Macrophytes and Emerging Contaminants: Insights on Removal and Toxicological Responses

Phytoremediation has emerged as a sustainable and economically viable approach for wastewater treatment, with macrophytes playing a critical role in enhancing contaminant removal. However, existing literature predominantly emphasises the synergistic interaction between substrates and macrophytes, often overlooking the independent biological contributions and physiological "costs" borne by the macrophytes themselves. Amidst the growing prevalence of emerging contaminants (ECs) such as microplastics, pharmaceuticals and personal care products, it is essential to clarify their interactions with macrophytes and the consequent implications for plant vitality. This review provides a comprehensive analysis of how macrophytes independently facilitate the removal of ECs, while simultaneously evaluating the toxicological repercussions of such exposure. It highlights a critical toxicity-removal feedback loop in which EC-induced oxidative stress, membrane damage, and transcriptomic shifts can eventually diminish a plant's long-term remediation capacity. Novel insights are provided into the size-dependent toxicity of nanoplastics (100 nm), which, unlike larger microplastics, penetrate cellular barriers to inhibit nitrogen-cycling enzymes and disrupt rhizosphere exudation. Furthermore, this review explores the synergistic and antagonistic effects of complex chemical mixtures (e.g., chloroacetic acid and N-nitrosodimethylamine), demonstrating that combined stressors can trigger a collapse of antioxidant defense. By bridging the gap between removal efficiency and molecular toxicology, this study offers a new framework for species selection and the sustainable management of nature-based treatment systems in an era of complex chemical pollution.