Observation and modelling of bubble growth and rise in muddy sediments.

泥质沉积物中气泡生长和上升的观察和建模。

• 批准号: 106084-2006
• 负责人: Boudreau, Bernard
• 金额: $ 3.62万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=362758
• 关键词: Observation; modelling; bubble; growth; rise

Just like in bread, micro-organisms in nearshore and marsh sediments ferment (dead) organic matter to produce free gas that forms bubbles.  These natural bubbles are primarily made of methane, and they constitute the most important way this gas enters the atmosphere from marine and freshwater sediments.  These bubbles make it almost impossible to image the bottom with sound (sonar), and can cause instabilities in the sediment which threaten structures on the seafloor.   My research aims to understand and predict how these bubbles grow, what size they can reach, what numbers can exist in a volume of sediment, and how and when they rise and leave the sediment.  The reason it is difficult to know these things is because we cannot see what happens in sediments.  We have discovered some very odd things about these bubbles.  Using an X-ray CT scanner, like those found in hospitals, we have found that these bubbles are not spheres, but thin disks.  And we can predict the shape and size if we assume that the sediment acts like an elastic material (like a sponge) that tears apart to make room for a new hole filled with gas, which is a bubble.

就像面包一样，近岸和沼泽沉积物中的微生物发酵（死亡）有机物，产生形成气泡的游离气体。这些天然气泡主要由甲烷组成，它们构成了这些气体从海洋和淡水沉积物进入大气的最重要途径。这些气泡使得几乎不可能用声音（声纳）成像底部，并可能造成沉积物的不稳定，从而威胁到海底结构。 我的研究旨在了解和预测这些气泡如何生长，它们能达到多大的尺寸，在一定体积的沉积物中存在的数量，以及它们如何以及何时上升并离开沉积物。很难知道这些事情的原因是因为我们无法看到沉积物中发生了什么。我们发现了一些关于这些气泡的非常奇怪的事情。使用X射线CT扫描仪，就像在医院里发现的那样，我们已经发现这些气泡不是球体，而是薄圆盘。2如果我们假设沉积物像弹性材料（像海绵）一样撕裂，为一个充满气体的新洞腾出空间，我们就可以预测气泡的形状和大小。