LAKE TYPOLOGY BASED ON THE USE OF SEDIMENT ALKANES IN THE EAST AND WEST BASINS OF TAIHU LAKE, CHINA

This is the first time that alkane based organic markers have been use d to distinguish between different lake types. This study also provide s the first description of the organic geochemical character of the su rface sediments of Taihu Basin. Taihu Lake is one of the largest fresh water lakes in China. Its east basin supports a dense population of va scular plants (sediment C/N = 13.8) while the west basin is nearly fre e of vascular plants and supports a high phytoplankton (predominantly cyanobacteria) biomass (sediment C/N = 7.95). In the eutrophic west ba sin, the normal alkanes and fatty acids were primarily short chain mol ecules (major carbon peaks at C-15 and C-17) while the mesotrophic eas t basin sediments contained normal alkanes and fatty acids with longer chain molecules (major carbon peaks at C-24 to C-30) Thus alkane and fatty acid carbon peak data provide paleolimnologists with another too l to aid them in distinguishing between mesotrophic - vascular plant d ominated lakes and eutrophic-cyanobacteria dominated lakes.