Carbon Cycle

The diagram on the right depicts the major pathways, transformations, and chemical species in mat carbon cycling. Thickness of the arrow depicts relative abundance.
  1) New carbon enters the mat and is fixed by oxygenic photosynthesizers (cyanobacteria and diatoms).
  2) These organisms create most of the dissolved organic carbon (DOC) and particulate organic carbon (POC) that is produced in the mat.
  3) The DOC and POC are mineralized through hetertrophic processes such as respiration and fermentation,
  5) creating a DIC pool within the mat.
  4) Some of the DOC/POC may diffuse out of the mat into the water column. Mat DIC has several potential fates.
  6) Some may utilized by anoxygenic photrophic bacteria in
  7) anoxygenic photosynthesis to create DOC and POC.
  8) Some DIC may be fixed by chemolithotrophic bacteria
  9) to form DOC and POC.
  10) In some mats, DIC may be utilized by methanogens
  11) to produce methane.
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  12) The methane, in turn, may be mineralized back to DIC by
  13) methylotrophic bacteria.
  14) Under anoxic conditions, the methane may diffuse out of the mat.
  15) During the day, most DIC is recycled by cyanobacteria.
  16) Some DIC will diffuse out of the mat. During the day, because of photosynthesis there is a net flux of DIC into the mat. At night, because there is no photosynthesis, there is a net flux of DIC out of the mat.