Trace-metals are a source of nutrients or toxic agents depending on their concentration and speciation. The speciation is known as the distribution of the total concentration among its possible species. It is a relevant concept to understand the bioavailability of trace-metals to plants or microorganisms, because it is seen that the uptake depends in many cases on the mobility and kinetics of dissociation of the compounds present in the system. To tackle this problem, several analytical techniques have been developed to measure either the concentration of the free metal ion (e.g Donnan Membrane Technique (DMT)) or an available concentration of metal (e.g Diffusive Gradients in Thin-Films (DGT).
DGT is a passive sampler that mimics the physicochemical processes involved in the uptake of metals by measuring the flux that receives the surface or microorganisms and algae. The flux is then expressed as a free metal concentration that would produce the same accumulation in a system with only free metal. This concentration is known as the available DGT concentration (cDGT).
In my thesis, we are developing a theoretical framework that allows to split cDGT in terms of the concentration, mobility and lability of each metal species present in the system.
In this task, we combine experimental measurements with numerical methods that solving the diffusion-reaction equations within the boundary conditions of the DGT technique allow to depict the concentration profiles as well as to calculate the accumulation.
Finally, by using a set of devices with different configurations we can obtain complementary information which can be used to estimate the lability or mobility of the species present and predict the metal availability in natural waters.
Trace-metals, Speciation, Bioavailability, Diffusive Gradients in Thin-Films (DGT), Donnan Membrane Technique (DMT)
Master : Atomistic and Multiscale Computational Modelling in Physics, Chemistry and Biochemistry (UB)
Degree: Chemistry (UB)
Jaume Puy Llorens (UdL)
Joan Cecilia Averós (UdL)
Yue Gao (VUB)