Principles and application in soils and sediments

Abstract

Soon after the first work reporting on the use of diffusive gradients in thin-films (DGT) to measure trace metal ion concentrations in seawater[1], a gel holding device was adapted from its slightly older diffusive equilibria in thin-films (DET) counterpart [2] and used to accommodate a planar DGT probe. The adapted probe was used to investigate solute distributions around the sediment-water interface of a freshwater sediment at high-resolution [3]. The use of DET and DGT for high resolution measurements of solute concentrations and fluxes in sediments and soils is described in the appropriate context in Chapter 8, however the work by Zhang et al. [3] remains of great relevance to this chapter. It was the first to recognize the differences between DGT measurements in purely aqueous media and those carried out in a porous environment, such as a soil or sediment. Subsequent work on soils and sediments has helped to develop and then validate the theories that underpin the use of DGT in these dynamic porous media and thus allow insight into processes that govern the cycling of trace elements and nutrient in soils and sediments and their availability to terrestrial and aquatic biota.