Biologically driven DOC release from peatlands during recovery from acidification.

Area of Science:

• Environmental Science
• Microbiology
• Biogeochemistry

Background:

• Peatlands store significant global soil carbon, with destabilization contributing to increased dissolved organic carbon (DOC) in freshwater systems.
• Recovery from acidification is a proposed mechanism for enhanced peat decomposition and DOC release, but the biological role remains unclear.

Purpose of the Study:

• To investigate the biological mechanisms underlying DOC mobilization in peatlands, particularly the role of pH and microbial activity.
• To identify key enzymes and microbial groups involved in peat decomposition and DOC release.

Main Methods:

• Analysis of extracellular enzyme activities and microbial composition across diverse peatland sites.
• In situ pH manipulation experiments to assess the impact on enzyme activity, microbial populations, and DOC production.
• Gene knockout and addition experiments targeting phenol oxidase to determine its direct role in DOC and phenolic release.

Main Results:

• Higher pH correlated with increased phenol oxidase activity, greater abundance of Actinobacteria and fungi, and elevated pore-water DOC concentrations.
• Experimental pH increases enhanced phenol oxidase activity, DOC production, and Actinobacterial/fungal populations.
• Phenol oxidase activity was central to DOC and phenolic mobilization, as evidenced by knockout and addition experiments.

Conclusions:

• pH increases in peatlands activate phenol oxidase, a key enzyme driving the release of dissolved organic carbon and phenolics.
• This study reveals a significant biological mechanism contributing to DOC mobilization from peatlands, with implications for freshwater ecosystem function and carbon cycling.