HR: 1340h
AN: PP23B-1428    [Abstracts]
TI: Thermal, hydrological, and biological signals with constraints of geochemical records in coral skeletons, southern Taiwan
AU: * Chiang, H
EM: d91224004@ntu.edu.tw
AF: Dept. of Geosciences, National Taiwan University, P.O. Box 13-318, Taipei, 106 Taiwan
AU: Shen, C
EM: River@ntu.edu.tw
AF: Dept. of Geosciences, National Taiwan University, P.O. Box 13-318, Taipei, 106 Taiwan
AU: Chen, Y
EM: ygchen@ntu.edu.tw
AF: Dept. of Geosciences, National Taiwan University, P.O. Box 13-318, Taipei, 106 Taiwan
AB: Combination of {\it Porites} $\delta$$^{18}$O and Sr/Ca records can be utilized to reconstruct not only the thermal but also hydrological history, which is based on that coral Sr/Ca is controlled by SST and seawater Sr/Ca while $\delta$$^{18}$O is by SST, salinity, and rainfall-influenced seawater $\delta$$^{18}$O. Therefore, residual $\delta$$^{18}$O extracted by removing temperature effects enable us to explore the variation of seawater $\delta$$^{18}$O that is governed by salinity-induced and rainfall-induced changes. We use the Q-ICPMS (Agilent 7500s, equipped in NTU) to efficiently and successfully analyze the coral samples under the precision of 4\permil for Sr/Ca. A twenty-years-old living {\it P. lobata} coral collected in southern shallow sea of Taiwan (namely Nanwan) was subsampled by the resolution of 2-3 weeks along maximum extension axis. Each sample was firstly rinsed by HClO, and then cleaned by the standard procedure. Our Sr/Ca results of 2002\sim2003 after normalizing the seawater Sr/Ca between Nanwan and Hawaii show a similar regression as previous presented, i.e., Sr/Ca ($\mu$mole/mole) = -0.0517\times SST (\deg C) +10.316. By removing SST-induced $\delta$$^{18}$O variations, the fluctuant pattern of residual $\delta$$^{18}$O from the middle 2001 to beginning of 2003 is qualitatively consistent with that of independently precipitation records. However, it is still not sufficient for us to establish a simply quantitative relationship, possibly derived from the complex hydrology. In addition, the $\delta$$^{13}$C values of coral skeleton in spawning season of 1994 and 1995 surprisingly show negative anomalies, probably inferring a reduced spawning or even ceased. The independent support is that the coral underwent relatively high extension rates in above-mentioned two years than the other years where the produced energy is distributed to both of growth and spawning. Based on the ecological site survey and the morphology of collected coral, the anomalies are probably related to the anemone booming event in the surrounding sea.
DE: 4808 Chemical tracers
DE: 4835 Inorganic marine chemistry
DE: 4870 Stable isotopes
DE: 4875 Trace elements
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting