17. 3 ka以来冲绳海槽中南部有机质来源

基于AMS14C测年、有机碳、氮含量及其同位素等指标分析，探讨了冲绳海槽中南部OKT-3孔末次冰消期以来沉积物有机质来源及其对古海洋环境演化的响应。结果显示，OKT-3孔沉积物中有机质主要由中国大陆和中国台湾等陆源有机质，以及海洋自生有机质组成。末次冰消期至全新世晚期（17.3~4 ka B.P.），中国大陆源有机质贡献逐渐下降，中国台湾源有机质贡献逐渐上升，表明海平面变化、黑潮变动是该阶段有机质来源的主要控制因素。4~1.5 ka期间，陆源有机质供给变化趋势与黑潮变动不一致，表明该时期陆源输入非黑潮单一控制，还可能受季风降雨等变化影响。值得注意的是，OKT-3孔海源有机质贡献在B-A和PB时期高、YD时期低，与北太平洋地区的生产力变化相似，反映了北太平洋中层水（NPIW）对海水表层生产力的控制作用，NPIW是连通冲绳海槽与北太平洋的重要纽带。

Organic Matter Sources in the Middle Southern Okinawa Trough since 17.3 ka:A response to paleoenvironmental evolution

A piston core （OKT-3） is collected from the middle southern Okinawa Trough （26.018 °N， 125.282 °E） at a water depth of 1 792 m， providing depositional records since 17.3 ka. Total organic carbon， total nitrogen content， and organic carbon isotope data in this study， combined with previous data， have been analyzed to discuss the organic matter source and its response to paleoenvironmental evolution since the last deglaciation. The organic component of core OKT-3 is composed of terrestrial and marine organic matter. Terrestrial organic matter is mainly derived from the Changjiang and Taiwan Rivers， which is controlled by sea level change， the Kuroshio Current， and climate variation. The Changjiang-sourced organic matter of core OKT-3 showed a decreasing trend during 17.3~4 ka B.P.， consistent with the decreasing contribution of Changjiang-derived detrital sediments. In contrast， the Taiwan-sourced organic matter， which is transported by the Kuroshio Current， showed an increasing trend. It is worth noting that the Changjiang-sourced and Taiwan-sourced organic matter did not exhibit synchronous changes with the Kuroshio Current during 4~1.5 ka B.P.， which may be controlled by summer monsoon. Marine organic matter from core OKT-3 showed two peaks during B?lling-?ller?d and Pre-Boreal periods， with low values during the Younger Dryas period. Consistency between marine organic matter and primary productivity suggests that North Pacific Intermediate Water （NPIW） acts as a conveyor belt transporting nutrient from the North Pacific to the Okinawa Trough. NPIW passes through the Kerama Gap to the Okinawa Trough and carries nutrients to the surface water by way of upwelling. The consistency between marine organic matter and δ15N further suggests there may exist a link between the Okinawa Trough and the North Pacific， and NPIW may play an important role.