Biomarkers in surface sediments from the Ob and Yenisei estuaries and the southern Kara Sea

Organic-geochemical bulk parameter (Total organic carbon contents, C/N ratios and d13Corg values), biogenic opal and biomarkers (n-alkanes, fatty acids, sterols and amino acids) were determined in surface sediments from the Ob and Yenisei estuaries and the adjacent southern Kara Sea. Maximum TOC contents were determined in both estuaries, reaching up to 3 %. Relatively high C/N ratios around 10, light d13Corg values of -26.5 per mil (Yenisei) and -28 to -28.7 per mil (Ob), and maximum concentrations of long-chain n-alkanes of up to about 10 µg/g Sed clearly show the predominance of terrigenous organic matter in the sediments from the estuaries. Towards the open Kara Sea, all p arameters indicate a decrease in terrigenous organic carbon. Brassicasterol as well as the short-chain n-alkanes parallel this trend, suggesting that these biomarkers are probably also related to a terrigenous (fresh-water phytoplankton) source. […]

有机地球化学总体参数（总有机碳含量、C/N 比率及 d13Corg 值），生物成因的蛋白石和生物标志物（正构烷烃、脂肪酸、甾醇和氨基酸）在鄂毕河和叶尼塞河的河口及邻近的卡拉海南部表层沉积物中得以测定。两个河口地区的最大 TOC 含量均达到 3% 之高。C/N 比率约为 10，d13Corg 值分别为叶尼塞河的 -26.5‰ 和鄂毕河的 -28.0‰ 至 -28.7‰，以及长链正构烷烃的最大浓度为约 10 µg/g 沉积物，这些数据明确指示了河口沉积物中陆源有机质的占主导地位。向卡拉海开阔区域延伸，所有参数均显示出陆源有机碳含量的降低趋势。芥菜甾醇以及短链正构烷烃与这一趋势相一致，暗示这些生物标志物可能也与陆源（淡水浮游植物）来源有关。