MERCURY IN MARINE SEDIMENT FROM A CONTAMINATED AREA OF THE NORTHERN TYRRHENIAN SEA - LESS-THAN-20 MU-M GRAIN-SIZE FRACTION AND TOTAL SAMPLEANALYSIS

Mercury concentrations are reported for total samples and the <20 mu m grain-size fraction of surface marine sediments and cores collected i n an area of the northern Tyrrhenian Sea, affected by the Mt. Amiata r egion (Tuscany, Italy), known for past Hg mining activity. The surface sediments are contaminated with mercury; concentration gradient decre ases from the coast seaward. The highest concentrations were found in the < 20 mu m grain-size fraction of surficial sediments and indicate transport of mercury from the land to the sea by the rivers which drai n the Mt. Amiata area. The Hg concentration in the > 20 mu m fraction was negligible with respect to that present in the fine fraction. The cores showed a Hg concentration gradient which decreased from the surf ace to the deepest profiles indicating an increase of Hg contamination from the past to the present.