Impact of Stream Geomorphology on Greenhouse Gas Concentration in a New York Mountain Stream

Abstract

As increased greenhouse gas concentrations (GHG: N2O, CO2, CH4) in our atmosphere remain a major concern, better quantifying GHG fluxes from natural systems is essential. In this study, we investigate GHG concentrations in saturated riparian sediments (dry, wet, mucky), streambed hyporheic zone sediments (pools, riffles), and stream water in a New York mountain stream for summer baseflow conditions, and attempt to identify the primary drivers (e.g., DO, DOC, NO3−, and NH4+, temp) of GHG concentrations at these locations. Although DO, DOC, NO3−, and NH4+ concentration patterns certainly explained some of the observed trends, the overall differences in GHG abundance in riparian water vs. hyporheic pool water vs. hyporheic riffle water strongly suggest that water velocity/mixing with the atmosphere is a key control on GHG concentration across locations. When all floodplain locations are considered, in-stream pools are hot spots of CO2 and CH4 concentrations relative to other in-stream locations. On the other hand, riparian areas are hot spots of CH4 and CO2 concentrations relative to stream locations. No clear patterns are observed for N2O.