Distinctive 13C isotopic signature distinguishes a novel sea ice biomarker in Arctic sediments and sediment traps

Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis

“…All these autochthonous natural inputs overlap with the allochthonous inputs derived from land plants and fossil material. The δ 13 C values for the n-alkanes, typical of C 3 vascular plants, were consistent with those previously reported in surface sediments from the Beaufort Sea (Drenzek et al, 2007) and the Franklin Bay (Belt et al, 2008). Higher abundance of terrestrial LCOH and LCFA was measured in the shallow sediments (Tables 6 and 10), but the percentage of terrestrial material was higher in sediments underlying a deeper water column because of the higher lability of marine organic matter.…”

“…These results are consistent with the large range in δ 13 C bulk values (−27 ‰ to −18 ‰) displayed by biogenic particulate OM in the Arctic Ocean (Goericke and Fry, 1994). The δ 13 C values observed for the straight-chain polyunsaturated alkene n-C 21:6 ranged from −33 to −37 ‰ (Table 11) and are more depleted than those obtained in the sediment samples (−29 to −31 ‰) and the value reported by Belt et al (2008) in a sediment trap from the Franklin Bay (−28 ‰). Although δ 13 C values of −35 to −42.2 ‰ for polyunsaturated highly branched isoprenoid isomers from the Baffin Bay were suggested to result from freshwater diatoms (Belt et al, 2008), the so depleted values obtained in marine waters (sites 240, 345, 460 and 540) suggest that the algal compounds (hydrocarbon n-C 21:6 and C 20:5ω3 and C 22:6ω3 FAs) are derived from slow-growing phytoplankton (Benthien et al, 2007).…”

“…These heavy δ 13 C values are well comparable with the data of Belt et al (2008) from sediments of the Franklin Bay, and are distinguishable from those of OM of planktonic origin (e.g. phytol).…”

“…The δ 13 C values observed for the straight-chain polyunsaturated alkene n-C 21:6 ranged from −33 to −37 ‰ (Table 11) and are more depleted than those obtained in the sediment samples (−29 to −31 ‰) and the value reported by Belt et al (2008) in a sediment trap from the Franklin Bay (−28 ‰). Although δ 13 C values of −35 to −42.2 ‰ for polyunsaturated highly branched isoprenoid isomers from the Baffin Bay were suggested to result from freshwater diatoms (Belt et al, 2008), the so depleted values obtained in marine waters (sites 240, 345, 460 and 540) suggest that the algal compounds (hydrocarbon n-C 21:6 and C 20:5ω3 and C 22:6ω3 FAs) are derived from slow-growing phytoplankton (Benthien et al, 2007). Indeed, the isotopic signature of pelagic phytoplankton from high latitudes, with relatively high concentrations of CO 2 , can be significantly depleted in 13 C, with δ 13 C values ranging from −18 to −28 ‰ in the Arctic Ocean (Goericke and Fry, 1994;Gradinger, 2009;Iken et al, 2005;Ruttenberg and Goñi, 1997;Schubert and Calvert, 2001;Tremblay et al, 2006).…”

“…The issue of δ 13 C end-member determination is particularly problematic in this area (Amiel and Cochran, 2008;Belt et al, 2008;Forest et al, 2007), because there are other sources of POC than those derived from terrestrial vegetation and marine productivity. In particular, the fossil contribution from the river drainage basins may represent a significant source of POC with intermediate δ 13 C values, and the algal productivity in the rivers could be a source of δ 13 C-depleted POC (Goñi et al, 2005).…”