Chemometric Approach To The Analytical Characterisation Of Bagnoli (NA, Italy) Sea-Site
G. Visco, L. Campanella, L. Ribezzi
Dipartimento di Chimica Università "La Sapienza", P.le Aldo Moro 5, 00185 Roma, Italy

The Bagnoli gulf is surely one of the most beautiful in the world. Since it was famous Greek’s age when people was attracted in Neapolitans site from by Flegrea’s termalism.
It was in the past an industrial site starting from a glass manufacture in 1853 and developing then toward siderurgy, due to the need of a zone where industrial activities could rise.
In 1905 the building of the first blast furnace begins. In 1927 the first cement factory was born and in 1936 the production of Eternit (cement-amianthus) started. Successively, also, starting from 1954 chemical industries developed. In 1996 the remediation of the site started.
These historical data have been token into account when the analytical characterisation obliged to some choices about the indexes and parameters to be considered.
Sampling was performed according to the not probabilistic “purposive sample” method; water columns were sampled probabilistically with “patterned sampling” method.
Ten water columns were analysed on measuring, by graphite furnace AAS (GF-AAS), the concentration of heavy metals (Cd, Cu, Cr, Hg, Ni, Pb), pH, suspended matter (TSS 105ºC, TSS 180ºC, VSS). The accuracy was investigated by internal standard addition method.
Suspended matter was determined by filtration on cellulose acetate filters (0.2 um).
For each index ranges and distribution were looked for by graphical method to identify similarity and by matrix to identify extreme limits.
These simple statistical methods do not show univocal answer to our analytical questions so we proceeded with deep statistical analysis.
The chemometric approach seemed to the best in order to draw some conclusions to identify similarity and to clarify the trend.
PCO (Principal Coordinate Analysis), with the main advantage of using many different kinds of similarity on distance measurements, and PCA for the individuation of the most meaning variables (metal, pH, TSS or VSS) and of dendrograms of Cluster Analysis allow to find traversal planes of similarity confirming the analytical hypothesis.
The result show that the strong gulf and Tirreno sea streams toward south have diluted and vehicled outside the pollutants.
On the contrary the deepest water and probably the sediments are probably much more dangerous and need an appropriate investigation. Before any data are obtained it is absolutely advisable not to stir the sea depths in order to avoid any movement of immobilised pollutants.