Nanoscale phenomena dominate many of the important processes near the surface of the Earth. Therefore these phenomena are of special importance to the environment and human health. As nanoscale processes are intrinsically molecular, there is an immediate synergy between the study of nanoscale particles in natural systems and the disciplines of mineralogy, chemistry, physics and materials science.

Since nanoparticulates have unique properties as isolated entities (e.g. Gilbert et al., 2004), it is tempting to focus on the nanoparticle in isolation. however, for nanoparticles in the environment in particular, it is important to analyse their properties in relation to their immediate atomic-scale environment, e.g. the nanoparticle-host interface. Often, certain types of nanoparticles are associated with specific host phases such as noble metal nanoparticles in sulphides, carbonate nuclei on organic templates, arsenic sulphides on Fe sulphides or oxides, or atmospheric nanoparticles on or in dust particles. In many cases, the nanoparticle structure, stability, chemistry, charge, electronic and magnetic properties, and finally, reactivity, are based on these interface properties. Thus, it is essential to develop an understanding of these interface properties at the atomic level. In order to capture the specific details of these interface properties, it is necessary to apply a combination of approaches in nanoscale characterization. These methods include a wide variety of microbeam and spectroscopic techniques, the synthesis of nanoparticles under controlled conditions (e.g. utilizing ion implantation), the study of surface and interface clusters, and the use of quantum-mechanical and molecular-dynamics simulations to understand the observed processes. In addition, as a number of structural and electronic properties of nanoparticles and their interfaces are still difficult to determine experimentally, molecular simulations can further our understanding of nanoscale phenomena.