Diffusion of gases dissolved in peat pore water

Diffusion is usually thought to be ineffective at transporting solutes over distances of several metres – the depth of many peat deposits. But this is to neglect the importance of time. We derive equations that show that in peat that has accumulated over millennia then diffusion alone can remove to the air about 95 % of the gases carbon dioxide and methane generated by microbial decay within the main peat mass. Gas concentration profiles in simulations of peat grown slice-by-slice over 10,000 years have a smooth convex profile with concentration increasing downwards, as they do in Nature.