“…Section 6.1 will examine the predicted kinetics of several of the more important transport mechanisms for trace elements: passive diffusion, transport through ion channels, carrier mediated transport and active transport. Endocytocis and the contribution of food to multicellular organisms will not be examined (see Chapter 8 in this volume, [248]). In Section 6.2, the limitations of the major techniques used for the measurement and interpretation of elemental internalisation fluxes will be discussed.…”