Monday, 4 July 2011

Sea surface microlayers

A couple of months ago I went to Amiens.  This small town in Normandy where Jule Vern lived and presided as mayor wrote some great science fiction/adventure novels.  I have read some of the father of science fiction and he has inspired me to write some as well.  This month I started reading 20,000 Leagues Under the Sea from Jules Vern.  This book with its very detailed account of islands, atolls, fish, mollusks, cestaceans and other aquatic life is so colorful I cannot put it down.  After reading a couple of paragraphs from the book I am reminded of some underwater adventures of my own to see the freshwater tropical fish in Lake Malawi, to the colorful red coral breathing on the bottom of the great barrier reef and feeding bread to surgeon fish in the Caribbean.  So after reading some of Jules Vern's masterpiece and with aquatic adventures of my own I wanted to relate it to science and this blog somehow.

Last year I went to Quebec and met some researchers from Croatia (another place I have visited to see the underwater life).  They were looking at characterization of sea-surface microlayers by monolayer techniques.  'Sea surface microlayers I asked?'  I had never heard of such things.   'The Sea surface (SML) is the top 1000 micrometers (or 1 millimeter) of the ocean surface.  So unlike Captain Nemo's Nautilus you do not have to go so far down into the ocean to explore this.  The Croatian researcher went onto explain that this boundary layer is where all the exchange occurs between the atmosphere and the ocean.  In relation to the book Captain Nemo exclaims 'that the ocean is a living organism with arteries ect.' so this boundary might be seen as the lungs for the ocean. Interestingly enough it is only at this surface that it occurs and the the chemical, physical, and biological properties of the SML differ greatly from the sub-surface water just a few centimeters beneath.  In the novel the ocean strata is quite complex and going down from 1mm, 1cm to one meter may change greatly in temperature, salt and other chemical compositions.

Strata of Ocean
By studying the SML with compressible monolayers and other devices like Brewster Angle Microscopy one can understand how these films work It was found that the mechanisms responsible for initial film formation and its later development are diffusion from the bulk and adsorption.  It is found that this layer of fat on the surface of the ocean is spontaneously made.  When you disrupt this layer with some toxin like surfactants, an oil spill or otherwise it can disrupt a lot of the oceans balance.  Polluting the water even the smallest 1 mm layer will be affected.  By studying these thin films you can understand the effects of the optical properties of the ocean, the pollution in the ocean and many other factors.  Just 1 mm can tell a lot!  Maybe when I venture from 20,000 Leagues to another literature classic Flatland I might get better insight into how 1 mm of fats on the ocean can effect many other things in our world.