Physical and chemical associations of radionuclides and trace metals in estuarine sediments: an example from Poole Harbour, Southern England

The physical (grain size) and chemical (mineral, oxyhydroxide coatings and organic matter) associations of 60Co, 137Cs, 210Pbxs, Pb, Zn and Cu have been examined in two intertidal sediments (from low and medium energy environments). 60Co, 210Pbxs, Pb, Zn and Cu show a distribution with particle size controlled by Fe- and Mn-oxyhydroxides and total organic carbon. Activity/concentration maxima for these isotopes and elements occur in the 2–8 μm size fraction. A proportion of the 60Co present appears to have been diagenetically mobilised. In contrast 137Cs is strongly sorbed by clay particles and is virtually non-exchangeable.