RARE EARTH ELEMENT EXCHANGE THROUGH THE BOSPORUS: THE BLACK SEA AS A NET SOURCE OF REES TO THE MEDITERRANEAN SEA

Abstract

The Bosporus is the only source of seawater to the Black Sea and helps to maintain the basin-wide salinity gradient that caused the Black Sea to become the largest permanently anoxic basin in the world, some 3000 years ago. Concentrations of dissolved rare earth elements (REEs) in each of the three layers of water that make up the Bosporus inflow/outflow system, substituted into a simple hydrographic model that evaluates the entrainment of outflowing Black Sea water in the inflowing Mediterranean Sea water, suggest that the Black Sea acts as a net source of REEs to the Mediterranean Sea. This holds true for Ce, which shows a considerable range of concentrations in the outflowing Black Sea water, even if the lower end of that range is taken to represent the Ce concentration of the Black Sea endmember.