Radiocarbon carbon history

Plant remains and mollusk shells from marine Holocene layers in the central depression (layers containing Cerastoderma, station 15) have been dated by radiocarbon methods [16]. The results provided evidence of marine sedimentation being confined to the second half of the Holocene and permitted us to date some large regressive phases in the history of the Aral. Other studies have been performed in the central basin, including oxygen isotope analysis of carbonates in mollusk shells... 

It is unusual to think of any type of atmospheric contamination - especially by a radioactive species -as beneficial however, bomb-produced radiocarbon (and tritium) has proven to be extremely valuable to oceanographers. The majority of the atmospheric testing, in terms of number of tests and production, occurred over a short time interval, between 1958 and 1963, relative to many ocean circulation processes. This time history, coupled with the level of contamination and the fact that becomes intimately involved in the oceanic carbon cycle, allows bomb-produced radiocarbon to be valuable as a tracer for several ocean processes including biological activity, air-sea gas exchange, thermocline ventilation, upper ocean circulation, and upwelling. 

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