Peat bogs are highly effective carbon sinks because waterlogged, anaerobic conditions limit the decomposition of dead organic matter. When these wetland ecosystems are drained for agricultural use, oxygen penetrates deep into the peat profile as shown in the diagram below.
Which of the following processes and biological agents are primarily responsible for the rapid release of carbon dioxide (CO2\text{CO}_2CO2) into the atmosphere following drainage?
Aerobic respiration by saprobiontic microorganisms
Anaerobic fermentation by methanogenic archaea
Extracellular hydrolysis by mycorrhizal fungi
Denitrification by anaerobic pseudomonad bacteria