Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island,Western Antarctic,were dated using 210Pb.Changes in the fatty acid ratios of nC18:2/nC18:0 from the penguin droppings reflect climate changes coincident with ENNO events during 1931-2006.The occurrence of the minimum values in the depth of 2-3 and 6-7 cm are consistent with the end of ENSO in 1958 and 1983,respectively,reflecting a lag of the biomarker records in AD2 penguin droppings-amend soil in climatic signatures.This study also reveals that the changes in the relative concentration of n-alkanes nC23,the ratios of nC23/nC17 and nC21 /nC22+,and carbon preferential index(CPI) values collectively indicate the variations of soil microor-ganism and lower plant,which are closely related to climate changes.The ratios of bacterial fatty acids iC15:0/aC15:0 reflect the increasing significance of microorganism activities during the two periods that occurred at the end years of ENSO.Decrease in CPIA value and increase in nC21 /nC22+ indicate that low molecular weight fatty acids are derived from microorganism;and their insignificant correlation with Pr/Ph suggests microorganisms play an important role in the relatively simply ecosystem in the Antarctic and are closely linked to climatic conditions.In addition,the observed penguin community indicates the popula-tion of penguin can largely reflect the impacts of global climate changes on the ecosystem.
Biomarkers including brassicasterol, dinosterol and alkenone in sediments are used as indicators to reconstruct changes to the phytoplankton community in surface and sub-aerial sediments of Prydz Bay, Antarctica. The results indicate that the bio- marker records in surface and core sediment samples changed with time and space. The total content of phytoplankton biomarkers ranges from 391.0--1 470.6 ng.g-l. The phytoplankton biomass has increased in Prydz Bay over the past 100 years. This variation may be mainly related with climate change in the region. The total biomarker contents in surface sediments from 5 stations in Prydz Bay are in the range of 215.8--1 294.3 ng.g4. The phytoplankton biomass in Prydz Bay is higher than that outside of the bay. This is similar to the distributions of chlorophyll a, organic carbon and biogenic silica in surface waters determined through in situ investigation. Such consistency indicates a coupling between the bottom of the ocean and biogeochemical processes in the upper water.
