Metal and Metalloid Speciation in Aquatic Environments: Concepts, Techniques and Applications

Abstract

Aquatic environments are dynamic systems, where metals and metalloids are continuously transformed and mobilised through different chemical forms among organic and inorganic substances and particulate material. These different forms of an element have different behaviours in a way that its total concentration provides just incomplete information related to mobility, bioavailability and toxicity. This work aimed to show the main features of the behaviour of metals and metalloids in aquatic environments and present the main techniques used in the investigation of chemical species and/or interactions with colloids and particulate material. Some of these techniques include filtration, ultrafiltration (UF), diffusive gradients in thin films (DGT), scanned deposition potential (SCP) and absence of gradients and nernstian equilibrium stripping (AGNES). Speciation and fractioning studies of water samples can indicate the potential bioavailability and mobility of metals and metalloids, especially when different techniques are used together.