Biomarkers as organic-carbon-source and environmental indicators in the Late Quaternary Arctic Ocean: problems and perspectives

Abstract

In order to examine the variation in marine and terrigenous sources of the organic matter during the last 15,000 Cal. yr Ž BP, hydrogen index values, CrN ratios, and specific biomolecules short-and long-chain n-alkanes, short-chain fatty acids, . sterols, alkenones, and pigments were determined in three sediment cores from the Laptev Sea continental margin. The results show that the interpretation of the biomarker data is much more complicated and less definitive in comparison to similar data sets from low-latitude open-ocean environments. This is mainly caused by the complexity of the Arctic Ocean system, which is characterized by a high seasonality of sea-ice cover and primary productivity, sea-ice sediment transport Ž . and a high fluvial supply of freshwater aquatic organic matter. A combination of organic geochemical, organic petrographic and micropaleontological data may yield to a more precise identification of organic-carbon sources for these Ž . complex systems. On the Laptev Sea shelf cores KD9502-14 and PS2725-5 , terrigenous organic-carbon input controlled by river discharge seems to be predominant during the last about 10,000 Cal. yr BP. Maximum supply of terrigenous organic Ž . carbon was reached in the Early Holocene i.e., about 9000-10,000 Cal. yr BP . Further offshore at the upper continental Ž . slope core PS2458-4 , a major change in organic-composition occurred near 10,000 Cal. yr BP. During this period hydrogen indices as well as the amounts of short-chain n-alkanes, short-chain fatty acids, dinosterol and brassicasterol significantly increased, indicating increased relative proportions of marine organic matter preserved in the later time interval. q 1999 Elsevier Science B.V. All rights reserved.

Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea

“…The slight differences observed between these samples are in accordance with existing knowledge on diagenetic transformation of bottom sediment OM in continental shelf and deeper sediments (Degens and Mopper, 1976;Yunker et al, 1995;Fahl and Stein, 1999;Yamamoto et al, 2008;Petrova et al;.…”

Particulate matter fluxes in the southern and central Kara Sea compared to sediments: Bulk fluxes, amino acids, stable carbon and nitrogen isotopes, sterols and fatty acids

“…Sterols support the terrestrial source: they had high fluxes as well as their maximum contents (not shown) in these two cups (Table 1). Whereas campesterol and X -sitosterol are derived from higher land plants (Huang and Meinschein, 1976;Volkmann, 1984), dinosterol and brassicasterol can be derived from both fresh water and marine algae (Fahl and Stein, 1999;Robinson et al, 1984;Thiel, 1993;Yunker et al, 1995). As fluxes and contents of all sterols were significantly correlated we can assume that the algal sterols were mainly fresh-water derived.…”

Atlantic Water advection vs. glacier dynamics in northern Spitsbergen since early deglaciation

“…Brassicasterol and dinosterol have been used as phytoplankton biomarkers (see Fahl and Stein, 1999;Volkman, 1986;Volkman et al, 1993). For extraction of IP 25 and sterols, 3 g of sediment was ultrasonicated (Sonorex Super RK 510, 35 Khz, 15 min) using dichloromethane:methanol (2 : 1, v/v) as solvent.…”