Chronological records of metal deposition in sediments from the Strait of Sicily, central Mediterranean: assessing natural fluxes and anthropogenic alteration

Sediment box-cores were recovered from the Strait of Sicily along two onshore-offshore transects in water depths of 29-500 m. Samples were dated by Pb-210 and analysed for major and trace elements. Inspections of chronological profiles integrated with application of statistical algorithms to the geochemical dataset and supported by in situ hydrological observations were used to assess factors driving element distributions. Mineralogical and chemical variability of sediments offshore of the southwestern Sicily coast reflect the irregular sea floor morphology of the Adventure Bank. Anthropogenic inputs explain enrichments with respect to background values for Sb, As, Pb, and Hg, that become more marked since approximately the 1960s. Clear fluctuations of major and trace element concentrations along a + 150 year record and high background values of some trace metals (notably Cr. Ni, and locally As) are interpreted as signals of geothermal and/or magmatic activities in the Strait of Sicily. A combined effect of current flowing, sea floor morphology and thermohaline gradient appears to encourage trace metal accumulation in front of the southern coast of Sicily.