Earthworm-mediated Remediation and Mitigation of Heavy Metals Toxicity in Plants

Earthworms are the ecosystem engineers that convert waste into vermicompost. The vermicompost is further utilized to improve the soil's organic composition, condition, and health. Recently, earthworms have been explored as an effective, efficient, and eco-friendly remediation approach called ‘vermiremediation’ to mitigate the toxic elements from the soil. The soil contains different types of essential or non-essential elements. The presence of these elements above threshold levels in the soil leads to its contamination. The major soil contaminants include xenobiotic compounds, agrochemicals, and heavy metals. The plants exposed to higher amounts of heavy metal-containing soils show symptoms of metal-induced phyto-toxicities that result from the loss of soil fertility, disturbance in nutrient uptake and translocation, and interruption in the regular physiological functions of affected plants. To overcome heavy metal-induced toxicities in plants and soils, the treatments of earthworms, either alone or in combination with PGPR or other soil amendments, are being tried. The present chapter is an attempt to compile information about phytoremediation and vermiremediation, distribution of earthworms in contaminated soils, remediation and amelioration of heavy metals by earthworms, and factors affecting bioaccumulation of heavy metals in earthworms.