In situ Measurement of Depth Profiles of Labile Metal Species in Sediments by Technique of Diffusive Gradients in Thin Films
AbstraktThe technique of diffusive gradients in thin films (DGT) presents a new approach in in-situ measurement of trace metal species in environmental systems. Using the DGT technique, trace metals are measured by their accumulation on a selective chelating resin after passage through a well-defined diffusive gel layer. The layer used in this work has an open structure that allows free diffusion of inorganic labile species and some organic metal complexes. Accumulated metals are subsequently analyzed after washing the resin layer with a known volume of acid solution by F AAS for major metals (Fe, Mn) and electrothermal AAS for trace metals (Cd, Pb). The depth profiles in an artificial lake sediment with 0.5 cm resolution for major and trace metals, obtained using two DGT units with different thickness of diffusive gel layer (0.4 and 1.2 mm) are discussed. Reliable depth profiles of trace metals in sediments are essential for studies of pollution, trace metal cycling and processes occurring in sediments.