Browsing by Subject "metals"
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Item Oxhide ingots, copper production, and the mediterranean trade in copper and other metals in the bronze age(Texas A&M University, 2007-09-17) Jones, Michael RiceThe production and trade in copper and bronze was one of the major features of the complex societies in the Near East and Mediterranean during the third to first millennia B.C. While finished metal objects are common finds from the period, ancient metal ingots and hoards of scrap metal, as well as archaeological evidence of metallurgical activities, are often more important sources of information for how ancient technology and trade functioned. Shipwrecks, particularly those found off the coast of Turkey at Uluburun and Cape Gelidonya, as well as mining and smelting sites in the Mediterranean region, provide invaluable information on the production and trade of copper and tin, the main ingredients of bronze. In this thesis, I examine the evolution of the copper trade in the eastern and central Mediterranean, particularly during the Late Bronze Age, when ??????oxhide?????? ingots were widely exported. Finds of oxhide ingots have increased dramatically in recent years, and no synthesis of all of this newly available evidence is currently available. I attempt to analyze this new evidence in relation to older finds and research, with a particular focus on the cargo of the Uluburun shipwreck, the largest collection of Bronze Age metal ingots from a single site in the Mediterranean. The history of oxhide ingot production is complex, but by the Late Bronze Age Cyprus was supplying much of the copper used to neighboring regions, with revolutionary effects on societies in Cyprus and elsewhere. The archaeological evidence shows that oxhide ingots are early examples of a standardized industrial product made for export by emerging state-level societies during the second millennium B.C. and fueled the development of international trade, metallurgical technology, and complex social institutions in a variety of Mediterranean societies from Egypt and the Levant, Greece, Cyprus, to Sardinia in the central Mediterranean.Item Role of natural organic matter in governing the bioavailability of toxic metals to american oysters(Texas A&M University, 2006-08-16) Haye, Jennifer MarcelleColloidal macromolecular organic matter (COM), which makes up a large portion of the bulk dissolved organic matter (DOM) in marine environments, has the capability to modify the bioavailability of potentially toxic metals to aquatic organisms. In order to better understand the bioavailability of some of these metals to estuarine bivalves, American Oysters (Crassostrea virginica) were exposed to different types of natural colloidal (COM) and model (alginic acid, carrageenan, and latex particles) organic biopolymers, tagged with gamma-emitting radioactive metal ions (110mAg, 109Cd, 57Co, 51Cr, 59Fe, 203Hg and 65Zn) or 14C (to sugar OH groups). Natural COM was obtained from Galveston Bay water by 0.5??m filtration, followed by cross-flow ultrafiltration, using a 1kDa ultrafilter, diafiltration and freeze-drying. COM and DOM model compounds were used in the bioavailability experiments at 2 ppm concentrations. Separate 16-hour experiments using varying sizes of latex particles assessed the lowest size of colloids that can be filtered from the water. Results showed that filter-feeding bivalves could efficiently remove particles as small as 0.04??m (40nm) in diameter, with removal halftimes of 2.5 to 5.5 hours, equivalent to filtration rates of about 50??15 ml/hour, or about 3 L d-1 g-1, which are typical values for these oysters. Results of the 20-hour bioavailability experiments demonstrated that oysters could effectively filter metals bound to COM, with the metals bound to alginic acid COM being removed at the highest rates from the water. However, the metals bound to alginic acid were not found in oyster meat in the highest amounts: it was the metals associated with the carrageenan COM. The 14C labeled biopolymer data also showed alginic acid to be removed from the water at the highest rate and, contrary to the metals, was also present in the meat in the greatest amounts. Thus, while previous experiments suggested that the quantity (i.e., concentration) of natural organic matter is important for metal bioavailability, it was shown here that the ??quality??, i.e., the type of natural organic matter, is also a factor for controlling bioavailability, removal and incorporation rates of metals to oysters.