New and old coral radiocarbon records revisited for the subtropical and tropical Atlantic Ocean

Abstract Ocean radiocarbon ( 14 C) is a proxy for air-sea exchange, vertical and horizontal mixing, and water mass identification. Here, we present five pre- to post-bomb coral Δ 14 C records from West Flower Garden Bank and Santiaguillo reefs in the Gulf of Mexico, Boca de Medio, and Isla Tortuga near the Cariaco Basin north of Venezuela. To assess basin-wide Δ 14 C variability, we compiled the Atlantic Ocean reef-building surface coral Δ 14 C records (24 corals and 28 data sets in total) with these new records. Cumulatively, the Δ 14 C records, on their independent age models, reveal the onset of post-bomb Δ 14 C trends in 1958 ±1 to 2 years. A general decrease in maximum Δ 14 C values occurs with decreasing latitude reflecting the balance between air-sea gas exchange and surface water residence time, vertical mixing, and horizontal advection. A slightly larger atmospheric imprint in the northern sites and relatively greater vertical mixing and/or advection of low- 14 C waters influence the southern Caribbean and eastern Atlantic sites. The eastern Atlantic sites, due to upwelling, have the lowest post-bomb Δ 14 C values. Equatorial currents from the eastern Atlantic transport low Δ 14 C water towards the western South Atlantic and southern Caribbean sites. Decadal Δ 14 C averages for the pre-bomb interval (1750–1949) for the low latitude western Atlantic are relatively constant within analytical (3–5‰) and chronological uncertainties (∼1–2 years) due to mixing and air-sea exchange. The compiled Δ 14 C records provide updated regional marine Δ 14 C values for marine reservoir corrections.