Wednesday 25 March 2015

Trace elements

 A few weeks ago I tasked my final year Environmental Chemists to find out the relative concentration of ‘trace elements’ in a) the Earth’s crust b) the human body and put the results together as a poster.   Last year’s EnvChems did something similar with detergents in November 2013. Trace elements were defined as being present in the body at concentrations so low that you'd have difficulty believing that they were essential.  If we are 70% water (or is it 90%?), it is clear that we have a lot of Hydrogen and Oxygen about our person, for example.  Other elements are present in lesser amounts but some are too 'obvious' to be worth discussing - Carbon in carbohydrates, Calcium in bones etc. Here's a diagram which identifies the elements which are known or suspected to be of vital importance in human physiology.  The paler the highlight the less required - but not the less important!
As there are twelve in the class, with me making up the full coven, I listed out F, Zn, Si, As, Cu, I, Br, Se, Cr, Mn, Co, Mo, V and invited The Lads to chose one each. I asked everyone to deliver
  • the two abundances in 
    • % or ppm for earth data 
    • g, mg, or μg per 70kg human
  • a few notes on what that element did for us
  •  'something interesting to say about their element. 
I drew the short straw of johnny-no-friends selenium, which was really rather interesting.  The land of the farrrm is deficient in selenium, and that's one of the main reasons why we buy a 20kg bucket of mineral lick at regular intervals. But my 'something interest' soundbyte was a more bio-genetical fact about selenocysteine being the 21st amino acid.

It was a collective project  for a group that apparently doesn't hang out together outside of class, so I was happy enough with the results. I would have done it out a bit different, but then my peculiar obsessions are not everybody's and I backed off and let them tell it like they saw it.  I suggested, for example, that the references should be trimmed by or  but the final poster came out with a clatter of these informationless tokens tucked into the bottom right-hand corner.  It was surely better to write them as: F; Mo; etc.

In any case, I sent out a calling-all-cars e-mail to staff and post-graduate students which included the sentence:
"The poster is now on the wall outside the molecular biology lab so that biologists can learn something as they come out."
One of my colleagues was quick to point out that "as they come out" could be taken as the process by which people declare their BLTness. Ooops, open mouth . . . insert foot, that's me.  I shall spend the rest of the week worrying about being hauled before a Dignity At Work Tribunal to ask why I am singling out people of a particular orientation for attention.

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