FLUORIDE DISTRIBUTION IN SOILS IN THE VICINITY OF A POINT EMISSION SOURCE IN GREECE

Soil contamination by atmospheric fluorides was studied in the vicinity of an alumina production plant. Samples were collected at depths of 0-5, 5-15, and 15-30 cm. Natural vegetation fluoride levels were used to determine areas of relatively high and low airborne fluoride impact, and soil sampling locations within these respective areas were segregated accordingly. Soil samples were analyzed for total and water-extractable F. Both measurements, especially the water-extractable fraction, reflected the gradient of F exposure. The F concentration in the soil solution exhibited a similar dependence upon distance from the emission source. Total soil fluoride decreased with depth at high impact sites, but increased with depth at low fluoride impact sites. The water-extractable F concentration increased systematically and significantly with depth at high impact areas. Total soil fluoride for all depths decreased with distance from the emission source and approximated to background levels at about 20 km.