Heavy metals, occurrence and toxicity for plants: A review

Environmental Chemistry Letters (Impact Factor: 1.91). 09/2010; 8(3):199-216. DOI: 10.1007/s10311-010-0297-8

ABSTRACT Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity
in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper,
lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy
metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability,
crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic
activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil.
This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and
relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing
in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various
physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and
tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including
copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when
metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This
review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.

KeywordsHeavy metals-Environment-Toxic effects-Plants-Anthropogenic activities

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Available from: Sreekanth Tvm, Jan 03, 2014
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    • "Normal levels of Cd in uncontaminated soils range from 0.01 to 0.7 mg/kg (Nagajyoti et al., 2010; Sanit a di Toppi and Gabbrielli, 1999), but this threshold is often exceeded because of several human activities. Cd 2þ competes with other cations for root intracellular access, using the same membrane transporters for the uptake of essential ions, such as "
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    ABSTRACT: Over time, anthropogenic activities have led to severe cadmium (Cd) and arsenic (As) pollution in several environments. Plants inhabiting metal(loid)-contaminated areas should be able to sequester and detoxify these toxic elements as soon as they enter roots and leaves. We postulated here that an important role in protecting plants from excessive metal(loid) accumulation and toxicity might be played by arbuscular mycorrhizal (AM) fungi. In fact, human exploitation of plant material derived from Cd- and As-polluted environments may lead to a noxious intake of these toxic elements; in particular, a possible source of Cd and As for humans is given by cigarette and cigar smoke. We investigated the role of AM fungus Funneliformis mosseae (T.H. Nicolson & Gerd.) C. Walker & A. Schüßler in protecting Nicotiana tabacum L. (cv. Petit Havana) from the above-mentioned metal(loid) stress. Our findings proved that the AM symbiosis is effective in increasing the plant tissue content of the antioxidant glutathione (GSH), in influencing the amount of metal(loid)-induced chelators as phytochelatins, and in reducing the Cd and As content in leaves and roots of adult tobacco plants. These results might also prove useful in improving the quality of commercial tobacco, thus reducing the risks to human health due to inhalation of toxic elements contained in smoking products. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    Plant Physiology and Biochemistry 04/2015; 92. DOI:10.1016/j.plaphy.2015.04.001 · 2.35 Impact Factor
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    • "Cd is a particularly hazardous heavy metal because it can be accumulated by plants to levels toxic to humans and animals when consumed even in small amounts [6] [7]. The transfer of Cd to agricultural areas in the vicinity of the mine therefore poses a major human health risk and also impacts on the environment [7] [8]. "
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    ABSTRACT: This paper reviews contamination status, sources and remediation of Cd in agricultural land in Mae Sot District, Tak Province, Northwestern Thailand. The Cd contamination became an environmental issue because mining of a Zn deposit area located uphill of the Mae Tao creeks caused movement of Cd and Zn along the creek to contaminate agricultural soils downstream. Blood Cd levels of residents in this contaminated area were found to exceed the national average of 0.5 µg g-1 creatinine. The main route of Cd exposure in this area is the consumption of rice locally grown in this Cd contaminated area. Remediation of Cd-contaminated soils is therefore necessary to reduce public health risks. Remediation technologies considered include chemical remediation and phytoremediation.
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    • "In view of its toxic nature, many heavy metal ions are grouped as hazardous pollutants causing adverse effects to human kind. These highly toxic heavy metal ions such as chromium (Cr), Pb, Cd, iron (Fe), mercury (Hg), etc. [1] [2], lead to carcinogenic side effects when their concentration is higher than the permissible limits [3] [4]. Pb(II) and Cd(II) ions have been identified as one of the most toxic heavy metal ions due to their detrimental effects on the human nervous system, blood circulation, kidneys and reproductive system. "
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    ABSTRACT: Graphene manganese ferrite (MnFe2O4-G) composite was prepared by a solvothermal process. The as-prepared graphene manganese ferrite composite was tested for the adsorption of lead (Pb (II)) and cadmium (Cd(II)) ions by analytical methods under diverse experimental parameters. With respect to contact time measurements, the adsorption of Pb and Cd ions increased and reached equilibrium within 120 and 180 mins at 37 °C with a maximum adsorption at pH 5 and 7 respectively. The Langmuir model correlates to the experimental data showing an adsorption capacity of 100 for Pb (II) and 76.90 mgg−1 for Cd (II) ions. Thermodynamic studies revealed that the adsorption of Pb and Cd ions onto MnFe2O4-G was spontaneous, exothermic and feasible in the range of 27°- 47 °C. Cytotoxicity behavior of graphene against bacterial cell membrane is well known. To better understand its antimicrobial mechanism, the antibacterial activity of graphene and MnFe2O4-G nanocomposite was compared. Under similar concentration and incubation conditions, nanocomposite MnFe2O4-G dispersion showed the highest antibacterial activity of 82%, as compared to graphene showing 37% cell loss. Results showed that the prepared composite possess good adsorption efficiency and thus could be considered as an excellent material for removal of toxic heavy metal ions as explained by adsorption isotherm. Hence MnFe2O4-G can be used as an adsorbent as well as an antimicrobial agent.
    Applied Surface Science 02/2015; 327:27. DOI:10.1016/j.apsusc.2014.11.096 · 2.54 Impact Factor
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