Radiological consequences of amending soils with bauxite residue gypsum mixtures

This paper reports on the gamma (ã) radiation flux from sandy soils of the Swan Coastal Plain treated with bauxite residue/gypsum at various application rates and assesses the radiological significance of soil amendment in relation to currently accepted standards. Amendment rates of up to 2000 t ha-1 of bauxite residue were used. There is a linear increase of incremental ã dose with increasing rate of residue. The 1 mSv limit for incremental ã dose exposure for the general public is reached for 100% occupancy at an amendment rate of 1500 t ha-1 of bauxite residue. The gamma rate of approximately 0.15 µGy h-1 is similar to that for soils of much of the area between Bunbury and Capel in the south-west of Western Australia and is significantly lower than levels for Minninup beach where there are deposits of mineral sands.