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On-Farm Measurements of Methane and Select Carbonyl Emission Factors for Dairy Cattle

This study aims to determine the emission factors of methane and carbonyl compounds from dairy cattle, which will help in understanding and reducing the impact of these emissions on air quality. By measuring these compounds on farms, it will contribute towards better VOC emission factors and modeling for the agricultural sector.

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On-Farm Measurements of Methane and Select Carbonyl Emission Factors for Dairy Cattle

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  1. On-Farm Measurements of Methane and Select Carbonyl Emission Factors for Dairy Cattle Teresa Cassel, Robert Flocchini, Peter Green, Richard Higashi University of California, Davis with Barry Goodrich, Matt Beene, Charlie Krauter California State University, Fresno

  2. Purpose • Violation of NAAQS for ozone in CA • Permitting of Ag based on VOC emission • Need for better VOC emission factors • Multiple aspects to achieving goal • Emission rate modeling • Consideration of biogenic source variability • Quantification of VOC as defined by EPA

  3. Volatile Organic Compounds “…any compound of carbon, excluding CO, CO2, CO3H2, metallic carbides or carbonates, and NH4+CO3-, which participates in atmospheric photochemical reactions. This includes .[all]… other than the following, which have … negligible photochemical reactivity:” Jenkin and Hayman, 1999. U.S. EPA definition of VOC (40 CFR Part 51 Section 51.100 (s))

  4. Speciation TOC OCls, esters, & alkanes phenols alcohols ethers aldehydes & ketones benzenes alkenes & alkynes acids nitrogenous TOC in water Limited speciation in can only Speciation VOC Collection and Recovery Strategies Increasing MIR TO-15, etc. SCAQMD 25.3 DNPH

  5. OCls, esters, alkanes aldehydes & ketones Carbonyl SpeciationDNPH OFF-THE-SHELF: inexpensive, long shelf life, well defined for ambient air measurement. OPTIMIZATION:experience interpreting published methods and miniaturizing applicable.

  6. Carbonyl SpeciationDNPH STANDARD • Acetaldehyde • Acetone • Acrolein • Benzaldehyde • Butyraldehyde • Crotonaldehyde • Dimethylaldehyde • Formaldehyde • Hexaldehyde • Isovaleraldehyde • Propionaldehyde • o-Tolualdehyde • m-Tolualdehyde • p-Tolualdehyde • Valeraldehyde

  7. Total Organic Carbon – SC 25.3 Methane Ethane Non-Methane, Non-Ethane Organic Carbon CONTEXT: Developed for natural gas (clean) burning sources so impact of more labile constituents unknown. EXTERNAL ANALYSIS: No in-house control of analytical error. CARBON COUNTING: Requires estimate of molecular weight to compute air concentration.

  8. Calibration Standards Sample Injection Loop Sample Initially Forward Through Column Then Back-Flushed Through Column Speciation Column Non-Methane Organics CO, CH4, CO2 Oxidation Catalyst Reduction Catalyst H2 Flame Ionization Detector H2 Combustion Air

  9. Units Translation • Using data produced by “established” analytical lab, reverse engineer “correction factor”.

  10. Lab Recovery experiment 5 min. and 1 hour samples from standard C4 mixture diluted w/ N2.

  11. Predominant Wind Direction Sampling locations Free stall + Open lot Lagoon

  12. Methane Emission Factors Nutrient Cycling in Agroecosystems 60: 133-145, 2001

  13. Carbonyl Emission Factors

  14. Carbonyl Emission Factors

  15. Upwind corrected Carbonyl concentrations

  16. Upwind corrected Carbonyl concentrations

  17. TNMHC Emission Factors

  18. Conclusions • Modeling assumptions validated by CH4 • Emission factors (per head) of monitored compounds lower for lagoons than corrals • All seasons, sites, and sampling methods • Should be summed to get facility-wide EFs • Monitored compounds not direct measure of ROG, as defined • Source specific compound list still needed

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