Palucci A. Seawater Dual Fluorescence Analysis during the Arctic Summer 2006 Polish Oceanographic Campaign

The new spectrofluorometer, already developed at the ENEA FISLAS section, was implemented, for the first time, to marine seawater quality monitoring. The apparatus, installed onboard of the Polish oceanographic research vessel Oceania performed in-situ measurements along the scheduled tran-sects in the 2006 arctic campaign. The instrument has been equipped with two excitation lasers at 266 nm and 405 nm, respectively, in order to maximize the fluorescence emission of dissolved organic matter (CDOM, tryptophan, tyrosine) in seawater and phytoplankton pigments (chlorophyll-a, phycoerythrin, phycocyanin), respectively. Furthermore, two filtration stages have been added in the hydraulic circuit. The first acts to block larger interference hydrosols and allows to monitor phytoplankton cells in the sampling cuvette, while the second filter completely stops all particles and the dissolved matter can be analysed in the second cuvette. The protocol adopted allowed for discrimination between algal carotenoids pigments and con-current organic matter fluorescence. Both cuvettes are optically matched via fibre optic cables to com-pact spectrum analysers. The spectrofluorometric data, after proper fitting analysis, have been released in Raman units and successively transformed in absolute values upon comparison with in-situ calibration. Thematic maps of particulate and dissolved organic matter have been released for vertical transects and superficial distributions. Statistical analysis among Chlorophyll-a fluorescence and the other main components (CDOM, tyrosine, tryptophan and carotenoids) put in evidence, a part from a general trend to decrease versus depth for all the substances, the high correlation degree between Chl-a and retrieved carote-noids fluorescence respect to the others