Assessment of the sources of sedimentary organic matter in the Bohai Sea and the northern Yellow Sea using biomarker proxies

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• 作者：Lei Xing^a ; ^b ; Di Hou^a ; Xinchen Wang^a ; Li Li^a ; Meixun Zhao^a ; ^b ; ^{maxzhao@ouc.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Biomarker ; Terrestrial organic matter ; The Bohai Sea ; The northern Yellow Sea ; BIT
• 刊名：Estuarine, Coastal and Shelf Science
• 出版年：2016
• 出版时间：5 July 2016
• 年：2016
• 卷：176
• 期：Complete
• 页码：67-75
• 全文大小：2373 K

文摘

To evaluate the applicability of source proxies and to assess the sources of sedimentary organic matter in the Bohai Sea (BS) and the northern Yellow Sea (NYS), we analyzed total organic carbon (TOC), total nitrogen (TN), δ¹³C of TOC, n-alkanes, phytoplankton biomarkers, and glycerol dialkyl glycerol tetraethers (GDGTs) including branched GDGTs (brGDGTs) in 60 surface sediment samples covering the BS and the NYS. Spatial distribution comparison and principal component analysis indicate that with the exception of brGDGTs, terrestrial biomarkers have different spatial distribution pattern from marine biomarkers, suggesting that the sources control the distributions of these biomarkers in spite of hydrodynamic forcing. Significantly positive correlation (R² = 0.5) between TOC normalized brGDGTs content and TOC normalized crenarchaeol content suggested in situ production of brGDGTs in the BS and the NYS. The δ¹³C values, TMBR [terrestrial and marine biomarker ratio: (C₂₇ + C₂₉ + C₃₁n-alkanes)/[(C₂₇ + C₂₉ + C₃₁n-alkanes) + (brassicasterol + dinosterol + alkenones)] ] and BIT (branched isoprenoid tetratether index) proxy indicated high terrestrial organic matter (TOM) input near the Huanghe River Estuary, while TOC/TON did not reveal similar distribution pattern. Quantitative estimates of TOM using a binary model revealed much higher TOM percentage from δ¹³C (avg. 58%) and TMBR (avg. 31%) than from BIT (avg. 7.4%). Our results suggest that, owing to significant in situ production of brGDGTs, the BIT is not a good proxy for indicating soil OM contribution in marine sediments from the BS and the NYS.