title: Bias and association of sediment organic matter source apportionment indicators: A case study in a eutrophic Lake Chaohu, China.
abstract: The sources of sediment organic matter (SOM) could be explained by various indicators. To test their biases and associations, the present study determined multiple indicators for SOM source apportionment, including elemental analysis (carbon and nitrogen, and their stable isotope δ13C and δ15N), n-alkanes compositions as well as derivative indicators (e.g., terrigenous to aquatic ratio), and carbon isotopes of n-alkane in Lake Chaohu, a eutrophic lake. The spatial variation of anthropogenic effects could be revealed by SOM elemental variations. The n-alkanes of all samples had a bimodal distribution with the 1st peak at n-alkane with 17 carbons (C17) and the 2nd predominant peak at C29. The parity advantage index of n-alkanes indicated that the sediments had mixed characteristics of both endogenous and terrigenous sources. Some n-alkanes indicators also revealed eutrophication characteristics of dominant algae in Lake Chaohu. SOM received a mixed contribution of plankton (I), low-latitude terrestrial high-grade plants (II) and microbial material (III) as indicated by isotopic compositions of long-chain n-alkane. Multiport element model (MEM) showed the contribution of self-generated sources of organic matter in Lake Chaohu is >50%, indicating the historic serious eutrophication in Lake Chaohu. The main sources of SOM in the eastern part of the lake were algae and terrestrial input, with little input from microbes, and the contribution from algae decreased from west to east. The multiple indicators' judgment by MEM and principle component analysis (PCA) was of ecological significance and proposed because they offered scientific tools for disclosing the historic variations of SOM as well as their sources.
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA. Electronic address: xufl@urban.pku.edu.cn.
authors.forename: Fu-Liu
authors.initials: FL
authors.lastname: Xu
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China. Electronic address: harveymylife@aliyun.com.
authors.forename: Wei
authors.initials: W
authors.lastname: He
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Qi-Shuang
authors.initials: QS
authors.lastname: He
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Yi-Long
authors.initials: YL
authors.lastname: Li
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Kang
authors.affiliation: MOE Laboratory for Earth Surface Processes, College of Urban & Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Wen-Xiu
authors.initials: WX
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: Xiong
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
keywords: Isotope fingerprinting; Lake Chaohu; Lipid molecular biomarkers; Sediments organic matter; Source apportionment