JC010: Mud volcanoes and submarine canyons


Core samples...what happens to them?

When cores are taken the scientist may want to analyse the sediment or what is in the sediment. One of the things investigated on this trip is the distribution of macro and meiofauna in the sediment layers. 

fauna = animal
meiofauna = animals of 32 microns to 1 mm 
macrofauna =  animals over 1mm

This is what happens when the cores reach the surface:

The cores coming to the surface (far left)



Now above the surface.  Core tubes looking good (right)

First the height of the sediment is measured.

Next the water that is on the top of the sediment is siphoned of and put in a bucket that will ONLY collect the water from the top of the sediment. When the last centimetre is reached the water is removed using a syringe.

Now the top centimetre is removed using a plastic spacer that is 1cm deep.  This is placed on the top of the core and the core pushed up until it is level with the top.  Now a metal plate carefully slides under the plastic spacer slicing off the top centimetre and the slice is removed and placed in the bucket for slices 0cm to 1cm  from the surface of the sediment.

A specially made support is now used to push the core up into the next spacer placed on the surface and another core is taken.

Other slices are taken from the different levels and put in the correct bucket.

So we end up with the core slices from all the cores collected in 7 buckets containing:

  • Water on the surface
  • Sediment from 0-1cm
  • Sediment from 1-3cm
  • Sediment from 3-5cm
  • Sediment from 5-10cm
  • Sediment from 10-15cm
  • Sediment from 15-20cm  

Most of the fauna live in the top 3 centimetres so these buckets also contain a chemical called formaldehyde (CH2O, also known as Formalin when dissolved in water), to preserve the fauna as quickly as possible.

When all the cores have been sliced and put in the buckets the cores are gently mixed so that the sediment can be filtered and the fauna collected. Richard was given this mucky job (see above)!

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