RESUMO
The results of a first direct determination, obtained with the lidar technique, of the mercury flux emitted from a geothermal power plant are reported in this chapter. The value determined for the Bellavista power plant (20 MWe) (Mt. Amiata, ltaly) proved to be 158 to 210 kg/year, or one third the value measured with the same technique for a large chlor-alkali plant (120,000 Mg/year of chlorine). The measured flux value is particularly high, probably because the power plant is located in a highly mineralized zone. The deteminations of the rnercury concentration in the air and soil reveal that the contamination of the environment surrounding the geothermal power plant is limited to a restricted zone (500 to 600 m from the plant) with an asymmetry linked to the direction of the prevailing winds.