Marine reservoir correction in the south of Vietnam estimated from an annually-banded coral.

Abstract

We measured radiocarbon in an annually-banded coral core collected from Con Dao Island, Vietnam, 90 km from the mouth of the Mekong River, and estimated the regional correction of the marine reservoir age (Delta R value). Twelve samples were continuously taken from the annual bands (AD 1949-1960) which were clearly identified under UV light ( approximately 352 nm) as well as by X-radiography. The (super 14) C content of the samples was determined using an accelerator mass spectrometer at the National Institute for Environmental Studies, Tsukuba, Japan. Results provide a Delta (super 14) C time series showing a relatively steady value of -48.6+ or -4.6 per mil for the period of 1949-1955 and an abrupt increase starting from 1956 that indicates a quick response to the atmospheric testing of nuclear bombs. Using the prebomb (super 14) C data, the Delta R value in the south of Vietnam is estimated to be -74+ or -39 yr.