Based on the molecular distribution of bound fatty acid (BFA) compound classes in core sediments of Lake Dianchi combined with the compound-specific delta C-13 values of the straight-chain BFAs, origin and vertical changes of organic matters in the sediments were investigated. The results indicated a significant change of BFA sources over the past 700 years. Contrast to the low concentrations of the terrestrial BFAs, the abundance of BFAs derived from the plankton/bacteria in the top sections (1944-recent) was more than 80 %. The increasing proportions of the branched and unsaturated BFAs in total fatty acids were closely correlated with the heavy eutrophication and the frequent algal blooms in the decades. Furthermore, the positive shift of delta C-13 of C16 and C18 (similar to 2 parts per thousand) in the upper section might be an indicator of the excess phytoplankton productivity. However, it was found that the plankton/bacteria-derived BFAs were more easily degraded during the early diagenetic process. The special compound carbon isotopic compositions of the long straight-chain BFAs (C24 and C26) in the sediments showed a depletion of heavier delta C-13 values (ca. -30 parts per thousand) in the midsections (1559-1787), reflecting a relatively growing contribution of C3 plants to C4 plants or that C4 plant growth was inhibited in cold and arid climates during the period.

Publication name	ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH　Volume: 20 　Issue: 4 　Pages: 2390-2397　Published: APR 2013
Author(s)	Wang, Lifang; Wu, Fengchang; Xiong, Yongqiang; Fang, Jidun
Corresponding author	WU Fengchang  wufengchang@vip.skleg.cn Chinese Acad Sci, State Key Lab Desert & Oasis Ecol, Xinjiang Inst Ecol & Geog, Urumqi 830011, Xinjiang, Peoples R China.
Author(s) from IGCAS	WANG Lifang

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