Estimates of atmospheric inputs to the Mediterranean (MED) and some coastal areas are reviewed, and uncertainities in these estimates considered. Both the magnitude and the mineralogical composition of atmospheric dust inputs indicate that eolian deposition is an important (50%) or prevailing (>80%) contribution to sediments in the offshore waters of the entire Guerzoni et al.,"The role of atmospheric deposition in the biogeochemistry of the Mediterranean Sea"2 Mediterranean (MED) basin. Model data for trace metals and nutrients indicate that the atmosphere delivers more than half the lead and nitrogen, one-third of total phosphorus, and 10% of the zinc entering the entire basin. Measured data in sub-basins, such as the north-western MED and northern Adriatic indicate an even greater proportion of atmospheric versus riverine inputs.When dissolved fluxes are compared (the form most likely to impinge on surface water biogeochemical cycles), the atmosphere is found to be 5 to 50 times more important than rivers for dissolved Zn and 15 to 30 times more important for Pb fluxes.Neglecting co-limitation by other nutrients, new production supported by atmospheric nitrogen deposition ranges from 2-4 g C m -2 yr -1 , whereas atmospheric phosphorus deposition appears to support less than 1 g C m -2 yr -1 . In spite of the apparently small contribution of atmospheric deposition to overall production in the basin it has been suggested that certain episodes of phytoplankton blooms are triggered by atmospheric deposition of N, P or Fe. Future studies are needed to clarify the extent and causal links between these episodic blooms and atmospheric/oceanographic forcing functions. A scientific program aimed at elucidating the possible biogeochemical effects of Saharan outbreaks in the MED through direct sampling of the ocean and atmosphere before and after such events is therefore highly recommended.

Data are presented for a number of parameters for aerosols and rainwaters collected at a station on Sardinia. The findings are interpreted with special reference to Saharan dusts, and are compared to other data on these dusts obtained from a variety of sites around the Mediterranean Sea. At the Sardinia site the particle size distribution of the Saharan outbreaks exhibits a bimodal structure, the two modes being between 1 and 2 µm and 20-25 µm. The presence of giant particles strongly affects the deposition velocities of the Saharan aerosols. Source markers for the Saharan dusts are palygorskite, kaolinite, calcite, dolomite and rounded quartz grains.The input of Saharan dust has important effects on the chemistry of the Mediterranean aerosols. These include: (i) increases in the atmospheric concentrations and sea surface fluxes of crust-controlled trace metals (e.g.; Al, Fe); (ii) decreases in the EFcrust values of non-crust-controlled trace metals (e.g.; Cu, Zn and Pb) in the aerosols, and (iii) changes in the solid state speciation of Cu, Zn, and Pb, which decrease their solubilities in sea water. The Saharan dusts also affect the composition of rainwater by raising the pH, following the dissolution of calcium, and by decreasing the solubility of trace metals such as Cu, Zn and Pb.Wet deposition controls the flux of Saharan dust to the Mediterranean Sea, but dry deposition can also be important. The dust transport occurs in the form of "pulses", and the annual dust flux can be controlled by few episodes of Saharan outbreaks; e.g. sometimes a single outbreak can account for 40-80 % of the flux. Saharan dust deposition fluxes range from 2 to 25 g m -2 (average; ≅ 10) in the W Mediterranean between 39° and 42° N, between 6 and 46 g m -2 (avg. ≅ 20) in the E Mediterranean, and 0.4 to1.0 g m -2 over the Alps on continental Europe. The present day Saharan dust fluxes (≈ 1 mg cm -2 yr -1 ) account for about 10-20% of the recent deep-sea sedimentation in the Western Mediterranean (3-15 mg cm -2 yr -1 ).

No abstract

Comparison of 1927Comparison of , 1970Comparison of and 2002 bathymetric surveys in the Lagoon of Venice was used to reconstruct historical changes in sedimentation. A detailed GIS-based analysis of the charts revealed the timing and pattern of geomorphic changes and allowed calculation of sediment deposition and erosion for the lagoon as a whole and each of its four sub-basins: Treporti, Lido, Malamocco and Chioggia.Two main developments are discernible from comparative observation of the areal distribution of the main elevation ranges: the collapse of the saltmarshes, which decreased by more than 50%, from 68 km2 in 1927 to 32 km2 in 2002, and the progressive deepening of the lagoon, with a huge increase in the area of subtidal flats (between -0.75 and -2.00 m depth), from 88 to 206 km2 during the same period.On the whole, the lagoon showed a clear-cut shift in the most frequent elevation (modal depth) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 There was a net loss of about 110 Mm 3 of sediments from the lagoon, most of which (73 Mm 3 , ca.70%) was in the earlier period. A significant amount was lost by dredging and direct disposal outside the system, either on land or at sea, and there was a net loss of 39 Mm 3 from the lagoon to the sea through the inlets, at an annual rate of 0.5 Mm 3 .Comparison of erosion rates in the two periods highlighted an alarming acceleration, from a net sediment loss of 0. Deterioration caused a shift from a highly differentiated lagoon morphology in the 1930s to a sediment-starved and subsidence-dominated structure in the 1970s, and from there to the high-energy and marine-like lagoon of today.The results demonstrate the potential application of GIS to reconstructing the recent chronology of sediment distribution and improving our understanding of the geomorphic 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 3 processes shaping the seafloor, while providing insight into the possible impacts of environmental changes brought on by natural and anthropogenic forcing.

(220 parole) Aerosols and precipitations collected over Sardinia are mainly controlled by two endmembers: Saharan and European. European background aerosols in Sardinia show a 3 to 25-fold decrease in EF crust values for Cd, Zn, Pb, and Cr compared with coastal stations in the Western Mediterranean. Partitioning of total atmospheric deposition between the soluble and the insoluble phases shows that Al, Si, Fe and Pb originating from the atmosphere are mostly in the insoluble form. For Ca, Cd, Cr metals the dissolved fraction represents 50-90 % of the total input.Aerosol dissolution experiments performed at particle concentrations ranging from 3 to 300 mg l -1 show Cd and Pb exhibiting low solubility at the high mass particle concentration. Solubility of Pb increases with the EF crust values and the finest grain-size of the aerosols (<1µm), and is less affected by pH. Al and Fe solubilities appear to be mainly controlled by the particulate load. Dissolution of both metals decreases significantly from 30% (13 % for Fe) at aerosol loads lower than 5 mg l -1 , to less than 1% for both metals, at total aerosol concentrations greater than 50 mg l -1 , which are encountered during Saharan transport.Fluxes (dry +wet) of metals at Sardinia show that ≅ 30% for Cd and Pb, to more than 80 % for Fe and Al are due to Saharan contribution.2