Plants in Polluted and Disturbed Environments: Phytoremediation, Emerging Contaminants and Soil–Plant–Microbe Interactions

Phytoremediation can restore vegetation and moderate exposure to soil contaminants, yet its effectiveness often depends on processes occurring within a small, chemically dynamic volume of root-influenced soil. Rhizosphere engineering seeks to direct these processes by selecting plant traits, modifying root exudation, recruiting resident microbial functions, introducing compatible inoculants and managing the soil environment. This critical narrative review evaluates the mechanistic and translational evidence for these approaches in soils affected by potentially toxic elements, petroleum hydrocarbons and other persistent organic contaminants. Peer-reviewed experimental studies, field investigations and relevant syntheses were considered, with emphasis on causal attribution, pollutant fate, biological function and the durability of remediation outcomes. Root exudates alter nutrient supply, microbial substrate preferences, sorption and contaminant speciation, but their effects are conditional on concentration, plant development and soil chemistry. Bacteria and fungi can improve plant establishment, catalyse organic contaminant transformation or alter metal mobility; the same intervention can therefore favour phytoextraction in one context and immobilisation in another. Experimental evidence is persuasive for selected plant-microbe combinations and short-term mesocosms, whereas evidence for persistent field-scale enhancement remains less uniform. Contrasting hydrocarbon studies demonstrate that enriched degrader genes and changed microbiomes do not necessarily translate into greater net removal relative to unplanted controls. Mixtures of metals and organics create additional trade-offs between contaminant availability, plant stress and off-site transfer. The review proposes an outcome-led approach in which engineering choices are linked to a specified remediation mechanism, site-specific soil constraints and independently measured end points. Priority research needs include longitudinal field comparisons, flux-based pollutant accounting, direct tests of microbial activity and colonisation, and monitoring of leaching, food-chain exposure and contaminated biomass. Rhizosphere engineering is best treated as a controllable ecological intervention whose value must be established by improved risk-relevant outcomes rather than by microbiome change alone.