Anoxic basins are ofgreat interest to oceanographersofall disciplines. Theirextreme conditionsresult from acombinationofhigh oxygen utilization and restricted circulation. It is necessery to understand present -day anoxic environments ifwe are to understand the early evolution of the oceans (e.g. SiIlen, 1965). Sarmiento et al.(1988a) explored the causes of anoxia in the global ocean, which is in effect a "closed" basin and in marginal seas such as the Eastern Mediterranean (Sarmiento et al. 1988b). Anoxic conditions have been proposed toexist in various ocean basins at different times in the geological past (e.g. the Crataceous period; Weissert, 1981) and possibly as recent as the last glacial maximum (e.g., Sarmiento and Toggweiler,1984). The modern Black Sea has been considered as the type anoxic basin. It is the world's 2 3 largest permanaently anoxic basin (area = 423,000 km ; volume = 534,000 km ) and is thought to be aquasi-steady state system. It is extremely isolated from the rest ofthe world's oceans. Only the narrow and shallow Bosporus Strait provides water exchange with the Mediterranean. Concentrationsofhydrogen sulfide reach valuesof350 Mm in the deep water and the oxygen-hydrogen sulfide Interface exists between 80 and 200m waterdepth. The hydrographic regime is characterized by low salinity surface water of riverine origin overlying high salinity deep waterofMediterranean origin. Asteep pycnocline is the primary phycical barrier to mixing and is the origin of the stability of the anoxic interface.

Klappentext

Proceedings of the NATO Advanced Research Workshop, Çesme, Izmir, Turkey, October 23-27, 1989

Inhalt
Hydrographic Variability in the Black Sea.- Double Diffusive Intrusions, Mixing and Deep Sea Convective Processes in the Black Sea.- On the Dynamics of the Southern Black Sea.- Noble Gases and Tritium in the Black Sea.- Factors Affecting the Oxygen Isotopic Composition of the Black Sea.- Geochemical and Structural Aspects of the pycnocline in the Black Sea (R/V Knorr 134-8 Leg 1,1988).- Nitrogen Transformations in the Oxic Layer of Permanent Anoxic Basins: The Black Sea and the Cariaco Trench.- Thermodynamic Modelling of Trace Metal Speciation in the Black Sea.- Total and Suspended Cadmium, Cobalt, Copper, Iron, Lead, Manganese, Nickel, and Zinc in the Water Column of the Black Sea.- Potential for Manganese (II) Oxidation and Manganese (IV) Reduction to Co-occur in the Suboxic Zone of the Black Sea.- Sulfur and Iodine Speciation in the Water Column of the Black Sea.- The Oxidation of H2O with O2 in The Black Sea.- Ruthenium-106 in the Black Sea.- 137Cs and 239,240Pu Concentrations in the Black Sea Water Column.- Radionuclide Distributions in Recent Black Sea Sediments.- Microbial Processes in the Black Sea Water Column and Top Sediment: An Overview.- A Review of the General Food Web in the Black Sea.- Biogenic Aggregate Sedimentation in the Black Sea Basin.- On the Sulfur and Carbon Balances in the Black Sea.- Organic Matter Sources in the Black Sea as Inferred from Hydrocarbon Distributions.- Organic Carbon and Nitrogen Geochemistry of Black Sea surface Sediments from Stations Spanning the Oxic: Anoxic Boundary.- The Nature and Distribution of Fluorescent Dissolved Organic Matter in the Black Sea and the Cariaco Trench.- Recent Geological Evolution of the Black Sea: An Overview.- The Effects of Neotectonic Movements on the Recent Sedimentation of the SW Black Sea.- Upper Holocene Sediments of the Black Sea: Summary of Leg 4 Box Cores (1988 Black Sea Oceanographic Expedition).- Uranium Precipitation in Black Sea Sediments.- Pollution Chronology of the Golden Horn Sediments.- Sampling and Analysis of Aerosols in the Black Sea Atmosphere.