GREENHOUSE GAS EBULLITION IN STREAMS OF VARYING WATERSHED LAND USE AND SEDIMENT COMPOSITION
Streams are significant contributors to global carbon and nitrogen cycles, and major sources of greenhouse gases (GHGs). This study quantified ebullitive (bubble) emissions in two streams of contrasting land use (urban and forest) and sediment composition in Northeastern Massachusetts. Twelve inverted funnel-style bubble traps were installed at each study site to capture gas from ebullition and obtain CO2, CH4, and N2O concentrations and flux rates. Sediment composition was characterized using organic content and particle size analyses. Findings indicate significant ebullitive CH4 flux rates (0.01-13.77 mmol C/day) and high CH4 concentrations in gas bubbles (1-53%), especially in the urban stream, that are similar to findings of previous ebullition studies in wetland streams in other regions (Crawford et. al, 2014). These results suggest that GHG emissions via ebullition must be considered in highly impacted urban streams as well as in streams draining more natural areas. Although there was no significant correlation in the measured bubble rates and sediment composition, data suggest that major disturbances, such as storm flow events, or rapid air pressure or temperature changes are more likely to cause ebullition, suggesting short-term temporal variability may be important.
Bonnie Turek (Primary Presenter/Author), University of New Hampshire, firstname.lastname@example.org;