Different strategies to enhance the bioavailability of heavy metals in the soil are also discussed shortly. Recent literature is gathered to critically review the sources, hazardous effects of toxic heavy metals and environmentally sustainable phytoremediation technique for heavy metal polluted soils to offer widespread applicability of this green technology. There are different types of phytoremediation including, phytostabilization, phytostimulation, phytotransformation, phytofiltration and phytoextraction, the latter being most extensively acknowledged for remediation of soils contaminated with toxic heavy metals. Phytoremediation is an emerging technology implementing green plants to clean up the environment from contaminants and has been considered as a cost-effective and non-invasive alternative to the conventional remediation approaches. Conventional techniques for reclamation of such soils are expensive and environmental non-friendly. Therefore, decontamination of heavy metal contaminated soils is very important to reduce the associated risks and for maintenance of environmental health and ecological restoration. The present work aims to review the progress of recent research on the isolation, identification and diversity of metal resistant endophytic bacteria and illustrate various mechanisms responsible for plant growth promotion and heavy metal detoxification/phytoaccumulation/translocation in plants.ДЄbstract: Soil contamination with toxic metals is a widespread environmental issue resulting from global industrialization within the past few years. Besides, they also alter metal accumulation capacity in plants by excreting metal immobilizing extracellular polymeric substances, as well as metal mobilizing organic acids and biosurfactants. Endophytic bacteria improve plant growth in metal polluted soils in two different ways: 1) directly by producing plant growth beneficial substances including solubilization/transformation of mineral nutrients (phosphate, nitrogen and potassium), production of phytohormones, siderophores and specific enzymes and 2) indirectly through controlling plant pathogens or by inducing a systemic resistance of plants against pathogens.

In recent years, phytoremediation assisted by bacterial endophytes has been highly recommended for cleaning up of metal polluted soils since endophytic bacteria can alleviate metal toxicity in plant through their own metal resistance system and facilitate plant growth under metal stress.

This process is experimental and the keywords may be updated as the learning algorithm improves.Abstract: Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up pollutants from the soil, water and air. These keywords were added by machine and not by the authors. The sacred spaces and the hierarchy of authorities that existed in Iron Age agrarian Igbo society, as well as its cosmology centered on the earth-goddess (Ala/Ana), were further used to affirm the politico-religious accomplishments of Igbo mini states and the interconnectedness of religious and political power in the forest region of Nigeria and other parts of the world. Thus, for example, when the early inhabitants of Igboland shifted from foraging to agriculture, their politico-religious organization changed from a stateless system to mini states, which acquired increasing complexity during the Iron Age, culminating in the development of the Igbo-Ukwu mega state during the ninth-tenth centuries. To further illustrate the fruitfulness of the diachronic approach, its variables were identified and applied in explaining the broad changes that occurred in Igbo history over time. The book also delved into methodological problems, calling attention to the limitations of the existing synchronic studies and the contributions the diachronic approach has made in advancing our knowledge of the African past, including the history of the so-called stateless societies. It began with discussing the ecological background of the Igbo and the antiquity and complexity of their cultural history as evidenced by their traditions of origins and migrations and the classifications of Forde and Jones. This book has attempted to present an overview of Igbo history from the Late Stone Age to modern times.

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