期刊
ORGANIC GEOCHEMISTRY
卷 42, 期 9, 页码 1025-1038出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.orggeochem.2011.07.002
关键词
-
资金
- Polish Ministry of Science and Higher Education [NN 304 3543 33]
We present an organic geochemical study of surface sediments of Lake Sarbsko, a shallow coastal lake on the middle Polish Baltic coast. The aim was to provide evidence concerning the origin of the organic matter (OM) and its compositional diversity in surface deposits of this very productive, highly dynamic water body. The content and composition of the OM in the bottom sediments were investigated at 11 sampling stations throughout the lake basin. OM sources were assigned on the basis of bulk indicators [ total organic carbon (TOC), total nitrogen (TN), delta C-13(TOC) and delta N-15 and extractable OM yield], biomarker composition of extractable OM and compound-specific C isotope signatures. The source characterization of autochthonous compounds was verified via phytoplankton analysis. The distribution of gaseous hydrocarbons in the sediments, as well as temporal changes in lake water pH, the concentration of DIC (dissolved inorganic carbon) and delta C-13(DIC) were used to trace OM decomposition. The sedimentary OM is composed mainly of well preserved phytoplankton compounds and shows minor spatial variability in composition. However, the presence of CH4 and CO2 in the bottom deposits provides evidence for microbial degradation of sedimentary OM. The transformation of organic compounds in surface, bottom and pore waters via oxidative processes influences carbonate equilibrium in the lake and seasonally favours precipitation or dissolution of CaCO3. The data enhance our understanding of the relationships between the composition of sedimentary OM and environmental conditions within coastal ecosystems and shed light on the reliability of OM proxies for environmental reconstruction of coastal lakes. (C) 2011 Elsevier Ltd. All rights reserved.
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