Spatial and temporal distribution of atmospheric mercury species over the Adriatic Sea.

Field measurements of atmospheric mercury and related species were carried out during an intensive cruise campaign performed over the Adriatic sea from October 26th to November 12th, 2004 on board the R/V Urania. Hg-0 ranged between 0.8 and 3.3 ng/m(3) with an average of 1.6 +/- 0.4 ng/m(3) over the entire period. Hg(II) concentrations ranged from 0.1 to 62.8 pg/m(3) with an average of 6.7 +/- 11.7 pg/m(3) whereas Hg-p levels were in a range of 0.04 and 51 pg/m(3) with an average of 4.5 +/- 8 pg/m(3). Higher Hg-0 and Hg-p concentrations were observed in the Gulf of Venice and Gulf of Trieste due primarily to air masses transported from the mainland reflecting the contribution from anthropogenic sources. In contrast, higher Hg( II) concentrations observed during the first period of the cruise campaign were likely due to the occurrence of photo-oxidants production which are the main players of the gas phase oxidation of Hg-(g)(0) to Hg(II)((g)). These findings have been confirmed by the backward trajectories analysis of air masses crossing the studied area during selected days. Keywordsmercury speciation, halogens, marine boundary layer, adriatic sea, photochemistry, MARINE BOUNDARY-LAYER, REACTIVE GASEOUS MERCURY, MEDITERRANEAN SEA, ANTHROPOGENIC SOURCES, POLAR SUNRISE, DEEP WATERS, NY-ALESUND, SPRINGTIME, DEPOSITION, EMISSIONS