfaces to reduce the available metal concentration in the surroundings. This process of biosorption is due to binding of metals to cell wall components, and this process is specifically predominant in gram-positive bacteria, while in gram-negative bacteria an outer membrane is protecting the cell wall surface 2009a). The production of, e.g., melanin-like pigments can be involved in metal resistance and protection from resulting oxidative stress in cells encountering heavy metals. Intracellular storage by binding to chaperone molecules, storage proteins or small peptides like metallothioneins and metallohistins can sequester metals and protect cells from their toxic effects even after uptake of heavy metals into the cytosol (Schmidt et al. 2010). After entering the cell by unspecific uptake,...

Extracellular Chelators

Extracellular metal binding, e.g., polysaccharides or proteins, can immobilize metals and thereby prevent the cells from metal toxicity by complex formation. Microorganisms, fungi, and plants developed different strategies to scavenge and adsorb essential metals from the environment. Since many metals are essential, these include both accumulation and protection mechanisms.

Intracellular Sequestration

In addition to peptides, intracellular phosphates can sequester metals by ionic interactions. The fungus Cladosporium cladosporioides, e.g., revealed intracellular crystals of manganese and phosphor (1.6 1) on 15 mM MnSO4of a size ranging from few nm to 200 nm (Shao and Sun 2007). Pseudomonas aeriginosa was able to accumulate nickel as phosphide and carbide crystals in the perimplasm (56 ), in the membrane (30 ) and in cytoplasm (11 ) on 0.4 mmol l Ni (Sar et al. 2001). Within the cytosol of the heavy metal-resistant S. acidiscabies E13, the main amount of nickel was eluted with almost no protein but high phosphorous content indicating an intracellular binding of nickel to reduce metal toxicity (Schmidt et al. 2007). In general, intracellular accumulation of heavy metals is widespread in bacteria and could also be shown for streptomycetes, especially by intracellular phosphates, which could have special relevance to remediation directly of contaminated environments.

Role of Mycelium in Heavy Metal Stress Alleviation

More than 95 of ECM trees are ensheathed by a mycelial mantle around the short root. Nutrients, water and elements released from the soil to the plant are transported by the fungus, including ECM fungi rather than root tips responsible for contact to soil and nutrient equisition (Smith and Read 2008). As shown in Fig. 10.1, the mycelial mantle can play a role as a filter accumulating heavy metals and protecting plants from toxic effects. The abundance of the extramatrical mycelium was shown to be important for heavy metal (HM) binding by the fungus. Most of the HMs were demonstrated to be bound to cell wall components like chitin, cellulose, cellulose derivatives, and melanin. The chemical nature of HM binding within the fungal cells is less clear. Polyphosphate granula, which were proposed to have this function, seem to be artifacts of specimen preparation. The high N concentrations associated with the polyphosphate granules rather indicate the occurrence of HM-thiolate binding by...

Effect of Metals on ECM Communities

Dormant spore banks or other resistant propagules (Izzo et al. 2005 Nara 2006b). Mycorrhizal fungi that colonize podzolic acidic soils can be exposed to high levels of toxic metals such as Al, Fe, and Mn. For a successful symbiosis, both partners must be able to withstand the metal toxicity during all stages of colonization. We assessed the distribution of ECM in a 15-year-old oak (Quercus robur) mixed forest on podzol with acidic pH of 2.85-3.40 near Greiz, Germany. The results show that the observed abundance of ECM types was lower than on alkaline or slightly acidic substrates. The statistical analysis by canonical correspondence analysis indicated that a group of heavy metals, including Al, Cr, Fe, and Pb, strongly contributes to the reduced abundance of ECM fungi Laccaria amethystina, Paxillus involutus, or brown rhizomorphs. Russula ochroleuca, Lactarius quietus, and Pisolithus tinctorius were in sharp disagreement with these heavy metals but correlated positively with Mn, Cd,...

Ore Deposits of Mitterberg Hochkonig

Later, chalcopyrite and ankerite were translocated at higher temperatures. (3) During the Alpine orogenesis, heavy metals were mobilized again and deposited in joints as chalcopyrite, fahlore (Cu-As ores) and ankerite. These mobilization processes also enriched uranium next to the joints, which had its origin in the neighboring rocks. The northern deposits (2) and (3) are partly covered by limestones of the Hochkonig. Younger ore joints frequently penetrate ones (Bernhard 1965 Siegl 1972 Tollmann 1977).

Prehistoric Mining at Mitterberg Hochkonig

After intensive archeological studies, the mining and smelting techniques were reconstructed in detail ore was loosened by tools made from stone or bronze, but especially by heating the stone with fire, followed by sudden chilling with cold water. Ore was hand-picked from the excavated rocks in situ waste rock was discarded and deposited. Metal extraction was incomplete and as a result, spoil contained high concentrations of heavy metals, and those spoil heaps have remained virtually barren ever since. Ore was processed at Troiboden and in several other places (Henselig 1981 Sperl 1987). Remains of the furnaces and intermediate products enabled the reconstruction of the metallurgical process (Herdits 1997) roasting of the sulfidic ores, predominantly chalcopyrite and fahlore, resulted in the formation of matte (Cu2S and different Fe oxides). Matte was oxidized by the blast, resulting in the emission of SO2, the formation of reduced copper and slag containing FeO and silicate flux....

Troiboden Mitterberg Hochkonig

Ecologically relevant remains of prehistoric mining form different habitats. Although the copper-tolerant vegetation shows certain differences, it is always dominated by Silene vulgaris and is allocated to the alliance Galio anisophylli-Minuartion vernae (Ernst 1974 the validation of this syntaxon was later questioned by Punz and Mucina 1997). Silene vulgaris was shown to accumulate up to 235 mg kg-1 Cu (compare 0), whereas Vaccinium myrtillus or Picea abies exclude heavy metals virtually completely (Mutsch 1980). Four types of habitats can be distinguished and were described in detail by Korber-Ullrich 1996 2. Two smelting sites are characterized by a red substrate clearly distinguished from the peaty soil in the surroundings. At one smelting site, 1,100 mg kg-1 Cu is found in the periphery, compared to 4,730 in the center in the other, the Cu content is rising from 2,700 mg kg-1 at the upper to 8,100 mg kg-1 at the lower end. The most contaminated areas carry only lichens such as...

Heavy Metal Localization Translocation and Distribution in Wetland Plants

Weis and Weis (2004) reported that the root epidermis served as a barrier to transport of Pb to above-ground tissues, but not to the other metals The endodermal casparian strip provided a barrier to the movement of all three metals into the stele . Heavy metals in the leaves were highest in the order of xylem mesophyll hypodermal tissue . In the cell walls, heavy metal concentrations were also higher than in intracellular locations (Weis and Weis, 2004)

Characteristics of Vegetation

Toxic concentrations of heavy metals in the soil, properties of a poorly developed soil as well as low nutrient status, and water-deficiency conditions maintain physiognomy, structure, and floristic composition of vegetation on mine spoil heaps (Banasova et al. 2006 Ernst 1974). It is the characteristic that annual plants show neither vigor nor persistence on metalliferous soils (Baker et al. 2010). The specific feature of plant communities on mine heaps in both sites is the prevalence of perennial vascular plants and non-vascular lichens and mosses. High heavy metal concentrations are too toxic for expanding of trees. Extreme ecological conditions retard natural succession. Sporadically dwarf trees of Betula pendula, Salix caprea or Picea excelsa could be found. Although the surrounding meadows are species-rich, the number of inhabited species on the heaps has been restricted because of the low potential of most plants to evolve metal resistance and to survive there (Banasova et al....

Heavy Metal Release by Wetland Plants

Heavy metal release by plants can increase the bioavailability of heavy metals within estuaries, especially in urban and industrialized areas (Berk and Burke, Weis, and Weis (2000) reported leaf excretion by Spartina alterniflora and Phragmites australis growing together in the same sediment in a contaminated area of the Hackensack Meadowlands in northern New Jersey. Leaves of S. alterniflora were found to release two to four times more Pb, Cu, Cr, and Zn than leaves of P australis at the peak of the growing season Leaf concentrations of Cu and Zn were comparable in the leaves of the two species, while S alterniflora had higher leaf concentrations of Pb and Cr Thus, S alterniflora can release larger quantities of heavy metals into the wetland environment than P australis

Characteristics of Arabidopsis arenosa Rumex acetosella and Their Relations to Zn Pb Cd and Cu

Tolerance of metal toxicity can be demonstrated at different levels in cells, tissues, and organs of a plant (Ernst et al. 1992). Plant roots are directly exposed to negative effects of toxic heavy metal ions. Changes in their growth is one of the fastest and most obvious responses of plants to toxic concentrations of heavy metals, and they can be measured easily (Appenroth 2010 Macnair 1993). Determining root growth exposed to increasing heavy metal concentrations is an effective method for assessing the degree of tolerance of this kind of stress. However, as the root length is not a direct measure of tolerance and, sensitivity to metal ions can change with plant age, it is reasonable to consider more parameters to characterize plant tolerance.

Hyperaccummulation A Key to Heavy Metal Bioremediation

Industrialization, along with numerous benefits, brought up important issues such as environment awareness and environment protection. Strict regulations compel industries to find ways to limit the discharge of pollutants into the environment or to use eco-friendly approaches to clean up contaminated sites. Heavy metals are challenging pollutants, as they are natural components of the earth's crust, they are persistent in the environment and are nondegradable. Regarding the interaction with the living organisms, they have a dualistic behavior. On the one hand, many of the heavy metals are essential in minute amounts for the normal metabolism, binding to and stabilizing biomolecules, or acting as cofactors for various enzymatic processes. On the other hand, heavy metals can be toxic in high concentrations, mainly by nonspecific binding to biomolecules or by intereference to other metals' metabolism. The sources of heavy metal pollution can be industrial effluents, automobile...

Hyperaccumulation as a Primary Tool for Heavy Metal Bioremediation

Metal bioremediator would have the following characteristics tolerance to nonphysiological metal concentrations, abundant growth on in the contaminated site, hyperaccumulating capacity, and facile separation from the bioremediated site. Nevertheless, heavy metals inhibit very often the biological remediation processes due to metal sensitivity of most organisms. Under such circumstances, strategies for efficient operation have to be considered and heavy metal hyperaccummulating plants seem to be the best models to follow when designing or developing a suitable heavy metal bioremediator. Hyperaccumulation was a term first used by Brooks et al. (1977) for plants that are endemic to metalliferous soils and are able to tolerate and accumulate metals in their above-ground tissues. Metal hyperaccumulator plants are naturally capable of accumulating trace elements, in their above-ground tissues, without developing any toxicity symptoms (Baker 2002 Baker and Brooks 1989). The concentrations of...

The Structure of the Organic Matter

(2004) and their general appreciation underlined the fragmentary and often inconsistent existing knowledge. The major sources of OM in soil are plants and microorganisms. Plant litter and its particulate form decomposition products (Berg and McCluagherty 2008) play a major role in metal immobilization in top soil. On the other hand, DOM turnover is dominated by microorganisms, directly and by exuded compounds, although in the rhyzosphere the plants seem to play an equally important role by the root exudates. Of the total DOM in a lake, 78 originated from bacteria, compared to 50 in a forest soil (Schulze et al. 2005). Heavy metals in aqueous solution have an influence on the biodegradability of OM, either by toxicity (reduction of degradation rate), or by flocculation (increase of degradation rate by facilitating the attachment of microbial colonies on larger organic structures) (Marschner and Kalbitz 2003).

Role in the Mobilization of Metals

Molecular account of the interactions between organic matter and metals in the context of aqueous chemistry was given by Dudal and Gerard (2004). Trace element transport and transport pathways in soil, factors influencing mobility and transport models have been reviewed by Carrillo-Gonzalez et al. (2006). Zhou and Wong (2003) reviewed the effects of DOM on the behavior of heavy metals in soil. In a soil amended with sewage sludge, the OC had an indirect effect on metal mobility by determining a disaggregation of soil macro-aggregates responsible for the accumulation of heavy metals in the coarsest fraction (Parat et al. 2007). Another interesting finding in field experiments with sewage sludge was the importance of space-time variations of OM distribution on the mobility of Cu, Ni, and Pb, when increase of mobility of these elements especially at high pHs was noticed (Ashworth and Alloway 2008). In an attempt to simulate the fate of tailings placed above alluvial soils, Flores and...

Restoration Techniques Used in Poland Versus Spontaneous Succession

Phytostabilization is the only feasible strategy to reduce the toxic potential of industrial wastes (Pierzynski et al. 2000) because it minimizes wind and water erosion as well as the uptake of heavy metals by plants. The tailing has the form of a steep hill. The oldest wastes are localized at the base while the younger layers are deposited progressively above. The restoration of the tailing includes covering it with a ca. 20-cm layer of humus. The use of soil without heavy metals is usually avoided as it is costly when the area is large. The thickness of the material varies from 20 cm to 2 m in places where the material slides down into local depressions as a result of water erosion. There are two important reasons for using this humus layer procedure. (1) Such a layer allows for easier establishment of the vegetation by arresting the factors which limit plant growth. (2) In this way, the transfer of heavy metals into the plant material will be diminished. In toto, almost 100 plant...

Use of Xerothermic Plants for Restoration

Despite the recent data outline, little is known about how individual plant species survive on wastes. Therefore, we engaged in research designed to introduce a wide group of plants from the calcareous grassland (Turnau et al. 2008). Plants were selected on the basis of floristic studies, and the seeds originated from dry calcareous grasslands or from private gardens where such plants were cultivated to obtain seeds. The seeds were germinated under laboratory conditions and introduced into soils with industrial wastes to adapt the seedlings to the presence of heavy metals. Plants of a few weeks were introduced into the tailing. The survival of most plant species in the first year was 100 . These included mycorrhizal plants such as Melica transsilvanica, Bromus inermis, Agrostis capillaris, Agropyron intermedium, Brachypodium pinnatum, Cirsium pannonicum, Ononis arvensis, and Verbascum thapsus. Nonmycorrhizal were Echium vulgare and Carex spp., although they were colonized by dark...

Molinia caerulea as a Colonizer of the Bare Substratum

These bulb-shaped structures can release nutrients more than once in spring, allowing regrowth after drought periods. Once established, Molinia persists in increasing biomass and tussock diameter, which leads to changes in local soil conditions as erosive processes become less threatening and increased organic matter accumulation improves microbial activity. Furthermore, M. caerulea is among the plants which take up relatively few heavy metals as compared to other plants growing in the tailings. TXRF analysis of M. caerulea (unpublished data) show higher concentrations of Pb, As, and Zn, lower concentrations of Sr, Rb, Fe, Mn, and Ti, and no statistical differences in Cu and Ni concentrations in shoots in comparison with samples from heavy-metal-poor soil. Low concentration of heavy metals in grasses is probably the result of relatively small amount of polysaccharides that can bind Ca and heavy metals within intercellular spaces (Broadley et al. 2003)....

CrVI CuII and CdIIResistant Actinomycetes 1721 Isolation and Selection

To find actinomycete strains for cadmium bioremediation purposes, 46 strains were isolated from two contaminated places and one noncontaminated place eight from the soils of a former uranium mine polluted with several heavy metals and four from the Rio Hondo Dam, Tucumin state, Argentina, polluted by effluents from sugar mills, paper industry, mining, etc. Thirty-four colonies were isolated from the marine sediments from Ushuaia, considered nonpolluted. The unpolluted site was chosen to isolate actinomycetes, which could serve to look for presence of resistance mechanisms against cadmium in strains coming from pristine sites. A qualitative screening assay was carried out in Petri dishes containing MM agar medium containing (in g L-1) glucose, 10.0 L-asparagine, 0.5 K2HPO4, 0.5 MgSO47H2O, 0.20 FeSO4 7H2O, 0.01 agar 15 (Amoroso et al. 1998). Rectangular troughs were cut in the center of plates and filled with 5 mM filter - sterilized solution of Cr(VI) as K2Cr2O7, CuSO4 16,40 and 80 and...

Diversity of Fungal Fruiting Bodies at the Test Field Site

Nitrophilic species (Lange 1982, 1991), such as Marasmius oreades, Lycoperdon pretense, Leucoagaricus leucothites, and certain Agaricus species are especially abundant, indicating the influence of the surrounding agriculture. However, certain parts of the study area are rather dominated by nitrophobous (Lange 1982, 1991) species, such as Rickenella fibula and Entoloma sericeum. These species accompany more open vegetation dominated by mosses and lichens rather than herbs. This indicates a heterogenous distribution of nitrogen. On the test field plots, fruiting bodies of nitrophilic species are becoming more abundant with the addition of nutrient-rich substrates. While on the control plot fruiting bodies were never observed, addition of top soil led to occasional growth of Agaricus semotus, which is known from humus-rich habitats (Vellinga 2001). The compost plot yielded abundant fruiting bodies of Leucoagaricus leucothites and Cyathus olla, both clearly...

Methods of Determination of Heavy Metal Forms Single Chemical Extraction

The forms of HMs in biosolids are usually studied by selective chemical extraction techniques . The HM fractions defined by these methods are those representing soluble, exchangeable, organic, adsorbed, and precipitated forms The soluble forms of heavy metals in biosolids can be determined using a simple extraction with water The procedure has been performed with variations by Jenkins and Cooper (1964), and Bloomfield and Pruden (1975), who applied repeated percolation through columns that contained biosolids with water by Lagerwerff, Biersdorf, and Brower (1976), who used tap water and by Emmerich et al (1982), who used river water The concentration of heavy metals (percent of total) found in the above cases ranged from

Cd Cr and Pb Accumulation in Fungi at the Test Field Site

Our results underline the relevance of fungi for element cycling, especially at contaminated habitats. Their partly immense metal uptake capacities and resistances suggest an important role through modification of soil element mobility and distribution of heavy metals through the food chain. It also makes use of fungal fruiting bodies for mycoremediation approaches attractive. absolute values within subplots was quite high. Thus, yearly differences are not significant. Apart from an exceptionally high Pb values on the C2 subplot in 2008, and a very low Cd uptake on the MS1 plot in 2008, uptake of the three tested metals remained within the same order of magnitude. Uptake occurred in a similar pattern, even in fruiting bodies outside the test field. Exceptions are the C2 and MS1 plots in 2008. Correlation, indicated by Pearson's r, was always higher than 0.98. Additionally, Cr and Pb uptake were correlated in these samples (Pearson's r 0.88). Assuming that translocation to fruiting...

Heavy Metal Fractions in Biosolid Amended Soils

Growth, and the concentration of potentially toxic heavy metals Tsadilas et al (1995) reported that the application of biosolids on acidic soil increased the pH to about 7 0 and then tended to retain it at this value They also found that the application of biosolids increased the soil electrical conductivity and organic matter content A significant reduction in soil pH due to the application of biosolids was reported by several other researchers (Hinesly, Jones, and Ziegler, 1972 Emmerich et al , 1982, and references therein) Epstein, Taylor, and Chaney, (1976) reported that biosolid application increased the water retention capacity of soil, the salinity, and cation exchange capacity, and reduced the redox potential (Eh) . Gerritse et al . (1982) found a significant effect of biosolids in the Eh of biosolid solutions . Williams et al . (1987) reported that biosolid application on soil changed its pH, while reducing its bulk density. Regarding the influence of biosolids on the...

Bioremediation and Heavy Metal Uptake Microbial Approaches at Field Scale

Pollution of the biosphere with toxic heavy metals is a widespread ecological problem resulting from anthropogenic activities such as fossil fuel burning, ore mining and smeltering, industrial and municipal waste disposal, and agricultural activities (Nriagu 1979 Adriano 2001 Kratz and Schnug 2006). In Western Europe alone, about 300,000 sites have been contaminated with heavy metals (Gade 2000 McGrath et al. 2006). The retention time of metals in soil is thousands of years because, unlike organic pollutants, metals are not degraded biologically. They rather are transformed from one oxidation state or organic complex into another and therefore persist in soil (Gisbert et al. 2003). However, the mobility of (heavy) metals may change, resulting in wash-out into ground and surface waters or uptake into plants via microbial physiological processes. While the major metal contamination is specific for each site, most operations will lead to multimetal contamination, which in most cases...