"Ammonia does not stay in the atmosphere very long in its gaseous form," Auvermann said. "Unless it reacts with other gases to form fine particles, it's gone from the air within a few hours to a few days. And we don't see much of the fine particles around here that would suggest otherwise."
Casey and Parker aggregated hydrogen sulfide field data for the reporting process. Their research shows emission rates for hydrogen sulfide are lower during dry weather conditions and higher in wet conditions. On average, they are three times lower than ammonia concentrations approaching the minimum detection levels by sophisticated equipment.
"Hydrogen sulfide is not currently classified as a hazardous air pollutant by EPA; it is primarily of local and of minor regional concern," Casey said. "The regulation of hydrogen sulfide varies from state to state."
Concentrations measured at the center of a commercial Panhandle feed yard were substantially below the Texas regulatory threshold for the property boundary during the majority of the two-year monitoring period, he said. And concentrations at the boundary were considerably less than those measured at the center of the yard.
"What these researchers have found is that both ammonia and hydrogen sulfide represent exceedingly low concentrations over relatively large emitting surfaces and long time scales," Sweeten said. "The annual emission numbers can add up to the low threshold values of reporting that EPA just set, but they do not reach levels of general public concern."
Weinheimer said with the quick response of the research group, the National Cattlemen's Beef Association was able to send out "reporting packets" to feed yards in early January and conduct a Webinar on Jan. 15 to explain the requirements to its members.
"From day one, this project has been founded on solid
|Contact: Dr. John Sweeten|
Texas A&M AgriLife Communications