Towards integrated plant-surface-subsurface hydrological modelling of bioreactive solute transport
Abstract
The number of synthetic chemicals found in terrestrial and aquatic ecosystems is increasing given that about 300,000 such chemicals are approved for urban, industrial and agricultural applications. In the environment, these chemicals can biodegrade into their corresponding transformation products. Microbial metabolic strategies and the occurrence of promoting/inhibiting substances affect biodegradation effectiveness. In addition, there is a growing interest in the exploitation of nature-based solutions, like phytoremediation, to improve soil and water quality given that vegetation effortlessly contributes to the removal of known - and unknown - contaminants through absorption and degradation. Water flow and solute bioreactive transport models are nowadays crucial tools to evaluate environmental remediation opportunities at large spatial scales. However, these models typically (1) enforce first-order degradation kinetics, thus neglecting microbial metabolic strategies, which can be described by means of Michaelis-Menten-Monod (MMM) kinetics and (2) disregard the mechanistic understanding of the transformation of dissolved chemicals within the plant system.
As part of the European Union-funded projects REWATERING (MSCA-PF) and AQUIGROW (Water4All), we are (1) implementing the MMM framework for modelling substrate consumption, (2) coupling a dynamic, mechanistic, multi-compartment plant model describing bioreactive transport processes among and within roots, stem, leaves and fruits and (3) accounting for any number of biochemical species within an integrated, surface-subsurface, flow-transport hydrological model. The hydrological model (CATchment HYdrology, or CATHY) already simulates water fluxes accounting for the interactions among surface water, groundwater and vegetation, including the vegetation stress response based on root zone abiotic conditions. The coupled model will serve in this study to explore the effectiveness of bio- and phyto-remediation in relation with local conditions by means of synthetic scenarios.