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SFS Annual Meeting

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DYNAMIC HETEROGENEITY OF GREENHOUSE GASES IN STREAMS

Freshwaters are sources of greenhouse gases (GHGs) to the atmosphere. However, the spatial and temporal heterogeneity of GHG fluxes, and how they relate to land use, remains a major source of uncertainty in regional and global carbon budgets. To understand interactions between land use and GHG dynamics, we measured CH4 and CO2 in Stroubles Creek, a second-order stream in Virginia, which flows through three land use transitions (urban, agriculture, forest). Weekly sampling at a single site (6/26/2017-8/29/2017) was supplemented with three synoptic samplings along 11.6km of Stroubles and one campaign throughout the watershed. All sites were supersaturated with respect to atmospheric CH4 and CO2: in-stream concentrations ranged from 8-739ppm CH4 and 929-4741ppm CO2. Sites draining more modified landscapes had higher concentrations of CH4 (11-46x) and CO2 (1.4-3.9x) than forested reaches. CH4 and CO2 were positively correlated with open/low-intensity urban land use (r2= 0.60 and 0.70, respectively). Forested Stroubles reaches had lower GHG concentrations than other forested streams sampled within the watershed. A more critical look at mechanisms controlling the heterogeneity of stream CO2 and CH4 is key to understanding the magnitude and variability of freshwater contributions to GHG budgets.

Morgan Gallagher (Primary Presenter/Author), Department of Crop and Soil Environmental Sciences, Virginia Tech, mtg3@vt.edu;


Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Tech, ehotchkiss@vt.edu;