Radiocarbon reservoir ages in the Mediterranean Sea and Black Sea

We measured apparent marine radiocarbon ages for the Mediterranean Sea, Bla ck Sea, and Red Sea by accelerator mass spectrometry radiocarbon analyses o f 26 modern, pre-bomb mollusk shells collected living between AD 1837 and 1 950. The marine reservoir (R(t)) ages were estimated at some 390 +/- 85 yr BP, 415 +/- 90 yr BP and 440 +/- 40 yr BP, respectively. R(t) ages in the M editerranean Sea and Black Sea are comparable to those for the North Atlant ic Ocean (<65<degrees>N), in accordance with the modern oceanic circulation pattern. The DeltaR values of about 35 +/- 70 yr and 75 +/- 60 yr in the M editerranean area show that the global box-diffusion carbon model, used to calculate R(t) ages, reproduces the measured marine C-14 R(t) ages in these oceanic areas. Nevertheless, high values of standard deviations,larger tha n measurement uncertainties are obtained and express decadal R(t) changes. Such large standard deviations are indeed related to a decrease of the appa rent marine ages of some 220 yr from 1900 AD to 1930 AD in both the Mediter ranean Sea and the western North Atlantic Ocean.