Cossa, D. ., IFREMER, La Seyne sur mer, France, dcossa@ifremer.fr
Averty, B. ., IFREMER, Nantes, France, baverty@ifremer.fr
Kérouel, R. ., IFREMER, Brest, France, rkerouel@ifremer.fr
Pirrone, N. ., CNR-IIA, Rende, Italy, n.pirrone@cs.iia.cnr.it

THE NUTRIENT TYPE DISTRIBUTION OF METHYLMERCURY IN THE MEDITERRANEAN WATERS: RELATIONSHIPS WITH PHOSPHATE

Methylated mercury species (MeHg) are bioactive molecules, which play the major role in the biomagnification of mercury in aquatic food webs. Sources of MeHg in the open oceans are still on debate. High definition vertical profiles of MeHg have been performed in the open waters of the Mediterranean Sea in spring 2004. MeHg concentrations ranged from 0.008 to 0.430 pM (mean: 0.171 pM, standard deviation 0.130 pM for 66 determinations). Systematically the MeHg vertical distributions exhibited nutrient type profiles with the maximum concentrations occurring with the PO4 maxima. Within the upper 600 m the relationships between MeHg and phosphate were highly significant: MeHg(pM) = 0.996 PO4(µM) + 0.037 (R = 0.975, n=6) for the Open Northwestern Mediterranean; MeHg(pM) = 1.237 PO4(µM) + 0.034 (R = 0.993, n=10) for the Open Tyrrhenian Sea; MeHg(pM) = 1.241 PO4(µM) + 0.010 (R = 0.926, n=7) for the Open Ionian Sea; MeHg(pM) = 0.868 PO4(µM) + 0.015 (R = 0.960, n=9) for the Ionian Sea off Catania) and MeHg(pM) = 1.312 PO4(µM) + 0.056 (R = 0.951, n=7) for the Strait of Otranto. The results indicate that the MeHg cycle is involved in the organic matter regeneration processes and suggest that its formation in this region of the Ocean is the result of microbiological activity in the upper part of the water column.

Oral presentation

Presentation is given by student: No
Session #:187
Date: 03-07-2008
Time: 10:00