Mercury in marine sediment from a contaminated area of the northern Tyrrhenian Sea: < 20 μm grain-size fraction and total sample analysis

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