Dynamics of Biouptake Processes: The Role of Transport, Adsorption and Internalisation

Critical Evaluation of Physicochemical Parameters and Processes for Modelling the Biological Uptake of Trace Metals in Environmental (Aquatic) Systems

“…Although it is entirely artificial to consider the solute fluxes as independent from one another (as we have done thus far), it is beyond the scope of this chapter to quantitatively describe bioaccumulation in the absence of some simplifying concepts. Several authors, including contributors to this volume [32,266], have carefully examined the role of two or three coupled processes on the internalisation of trace elements. Mathematical modelling, in the presence of simple boundary conditions, has been used to solve reasonably complex transport problems by combining a limited number of important processes, including mass transfer and uptake (e.g.…”

“…In a similar manner, k à d (equation (30)) would be expected to decrease with decreasing distance from the organism to the point where the complexes can become non labile at the organism surface, even when they are labile in the bulk solution. For example, for metal complexes with HS, it has been shown that heterogeneity may strongly influence the transport flux to electrodes [142,326,[328][329][330][331] and microorganisms [266,326], even when the complexes remain labile in the bulk solution. This observation is especially important when the internalisation flux is of the same order of magnitude as the limiting diffusion flux.…”

Experimental verification of the metal flux enhancement in a mixture of two metal complexes: the Cd/NTA/glycine and Cd/NTA/citric acid systems

“…6). The main result of this figure is that there is also a good convergence of the theoretical results of the mixture system (at the rigorous level, by using eqn (10) or by using the reaction layer approximation, eqn (15) in ref. 16) with the experimental ones, while the theoretical results given by eqn (4) that neglect the interaction between the complexes diverge yielding lower flux values.…”

“…Moreover, the lability degree has also been introduced to indicate the percentage of the complex contribution to the uptake flux with respect to its maximum contribution obtained when the kinetics of the complexation processes were fast enough to reach equilibrium at any time and relevant spatial position. 3,4,7,[9][10][11] It has been shown that the lability degree depends on the kinetic constants, diffusion coefficients, size of the sensor, composition of the system, etc.…”

Mobilisation of Organic Compounds and Iron by Microorganisms

“…Their extended model assumed that the actual substrate concentration at the cell's surface is controlled by the dynamic interplay of substrate consumption by the cell and the resupply of substrate by diffusion from the bulk substrate solution towards the cell. The main parameters controlling the steady-state substrate concentration are the biologically determined substrate uptake rate and the diffusion coefficient [16]. Surprisingly, calculations showed that the cell surface substrate concentrations were generally only marginally reduced, i.e.…”