The suite of tracers introduced to the Black Sea following the Chernobyl nuclear reactor accident will be used to study physical and geochemical processes in the Black Sea. The evolution of the distribution of "soluble" radionuclides, such as Cs-134, Cs-137, and Sr-90, will be measured over a two-year period and used to constrain deep water ventilation rates. Radionuclides having particle associating characteristics, such as Ce-144, Ru-106, Ag-110m, and Cm-242, will be used to trace metal scavenging from the upper Black Sea waters and transport to and through the chemocline. The effects of the oxidation/reduction reactions around the oxic/anoxic boundary on the distribution and phase association of nuclides sensitive to the prevailing redox conditions will be studied. The time-series of proposed field studies is expected to distinguish between direct fallout of debris from the accident and that which subsequently is delivered to the Northwest Black Sea by riverine transport from contaminated areas in the watershed of the Danube and Dneper.
