Assessment and quantification of NOx sources at a regional background site in North China: Comparative results from a Bayesian isotopic mixing model and a positive matrix factorization model

Zheng Zong; Yang Tan; Xiaoping Wang; Chongguo Tian; Yunting Fang; Yingjun Chen; Yin Fang; Guangxuan Han; Jun Li; Gan Zhang

doi:10.1016/j.envpol.2018.08.026

Assessment and quantification of NO_x sources at a regional background site in North China: Comparative results from a Bayesian isotopic mixing model and a positive matrix factorization model

Environ Pollut. 2018 Nov;242(Pt B):1379-1386. doi: 10.1016/j.envpol.2018.08.026. Epub 2018 Aug 14.

Authors

Zheng Zong¹, Yang Tan², Xiaoping Wang³, Chongguo Tian⁴, Yunting Fang⁵, Yingjun Chen⁶, Yin Fang⁶, Guangxuan Han², Jun Li³, Gan Zhang³

Affiliations

¹ Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
² Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.
³ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
⁴ Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China. Electronic address: cgtian@yic.ac.cn.
⁵ Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110164, China.
⁶ Key Laboratory of Cities' Mitigation and Adaptation to Climate Change in Shanghai (CMA), College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.

PMID: 30138830
DOI: 10.1016/j.envpol.2018.08.026

Abstract

Regional sources of nitrogen oxides (NO_x) in North China during summer were explored using both a Bayesian isotopic mixing model and a positive matrix factorization (PMF) model. Results showed that the nitrogen isotope (δ¹⁵N) composition of particulate nitrate (NO₃^-) varied between -8.9‰ and +14.1‰, while the oxygen isotope (δ¹⁸O) composition ranged from +57.4‰ to +93.8‰. Based on results from the Bayesian isotopic mixing model, the contribution of the hydroxyl radical (•OH) NO_x conversion pathway showed clear diurnal fluctuation; values were higher during the day (0.53 ± 0.16) and lower overnight (0.42 ± 0.17). Values peaked at 06:00-12:00 and then decreased gradually until 00:00-06:00 the next day. Coal combustion (31.34 ± 9.04%) was the most significant source of NO_x followed by biomass burning (25.74 ± 2.58%), mobile sources (23.83 ± 3.66%), and microbial processes (19.09 ± 5.21%). PMF results indicated that the contribution from mobile sources was 19.83%, slightly lower as compared to the Bayesian model (23.83%). The PMF model also reported a lower contribution from coal combustion (28.65%) as compared to the Bayesian model (31.34%); however, the sum of biomass burning and microbial processes in the Bayesian model (44.83%) was lower than the aggregate of secondary inorganic aerosol, sea salt, and soil dust in PMF model (51.52%). Overall, differences between the two models were minor, suggesting that this study provided a reasonable source quantification for NO_x in North China during summer.

Keywords: Bayesian isotopic mixing model; NO(x) sources; Nitrogen/oxygen isotope; PMF model.

MeSH terms

Aerosols
Air Pollutants / analysis*
Bayes Theorem
China
Coal
Dust / analysis
Environmental Monitoring / methods
Nitrates / analysis
Nitrogen Isotopes / analysis
Nitrogen Oxides / analysis*
Oxygen Isotopes / analysis
Power Plants
Seasons

Substances

Aerosols
Air Pollutants
Coal
Dust
Nitrates
Nitrogen Isotopes
Nitrogen Oxides
Oxygen Isotopes