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

就像面包一样，近岸和沼泽沉积物中的微生物会发酵（死亡）有机物，产生自由气体，形成气泡。这些天然气泡主要由甲烷构成，它们是甲烷从海洋和淡水沉积物进入大气的最重要途径。这些气泡使得用声音（声纳）对海底成像几乎不可能，并且会导致沉积物的不稳定，从而威胁到海底的结构。我的研究旨在了解和预测这些气泡是如何生长的，它们可以达到多大的大小，在沉积物中可以存在多少数量，以及它们是如何以及何时上升并离开沉积物的。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。关于这些气泡，我们发现了一些非常奇怪的东西。使用x射线CT扫描仪，就像在医院里发现的那样，我们发现这些气泡不是球体，而是薄圆盘。我们可以预测它的形状和大小，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，这是一个气泡。

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.