Students Research Presentations: A potent greenhouse gas source: nitrous oxide emission during base flow and storm flow in the Choptank River basin

Year:

2015

Source:

ASLO Aquatic Sciences Meeting, Granada, Spain

Abstract:

Nitrous Oxide (N₂0) is a potent greenhouse gas, and streams, rivers, and groundwater act as sources of N₂0 to the atmosphere. Four streams were sampled in four agriculturally dominated watersheds in the Choptank River Basin. N₂0 gas concentrations and stream parameters were measured to estimate N₂0 flux to the atmosphere for comparison with N₂0 fluxes estimated with the IPCC protocols. N₂0 fluxes (F, µmol N₂0-N m^-2 h^-1) were calculated using measured N₂0-N concentrations (Cm, µmol N₂0-N L^-1) in excess of atmospheric equilibrium (Ceq, µmol N₂0-N L^-1) and a gas exchange coefficient k (m h^-1) (F = (Cm - Ceq) * k). Fluxes of N₂0 ranged over 0.17-23.10 µmol N₂0-N m-2 h-1 in the four watersheds, and were similar to those calculated using the IPCC protocols and also to N₂0 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—N₂0 levels decreased during the storm event, while DO levels increased—which suggests that the rainfall itself caused an increase in gas exchange.

Mentors:

Tom Fisher, Ph.D.

Students:

Nicholas Dylla, Elmhurst College