关于大西洋海底沉积物中黑碳的新见解
Kari St Laurent1,2, Mark Cantwell3, Rainer Lohmann1
1Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, U.S.A.
概括
大西洋沉积物中的黑碳 (BC) 比预期更年轻,这表明这些海洋环境是最近产生的BC的重要沉池,可能来自生物质燃烧. 这一发现挑战了以前关于海洋系统中BC衰老的假设.
科学领域:
- 海洋地球化学 海洋地球化学
- 有机地化学 有机地化学
- 古海洋学是古海洋学.
背景情况:
- 黑碳 (BC) 是海洋沉积物的常见成分,由于长时间的海洋运输和陆地老化,通常被认为是老的.
- 了解沉积BC的年龄和来源对于重建过去的环境条件和评估碳循环至关重要.
研究的目的:
- 在亚热带大西洋沉积物中,量化黑碳 (BC) 在总有机碳 (TOC) 池中的比例.
- 为了确定这些沉积物中的BC的积累率和放射性碳年龄.
- 为了确定在亚热带大西洋沉积的BC的来源.
主要方法:
- 从亚热带大西洋的五个不同的地区收集了沉积物样本.
- 黑碳 (BC) 含量用化学热氧化方法量化.
- 用放射性碳测年法和稳碳同位素分析来确定BC年龄和来源分配.
主要成果:
- 在沉积性有机碳中BC的比例有很大差异,从阿根廷西北部盆地的17±6%到亚马逊三角洲的65±18%.
- 与西北阿根廷盆地 (1.3±0.4 mg cm-2 kyr-1) 相比,在塞拉利昂山坡 (8.4±4.1 mg cm-2 kyr-1) 中,BC的沉积积率明显高.
- 发现公元前的放射性碳年龄比总体有机碳更为现代,同位素签名表明生物质燃烧是主要来源.
结论:
- 亚热带大西洋沉积物充当相对较年轻的黑碳 (BC) 的重要沉积池.
- 增强的区域大气沉积,可能来自非洲草原火灾,可能会导致塞拉利昂升等地区的BC积累率更高.
- 这些发现表明,海洋沉积物中的BC可能并不总是像以前所认为的那样古老,这影响了过去碳循环的解释.
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