Feedback of threshold via estimating sources and composition of sedimentary organic matter across trophic gradients in freshwater lakes》.pdf

Science of the Total Environment 500–501 (2014) 373–382 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: /locate/scitote nv Feedback of threshold via estimating sources and composition of sedimentary organic matter across trophic gradients in freshwater lakes Xiaoguang Xu a, Wei Li a,⁎, Megumu Fujibayashi a, Munehiro Nomura a, Takashi Sakamaki a, Osamu Nishimura a,⁎, Xianning Li b a Graduate School of Engineering, Tohoku University, Aoba 6-6-06, Sendai 980-8579, Japan b School of Energy and Environment, Southeast University, Nanjing 210096, PR China H I G H L I G H T S • SOM composition in different trophic state lakes were systematically compared. • Multiple sources of SOM were identified using fatty acid biomarkers. • Terrestrial plant derived organic carbon was a useful predictor for sediment TOC. • Increasing trophic state led to rising aquatic source contribution to SOM pool. • The threshold of terrestrial to aquatic ratio along trophic gradients was 0.683. a r t i c l e i n f o a b s t r a c t Article history: The quantity and quality of sedimentary organic matter (SOM) in relation to material and energy flows are crucial Received 14 July 2014 for understanding the current state and future development of lake systems, yet, characterization of organic mat- Received in revised form 27 August 2014 ter sources and assessment of their relative contributions in different trophic-state lakes caused by anthropogen- Accepted 29 August 2014 ic impacts are scarcely known