Dioxins originate from activities in harbours (vessel traffic, spill of organic components) or can be released from all sorts of chemical industries. These pollutants are diffusely released in the system and bind to the clay particles in the sediment. Similarly, uranium (238U) is bound to the crystal structure of the clay particles. We analysed samples and observed a good correlation between the uranium and the dioxin concentration. This sample analysis, combined with the conceptual model of the mechanism (both dioxins and uranium bind to clay particles, make us use uranium as a proxy of the dioxin content in sediment.