Characterization of Siberian Arctic coastal sediments:: Implications for terrestrial organic carbon export -: art. no. GB1036
Characterization of Siberian Arctic coastal sediments:: Implications for terrestrial organic carbon export -: art. no. GB1036
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DOI：
10.1029/2003gb002087
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发表时间：
2004-03-10
影响因子：
5.2
通讯作者：
White, D
中科院分区：
文献类型：
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作者：
Guo, LD;Semiletov, I;White, D
2000年跨北极探险期间，沿着西伯利亚北极海岸线收集了表层沉积物，包括Ob、Yenisey、Khatanga、Lena和IndiGirka河口。为了更好地了解西伯利亚北极大空间尺度上河流出口的变化，对沉积物的元素组成(总有机碳、TOC、黑碳、BC和总N，以及常量和微量元素)、同位素特征(Delta(13)C、Delta(15)N、Delta(14)C、epsilon(ND)、Sr-87/Sr-86)和有机分子组成进行了表征。平均而言，沉积物中总碳的79+/-9%为有机碳，21+/-9%为无机碳。BC占TOC库的9+/-4%，西伯利亚沿岸总体呈自西向东递增的趋势。以哈坦加河为界，利用组合Ndsr同位素(epsilon和sr-87/sr-86)确定了西西伯利亚东部和西部两个不同的沉积物来源。沉积有机碳(SOC)的热解-GC/MS数据表明，西伯利亚北极海岸有机质的新鲜度从西向东增加，随着呋喃(多糖)相对于腈的相对丰度增加。土壤有机碳三角洲(13)C值变化范围为-27.1%(主要为陆源)~-23.8%，三角洲(15)N由东向西递增(3.1~5.2%)，并与C/N比值显著相关。土壤有机碳三角洲(14)C值在-805%~-279%之间，自东(印地吉卡河)向西(鄂毕河)呈一致的递增趋势。这些D14C值对应于鄂尔多斯河口2570+/-30yBP和印地格尔卡口13050+/-50yBP的14C年龄。最重要的是，D14C值与BC/TOC值显著相关(R2=0.91，n=6)，符合西伯利亚海岸多年冻土带自西向东递增的分布格局。综上所述，我们的结果表明，较老的有机碳来自于永冻土融化、河岸和海岸侵蚀过程中顽固的BC的释放，可能是由于北部生态系统持续的环境变化而增强的。
Surface sediments were collected during the 2000 TransArctic Expedition along the Siberian Arctic coastline, including the Ob, Yenisey, Khatanga, Lena, and Indigirka estuaries. Sediments were characterized for elemental composition (total organic carbon, TOC, black carbon, BC, and total N, as well as major and trace elements), isotopic signature (delta(13)C, delta(15)N, Delta(14)C, epsilon(Nd), Sr-87/Sr-86), and organic molecular composition to better understand river export variations over the large spatial scale of the Siberian Arctic. On average, 79 +/- 9% of the total C in sediments was organic while 21 +/- 9% was inorganic. BC made up 9 +/- 4% of the TOC pool, with a general increasing trend from west to east along the Siberian coast. The combined Nd- and Sr-isotopes (epsilon(Nd) and Sr-87/Sr-86) were used to define two distinct sediment sources between east and west Siberian regions with the Khatanga River as a boundary. Data from pyrolysis-GC/MS of the sedimentary organic carbon (SOC) indicated an increase in the freshness of the organic matter from west to east on the Siberian Arctic coast, with increasing relative abundance of furfurals (polysaccharides) with respect to nitriles. Values for the delta(13)C of SOC ranged from -27.1% (mostly terrigenous) to -23.8%, while delta(15)N increased from east to west (3.1 to 5.2%) with a significant correlation with C/N ratio. Values for the Delta(14)C of SOC ranged from -805 to -279%, with a consistent trend increasing from the east (Indigirka River) to the west (Ob River). These D 14 C values corresponded to a 14 C age of 2570 +/- 30 yBP in the Ob estuary and 13,050 +/- 50 yBP in the Indigirka estuary. Most importantly, D 14 C values were significantly correlated with the ratio of BC/TOC (R-2 = 0.91, n = 6), consistent with the distribution pattern of increasing permafrost zone from the west to the east along the Siberian coast. Together, our results suggest that older OC was derived from the release of recalcitrant BC during permafrost thawing and riverbank and coastal erosion, likely enhanced by ongoing environmental changes in the northern ecosystem.