末次盛冰期以来南海北部神狐海域沉积有机质的组成特征及其古气候/环境意义

通过对两根沉积柱GHE27L和GHE24L的总有机碳（TOC）、总氮（TN）、C/N比值及稳定碳同位素（δ13C_org）的分析,本文探讨了21.1 ka BP以来南海北部陆坡神狐海域沉积有机质的组成特征及可能的古气候/环境信息。沉积柱GHE27L的TOC含量、TN含量、C/N比值及δ13C_org值分别为0.53%~1.81%,0.07%~0.18%,8.2~16.0和-23.6‰~-20.3‰。沉积柱GHE24L各参数则分布为0.45%~1.65%,0.09%~0.24%,5.3~12.2和-22.6‰~-20.4‰。沉积柱总体有机质的剖面变化显示,末次盛冰期以来南海北部沉积有机质具有海洋和陆地混合来源,但以海洋有机质来源为主。冰期陆源有机质对总有机质的相对贡献比全新世高。末次盛冰期南海北部气候相对干旱,C₄植被发育。全新世夏季风增强、降雨增多。自2.0 ka BP以来,人类活动对南海北部海洋初级生产力产生一定的影响。

Composition of sedimentary organic matter in Shenhu, northern South China Sea since the Last Glacial Maximum and its implication for paleoclimate

The total organic carbon (TOC), total nitrogen (TN), C/N ratios and the stable carbon isotope of bulk sediment organic matter (δ13C_org) in the GHE27L and GHE24L cores, collected from Shenhu area in the northern South China Sea (NSCS), were analyzed to reveal the composition of sedimentary organic matter (OM) and the paleoclimate changes since the Last Maximum Glacial (LMG). The values of TOC, TN, C/N, and δ13C_org ranged from 0.53% to 1.81%, 0.07% to 0.18%, 8.2 to 16.0 and-23.6‰ to 20.3‰ in Core GHE27L, and 0.45% to 1.65%, 0.09% to 0.24%, 5.3 to 12.2 and-22.6‰ to-20.4‰ in Core GHE24L, respectively. The profiles of bulk OM indicated that the OM mixed origins from both terrigenous and marine OM, and that marine OC was the major source of OC in the NSCS since the LGM. The relative contribution of terrigenous OM in the glaciation was higher than that in the Holocene. The climate was dry and C₄ plants were to thrive in the NSCS during the last glaciation. The precipitation enhanced due to the strong summer Asian Monsoon in the NSCS during the Holocene. However, it seems that the primary productivity in the NSCS was impacted by the anthropogenic activities since the last 2.0 ka BP.