טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentYossef Osnat
SubjectTransport and Deposition of Atmospheric Mercury to the
Eastern Mediterranean
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Emeritus Yaacov Mamane


Abstract

It is the goal of this study to assess mercury emissions from natural and anthropogenic sources in the Mediterranean Region, to evaluate the transport, transformation and deposition processes using chemical and mesoscale atmospheric models, and to validate the models using field measurements of speciated mercury: total gaseous Hg (TGM), reactive gaseous mercury (RGM), and total particulate mercury (TPM).

Mesoscale modeling simulations using RAMS models were performed for the periods of the four 15-day field campaigns. Simulations results were plotted for TGM (ng/m3), TPM (pg/m3), and RGM (pg/m3) as isopleth maps of equal concentrations. Model simulations coupled with the field measurements lead to the following findings:

TGM is homogeneously distributed around the East Mediterranean region ranging from 1.4 to 1.6 ng/m3. Back trajectories to Israel in the summer suggest that mercury species are transported from Europe to the East Mediterranean. Measured TPM and RGM on the Israeli coast vary from 10 to 100 pg/m3.

Calculated RGM and TPM show low concentrations over Italy and Greece, but higher towards the East Mediterranean. Calculated RGM is fairly high over land and also in warm areas of the Mediterranean Sea, this in line with higher emissions of mercury from warm sea and hot desert soil to the atmosphere. Wet and dry deposition of RGM near emission sources, since RGM is highly soluble, explain why concentrations near the sources are low.    Significant differences between observed and calculated concentrations are obtained for short-term predictions. The RAMS model follows accurately large-scale phenomena, but is not effective in short time scale changes.

One of the main contributions of this study was to generate a new database of atmospheric mercury concentrations in Israel, and to apply extensive numerical simulations to predict atmospheric mercury in the East Mediterranean.