1334 / 2019-08-09 16:07:30

A high-resolution d18O record of modern Tridacna gigas bivalve and its oceanographic implications

6、海洋地球科学 > 专题8：热带海洋多尺度气候变化及其对全球气候的响应和影响

The lack of daily- to monthly-resolved paleoceanographic records beyond the instrumental era hinders our full understanding of global climate dynamics. Tridacna gigas shells have a large potential to quantitatively document the variability of the ocean surface environment on timescales from daily to inter-annual, while the applicability of the geochemical proxies of T. gigas needs to be quantitively investigated. Here we present a new method to establish daily-resolved chronology for a T. gigas shell from the southern South China Sea (SCS) by identifying daily growth laminae using a laser scanning confocal microscope (LSCM). Averagely 10-day resolved T. gigas shell 18O record over the period of 1989-2013 shows a high correlation with changes of local precipitation and the index of El Niño-Southern Oscillations (ENSO). Together with observed sea surface temperature (SST), we calculated seawater 18O (18Osw) and derived sea surface salinity (SSS) change in the southern SCS based on the T. gigas shell 18O record. The salinity-budget simulation results suggest that the SSS variability in the southern SCS is dominated by the vertical mixing and sea surface freshwater flux. Our study reveals that the T. gigas shell is an ideal archive for high-resolution and quantitative paleoceanographic reconstructions in tropical ocean regions, thus providing a new window to explore climate changes across time scales of human relevance.