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首页> 外文期刊>Marine Chemistry >The supply and preservation of ancient and modern components of organic carbon in the Canadian Beaufort Shelf of the Arctic Ocean
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The supply and preservation of ancient and modern components of organic carbon in the Canadian Beaufort Shelf of the Arctic Ocean

机译：在加拿大北冰洋的博福特架上供应和保存古代和现代有机碳的成分

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The provenance of organic matter in sediments from the Mackenzie River and Beaufort Shelf was investigated using the stable carbon and radiocarbon isotopic compositions of bulk organic matter and the stable carbon isotopic compositions of individual organic compounds, including lignin-derived phenols and lipid-derived fatty acids. Most river suspended sediments and shelf surface sediments contained organic carbon characterized by highly depleted Δ~(14)C values that were consistent with average radiocarbon ages exceeding 7000 years. The stable carbon isotopic signatures of lignin phenols were uniformly depleted (-25 ≥ δ~(13)C ≥ -32 per thousand), indicating the predominant contributions of C_3 vascular plant sources. The isotopic compositions of C_(14) and C_(16) fatty acids exhibited important contrasts between the river (-36 per thousand to -40 per thousand) and shelf (-25 per thousand to -29 per thousand) sediments that were consistent with contributions from freshwater algae and/or vascular plants in the former and marine phytoplankton in the latter. Using ~(14)C isotopic mass balance, the abundances of modem and ancient organic matter were quantitatively constrained. The fate of organic matter in the Beaufort Shelf was explored by normalizing these abundances to the specific surface area of sediments. Ancient organic carbon, which may include old pre-aged soil material as well as fossil bitumen or kerogen, accounted for the majority (～70%) of the particulate organic matter exported by the Mackenzie River and deposited in surface sediments of the Beaufort Shelf. Modern organic carbon accounted for ～30% in both river and shelf sediments, with significant contributions from vascular plant-derived materials in both river and shelf samples and from marine algae in the shelf sediments. Respiration (and/or leaching) of particle-bound marine organic matter dominates the carbon metabolism in the Mackenzie Delta/Beaufort Shelf region. However, land-derived pools, including modem carbon derived from vascular plants as well as ancient carbon also appeared to undergo a degree of post-depositional degradation prior to burial in the shelf. These novel source apportionments are reflected in an updated carbon budget for the study area.
机译：使用大块有机物的稳定碳和放射性碳同位素组成以及单个有机化合物（包括木质素衍生的酚和脂质衍生的脂肪酸）的稳定碳同位素组成，研究了麦肯齐河和博福特架子沉积物中有机物的来源。 。大部分河流悬浮沉积物和架子表面沉积物中都含有有机碳，其特征在于高度消耗的Δ〜（14）C值，这与超过7000年的平均放射性碳年龄一致。木质素酚的稳定碳同位素特征被均匀地耗尽（-25≥δ〜（13）C≥-32 /千），表明C_3维管植物来源的主要贡献。 C_（14）和C_（16）脂肪酸的同位素组成在河流沉积物（-36 /千至-40 /千）和沉积物沉积物（-25 /千至-29 /千）之间显示出重要的反差，与前者的淡水藻类和/或维管植物的贡献和后者的海洋浮游植物的贡献。利用〜（14）C同位素质量平衡，定量地限制了现代和古代有机物的丰度。通过将这些丰度归一化到沉积物的比表面积，探索了博福特架中有机物的命运。古老的有机碳，可能包括旧的老化土壤物质以及化石沥青或干酪根，占Mackenzie河出口并沉积在Beaufort Shelf表层沉积物中的颗粒有机物的大部分（约70％）。河流和陆架沉积物中现代有机碳约占30％，其中河流和陆架样品中维管植物来源的物质以及陆架沉积物中海藻的贡献显着。在Mackenzie三角洲/ Beaufort Shelf区域，与颗粒结合的海洋有机物的呼吸作用（和/或淋滤作用）主导着碳代谢。但是，包括维管束植物产生的现代碳以及古代碳在内的陆源池在埋藏于架子之前似乎也经历了一定程度的沉积后降解。这些新颖的来源分配反映在研究区域的最新碳预算中。

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