| Abstract |
Studies dealing with the mass balance in western Mediterranean Sea have shown that this region is continually acting as a reservoir of persistent organic pollutants (POPs), including polynuclear aromatic hydrocarbons (PAHs). Since the atmosphere is supposed to be a major source of PTSs to this region, investigation of the occurrence and behavior of these compounds in the Mediterranean basin atmosphere, is of great importance. Study of atmospheric and transport process of PAHs in the eastern Mediterranean marine environment, as well as intensive seasonal samplings were performed from 2000- 2002. Atmospheric, dry and wet deposition samples were collected monthly in the eastern Mediterranean. Sea water, sedimentary particulate matter and superficial sediment samples from the marine environment were also collected. The Environmental Chemical Processes Laboratory (E.C.P.L) station, University of Crete, situated in the northeast coast of Crete, was used as a control station for fate of PAHs in eastern Mediterranean atmosphere. Geographical distribution of PAHs was carried out during two field expeditions with research vessels &Aigeo, Philia&. Air samples were collected from a number of different stations over the eastern Mediterranean seawater surface. Atmospheric sources of PAHs were studied through seasonal sampling in the urban area of Heraklion. Sources of PAHs were determined using concentration diagnostic ratio and multivariate statistical analysis. Total concentration of PAHs in Heraklion atmosphere varied from 44.3 to 129.2 ng m-3. A clear seasonal trend was observed in particulate concentration of PAHs with maximum values detected during winter. Seasonal trends of gas particulate distribution account for most variations of PAHs concentration in air particles. Emissions from vehicles and fossil fuel burning are major sources of PAHs in Heraklion atmosphere. Total concentration of PAHs in the remote area of Finokalia varied form 4.14 to 57.16 ng m-3 and gas phase PAHs contribute 90% or more of total atmospheric levels. Long-range transport is a major source of PAHs in the eastern Mediterranean atmosphere. Atmospheric samples with highest concentrations of PAHs originated in eastern and central Europe. Contrarily, samples with lowest concentrations originated in the southwest. Concentration of gas phase PAHs was equally distributed over the eastern Mediterranean Sea while particulate phase was significantly higher close to urban areas. Gas phase reaction of PAHs with OH radicals, is an important production process of highly mutagenic and carcinogenic nitro-PAHs. During 17-21/08/01 in Finokalia, concentration of 2-NF and 2-NP varied from 3.35 to 78.88 pg m-3 and from 2.22 to 21.98 pg m-3 respectively. Highest concentrations were determined during noon hours, characteristic of reactions between gas PAHs with OH radicals Air/ sea exchange is estimated to introduce 865 tonnes of PAHs per year in the whole eastern Mediterranean basin, while wet and dry deposition fluxes were 235 and 75 tonnes per year, respectively. The vast majority (98.9 %) of total atmospheric input (934.5 ‘g m-2 y-1) into the marine environment remains in the euphotic zone. Sedimentation rates of total PAHs at depths of 250m and 1440m were 10.29 and 8.27 ‘g m-2 y-1 respectively, during the period 1/5/2001 to 15/10/2001. These rates account for only 1.1 and 0.8 % of total atmospheric deposition. Average concentration of total PAHs in the sediment varied from 2.2 to1056.2 ng g-1 dry weight. Average BC and OC contents varied from 0.3 to 5.6 mg g-1 and from 2.9 to 21.4 mg g-1 dry weight, respectively. Significant correlation (R2=0.94, p<0.001) between pyrogenic PAHs and black carbon content in coastal marine sediments further suggests the importance of atmospheric input of PAHs to the Eastern Mediterranean marine ecosystem.
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Μελέτη των ατμοσφαιρικών φυσικοχημικών διεργασιών και διεργασιών μεταφοράς που καθορίζουν το ισοζύγιο των πολυαρωματικών υδρογονανθράκων στο θαλάσσιο περιβάλλον της ανατολικής Μεσογείου
