DATE2016-08-18 12:53:00
AUTHORSYitzhak Jacobson (1), Ruth Yam (1), Saverio Devoti (2), Paolo Montagna (3), Aldo Shemesh (1)
  1. Weizmann Institute Of Science Rehovot (Israel)
  2. Istituto Superiore Per La Protezione E La Ricerca Ambientale Rome (Italy)
  3. Istituto Di Scienze Marine (ismar) Bologna (Italy)
ABSTRACTNatural, marine conditions, such as SST, productivity, precipitation and dust fluxes along with anthropogenic stress, affect seawater chemistry and are recorded in the shells of marine calcifying organisms. The reef builder vermetid D. petraeum is a sessile gastropod, secreting its aragonite shell in the tidal zones of the warm belt of the Mediterranean Sea, a region under high anthropogenic stress, thus a hotspot for climate change studies. Similar species are also abundant along the coasts of Florida, Bermuda and Brazil. We obtained cores from vermetid reefs across the Mediterranean Sea (Israel, Crete, Sicily and Tunis), dated to the last millennium. We subsampled these cores at resolution of 3-6 years, and analyzed them for stable isotopes (?^13C, ?^18O) and elemental concentration (Ca, Na, Sr, Mg, Al, K, Mn, Fe, Cu, Zn, Ba, U, Cr, Co, Ni, V, Rb, Pb, Li, B, Mo, Cd). ?^13C and ?^18O from the eastern Mediterranean were used to reconstruct seawater carbonate chemistry and SST following Sisma-Ventura et al. (2014). Element to calcium (El/Ca) molar ratios of recent samples are mostly in agreement with known values for marine biogenic aragonites. The trace elements results show a general partition into two major groups. The largest group of elements (Al, Fe, Mn, Co, Ni, Li, Ba, Mo, V, K, Rb) is associated with terrestrial sources to seawater such as atmospheric dust deposition, silicate erosion and fluvial input. Most of these elements show general decreasing trends of El/Ca ratios during the last millennium. The second group (Sr, U and Mg) exhibits temporal variability which resembles the Eastern Mediterranean SST trend for this period. The results of some elements show spatial variability across the Eastern and Central Mediterranean Basins. Pb/Ca of Israeli and Tunisian cores follows the known trend of anthropogenic lead pollution, while the Sicilian and Cretan cores show non-anthropogenic signals. Measured ?^18O from Israel, Crete, Sicily and Tunis follows a clear east to west gradient, resembling that of the temperature gradient in the Mediterranean basin.