Jarett P. Spinhirne

Multidimensional Gas Chromatography—Olfactometry for the Identification and Prioritization of Malodors from Confined Animal Feeding Operations

Odor profiling efforts were directed at applying to high-density livestock operations some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Solid-phase microextraction (SPME) was used for field air sampling of odorous air near and downwind of a beef cattle feedyard and a swine finisher barn in Texas. Multidimensional gas chromatography-olfactometry (MDGC-O) was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with these livestock operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from both cattle feedyard and swine barn facilities, with p-cresol consistently taking on the dominant odor impact role with ever increasing distance. In contrast, at- or near-site odor profiles were shown to be much more complex, with many of the well-known lower tier odorant compounds rising in relative significance. For the cattle feedyard at- or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to the more often cited livestock odorants such as hydrogen sulfide, the organic sulfides, and volatile fatty acids. This study demonstrates that SPME combined with a MDGC-O-mass spectrometry system can be used for the sampling, identification, and prioritization of odors associated with livestock.

Multidimensional Gas Chromatography-Olfactometry for Identification and Prioritization of Malodors from Confined Animal Feeding Operations

Odor profiling efforts were directed at applying to high-density livestock operations, some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Multidimensional-GC-Olfactometry was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with representative cattle feedyard and swine feeding operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from the cattle feedyard facilities; with para-cresol consistently taking on the preeminent odor impact role with ever increasing distance. In contrast, at or near-site odor profiles were shown to be much more complex; with many of the traditional lower tier odorant compounds rising in relative significance. Surprisingly, for the at or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to hydrogen sulfide, the organic sulfides and volatile fatty acids; the more often cited target odorants.

Background Odors in Tedlar® Bags Used for CAFO Odor Sampling

Tedlar® film is manufactured in a wet solvent process and continues to emit organic compounds after manufacturing. Tedlar® bags are used for odor sampling at concentrated animal feeding operations (CAFOs). Odor regulations for CAFOs vary widely, but maximum detection thresholds (DT) of 2 to 15 have been proposed downwind of feeding operations. Results at the WTAMU Olfactometry Laboratory have shown that both commercially available Tedlar® bags and homemade Tedlar® bags have a detectable background odor (DTs of 20 to 60 typical) even following standard protocols for purging. Purging the bags before sampling was not effective in reducing DTs to acceptable levels, as verified with SPME analysis. Heating the Tedlar® bags for 24 hrs, when combined with purging immediately after heating and again prior to odor sampling, reduced background DTs to less than 12. This is an acceptable range for odor sampling at open lot beef cattle feedyards or any other locations where DTs are expected to be greater than sixteen.

GENERATION AND CALIBRATION OF STANDARD GAS MIXTURES FOR VOLATILE FATTY ACIDS USING PERMEATION TUBES AND SOLID-PHASE MICROEXTRACTION

Volatile fatty acids (VFAs) are major components of odors associated with agricultural operations and livestock housing, solid waste processing and disposal, industrial and municipal wastewater collection, and treatment systems. Emission estimation and assessment of odor control methods depend on reliable air sampling and analysis methods for VFAs. The objective of this research was to develop and test a method for continuous and reliable generation of standard gas mixtures for VFAs based on permeation tubes. Standard gas mixtures for acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acids were generated with permeation tubes and monitored for a 100-day period. The gravimetric loss of VFAs from each tube was measured periodically and used to calculate the emission rate for each permeation tube. Emission rates were as high as 2,011 ng/(min cm) for acetic acid to as low as 49 ng/(min cm) for isovaleric and hexanoic acids. The emission rate was combined with the dilution flow rate to calculate standard concentrations. Five different concentrations for each VFA were obtained by adjusting the dilution flow rate. Gas concentrations were monitored with DVB/Carboxen/PDMS 50/30 .m SPME fibers using triplicate 1 min extractions. Maximum standard gas concentrations ranged from 21.9 ppmv for acetic acid to 0.22 ppmv for hexanoic acid. Minimum standard gas concentrations ranged from 3.0 ppmv for acetic acid to 0.03 ppmv for hexanoic acid. The relative standard deviations (RSDs) for all VFA concentrations ranged from .1.6% to .7.8%. Rapid (1 min) SPME extractions were sufficient to preconcentrate significant amounts of VFAs for separation on a GC-FID without derivatization. The SPME technology proved to be very useful for monitoring standard gas mixtures. Dilution gas flow rate did not affect the emission rates from permeation tubes. In contrast, low acid levels affected permeation rates of the acids from the tubes. The methodology described in this article could be used to generate and test standard gas mixtures for other odorous gases.

Evaluation of Sample Recovery of Malodorous Gases from Air Sampling Bags, SPME, and Sampling Canisters

Odorous gases associated with livestock operations are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75 µm SPME fibers, PVF (Tedlar), FEP (Teflon), foil, and PET (Melinex) air sampling bags, and standard 6 L Stabilizer™ sampling canisters after sample storage at room temperature. A standard mixture consisted of 7 VFAs from acetic to hexanoic, and 4 semi-VOCs including p-cresol, indole, 4-ethylphenol, and 2’-aminoacetopheone with concentrations ranging from 5.1 ppb for indole to 1,270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5 and 24 hrs sample storage time, respectively. This was followed by the PET bags (71.7% and 47.2%), FEP bags (75.4% and 39.4%), in-house-made Tedlar bags (47.3% and 37.4%), commercial Tedlar bags (67.6% and 22.7%), foil bags (16.4% and 4.3%), and canisters (4.2% and 0.5%), for 0.5 and 24 hrs, respectively. VFAs had higher recoveries than semi-VOCs for all bags and canisters. New FEP bags and new foil bags had the lowest and the highest amounts of chemical impurities, respectively. New commercial Tedlar bags had measurable concentrations of DMAC and phenol. Foil bags had measurable concentrations of acetic, propionic, butyric, valeric and hexanoic acids. Further research is warranted to determine how recoveries from bags affect odor concentrations as measured by olfactometry.

Real-Time Ventilation Measurements from Mechanically Ventilated Livestock Buildings for Emission Rate Estimations

A six-state USDA-IFAFS funded research project (Aerial Pollutant Emissions from Confined Animal Buildings, APECAB) was conducted with the purpose of determining hydrogen sulfide, ammonia, PM10, and odor emission rates from selected swine and poultry housing systems. An important aspect of emission studies is to be able to measure the mass flow rate of air through the housing system. For this research project, the decision was made to study only fan ventilated buildings due to the difficulty in estimated mass flow rates through naturally ventilated buildings. This paper highlights the various techniques used throughout the study to determine mass flow rate through fan ventilated swine and poultry housing systems.

CHARACTERIZING VOLATILE FATTY ACIDS AND OTHER GASES IN A RUMEN CLOSED IN VITRO FERMENTATION SYSTEM USING SOLID PHASE MICROEXTRACTION

A new method for rapid sampling and qualitative characterization of the headspace gases of closed in vitro cultures using solid phase microextraction (SPME) was evaluated for ruminal fluid and ruminal fluid with feed containing a feed additive. Gas sample collection was achieved by exposing a DVB/Carboxen/PDMS 50/30 .m SPME fiber to the headspace of cultures for 1 min every hour. This was followed by immediate analysis on a GC–MS and then reuse of the SPME fiber. Acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acids and toluene, dimethyl disulfide, and pentadecane were identified in the headspace. SPME technology facilitated rapid sampling and immediate analysis with a GC–MS to identify specific end products of microbial digestion. A SPME–based approach could serve as a new method for the characterization of ruminal fermentation end products and testing effects of feed additives on the formation of end products.

Ambient ammonia and hydrogen sulfide concentrations at a beef cattle feedlot in Texas

Concentrations of ammonia (NH3) and hydrogen sulfide (H2S) in ambient air were semicontinuously measured at a 50,000-head cattle feedyard in Texas panhandle in three seasons: fall 2002 (10 days), winter 2003 (14 days), and spring 2003 (15 days). Sampling was conducted at 1.5 m above the ground at one location each season at the western fence line of cattle pens. Gas concentrations were measured using continuous analyzers housed in an onsite instrument shelter. Measured concentrations were upwind or downwind of the feedyard pens depending on the wind direction. Wind directions, wind velocity, and air temperature were measured to correlate them with measured concentrations. Higher concentrations were measured when the sampling port was located downwind from the feedyard. The average NH3 concentrations for the fall, winter, and spring based on hourly-averages were 429 ppb, 475 ppb, and 712 ppb, respectively. The highest hourly average of 5,270 ppb for NH3 was measured in the spring 2003, followed by the 2,890 ppb in the fall 2002. The average H2S concentrations for the fall, winter, and spring based on hourly-averages were 7.73 ppb, 0.73 ppb, and 2.45 ppb, respectively. The highest hourly average of 34.9 ppb for H2S was measured in the spring 2003, followed by the 29.6 ppb in the fall 2002. The NH3 and H2S concentrations had a characteristic daily pattern with two local maximums in the early afternoon and early evening hours. The lowest concentrations were always measured during the night. The experimental setup worked well and proved itself to be reliable in widely different weather conditions and operational for unattended and automated measurements.

Estimation of Ammonia and Hydrogen Sulfide Emissions from Cattle Feedlots in Texas

A dynamic flow-through chamber system and continuous analyzers were used for on-site measurements of ammonia-nitrogen (NH3-N) and hydrogen sulfide-sulfur (H2S-S) fluxes from commercial feedlot surfaces in northwestern Texas during two week period in the summer of 2002. Manure pack moisture content, pH, and TKN were measured daily to characterize its relation with NH3-N fluxes. The preliminary average NH3-N and H2S-S flux from the feedlot surface were 1,669 ± 1,212 NH3-N µg/m2/min and 1.884 ± 1.497 H2S-S µg S/m2/min. Manure pack temperature and TKN was found to have a weak correlation with NH3-N flux.

Evaluation of Sample Recovery of Odorous VOCs and Semi‐VOCs From Odor Bags, Sampling Canisters, Tenax TA Sorbent Tubes, and SPME

Odor samples collected in field research are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75 μm SPME fibers, PVF (Tedlar), FEP (Teflon), foil, and PET (Melinex) air sampling bags, sorbent Tenax TA tubes and standard 6 L Stabilizer™ sampling canisters after sample storage for 0.5, 24, and 120 (for sorbent tubes only) hrs at room temperature. The standard gas mixture consisted of 7 volatile fatty acids (VFAs) from acetic to hexanoic, and 4 semi‐VOCs including p‐cresol, indole, 4‐ethylphenol, and 2’‐aminoacetophenone with concentrations ranging from 5.1 ppb for indole to 1, 270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5 and 24 hrs sample storage time, respectively. This was followed by the Tenax TA sorbent tubes (94.8...