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carbon cycle
    microbial life
  Introduction  
  Arctic ponds  
  Physicochemical portrait of a pond  
  Microbial life
  Photolysis of dissolved organic carbon  
  Implications for climate change  
 
Microbial life flourishes in Bylot Island ponds. These microbes, measuring from 1 to about 100 micrometers (1 µm = 1 thousandth of a millimeter), have been identified by molecular biology approaches and by microscopy. Here are some examples, seen through a microscope:

 

These ponds offer a relatively welcoming environment for very primitive microorganisms, such as Bacteria and Archaea, as well as for others, more evolved, such as green and golden algae (including, for example, diatoms). There are methanogens (microorganisms which produce CH4) among the Archaea, whilst among the Bacteria, there are methanotrophs (which consume CH4) and cyanobacteria. These latter form mats on pond bottoms and are responsible for significant photosynthetic activity. On the surface, these mats appear orange-coloured, due to the presence of photoprotective pigments (carotenoids), while underneath they are green. These microorganisms need water, light, nutrients and a carbon source for respiration and for photosynthesis. They are, however, very resistant: when the pond dries, their activity is simply interrupted until favourable conditions recur. The make-up of the ponds’ microbial assemblages influences the balance between the processes that generate and those that consume greenhouse gaz.

Remember that the simplified chemical reaction of respiration is :

C6H12O6 (aq) + 6O2 (g) 6CO2 (g) + 6H2O (l) (+ energy)

and that photosynthesis is simply the reverse :

6CO2 + 6H2O (+ solar energy) C6H12O6 + 6O2