There have been comprehensive studies on soil geochemistry throughout Cornwall particularly related to the distribution of arsenic within the area (e.g. Aston et al., 1975; Abrahams and Thornton, 1987) which has been recognised as a potential health risk (e.g. Kavanagh et al., 1998). However, previous published studies on the chemistry of the sediments within the Fal Estuary are relatively limited. The earliest studies included the work of Hosking and Obial (1966) and Yim (1972) who collected a limited suite of surface samples throughout the estuary and analysed their chemistry. A significant sampling programme was carried out in the late 1970’s and early 1980’s to examine the possibility of there being economically viable concentrations of tin; some of the data collected during this study were subsequently published by Pirrie and Camm (1999) and are included in this study. Bryan et al. (1980) carried out a detailed study of sediments and metal uptake in numerous estuaries in south west England; this work was followed up by the study by Bryan and Gibbs (1983) which focussed on the Fal Estuary. Sediment samples from Restronguet Creek were used in a number of experimental studies, particularly examining the sediment mineralogy, including the work of Thorne (1983a , 1983b), Johnson (1986) and Beer (1992). These studies showed that copper minerals were actively growing within the sediments in Restronguet Creek. More recent studies include work on: the down core geochemistry of the Tresillian River (Pirrie et al., 1997; Hughes,1999); evidence for the impact of mining on sedimentation rates (Pirrie et al., 1996; Pirrie and Camm, 1999); and the impact of mine waste discharge into the Fal Estuary (Pirrie et al., 1999a). This work has been part of a larger research programme examining all of the estuaries of Cornwall including the Camel and Gannel (Pirrie et al., 2000a, 2000b ); the Fowey (Pirrie et al., in press a); the Helford ( Pirrie et al., in press b) and the Hayle ( Pirrie et al., 1999b; Rollinson et al., submitted).
In addition to the presence of heavy metals as discrete particulate grains Turner (2000) examined the potential adsorbtion of Cr, Cu, Pb and Zn by hydrous Fe and Mn oxides in several UK estuaries, including the Fal, Hayle and Helford areas. The original source of the metals is either from mine drainage, or from the alteration within the sediment profile of the original sulphide mineral grains. Importantly, metals adsorbed onto Fe or Mn oxides are potentially bioavailable. Elsewhere within the estuary other mining activity has potentially released other contaminants into the sediments. Uranium was mined at a number of sites in Cornwall, and active migration of uranium series radionuclides is occurring in the vicinity of the spoil heaps around a disused uranium mine which drains into the River Fal (Read et al., 1991).