Nicholas Dylla, Elmhurst College

Class Year:

2014

Mentor:

Tom Fisher, Ph.D.

Abstract:

Nitrous Oxide (N₂O) is a potent greenhouse gas, and streams, rivers, and groundwater act as sources of N₂O to the atmosphere. Four streams were sampled in four agriculturally dominated watersheds in the Choptank River Basin. N₂O gas concentrations and stream parameters were measured to estimate N₂O flux to the atmosphere for comparison with N₂O fluxes estimated with the IPCC protocols. N₂O fluxes (F, μmol N₂O - N m^-2 h^-1) were calculated using measured N₂O-N concentrations (Cm, μmol N₂O-N L^-1) in excess of atmospheric equilibrium (Ceq, μmol N₂O-N L^-1) and a gas exchange coefficient k (m h^-1) (F = (Cm - Ceq) * k). Fluxes of N₂O ranged over 0.49-190.69 N₂O-N m^-2 h^-1 in the four watersheds, and were similar to those calculated using the IPCC protocols and also to N₂O fluxes from nearby agricultural fields. The IPCC flux estimates were not statistically different from the empirically derived fluxes (p > 0.05). This approach can potentially provide a quick method to estimate the role of gas fluxes from streams in watersheds. Also, sampling occurred during a storm event—N₂O levels decreased during the storm event, while DO levels increased—which suggests that the rainfall itself caused an increase in gas exchange.

Location:

Horn Point Laboratory