| Abstract |
The present work is focused on the study of the biogeochemical cycles of major and trace metals in the Eastern Mediterranean and Black Sea. Atmospheric deposition (wet and dry) and aerosol samples were collected at background areas and urban locations in the Mediterranean and Black Sea, along with sediment trap samples at two different depths.
Crustal originated elements (Al, Ca, Fe and Mn) were exclusively found in coarse particles (82-89%), while anthropogenic aerosol species (V, Cu, Cd and Pb) were associated with fine particles (59-70%).
Simultaneous measurements of PM1 and PM10 can highlight natural contributions, since PM1 is closely related to anthropogenic aerosol and thus better represent the anthropogenic particle fraction. During the warm season no significant difference in PM1 between urban and natural locations was observed, highlighting the role of long-range transport. On the other hand local anthropogenic sources dominated during the cold season. Thus the seasonal variations for elements of anthropogenic origin presented maximum values during the heating period for urban cities, while during the warm period for natural background. Crustal originated elements denoted higher concentrations and larger variations associated with intense sporadic peaks of mineral dust during spring and autumn in the Eastern Mediterranean and Black Sea, whereas during spring and summer in the Western, when the air mass trajectories originated from remote regions.
Mineral matter is the major component of PM10 particles at both Western (22%) and Eastern Mediterranean Basin (38%). Crustal elements can account for 36-46% of total PM10 mass in both sites in Athens, related to the frequent occurrence of Saharan dust transport to the Eastern Mediterranean and to dust resuspension due to vehicle circulation. Dust from local sources (mainly resuspension) contributed also significantly to the local PM10 mass (up to 33%) and 3-4% in PM1 particles.
The role of atmospheric deposition was further examined based on the atmospheric and seawater fluxes of various anthropogenic and teriggenious elements in both the Eastern Mediterranean Basin and the Black Sea. Atmospheric deposition is sufficient to balance major and trace metals, in both particulate and soluble forms, to the seawater of the Eastern Mediterranean and Black Sea. For elements V, Cr, Mn, Fe, Cu, Zn, Cd and Pb atmospheric deposition supplied 67-158% of the fluxes measured in the water column of the Cretan Sea. Correspondingly, from the surface towards the deeper water layers of the Black Sea 43-226% and 38-179% of Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb fluxes were provided by wet and dry atmospheric deposition, demonstrating its predominant role as an external source of major and trace metals in the areas studied.
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Βιογεωχημικός κύκλος μεταλλικών στοιχείων στην Ανατολική Μεσόγειο και Μαύρη Θάλασσα
