Thermal Desorption for Mercury Removal from Sediments Sampled from the Adriatic Sea

摘要

Overall sampling of the sediments in the Adriatic Sea at the mouth of the Isonzo (Soca) River in Italy has permitted updating of the extent and level of mercury contamination.The Isonzo River transports mercury-bearing residues from the Idrija mine (Slovenia);that area is contaminated due to the mining of cinnabar (HgS).The mercury mine started operations in the 15th century and was finally shut down in the 1980s because of the decreased demand for mercury.An attempt was made to remove mercury from the contaminated sediments by thermal de-sorption,with the aim of ascertaining whether low temperature and short residence time could be suitable parameters for sediment cleanup if future needs should so require.To date,no studies have been done on the health of the Italian population living in the Gulf of Trieste area;hence there is no known correlation between the anomalous mercury content of the sediments and symptoms attributable to the ingestion of even small quantities of mercury.Desorption times of about 20 to 30 minutes,at temperatures ranging from 325° C to 350° C,yielded residues with a mercury content below the limit imposed by Italian regulations for contaminated soils and sediments (5 ppm).The air and the mercury vapors driven off during roasting were treated before being released to the atmosphere.