Nanomaterials in the bioremediation of metal-contaminated soils

Abstract Soil is an essential component required for the sustenance of life. It supports the vital requirements of living beings by modulating a number of important services such as crop production, storage, recycling and transformation of nutrients, water, and substances, carbon sequestration, maintenance of biodiversity pool in terms of habitats, species, and genes. Crop production has a dependency on the soil quality and soil health. Unfortunately, soil quality and soil health is damaged by the increasing anthropogenic activities such as urbanization and industrialization drive, excessive dumping of agrochemicals in soil during intensive farming, release of waste water effluents containing toxic elements, and dumping of electronic waste containing heavy metal contaminants into soil. This chapter aims to describe a comprehensive picture of different nanomaterials used as soil amendments in the alleviation of the detrimental effects of heavy metal-contaminated soils on crop plants. In addition, the impact of different nanoamendments applied to soil has been reviewed in terms of their positive and negative effects on soil microbiota, especially the interaction between nanomaterials and beneficial soil microbes (arbuscular mycorrhizal fungi, plant growth-promoting bacteria), and soil enzymes, and on plant nutrition, crop growth, and productivity. The knowledge embedded in this review would help in designing sustainable strategies for enhancing crop productivity and minimizing bioaccumulation of heavy metals in crop plants and their subsequent biomagnification in the food chain in metal-stressed soils, without expanding the negative footprints of toxic metals in the environment by using minimal quantities of nanomaterials.