The evaluation of long–term heavy metal concentrations in the Gulf of Palermo was carried outin this study. Measurements of Cr, Cu, Hg, Pb and Zn concentrations were performed by atomicabsorption spectrophotometry (AAS) on dated fractions of a sediment core, dated by the 210Pbexmethod. They are found to cover a time period from 1951 to 2004. The constant sedimentation ratemodel was used for dating. Specific activities of 137Cs have also been measured in the sedimentcore sections as a check of the time scale derived by the 210Pbex method. A time-series analysisbased on temporal decomposition was used in order to investigate the presence of heavy metalpollution trend. The additive component model, widely used to estimate seasonal and long–termbehavior, was chosen for the temporal analysis. Results showed the presence of a specific heavymetal concentration trend. Residual time–autocorrelation has also been taken into account in orderto investigate their stochastic properties. Concentrations of some metals (Cu, Hg, and Zn) havebeen found increasing until the beginning of the 1970s. A peak around the beginning of the 1980shas been found for Cr and Pb. Heavy metal concentration in the sediment core show a significantdecreasing after these years. Our results for the concentration time trends are in good agreementwith other surveys performed in different areas of the world, and they can be explained in termsof the reduction of anthropogenic contribution to atmospheric emissions. Further investigations ontime properties and spatial distributions, are also planned.
|Titolo della pubblicazione ospite||VI INTERNATIONAL SYMPOSIUM ON NUCLEAR & RELATED TECHNIQUES XII WORKSHOP ON NUCLEAR PHYSICS, CD-ROM|
|Numero di pagine||10|
|Stato di pubblicazione||Published - 2009|