BIOAVAILABILITY OF ARSENIC IN SOIL AND MINE WASTES OF THE TAMAR VALLEY, SW ENGLAND

The southern part of the Tamar valley area in SW England is highly min eralised and mines in the region were the world's principal producers of tin, copper and arsenic during the mid nineteenth century. The Devo n Great Consols Mine, covering 67.6 ha (167 acres) is situated in this area. Residues from the mining activity resulted in unvegetated spoil tips and local soils highly contaminated with As (range 120-52600 mu g/g As). Sequential chemical extraction procedures were conducted on e ight surface samples (0-15 cm) taken from a 2.0 km long transect from within the mine site to agricultural grassland. The proportion of wate r extractable As in agricultural top soils was lower (0.05-0.3%) than the values obtained for mine wastes (0.02-1.2%). Arsenic was found to be concentrated in the Fe-organic and residual fractions, which accoun ted for up 93% of the total As in mine spoil and nearby soils.