New insights on black carbon in pelagic Atlantic sediments
New insights on black carbon in pelagic Atlantic sediments
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关于大西洋远洋沉积物中黑碳的新见解
DOI：
10.1016/j.marchem.2023.104312
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发表时间：
2023
期刊：
影响因子：
3
通讯作者：
Lohmann, Rainer
中科院分区：
文献类型：
--
作者：
St.Laurent, Kari;Cantwell, Mark;Lohmann, Rainer
黑碳（BC）普遍存在于远洋沉积物中，由于海洋停留时间长和陆地土壤中的预老化，推测具有较老的放射性碳年龄。在这里，我们分析了亚热带大西洋五个地区的沉积物，以量化总有机碳库中的黑碳部分。黑碳来自化学氧化法，占阿根廷西北盆地沉积有机碳的17 ± 6%，占亚马逊三角洲沉积有机碳的65 ± 18%。塞拉利昂海隆的黑碳沉积物积累速率（8.4 ± 4.1 mg cm−2kyr−1）是偏远的阿根廷西北海盆（1.3 ± 0.4 mg cm−2kyr −1）的六倍，这可能是由于每年非洲草原火灾导致区域大气沉积增加。亚热带大西洋沉积物中BC的放射性碳年龄比总有机碳年龄更现代，根据其稳定碳同位素特征和多环芳烃特征比值，BC来源被分配为生物质燃烧副产物。这项研究表明，亚热带大西洋沉积物作为一个重要的汇年轻的BC。
Black carbon (BC) is ubiquitous in pelagic sediments and presumed to have an older radiocarbon age due to long ocean residence times and pre-aging in terrestrial soils. Here, we analyzed sediments from five regions in the subtropical Atlantic Ocean to quantify the black carbon fraction of the total organic carbon pool. Black carbon, derived from the chemothermal oxidation method, comprised between 17 ± 6% of the sedimentary organic carbon in the Northwest Argentina Basin and 65 ± 18% in the Amazon Delta. Black carbon sediment accumulation rates were six times greater in the Sierra Leone Rise (8.4 ± 4.1 mg cm−2kyr−1) compared to the remote Northwest Argentina Basin (1.3 ± 0.4 mg cm−2kyr−1), possibly due to enhanced regional atmospheric deposition from annual African grassland fires. The radiocarbon age for BC from subtropical Atlantic sediments were more modern compared to the bulk total organic carbon, and BC source was apportioned as biomass burning byproducts from their stable carbon isotopic signatures and characteristic ratios of polycyclic aromatic hydrocarbons. This study demonstrated that subtropical Atlantic Ocean sediments serve as an important sink for young BC.