Reconstruction of surface ocean water pCO2(aq) in Nansha area,the South China Sea during the last 30 ka

The reconstruction of pCO2 in the tropic ocean is one of the most important issues to understand global cli-matic changes. In this study, the high-resolution strati-graphic analysis of core 17962 was conducted, which is lo-cated in the southern South China Sea (SCS). The contents of sedimentary organic matter, the stable carbon isotopic composition of sedimentary organic matter, and the d 13C values of black carbon and terrigenous n-alkanes were de-termined. And the d 13Cwc value of carbon derived from aquatic was calculated. On the basis of d 13Corg-pCO2 equa-tion proposed by Popp et al. (1989), we estimated the pCO2 in the Nansha area, SCS, since the last glaciation using d 13Cwc instead of d 13Corg. The results show that the average pCO2 was estimated at 240 ppmV during the last glaciation, and at 320 ppmV in the Holocene. A comparison of surface sea pCO2 with the atmosphere CO2 recorded in the Vostok ice core, indicates that CO2 in surface water of the southern SCS could emit into atmosphere during the last 30 ka.