Remediation Mechanisms of Tropical Plants for Lead-Contaminated Environment
Heavy metals, especially lead, are major environmental pollutants that pose a serious threat to the environment and human and animal health. Series of approaches is being practised in order to reclaim land contaminated with lead. Phytoremediation offers t
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Remediation Mechanisms of Tropical Plants for Lead-Contaminated Environment Olabisi Peter Abioye, Udeme Joshua Josiah Ijah, and Sesan Abiodun Aransiola
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Introduction
Heavy metals are a unique class of toxicants since they cannot be broken down to nontoxic forms. Concentration of these heavy metals has increased drastically, posing problems to health and environment, since the onset of the industrial revolution. Once the heavy metals contaminate the ecosystem, they remain a potential threat for many years (Jabeen and Ahmad 2012). The threat of heavy metals to human and animal health is aggravated by their long-term persistence in the environment (Gisbert et al. 2003). For instance, Pb, one of the more persistent metal, was estimated to have soil retention time of 150–5,000 years and was reported to maintain high concentration for as long as 150 years after sludge application to soil (Nanda Kumar et al. 1995). Lead (a chemical element with symbol Pb) is a silvery-white highly malleable metal. Among its physical properties, at normal environmental conditions this metal is presented in the solid state and is dense, ductile, and very soft with poor electrical conductivity when compared to most other metals. The chemical symbol for lead (Pb) is an abbreviation of the Latin word plumbum, meaning soft metal. Pb is rarely found in native form in nature, but it combines with other elements to form a variety of interesting and beautiful minerals. Galena, which is the dominant Pb ore mineral, is blue-white in color when first uncovered but tarnishes to dull gray when exposed to air. Archeological research indicates that Pb has been used by humans for a variety of purposes for more than 5,000 years. In fact, archeological discoveries found glazes on prehistoric ceramics. The Egyptians used grounded
O.P. Abioye (*) • U.J.J. Ijah • S.A. Aransiola Department of Microbiology, Federal University of Technology, P.M.B. 65, Minna, Niger State, Nigeria e-mail: [email protected] D.K. Gupta (ed.), Plant-Based Remediation Processes, Soil Biology 35, DOI 10.1007/978-3-642-35564-6_4, # Springer-Verlag Berlin Heidelberg 2013
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Pb ore as eyeliner with therapeutic properties and cosmetic kohl; Pb-based pigments were used as part of yellow red and white paint. In ancient Rome, Pb was used to build pipes for water transportation (Rehren 2007). Plants are the target of a wide range of pollutants that vary in concentration, speciation, and toxicity. Such pollutants mainly enter the plant system through the soil (Arshad et al. 2008) or via the atmosphere (Uzu et al. 2010). Among common pollutants that affect plants, lead is one of the most toxic and frequently encountered (Cecchi et al. 2008; Grover et al. 2010; Shahid et al. 2011). Lead continues to be used widely in many industrial processes and occurs as a contaminant in all environmental compartments (soils, water, the atmosphere, and living organisms). The prominence of environmental lead contamination results both from its persistence (Islam et al. 2008; A
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