Land reclamation using earthworms in metal contaminated soils

This chapter analyzes the use of earthworms for land reclamation, with special emphasis on metal-contaminated soils. The rapid industrial development of modern society has drastically altered the soil environment and negatively affected earthworm populations. Earthworms may be used to reclaim lands made derelict through human activity. Besides serving as valuable indicators in soil ecotoxicological evaluation and risk assessment, earthworms play an important role in terrestrial ecosystems by improving soil physical structure, soil fertility, and plant growth. For successful reclamation of metal-contaminated soils, it is necessary to improve unfavorable physical and chemical conditions of the substrates to allow plant establishment. Inoculation of earthworms into metal-contaminated soils can accelerate plant growth resulting in higher yields, increase nutrient and metal bioavailability, and enhance metal uptake by plants. Addition of earthworms to reclaimed soils is also essential for improving soil biodiversity and ecosystem sustainability. The role of earthworms in reclaiming heavy metal-contaminated soils is described in the chapter. Effects of earthworms on metal speciation and bioavailability are also elaborated in the chapter, along with the trials of earthworm inoculation for the reclamation of Pb/Zn mine tailings from Lechang (China). Copyright © 2008 Elsevier B.V. All rights reserved.