Methane emissions from canals draining tropical peatlands: Constraining temporal variability and emissions pathways

Abstract Drainage canals are potential hotspots of methane (CH 4 ) emissions from degraded peatlands in Southeast Asia. Estimates of CH 4 emissions from these canals remain scarce, and both the temporal variability and pathways of CH 4 emissions are uncertain. Here, we present a year‐round study of CH 4 emissions from canals draining peatlands in Southeast Asia. We quantified diffusive and ebullitive fluxes and tracked canal CH 4 dynamics by measuring δ 13 C‐CH 4 . Diffusion was the primary pathway of CH 4 fluxes throughout the year, accounting for > 80% of net CH 4 emissions. Periods of low rainfall limited CH 4 oxidation and enhanced diffusive CH 4 emissions, particularly in canals blocked to rewet the adjacent peat soils. By synthesizing data from past studies, we find an apparent decrease in canal CH 4 emissions with time following peatland drainage. Our results highlight the importance of considering seasonal to decadal variation in efforts to include drainage canals in the global CH 4 budget.