Insights into decontamination of soils by phytoremediation: A detailed account on heavy metal toxicity and mitigation strategies

Abstract

In the current era of rapid industrialization, the foremost challenge is the management of industrial wastes. Activities such as mining and industrialization spill over a large quantity of toxic waste that pollutes soil, water, and air. This poses a major environmental and health challenge. The toxic heavy metals present in the soil and water are entering the food chain, which in turn causes severe health hazards. Environmental clean‐up and reclamation of heavy metal contaminated soil and water are very important, and it necessitates efforts of environmentalists, industrialists, scientists, and policymakers. Phytoremediation is a plant‐based approach to remediate heavy metal/organic pollutant contaminated soil and water in an eco‐friendly, cost‐effective, and permanent way. This review covers the effect of heavy metal toxicity on plant growth and physiological process, the concept of heavy metal accumulation, detoxification, and the mechanisms of tolerance in plants. Based on plants' ability to uptake heavy metals and metabolize them within tissues, phytoremediation techniques have been classified into six types: phytoextraction, phytoimmobilization, phytovolatilization, phytodegradation, rhizofiltration, and rhizodegradation. The development of research in this area led to the identification of metal hyper‐accumulators, which could be utilized for reclamation of contaminated soil through phytomining. Concurrently, breeding and biotechnological approaches can enhance the remediation efficiency. Phytoremediation technology, combined with other reclamation technologies/practices, can provide clean soil and water to the ecosystem.

Plant growth promoting rhizobacteria modulates the antioxidant defense and the expression of stress-responsive genes providing Pb accumulation and tolerance of grass pea

“…Various plant species has been successful in absorbing contaminants and considered as potentially effective for remediation of metal contaminated area. Based on plants' ability to uptake heavy metals and metabolize them within tissues, phytoremediation approach have been classi ed into: phytostabilization, phytoextraction, phytovolatilization, rhizo ltration, phytodegradation, and rhizodegradation (Rai et al 2021). However, high levels of metals in soil could reduce the effectiveness of remediation as it decreased plant growth and biomass due to the low nutrient content and biological activity of polluted soils; although this constraint can be overcome by leveraging ecological relationships between soil, microorganisms, and plants (He et al 2020).…”

Nanotechnology in the Restoration of Polluted Soil

“…In this mechanism, microbes are capable of breaking down hazardous pollutants into nontoxic and harmless products [ 83 ]. Plant roots release natural carbon-containing substances, such as sugar, alcohol, and acid, and thereby provide the microorganisms with additional nutrients, which further stimulates rhizodegradation activities [ 84 ].…”

“…The HM-removal efficiency of CNTs also relies on the pH and temperature of the adjacent surrounding environment, contact time, and the dose of CNTs. The CNTs (0.05 g) remove 99.9% of Zn 2+ at 10.0 pH [ 84 ] and a high percent of Cd 2+ are removed at 3.0 pH [ 77 ]; FeS NPs removed 99.65% of Cr 6+ at 6.0 pH, while at high pH (>10.0) the FeS NPs elimination rate was decreased [ 91 ]. The equilibrium of the adsorption ability of NPs rests on temperature fluctuations.…”

Role of Ectomycorrhizal Symbiosis Behind the Host Plants Ameliorated Tolerance Against Heavy Metal Stress

“…The non-essential HMs are not required for cell metabolisms and are highly toxic for cells even in trace amounts ( Haferburg and Kothe, 2007 ). HM toxicity in plants can reduce plant biomass, seed germination, fruit yield, nutrition content, and root and shoot length and induce chlorosis and mortality ( Rai et al, 2021 ). The plant immune system, production of photosynthetic pigments such as carotenoids, chlorophylls, and reactive oxygen species (ROS) scavenging systems is also predominantly affected in the plants subjected to the high concentrations of HMs ( Rastgoo and Alemzadeh, 2011 ; Ghnaya et al, 2013 ).…”