title: Characterization of n-alkanes and their carbon isotopic composition in sediments from a small catchment of the Dianchi watershed.
abstract: The biomarker composition and stable carbon isotope values of organic matter (OM) in sediment cores from Shuanglong catchment of the Dianchi watershed show an unimodal n-alkane distribution ranging from C15-C33 with a strong predominance of odd-numbered n-alkanes, maximizing at n-C27, n-C29 and n-C31. Organic carbon to nitrogen (OC/N) ratio indicates a strong terrestrial influence on the OM. The values of δ(13)C27, δ(13)C29 and δ(13)C31 of n-alkanes range from -36.1‰ to -26.1‰, -34.1‰ to -30.1‰ and -33.8‰ to -28.7‰, respectively, suggesting a mainly C3 land plants origin. The carbon preference index (CPI25-31), odd-even preference (OEP27-31), average chain length (ACL25-33), pristine/phytane (pr/ph), Paq, (C27+C29)/2C31, nC16-23/nC24-33 and 3C17/(C21+C23+C25) values are also consistent with the predominance of C3 land plant-derived OM. Different sources of OM are reflected by the peak of n-C15, ascribed to a contribution by aquatic algae and photosynthetic bacteria. Eutrophication seems to be enhanced by both autochthonous (weak) and allochthonous (strong) contributions of OM. A major factor affecting the OM accumulation in the catchment and OM transportation to the Dianchi Lake may be increased by human activities from 1871 to 2011.
authors.affiliation: School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China. Electronic address: wangyanhua@njnu.edu.cn.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Yang
authors.affiliation: College of Economics and Management, Nanjing University of Aeronautics & Astronautics, Nanjing, Jiangsu 210016, China.
authors.forename: Jixiang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Gao
authors.affiliation: School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China.
authors.forename: Changchun
authors.initials: C
authors.lastname: Huang
authors.affiliation: School of Geography Science, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Xie
mesh_terms: D000473:Alkanes / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D005068:Eutrophication; D019015:Geologic Sediments / Q000032:analysis*; D006802:Human Activities; D060106:Lakes; D014881:Water Supply
chemical_list: D000473:Alkanes; D002247:Carbon Isotopes
keywords: Dianchi watershed; Organic matter; Sediment; n-Alkanes; δ(13)C