Palynology and sedimentology of core PG1214

A 3.5-m-long sediment sequence from a lake on Raffles Oslash, off Liverpool Land, East Greenland, was investigated for chronology, lithology, palynology and biogeochemistry. Radiocarbon-dating of plant remains and the lithology of the sediment succession indicate continuous sedimentation since deglaciation of the area prior to 10000 cal. yr BP. The postglacial palynological record shows little variation and evidence of a wind-transported pollen supply, both resulting from the geographical characteristics of Raffles Oslash. Significant variations in the biogeochemical data reflect changes in aquatic bioproduction. These changes depend to some extent on climatic changes; however, they are mainly due to variations in seabird breeding colonies in the catchment which influence nutrient and cadmium supply to the lake. Large seabird breeding colonies were present between 7500 and 1900, from 1000 to 500, and since c. 100 cal. yr BP. Their absence prior to 7500 cal. yr BP may be the result of unsuitable feeding conditions close to Raffles Oslash caused by a too dense or too open seaice cover. In contrast, between 1900 and 1000 and from 500 to 100 cal. yr BP, the seabird settlement was probably restricted by an insufficiently long breeding season due to cold climate conditions in East Greenland.对格陵兰东部利物浦地（Liverpool Land）外莱福尔斯Ø（Raffles Oslash）附近某湖泊的3.5米长沉积序列，开展了年代学、岩性学、孢粉学与生物地球化学研究。通过对植物残体的放射性碳定年以及沉积序列的岩性分析，结果表明该区域自距今10000校准年（cal. yr BP）前的冰消作用以来，沉积作用持续进行。冰后期孢粉记录仅存在微弱变化，且存在风传花粉供给的证据，这两点均与莱福尔斯Ø的地理特征密切相关。生物地球化学数据的显著变化反映了水生生物生产力的改变：这类变化在一定程度上受气候变化调控，但主要归因于汇水区内海鸟繁殖群落的变化——后者会直接影响湖泊的养分与镉供给。海鸟繁殖群落分别在距今7500至1900校准年、1000至500校准年，以及约100校准年至今这三个时期大量存在。在距今7500校准年之前，该区域并无海鸟繁殖群落，这可能是由于莱福尔斯Ø附近海域的海冰覆盖度过密或过疏，导致缺乏适宜的觅食条件。与之相反，在距今1900至1000校准年以及500至100校准年这两个时期，受格陵兰东部寒冷气候影响，繁殖季时长不足，海鸟的栖息活动可能受到限制。