Phytoremediation of Heavy Metal-Contaminated Environments: A Comprehensive Review of Mechanisms, Plants, and Microbial Application

Abstract

Heavy metal contamination in soil and water has increased in association with industrial development, urban expansion, mining activities, municipal waste disposal, and intensive agricultural practices. These contaminants are environmentally persistent because they are non-biodegradable and may accumulate in soil, aquatic systems, plants, and other organisms. Their movement through environmental compartments can affect soil fertility, plant growth, food quality, and ecological safety. Conventional remediation techniques, including chemical extraction, soil washing, and excavation, have been applied to contaminated sites; however, these methods may be costly, technically demanding, and disruptive to the environment. Phytoremediation provides an environmentally compatible and economically feasible alternative that uses plants and associated rhizosphere microorganisms to remove, immobilise, transform, or detoxify pollutants. This review discusses the major mechanisms of phytoremediation, including phytoextraction, phytostabilisation, phytodegradation, phytovolatilisation, and rhizofiltration. It also summarises the roles of hyperaccumulator plants, aquatic and wetland plants, woody species, agricultural crops, and microorganisms in the management of heavy metal-contaminated environments. Plant selection, contaminant characteristics, soil properties, and plant-microbe interactions are important determinants of remediation performance. The review highlights phytoremediation as a sustainable strategy for environmental restoration while recognising the need to improve plant selection, microbial-assisted approaches, and field-level efficiency.