Variation in hydrogen sulfide emissions from a U.S. Midwest anaerobic dairy lagoon

Hydrogen sulfide (H₂ S) emissions from midwestern United States dairy anaerobic waste lagoons are episodic and seasonal. Emissions were modeled using an inverse diffusion model in conjunction with measured concentrations and turbulence. The potential for lagoon mixing was estimated by the Brunt frequency using a theoretical Fourier series temperature profile model constructed from measured air and lagoon temperatures. Annual H₂ S emissions from the dairy parlor and holding area liquid waste, based on 318 d of measurement, were 212 g m^-2 or 807 g head of cattle^-1 . Hydrogen sulfide emissions were highest in the spring and the fall. Eleven days with emissions >7 g d^-1 head^-1 accounted for 25% of the annual emissions. Shear mixing appeared to dominate the mixing in the lagoon when the lagoon was estimated to be nearly isothermal. Wind shear correlated with significantly greater daily mean emissions. The H₂ S emissions from this lagoon appeared to result from a series of processes; biogenic production of H₂ S in the sludge, H₂ S-enriched bubbles rise through the lagoon by buoyancy and wind shear induced mixing, and bubbles bursting at the surface either due to desiccation of the bubbles or surface disturbances induced by wind and precipitation.