WANG Li-fang^1*, XIONG Yong-qiang², WU Feng-chang³, FANG Jidun¹, LI Yun²

(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;
3. State Environmental Protection Key Laboratory for Lake Pollution Control/Research Center of Lake Eco-environments; Chinese Research Academy of Environmental Sciences; Beijing100012, China)

Abstract: This study investigated one of the five great China's freshwater lakes－Chaohu Lake. Overall characteristics of organic matter, including δ¹³C, δ¹³N, TN and TOC, from a 18-cm surface sediment core were analyzed. The concentrations and stable carbon isotopic composition of the bound fatty acids were also analyzed. Based on the above analyses, this paper discussed the eutrophication process in the Chaohu Lake in recent 70 years. The results indicate that the paleoenvironment evolution recorded in the modern sediments of Chaohu Lake can be divided into two main stages, and the values of δ¹³N , TOC and TN increased at the 0-7cm interval, and it is related with the eutrophication process in the Chaohu Lake. Variations in C_16:0, C_18:2W6, C_18:1w7/_C18:1w9, （i-C_15:0+a-C_15:0）/nC_15:0 and TARFA indicate that the sedimentary organic matter was derived mainly from aquatic planktons and bacteria, and the abundance of aquatic algae led to the enhancement of lake eutrophication. The δ¹³C values of boundnC_16:0 fatty acids in Chaohu Lake sediments are better to record the enhancement of lake eutrophication in recent few decades. Consequently, the δ¹³C values of boundnC_16:0 fatty acids may be an important indicator to reflect lake eutrophication process.

Key words: bound fatty acid;, δ¹³C; eutrophication; sediment core; Chaohu Lake

EARTH AND ENVIRONMENT  Vol. 38, No.4, Tot No.282, 2010, Page 393-401