The study of impact of Antarctic ice melting event since Last Glacial Maximum for global environmental change

我们测量了从罗斯海表层沉积物中分离的单个、溶剂可提取的短链（C14、C16和C18）脂肪酸的放射性碳和氢同位素含量。对应的14C年龄与弹后溶解无机碳（DIC）储层相当。此外，表层（15厘米以上）沉积物中的14C分子变化表明，这些化合物可能有助于重建含有不确定（和可能可变）残余有机碳的南极边缘沉积物的年代学。初步的14C分子年代学表明，在过去的500 14C年里，残余有机质的积累速率没有改变。本研究的重点是确定化合物特异性14C和氢同位素分析作为重建南极冰融化事件年代学的技术的有效性。此外，我们还研究了南极半岛附近3个沉积物岩心，重建了近24年来南极冰盖的融化历史。在整个岩心中考察了南极大陆的漂流碎屑（IRD）和陆源物质，以获得融化事件的时间和规模。-我们利用K2O和Na2O的相对丰度来了解沉积物的起源。表层沉积物K2O/Na2O比值与区域内3种表层洋流的影响程度相关，因此该比值可以约束沉积物的源区。根据沉积有机碳的放射性碳定年和Cycladophora davisiana的相对丰度，构建了这些岩心的年代。通过对岩心IRD通量、K2O/Na2O比值、14C和辐射虫的分析，揭示了LGM时期至今IRD通量的时间变化和沉积物供应源区的变化。在25-17 ka和15-12 ka分别观测到IRD最大值，这表明在全球融水脉冲la事件期间，冰盖出现了相当大的扩张，而在全球融水脉冲la事件期间，冰盖迅速融化。少

We have measured the radiocarbon and hydrogen isotope contents of individual, solvent-extractable, short-chain (C14, C16, and C18) fatty acids isolated from Ross Sea surface sediments. The corresponding 14C ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular 14C variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain(and potentially variable) quantities of relict organic carbon. A preliminary molecular 14C chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 14C yr. The focus of this study is to determine the validity of compound-specific 14C and hydrogen isotope analysis as a technique for reconstructing chronologies of Antarctic ice melting events.Furthermore, we studied 3 sediment cores recovered from off Antarctic Peninsula to reconstruct the melting h … More istory of the Antarctic Ice sheet during the last 24 kyrs. Rafted Debris (IRD) and terriginous material from the Antarctic Continent were investigated throughout the cores to obtain the timing and the magnitude of the melting events.- We employed the proxy to understand the origin of the sediments using the relative abundances of K2O and Na2O. -Surface sediments K2O/Na2O ratio correlated with the the degree of the influence from 3 surface currents in the region and hence the ratio can constrain the source area of the sediments. Chronologies of these cores were constructed based on both radiocarbon dating of sedimentary organic carbon and the relative abundance of radiolaria Cycladophora davisiana. Analyzing IRD, K2O/Na2O ratio, 14C and radiolaria in the cores showed temporal variations of IRD flux as well as the source regions of the sediment supply during the LGM to the present. IRD maxima were observed in 25-17 and 15-12 ka that show the considerable expansion of the ice sheet during the, LGM and rapid melting of the ice sheet at the time of the global melt water pulse la event respectively. Less