Diffusive equilibrium (DET) and diffusive gradient in thin film (DGT) techniques with an inductively coupled plasma mass spectrometry detection of elements were applied to characterize uranium, manganese, iron and 238U/235U isotopic ratio depth profiles in sediment pore water at high spatial resolution and to monitor uranium uptake/remobilization processes in uranium spiked sediment core samples under laboratory, well controlled conditions. Modified constrained sediment DGT probes, packed with Spheron-Oxin® resin gel, were employed for selective uranium measurements. Spatially resolved DET and DGT responses were indicative of local redistribution of uranium in naturally uranium poor and rich sediments.