Phytoextraction of Toxic Metals and Metalloids from Contaminated Soils: Mechanisms, Plant Selection and Environmental Applications
Shweta Nag *
University Department of Botany, Ranchi University, Jharkhand, India.
*Author to whom correspondence should be addressed.
Abstract
Phytoextraction is frequently presented as a low-impact option for contaminated land, yet impressive shoot concentrations do not necessarily translate into meaningful reductions in soil contaminant inventories or exposure. This critical narrative review examines the physiological, edaphic and operational conditions under which plant-mediated removal of potentially toxic metals and metalloids can constitute defensible remediation. Relevant scholarly literature published from 1998 to 1 September 2026 was identified through accessible multidisciplinary, environmental and agricultural information sources, supplemented by citation-oriented searches. Mechanistic evidence was interpreted alongside greenhouse studies, repeated-harvest trials and field applications, with particular attention to differences between contaminant uptake, harvested removal and risk reduction. Three interacting constraints emerge: replenishment of the phytoavailable pool from soil solids; the trade-off between shoot concentration, biomass production and repeated-harvest persistence; and the capacity to contain, process and account for contaminated biomass without transferring hazards elsewhere. Cadmium and zinc extraction by selected hyperaccumulators, arsenic extraction by Pteris vittata, and nickel recovery on suitable ultramafic substrates have comparatively substantial experimental support, although field outcomes vary with soil chemistry, climate, depth and management. Lead removal remains especially constrained by low mobility and the secondary risks of chemical mobilisation. Molecular and microbial interventions reveal plausible improvements, but their translation to durable field performance is uncertain. The strongest assessment of success combines independently verified harvest fluxes and soil inventories with bioavailability, exposure indicators, ecological impacts and full biomass management. Phytoextraction should consequently be treated neither as universally benign land restoration nor as intrinsically ineffective because total soil concentrations decline slowly. Its value depends on clearly defined endpoints, carefully matched plant–soil combinations, long-term monitoring and explicit treatment of residual risks. Future work should prioritise controlled field comparisons, defensible mass balances, food-chain protection and transparent life-cycle accounting.
Keywords: Hyperaccumulation, soil bioavailability, arsenic, cadmium, nickel agromining, rhizosphere processes, harvested contaminant mass, remediation risk