通过河流出口老化的陆地有机物到北大西洋
1School of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA. praymond@mbl.edu
Nature
|February 24, 2001
概括
河流向海洋输出大量的陆地有机碳. 矛盾的是,这种碳并没有被大量检测到. 研究表明,在进入海洋之前,大部分碳都会降解,改变其组成.
科学领域:
- 地质化学 地质化学
- 海洋学 海洋学 海洋学
- 环境科学 环境科学
背景情况:
- 全球河流将大量的陆地溶解和颗粒有机碳运送到海洋.
- 从理论上讲,这种输入足以解释海洋溶解有机碳的循环.
- 然而,陆地有机物没有在海洋中发现与河流输入相匹配的数量.
研究的目的:
- 研究陆地有机碳的年龄和组成,这些有机碳是由河流排放到北大西洋西部.
- 确定陆地有机物在从河流到海洋的运输过程中的命运.
- 调和河流有机碳输入量与海洋有机碳储存量之间的差异.
主要方法:
- 在河流溶解物和有机颗粒物中分析天然放射性碳 (14C) 和稳定性碳同位素 (13C).
- 抽取四条流向北大西洋西部排放的河流的样本.
- 评估河流和沿海环境中的有机物降解过程.
主要成果:
- 河流输出旧的 (14C贫) 和年轻的 (14C丰富) 陆地溶解有机碳.
- 由河流出口的陆地颗粒有机碳主要是旧的.
- 年轻的溶解有机碳在河流和沿海水中被选择性降解,留下一种更耐火的成分.
- 这些发现与之前的建议相矛盾,即新生产的陆地有机物主导着河流出口.
结论:
- 河流有机物经历出口前显著的老化和降解.
- 选择性降解改变了陆地有机物质的结构,分布和数量,在海洋交付之前.
- 这些过程有助于解释海洋沉积物和海水中陆地有机物质的低检测率.
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