This paper reports on the results of contamination studies undertaken in the Forth and Tamar estuaries. Both estuaries have unique contamination (for British estuaries), with the Forth experiencing significant mercury (Hg) pollution and the Tamar experiencing significant arsenic (As) pollution. In addition, due to the presence of nuclear submarine bases in both estuaries, Co60 was detectable in the intertidal sediments. Temporal and spatial contamination patterns are analyzed in relation to historical and present pollution point sources. The effect of fluvial and marine sediment mixing on trace metal results and other processes controlling contaminant levels are reviewed. Preliminary results on quantifying sediment accretion rates using Cs levels are discussed.