Mercury (Hg) is a natural occurring element that is considered a priority global pollutant due to its unique properties and adverse effect on human health and environment. Hg raises even more concern in areas that have high background level, as in the case of the Mediterranean Basin, where peculiar climatic, geological, and anthropogenic conditions are in place. Despite the consensus in the scientific community that Mediterranean Basin is a net source of Hg to the atmosphere, the quantification of Hg evasion from the Mediterranean Sea surface is yet affected by an overall uncertainty due primarily to the lack of experimental data. This study presents experimental measurements of gaseous elemental mercury (GEM) in air and dissolved gaseous mercury (DGM) in surface seawater performed during three oceanographic campaigns carried out in the Mediterranean Sea: Med-Oceanor 2004 (26/10/2004-2/11/2004); Fenice 2010 (26/08/2010-13/09/2010); Fenice 2011 (28/10/2011-8/11/2011), on board the Italian Research Vessel Urania. We analyze the spatial variability of DGM, GEM and Hg fluxes with a special focus on polluted sites. Moreover, we assess the uncertainty of Hg evasion flux related to the use of different gas exchange models and to the analytical method for DGM measurement. Results show high emission rates in polluted sites compared to off-shore and unpolluted sites. Air-sea Hg flux estimations are significantly affected by the choice of parameterization in the gas exchange models. From our outcome, it is possible to infer that improvement in air-sea Hg exchange determination is essential for a better understanding of the Hg global cycle.
Mercury flux evasion from the Mediterranean Sea during three oceanographic campaigns: Evaluation of spatial variability and uncertainty of estimates
Laura Fantozzi
2019
Abstract
Mercury (Hg) is a natural occurring element that is considered a priority global pollutant due to its unique properties and adverse effect on human health and environment. Hg raises even more concern in areas that have high background level, as in the case of the Mediterranean Basin, where peculiar climatic, geological, and anthropogenic conditions are in place. Despite the consensus in the scientific community that Mediterranean Basin is a net source of Hg to the atmosphere, the quantification of Hg evasion from the Mediterranean Sea surface is yet affected by an overall uncertainty due primarily to the lack of experimental data. This study presents experimental measurements of gaseous elemental mercury (GEM) in air and dissolved gaseous mercury (DGM) in surface seawater performed during three oceanographic campaigns carried out in the Mediterranean Sea: Med-Oceanor 2004 (26/10/2004-2/11/2004); Fenice 2010 (26/08/2010-13/09/2010); Fenice 2011 (28/10/2011-8/11/2011), on board the Italian Research Vessel Urania. We analyze the spatial variability of DGM, GEM and Hg fluxes with a special focus on polluted sites. Moreover, we assess the uncertainty of Hg evasion flux related to the use of different gas exchange models and to the analytical method for DGM measurement. Results show high emission rates in polluted sites compared to off-shore and unpolluted sites. Air-sea Hg flux estimations are significantly affected by the choice of parameterization in the gas exchange models. From our outcome, it is possible to infer that improvement in air-sea Hg exchange determination is essential for a better understanding of the Hg global cycle.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
