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Assessment of Nitrogen Oxide Emissions and San Joaquin Valley PM 2.5 Impacts From Soils in California
Author(s) -
Guo Lei,
Chen Jianjun,
Luo Dongmin,
Liu Shang,
Lee Hyung Joo,
Motallebi Nehzat,
Fong Angel,
Deng Jia,
Rasool Quazi Z.,
Avise Jeremy C.,
Kuwayama Toshihiro,
Croes Bart E.,
FitzGibbon Michael
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd033304
Subject(s) - san joaquin , environmental science , cmaq , soil water , air quality index , denitrification , particulates , greenhouse gas , emission inventory , nitrate , environmental chemistry , atmospheric sciences , nitrogen , soil science , ecology , meteorology , chemistry , geography , organic chemistry , geology , biology
Soils are a source of atmospheric nitrogen oxides (NO x ), especially in regions with significant cropland where nitrogen (N) fertilizers are used to enhance crop yields. The magnitude of soil NO x emissions, however, varies substantially by region, depending on the local land use pattern and management activities. We estimated soil NO x emissions in California based on the DeNitrification‐DeComposition (DNDC) biogeochemical model, linked to a detailed spatial‐temporal differentiated California‐specific database. The DNDC‐generated surface fluxes were used in the Community Multiscale Air Quality (CMAQ) model to evaluate impacts of soil NO x emissions on formation of ambient particulate (PM 2.5 ) nitrate in the San Joaquin Valley (SJV) where cropland is the dominant land use. The DNDC‐generated soil NO x emissions contribute approximately 1.1% of total anthropogenic NO x emissions in California, at an emission rate of roughly 24 t day −1 (as NO 2 ) statewide and 9 t day −1 in the SJV. Cropland is the dominant source of soil NO x emissions in California, contributing nearly 60% of statewide soil NO x emissions, driven principally by fertilizer use. The PM 2.5 nitrate concentrations simulated by CMAQ using the DNDC‐generated soil NO x emissions are compatible with those observed in the SJV, suggesting that soil NO x emissions have limited impacts on PM 2.5 nitrate formation in the atmosphere. Our emission and air quality modeling results are further supported by long‐term ambient NO x ‐to‐carbon monoxide (CO) and satellite NO 2 data analyses in the SJV, which showed diurnal, monthly, and annual trends consistent with characteristics of NO x sources dominated by traffic combustion in both urban and agricultural regions.