DISPERSION OF GASEOUS VOLCANOGENIC FLUORIDE, ISLAND OF HAWAII

Fluoride was measured in samples of lichen collected in 1990 from 68 s ites on the island of Hawaii; in addition, fluoride levels were measur ed in 8 rainfall samples collected at the same time. The levels of flu oride in the lichens range from 6 to 332 mug g-1, which are similar to the levels measured on Etna. The highest levels of fluoride were dete cted close to Kilauea, and the concentration generally decreases with increasing distance from this volcano. This overall pattern of distrib ution is modified by local variations in wind direction, which relate to the topographic features of the island. Close to Kilauea, there are more localised controls on the fluoride levels, caused by circulating groundwaters and degassing lavas.