Modelling phytoremediation: Concepts, methods, challenges and perspectives

Phytoremediation can be effective for the removal, immobilization, mineralization, and/or detoxification of various pollutants in soils and water, including inorganic and organic pollutants, and radioisotopes. Although the feasibility of phytoremediation has been proven in the last decades, its performance is uncertain due to the complex interactions among soil, water, plants, weather, microorganisms, and pollutants, leading to its underutilizing globally. This paper aims to review the representations and methods for quantifying key phytoremediation processes via modelling. 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 in 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 are difficult to predict the phytoremediation period under real environmental conditions but it is a key assessment of phytoremediation performance and cost. Finally, we explore the opportunities to integrate the current knowledge from other disciplines, such as soil, agriculture, ecology, and plant research in a competition-based model. We highlight the key research priorities for effective integration of knowledge based on physical, chemical, and biological processes in modelling phytoremediation, including biogeochemical processes, soil amendments and agro-practices. Further studies need to consider the immobilization, mineralization and detoxification processes of pollutants in contaminated sites.