HR: 0800h
AN: A51B-0051    [Abstracts]
TI: Volatile Organic Compound (VOC) Emissions from Dairy Cows and Their Waste
AU: * Shaw, S
EM: slshaw@nature.berkeley.edu
AF: Department of Environmental Science, Policy, and Management, UC Berkeley 251A Hilgard Hall, Berkeley, CA 94720 United States
AU: Holzinger, R
EM: holzing@nature.berkeley.edu
AF: Department of Environmental Science, Policy, and Management, UC Berkeley 251A Hilgard Hall, Berkeley, CA 94720 United States
AU: Mitloehner, F
EM: fmmitloehner@ucdavis.edu
AF: Department of Animal Science, UC Davis , Davis, CA 95616 United States
AU: Goldstein, A
EM: ahg@nature.berkeley.edu
AF: Department of Environmental Science, Policy, and Management, UC Berkeley 251A Hilgard Hall, Berkeley, CA 94720 United States
AB: Biogenic VOCs are typically defined as those directly emitted from plants, but approximately 6% of global net primary production is consumed by cattle that carry out enteric fermentation and then emit VOCs that could also be considered biogenic. Current regulatory estimates suggest that dairy cattle in central California emit VOCs at rates comparable to those from passenger vehicles in the region, and thus contribute significantly to the extreme non-attainment of ozone standards there. We report PTR-MS measurements of ammonia and VOCs, and cavity-enhanced-absorption gas analyzer (Los Gatos Research, Inc.) measurements of CH₄, emitted from dairy cattle in various stages of pregnancy/lactation and their waste. Experiments were conducted in chambers at UC Davis that simulate freestall cow housing conditions. CH₄ fluxes ranged from 125-374 lb/cow/year. The compounds with the highest fluxes from '3 cows+waste' treatments were: ammonia (1-18), methanol (0-2.3), acetone+propanal (0.2-0.7), dimethylsulfide (0-0.4), and mass 109 (likely ID = p-cresol; 0-0.3) in lb/cow/year. Mass 60 (likely ID = trimethylamine) and acetic acid were also abundant. There were 10s of additional compounds with detectable, but small, emissions. A few compounds that were likely emitted (i.e. ethanol, formaldehyde, and dimethylamine) were not quantified by the PTR-MS. The total flux for all measured organic gases (TOG = CH₄ + PTR-MS VOCs(including acetone+propanal)) averaged 246±45 lb/cow/year for '3 cows+waste' treatments, and was dominated by methane (>98%). TOG flux for 'waste only' treatments averaged 1.1±0.1 lb/cow/year, and was instead dominated by VOC (>84%). The PTR-MS VOCs as a percent of TOG (0.6±0.2%) emitted from '3 cows+waste' treatments in chamber conditions was a factor of 10 smaller than that currently estimated by the California Air Resources Board. In addition, the ozone forming potentials of the most abundant VOCs are only about 10% those of typical combustion or plant-derived VOCs, implying dairy cattle have a smaller effect on ozone formation than currently assumed by air districts in central California.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0402 Agricultural systems
DE: 0426 Biosphere/atmosphere interactions (0315)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005