Modelling phytoremediation: Concepts, methods, challenges and perspectives

Phytoremediation can be an effective approach for the removal, immobilization, mineralization, or detoxification of various contaminants in soils or water, including inorganic and organic pollutants, and radioisotopes. Although phytoremediation has been proved in the last decades, its performance is uncertain due to complex interactions among soil, water, plants, weather, microorganisms, and pollutants, leading to underutilizing globally. This paper aims to review representations and methods of quantifying key phytoremediation processes in modelling phytoremediation. We examine the structures, methods, and ability of phytoremediation models that characterize the biogeochemical, hydrological, and phenological processes accountable for phytoremediation dynamics, along with discussions about their advantages and limitations. Then, we identify the knowledge gaps and challenges of incorporating biogeochemical, hydrological, and phenological processes into phytoremediation models in contaminated sites and representing spatial heterogeneity and temporal variability in large-scale applications. The existing phytoremediation models find it difficult to predict the phytoremediation length under real environmental conditions if such a length is key for the assessment of phytoremediation performance and cost. Finally, we explore opportunities to integrate the current knowledge from other disciplines, such as soil, agriculture, ecology, and plant research in a competition-based model and point out key research priorities for the effective integration of knowledge on physical, chemical, and biological processes in modelling phytoremediation, including biogeochemical processes and agro-practices. More studies also need to consider immobilization, mineralization and detoxification.