Controls on variability of dissolved greenhouse gas concentration and emissions from small streams in southeastern New Hampshire

Small streams often present the first opportunity for dissolved greenhouse gases to exchange with the atmosphere and can be potential hot spots for evasion. In this study three streams in southeastern New Hampshire representing differing landuse were monitored for emissions of nitrous oxide, methane, and carbon dioxide. Average emission rates of N2O varied from -84 μg N m-2 day-1 to 2,561 μg N m-2 day-1 and correlated strongly with NO 3- concentration. One stream, Rum Brook, was found to be a net sink for N2O from the atmosphere. Methane emissions varied from 1.1 mg C m-2 day-1 to 21 mg C m -2 day-1 and were highest at Rum Brook. Controls on CO2 evasion varied between sites with rates ranging from 569 to 1637 mg C m-2 day-1. Results indicate greenhouse gas evasion from small streams respond to a variety of biogeochemical drivers, resulting in broad temporal and spatial variation.