A High-Resolution Coral-Based Δ 14 C Record of Surface Water Processes in the Western Mediterranean Sea

• Published in: Radiocarbon
• Main Authors: Tisnérat-Laborde, Nadine, Montagna, Paolo, McCulloch, Malcolm, Siani, Giuseppe, Silenzi, Sergio, Frank, Norbert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2013
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1017/s0033822200048530; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822200048530

The first high-resolution time series of pre- and post-bomb radiocarbon measurements is reported for surface waters in the western Mediterranean Sea. The Δ 14 C record was obtained from the aragonite skeleton of Cladocora caespitosa using a 50-yr-old corallite collected in the Ligurian Sea in 1998. Laser-ablation ICP measurements of trace elements (Li/Mg and Sr/Ca) show a strong seasonal variability, enabling the chronology of the Δ 14 C record to be determined at annual timescales. The mean Δ 14 C of pre-bomb surface water is -56 ± 3%, corresponding to a reservoir age of 262 ± 29 yr. The post-bomb maximum occurs in 1972 with a Δ 14 C value of 90%, significantly lower than the peak of 150% observed in the North Atlantic. The dilution of the peak-amplitude of Δ 14 C in western Mediterranean surface waters is attributed to mixing of North Atlantic Central Water inflow with relatively depleted underlying Intermediate Mediterranean and Levantine Intermediate waters. Intensification of this mixing is observed in 1963–1964, consistent with the change in atmospheric circulation from a positive to negative NAO phase (1960–1967). The post-peak Δ 14 C variability is relatively limited, reflecting mainly local vertical mixing forced by wind stress.