Characterizing Sulfur and NonMethane Volatile Organic Compounds Emissions from Concentrated Animal Feeding Operations in North Carolina

摘要

Reduced sulfur and nonmethane volatile organic compounds (NMVOCs) contribute to odor, and have additional secondary environmental effects. Emissions for these classes of compounds were determined from a concentrated animal feeding operation (CAFO) hog farm in North Carolina. Integrated air samples were collected using fusedsilica lined and SUMMA canisters. The canisters were analyzed exsitu using gas chromatographyflame ionization detector (GCFID) and gas chromatographymass spectrometry (GCMS) procedures. Continuous measurements of hydrogen sulfide (H2S) were made insitu by a pulsed fluorescence H2S/SO2 analyzer. Sampling was conducted for all four seasonal periods during 20072008. In each sampling season, the barn and anaerobic lagoon were each monitored for 57 days. Anaerobic lagoon measurements were made using a dynamicflow through chamber system. During lagoon measurements, surface temperature, pH and sulfide were monitored. Meteorological parameters were measured at the site, including wind speed, wind direction, air temperature, and relative humidity. Lagoon H2S fluxes were approximately an order of magnitude higher than dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) fluxes, 1.33 mg m2 min1 compared to 0.12 and 0.09 mg m2 min1, respectively. H2S lagoon flux was significantly influenced by lagoon pH, lagoon temperature and wind speed. Average seasonal H2S barn emissions were 3.3 g day1 AU1. This was approximately two orders of magnitude higher than DMS and DMDS emissions, 0.017 and 0.035 g day1 AU1, respectively. Total H2S emissions from North Carolina hogs were calculated to be ~1.48 million kg yr1, contributing ~22% of statewide H2S emissions. Observational analysis suggests that there are over 100 NMVOCs in lagoon and barn samples. Preliminary analysis has identified 29 compounds, from a variety of different NMVOC chemical groups, including low odor threshold compounds and hazardous air pollutants (HAPs). Concentrations and emissions of NMVOCs will be evaluated with respect to seasonal variations and the influence of meteorological and physicochemical factors.