Methane Emissions from Dairy Operations in California's San Joaquin Valley Evaluated Using Airborne Flux Measurements.

Autor:	Schulze BC; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States., Ward RX; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States., Pfannerstill EY; Department of Environmental Science and Policy Management, University of California Berkeley, Berkeley, California 94720, United States., Zhu Q; Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, California 94720, United States., Arata C; Department of Environmental Science and Policy Management, University of California Berkeley, Berkeley, California 94720, United States.; Picarro Inc., Santa Clara, California 95054, United States., Place B; Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States., Nussbaumer C; Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, California 94720, United States.; Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, Mainz 55128, Germany., Wooldridge P; Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, California 94720, United States.; Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States., Woods R; Department of Meteorology, Naval Postgraduate School, Monterey, California 93943, United States., Bucholtz A; Department of Meteorology, Naval Postgraduate School, Monterey, California 93943, United States., Cohen RC; Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, California 94720, United States.; Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States., Goldstein AH; Department of Environmental Science and Policy Management, University of California Berkeley, Berkeley, California 94720, United States.; Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California 94720, United States., Wennberg PO; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States.; Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, United States., Seinfeld JH; Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, United States.; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Jazyk:	angličtina
Zdroj:	Environmental science & technology [Environ Sci Technol] 2023 Dec 05; Vol. 57 (48), pp. 19519-19531. Date of Electronic Publication: 2023 Nov 24.
DOI:	10.1021/acs.est.3c03940
Abstrakt:	State inventories indicate that dairy operations account for nearly half of California's methane budget. Recent analyses suggest, however, that these emissions may be underestimated, complicating efforts to develop emission reduction strategies. Here, we report estimates of dairy methane emissions in the southern San Joaquin Valley (SJV) of California in June 2021 using airborne flux measurements. We find average dairy methane fluxes of 512 ± 178 mg m -2 h -1 from a region of 300+ dairies near Visalia, CA using a combination of eddy covariance and mass balance-based techniques, corresponding to 118 ± 41 kg dairy -1 h -1 . These values estimated during our June campaign are 39 ± 48% larger than annual average estimates from the recently developed VISTA-CA inventory. We observed notable increases in emissions with temperature. Our estimates align well with inventory predictions when parametrizations for the temperature dependence of emissions are applied. Our measurements further demonstrate that the VISTA-CA emission inventory is considerably more accurate than the EPA GHG-I inventory in this region. Source apportionment analyses confirm that dairy operations produce the majority of methane emissions in the southern SJV (∼65%). Fugitive oil and gas (O&G) sources account for the remaining ∼35%. Our results support the accuracy of the process-based models used to develop dairy emission inventories and highlight the need for additional investigation of the meteorological dependence of these emissions.
Databáze:	MEDLINE
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