The Ligurian Sea extending from Punta Mesco to Marina di Massa and including the Gulf of La Spezia

Salinity of the water column

Fluorometers; discrete water samplers; spectrophotometers

At each station, samples were collected at the surface, about 2-3 m from the bottom and at a depth midway between the two using N.I.O. bottles. Dissolved oxygen, conductivity and temperature were measured in situ with a CTD Neil Brown mod. MARK III. The samples utilized for the analysis of inorganic mercury were conserved in glass bottles and acidified with HCl (Carlo Erba, RS) until a pH of 1 was obtained. Those utilized for the determination of cadmium were stored in stable polythene bottles. The surface and the bottom samples were analyzed for cadmium while the sample taken halfway between the two was used for the analysis of mercury. Inorganic mercury was determined using atomic fluorescence spectrometry following the separation of Hg with stannous chloride, the concentration of its vapours on gold granules and the heating of the amalgam in a current of argon. The method showed a standard deviation of 4.5 per cent at a concentration of 20 ng/l of Hg. Cadmium was determined using flameless atomic absorbance spectrometry after electrolytic deposition of Cd at a constant potential after bubbling nitrogen through the sample. A potential of -1.5V with respect to the reference electrode of saturated calomel was used as the reference. The method showed a standard deviation of about 10 per cent at a level of concentration of some tens of ng/l of Cd. The stations were confined to a bathymetry of 100m.

ENEA Centro Ricerche Ambiente Marino (La Spezia)
Forte S. Teresa Via S.Teresa 1
Lerici

19036
Italy