Characterization of n-alkanes and their carbon isotopic composition in sediments from a small catchment of the Dianchi watershed. (January 2015)

• Record Type: Journal Article
• Authors: Wang, Yanhua; Yang, Hao; Zhang, Jixiang; Gao, Wenjing; Huang, Changchun; Xie, Biao
• Is Part Of: Chemosphere. Volume 119(2015)
• Page Start: 1346
• Page End: 1352
• Publication Date: 2015-01
• Subjects: Dianchi watershed -- Sediment -- n-Alkanes -- δ13C -- Organic matter; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2014.01.085
• Languages: English
• ISSNs: 0045-6535

Abstract

Highlights: Strong predominance of odd-numbered n -alkanes maximizing at n -C27, n -C29 and n -C31 was observed. Organic matter within the sediments was deduced mainly from C3 land plants. Human activities enhanced the Dianchi watershed eutrophication from 1871 to 2011. 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, n C16–23 / n C24–33 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.