Distribution of gaseous Hg in the Mercury mining district of Mt. Amiata (Central Italy): A geochemical survey prior the reclamation project

摘要

The Mt. Amiata volcano is the youngest and largest volcanic edifice in Tuscany (central-northern Italy) and is characterized by a geothermal field, exploited for the production of electrical energy. In the past Mt. Amiata was also known as a world-class Hg district whose mining activity was mainly distributed in the central-eastern part of this silicic volcanic complex, and particularly in the municipality of Abbadia San Salvatore. In the present work we report a geochemical survey on Hg~0 measurements related to the former mercury mine facilities prior the reclamation project. The Hg~0 measurements were carried out by car for long distance regional surveys, and on foot for local scale surveys by using two LUMEX (915+ and M) devices. This study presents the very first Hg~0 data obtained with this analytical technique in the Mt. Amiata area. The facilities related to the mining areas and structures where cinnabar was converted to metallic Hg are characterized by high Hg values ( ＞ 50,000 ng m~(-3)), although the urban center of Abbadia San Salvatore, few hundred meters away, does not appear to be receiving significant pollution from the calcine area and former industrial edifices, all the recorded values being below the values recommended by the issuing Tuscany Region authorities (300 ng m~(-3)) and in some cases approaching the Hg background levels (3-5 ng m~(-3)) for the Mt. Amiata area.