Ammonia and methane dairy emission plumes in the San Joaquin Valley of California from individual feedlot to regional scales

作者：David J. Miller, Kang Sun, Lei Tao, Da Pan, Mark A. Zondlo, J. B. Nowak, Zhen Liu, Glenn S. Diskin, G. W. Sachse, A. J. Beyersdorf, R. A. Ferrare, Amy Jo Scarino · 发表于：Journal of Geophysical Research Atmospheres · 年份：2015 · DOI：10.1002/2015jd023241 · 被引用次数：53 · 研究领域：Atmospheric and Environmental Gas Dynamics、Atmospheric chemistry and aerosols、Odor and Emission Control Technologies

Abstract Agricultural ammonia (NH 3 ) emissions are highly uncertain, with high spatiotemporal variability and a lack of widespread in situ measurements. Regional NH 3 emission estimates using mass balance or emission ratio approaches are uncertain due to variable NH 3 sources and sinks as well as unknown plume correlations with other dairy source tracers. We characterize the spatial distributions of NH 3 and methane (CH 4 ) dairy plumes using in situ surface and airborne measurements in the Tulare dairy feedlot region of the San Joaquin Valley, California, during the NASA Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality 2013 field campaign. Surface NH 3 and CH 4 mixing ratios exhibit large variability with maxima localized downwind of individual dairy feedlots. The geometric mean NH 3 :CH 4 enhancement ratio derived from surface measurements is 0.15 ± 0.03 ppmv ppmv −1 . Individual dairy feedlots with spatially distinct NH 3 and CH 4 source pathways led to statistically significant correlations between NH 3 and CH 4 in 68% of the 69 downwind plumes sampled. At longer sampling distances, the NH 3 :CH 4 enhancement ratio decreases 20–30%, suggesting the potential for NH 3 deposition as a loss term for plumes within a few kilometers downwind of feedlots. Aircraft boundary layer transect measurements directly above surface mobile measurements in the dairy region show comparable gradients and geometric mean enhanc...