Abstract:
In this study, the α spectrometry technology was used to estimate the activities of
210Pb in the skeletons of black corals collected from the Xisha Islands (JYI-1, JYI-2) and Luhuitou Peninsula (LHT) of the South China Sea. According to the radial distribution characteristics of excess
210Pb in the cross-sections of black corals, we studied the chronology of black corals. The results reveal that specific activity of
210Pb exhibits an exponential decrease with distance from the edge of the black corals. The ranges of
210Pb specific activity in the coral skeleton are 10.28-73.41 mBq/g, 1.50-4.72 mBq/g and 5.35-12.67 mBq/g in the JYI-1, JYI-2 and LHT respectively. All black corals are long-lived and slow-growing organisms. They have been growing continuously for 185-267 a, with growth rates ranging from 17.8 to 26.5 μm/a. Moreover, the annual growth rates exhibit obvious distinction in diverse species collected from different regions. The sequence of the growth rate is JYI-2>JYI-1>LHT. With respect to counting growing rings, the results of radionuclide
210Pb in dating of black corals reveal a good conformity. The dating of black corals in this study will provide the basic data to study the evolution and reconstruction of climate change in the past centuries.