Nitrogen removal and greenhouse gas fluxes from integrated buffer zones treating agricultural drainage water

Integrated buffer zones (IBZ) are novel mitigation measures designed to decrease the loading of nitrogen (N) transported by subsurface drainage systems from agricultural fields streams. In IBZ, water flows into a pond with free surface followed an inundated, vegetated filterbed. This design provides environment favorable for denitrification and thus in nitrate concentration is expected as flow through IBZ. However, due establishment anaerobic conditions, there risk increasing emissions greenhouse gases nitrous oxide (N2O) methane (CH4). this year-long study, we evaluated N removal efficiency along N2O CH4 two pilot-scale IBZs (IBZ1 2). The had very different yearly efficiencies, amounting 29% 71% total load at IBZ1 2, respectively. was probably differences infiltration rates filterbed, which 22% 81% incoming site (IBZ2) highest net sink, while 0.9% removed emitted IBZ1. Both were sources but pathways emission. mainly lost directly atmosphere, waterborne losses dominated IBZ2. conclusion, effective removing three years after establishment, although acted gas sources, especially CH4, comparable those natural wetlands other transport measures.