Observations of C1-C5 alkyl nitrates in the Yellow River Delta, northern China: Effects of biomass burning and oil field emissions

Yingnan Zhang; Jingjing Sun; Penggang Zheng; Tianshu Chen; Yuhong Liu; Guangxuan Han; Isobel J Simpson; Xinfeng Wang; Donald R Blake; Zeyuan Li; Xue Yang; Yanbin Qi; Qi Wang; Wenxing Wang; Likun Xue

doi:10.1016/j.scitotenv.2018.11.208

Observations of C₁-C₅ alkyl nitrates in the Yellow River Delta, northern China: Effects of biomass burning and oil field emissions

Sci Total Environ. 2019 Mar 15:656:129-139. doi: 10.1016/j.scitotenv.2018.11.208. Epub 2018 Nov 15.

Authors

Affiliations

¹ Environment Research Institute, Shandong University, Ji'nan, Shandong, China.
² Key Laboratory of Coastal Environmental Process and Ecology Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong, China.
³ Department of Chemistry, University of California at Irvine, Irvine, CA, United States.
⁴ Jilin Weather Modification Office, Changchun, Jilin, China; Joint Laboratory of Weather Modification for Chinese Meteorological Administration and People's Government of Jilin Province (Key Laboratory of Jilin Province), Changchun, Jilin, China.
⁵ Environment Research Institute, Shandong University, Ji'nan, Shandong, China; Ji'nan Institute of Environmental Science, Ji'nan, Shandong, China. Electronic address: xuelikun@sdu.edu.cn.

PMID: 30504015
DOI: 10.1016/j.scitotenv.2018.11.208

Abstract

Alkyl nitrates (RONO₂) are important reservoirs of nitrogen oxides and play key roles in the tropospheric chemistry. Two phases of intensive campaigns were conducted during February-April and June-July of 2017 at a rural coastal site and in open oil fields of the Yellow River Delta region, northern China. C₁-C₅ alkyl nitrates showed higher concentration levels in summer than in winter-spring (p < 0.01), whilst their parent hydrocarbons showed an opposite seasonal variation pattern. The C₃-C₅ RONO₂ levels in the oil fields were significantly higher than those in the ambient rural air. Alkyl nitrates showed well-defined diurnal variations, elucidating the effects of in-situ photochemical production and regional transport of aged polluted plumes. Backward trajectory analysis and fire maps revealed the significant contribution of biomass burning to the observed alkyl nitrates and hydrocarbons. A simplified sequential reaction model and an observation-based chemical box model were deployed to diagnose the formation mechanisms of C₁-C₅ RONO₂. The C₃-C₅ RONO₂ were mainly produced from the photochemical oxidation of their parent hydrocarbons (i.e., C₃-C₅ alkanes), whilst C₁-C₂ RONO₂ compounds have additional sources. In addition to parent hydrocarbons, longer alkanes with >4 carbon atoms were also important precursors of alkyl nitrates in the oil fields. This study demonstrates the significant effects of oil field emissions and biomass burning on the volatile organic compounds and alkyl nitrate formation, and provides scientific support for the formulation of control strategies against photochemical air pollution in the Yellow River Delta region.

Keywords: Alkyl nitrate; Biomass burning; Observation-based model; Oil field; Sequential reaction model; Yellow River Delta.