This Research Front features contributions discussing and using the in-situ probe Diffusion Gradients in Thin-films (DGT) to determine trace element behaviour in environmental systems. The Research Front presents the state of the art in DGT science, beginning with a review by the joint originators and developers William Davison and Hao Zhang, which presents a readable introduction to the origins of the method and a high level discussion of its uses and applications. The research papers that follow illustrate some of these uses and highlight the flexibility of DGT by covering applications to a range of analytes in a range of environmental media.