对采自北极新奥尔松(Ny-lesund)一级海岸阶地上的海蚀凹槽沉积剖面进行沉积岩相学、同位素地球化学和元素地球化学研究,结果显示该剖面的70—118 cm段显著受到了海鸟粪沉积的影响,为含贝壳的海鸟粪土沉积层。该段粪土沉积层中大多数元素的浓度随深度表现出明显的波动特征,其中TOC、TN、Se、Sr、CaO、Pb、As、Zn等元素含量在深度剖面上表现出较为一致的垂向变化趋势。对粪土层的元素地球化学数据进行了聚类分析,结果表明在浓度剖面上具有较好协同关系的上述元素组合与海鸟粪有机质的输入密切相关,这些具有显著地球化学性质差异的元素共生组合是北极新奥尔松粪土沉积层的生物地球化学组合的标型特征,它们的含量变化主要受控于海鸟粪对沉积物的影响程度。海鸟粪土生物地球化学标型组合特征的识别为进一步研究该地区12—4 ka B.P.的海鸟生态系统和气候演化记录提供了科学基础。
A sediment core was collected from the Fildes Peninsula of Antarctica, which contained numerous seal hairs and was identified to be seal excrement deposition. By analyzing its total organic carbon (TOC) and concentrations of bio-elements, the seal population changes of the past century were reconstructed. The variation of seal population in the last century on the Fildes Peninsula is primarily controlled by human activities. The sealing industry in the early 20th century caused the dramatic decline of seal popula-tion. The protection of the Antarctic seals since the 1960s and the reduced seal's competition with whales for prey resources due to whaling lead to the recovery of seal population and make the high level of the seal population sustainable.
YANG QiChaoSUN LiGuangKONG DeMingHUANG TaoWANG YuHong
According to palaeoclimatic and modern instrumental data,numerous studies have indicated that the Arctic climate has undergone a significant warming during the past 100 years,and this may lead to significant impact on the fragile lake ecosystem.In this study,we collected a lake sediment core from the Nylesund of Svalbard and determined the concentrations of four pigments including chlorophyll derivatives,total carotenoids,oscillaxanthin and myxoxanthophyll in the sediments.Combined with other physical and chemical proxies such as calcium carbonate,total organic carbon,biogenic silicon etc.,we have reconstructed the historical changes of lacustrine primary productivity in Ny-lesund,especially for the past 100 years.The results showed that during the period of Little Ice Age（LIA）,the climate was unfavorable for the growth of the lake algae,and thus the lacustrine productivity declined.This result was supported by the relatively low contents of pigment and biogenic silica in the sediments.In contrast,the contents of total organic carbon（TOC） and sediment pigments increased significantly in the upper 5 cm（-1890AD）,reflecting the rapid growth of the lake algae,thus the great increase of lacustrine primary productivity,corresponding to the warming climate after LIA.However,the biogenic silica in the upper sediments still had a relatively low level,and this might be related to the growth competition with other algae species.Over the past 100 years,the ratio of Osc/Myx in the sediments decreased continuously,indicative of durative increase of myxoxanthophyll in blue-green algal pigments,and this might imply that the human activity had enhanced the nutrition level of the lake in the Arctic region.
During CHINARE-22 in austral summer of 2005-2006, a lake sediment core named DG4, which is impacted by penguin droppings, was retrieved from a lake catchment in Gardner Island of Vestfold Hills, East Antarctica. In this study, the concentrations of characteristic elements in the core, local bedrocks and fresh penguin guanos were determined. P, Se, F, S, As, Sr and Cu in DG4 were identified as the bio-element assemblage by R-clustering analysis and compared with those in the local bedrocks and fresh guanos, the results are similar to Y2 in Ardley Island, Antarctic Peninsula. On this basis, P and Se were identified as the optimum bio-elements in DG4 and F, P and S were identified in Y2, respectively. This work will provides the foundation for reconstructing the past penguin populations in Gardner Island of Vest- fold Hills, East Antarctica and comparing the penguin population dynamics between East Antarctica and Antarctic Peninsula.
