https://doi.org/10.1007/s13157-024-01847-y

Wetlands are active biogeochemical processing sites with conditions that promote carbon storage and the production and release of greenhouse gases (GHGs). Estimates of GHG release from wetlands, including small ponds, are still highly uncertain, and rarely consider diverse pathways of exchange, instead focussing primarily on diffusion. One way to resolve this uncertainty is to quantify and compare multiple pathways of GHG release and to consider specific wetland types. At four natural ponds in the Canadian Prairie Pothole Region (PPR), we investigated four flux pathways (diffusion, ebullition, exposed sediment, and vegetation-mediated) and found distinct differences between pathways for methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). The highest magnitude effluxes were via exposed sediment for CO2 and N2O and ebullition for CH4, though ebullition was not the dominant CH4 efflux pathway in two ponds. For pathways with potential for high GHG efflux, we used generalized least squares (GLS) regression to investigate physicochemical predictors. We identified significant relationships between air temperature and exposed sediment fluxes of CO2 and N2O, and between sulphate and dissolved oxygen concentrations and diffusive CH4 fluxes. Water temperature may be linked to ebullitive CH4 fluxes, but this was not statistically significant. This research identifies hotspots and physicochemical predictors for GHG efflux in the first study to directly compare four key flux pathways for PPR ponds, highlighting that processes occurring in different parts of the wetland can greatly outweigh their areal extent. This analysis will inform future work to synthesize and upscale GHG fluxes for these ponds.

https://doi.org/10.1007/s13157-024-01847-y