Role of the aquatic pathway in the carbon and greenhouse gas budgets of a peatland catchment

Abstract

Abstract Peatland streams have repeatedly been shown to be highly supersaturated in both CO 2 and CH 4 with respect to the atmosphere, and in combination with dissolved (DOC) and particulate organic carbon (POC) represent a potentially important pathway for catchment greenhouse gas (GHG) and carbon (C) losses. The aim of this study was to create a complete C and GHG (CO 2 , CH 4 , N 2 O) budget for Auchencorth Moss, an ombrotrophic peatland in southern Scotland, by combining flux tower, static chamber and aquatic flux measurements from 2 consecutive years. The sink/source strength of the catchment in terms of both C and GHGs was compared to assess the relative importance of the aquatic pathway. During the study period (2007–2008) the catchment functioned as a net sink for GHGs (352 g CO 2 ‐Eq m −2 yr −1 ) and C (69.5 g C m −2 yr −1 ). The greatest flux in both the GHG and C budget was net ecosystem exchange (NEE). Terrestrial emissions of CH 4 and N 2 O combined returned only 4% of CO 2 equivalents captured by NEE to the atmosphere, whereas evasion of GHGs from the stream surface returned 12%. DOC represented a loss of 24% of NEE C uptake, which if processed and evaded downstream, outside of the catchment, may lead to a significant underestimation of the actual catchment‐derived GHG losses. The budgets clearly show the importance of aquatic fluxes at Auchencorth Moss and highlight the need to consider both the C and GHG budgets simultaneously.