... Vázquez Comisión Nacional de Energía Atómica, Buenos Aires, Argentina Andrzej Markowicz and D... more ... Vázquez Comisión Nacional de Energía Atómica, Buenos Aires, Argentina Andrzej Markowicz and Dariusz Wegrzynek PhysicsChemistry ... Budapest, Hungary Jerzy Ostachowicz AGH-University of Science and Technology, Cracow, Poland Bogdan Constantinescu National ...
<p&amp... more <p>Current climatic trends are expected to lead to expansion of oxygen minimum zones and an overall decrease in oxygen concentration [O<sub>2</sub>] in the oceans. In order to improve predictions of future trends we need to create a better understanding of the natural oxygen cycle. The iodine to calcium ratio (I/Ca) of planktonic foraminifera is an increasingly popular proxy to assess upper water column oxygenation. Recent studies suggest that this ratio is mainly controlled by subsurface water dissolved oxygen concentrations. A thorough assessment of the proxy has been carried out for the South Atlantic, but is currently lacking for the Indian and Pacific Oceans, which contain the worlds’ most intense and large oxygen minimum zones. Here we present results of recent (Holocene) planktonic foraminifera (mixed layer and deep dwelling species) I/Ca measurements across a range of oceanographic conditions ([O<sub>2</sub>] varies between < 10 µmol/kg to > 200 µmol/kg) from the Indian and Pacific Ocean to further refine the proxy, using sample material provided by Lamont-Doherty Core Repository.</p>
... Vázquez Comisión Nacional de Energía Atómica, Buenos Aires, Argentina Andrzej Markowicz and D... more ... Vázquez Comisión Nacional de Energía Atómica, Buenos Aires, Argentina Andrzej Markowicz and Dariusz Wegrzynek PhysicsChemistry ... Budapest, Hungary Jerzy Ostachowicz AGH-University of Science and Technology, Cracow, Poland Bogdan Constantinescu National ...
<p&amp... more <p>Current climatic trends are expected to lead to expansion of oxygen minimum zones and an overall decrease in oxygen concentration [O<sub>2</sub>] in the oceans. In order to improve predictions of future trends we need to create a better understanding of the natural oxygen cycle. The iodine to calcium ratio (I/Ca) of planktonic foraminifera is an increasingly popular proxy to assess upper water column oxygenation. Recent studies suggest that this ratio is mainly controlled by subsurface water dissolved oxygen concentrations. A thorough assessment of the proxy has been carried out for the South Atlantic, but is currently lacking for the Indian and Pacific Oceans, which contain the worlds’ most intense and large oxygen minimum zones. Here we present results of recent (Holocene) planktonic foraminifera (mixed layer and deep dwelling species) I/Ca measurements across a range of oceanographic conditions ([O<sub>2</sub>] varies between < 10 µmol/kg to > 200 µmol/kg) from the Indian and Pacific Ocean to further refine the proxy, using sample material provided by Lamont-Doherty Core Repository.</p>
Thesprotia, one of the most remote regions in Greece, was inhabited from as early as the Palaeoli... more Thesprotia, one of the most remote regions in Greece, was inhabited from as early as the Palaeolithic period. The particular geomorphological terrain, with the mountainous and fragmented landscape, has been determinant in the formation of economic and social institutions throughout antiquity. Thesprotia was gradually developed into an important node of communication and transport of goods to the West and the mountainous hinterland of Epirus. During the second half of fourth century BC, socioeconomic changes occurred in the region and small villages were joined to form the first organised settlements. Elea, Gitana and Dymokastro were founded within a few years from one another, during the fourth century BC. Built at geographically crucial locations that ensured the control of the valleys or the riverside crossings and sea routes, they evolved gradually into political, economic and administrative centres for the surrounding areas. In the present study, 56 samples of glass, excavated from these three sites in Thesprotia, are investigated using analytical techniques (SEM-EDX and LA-ICP-MS). The chemical compositions of the samples show significant differences in raw materials used and provide evidence for provenance for the artefacts. This is the first study to examine Hellenistic glass from within a region of northern Greece. The results are compared with other published compositional data for Hellenistic glass. The analytical results for the majority of glass samples from the three sites in Thesprotia show with high probability a Levantine origin and therefore also possibly for the artefacts themselves. This confirms the archaeological record of trade in other materials/objects, while a small group of glasses from Gitana in Thesprotia were made in Egypt.
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