Effects of atmospheric and manure surface conditions on H2S emissions from an in-ground finisher hog manure slurry tank

Hydrogen sulfide (H2S) emitted by livestock operations can be detrimental to human health. The storage of hog manure is a significant agricultural source of H2S emissions. H2S emissions from a ground-level Midwestern hog finisher manure tank were measured for 8-20 days each quarter over a 15-month period. After excluding 4 days with outlier emissions the mean daily emission was 1.89 g H2S m(-2) day(-1). Mean daily emission was 1.39 g H2S m(-2) day(-1) when the slurry surface was liquid and 3.00 g H2S m(-2) day(-1) when crusted. Emissions however were not significantly different whether the surface was liquid or crusted when differences in temperature were considered. Diurnal variation in emissions was not correlated with air temperature, water vapor saturation deficit, or wind speed when the manure surface was crusted but was positively correlated with these variables when the surface was not crusted. Daily H2S emissions were modeled according to two-film theory incorporating resistance approach with limited success. Additional emissions measurements with greater documentation of the manure liquid composition and crust characteristics are needed to assess the component transport resistances in the emissions model.