Spatial characterization of HCHO and reapportionment of its secondary sources considering photochemical loss in Taiyuan, China

Jingya Hua; Yang Cui; Lili Guo; Hongyan Li; Jie Fan; Yanan Li; Yonghong Wang; Kankan Liu; Qiusheng He; Xinming Wang

doi:10.1016/j.scitotenv.2022.161069

Spatial characterization of HCHO and reapportionment of its secondary sources considering photochemical loss in Taiyuan, China

Sci Total Environ. 2023 Mar 20:865:161069. doi: 10.1016/j.scitotenv.2022.161069. Epub 2022 Dec 27.

Authors

Jingya Hua¹, Yang Cui², Lili Guo¹, Hongyan Li¹, Jie Fan¹, Yanan Li¹, Yonghong Wang³, Kankan Liu⁴, Qiusheng He¹, Xinming Wang⁵

Affiliations

¹ School of Environment and Resources, Taiyuan University of Science and Technology, Taiyuan 030024, China.
² School of Environment and Resources, Taiyuan University of Science and Technology, Taiyuan 030024, China. Electronic address: cuiyang@tyust.edu.cn.
³ State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: yonghongwang@rcees.ac.cn.
⁴ School of Environment and Safety Engineering, North University of China, Taiyuan 030051, China.
⁵ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.

PMID: 36584945
DOI: 10.1016/j.scitotenv.2022.161069

Abstract

Formaldehyde (HCHO) plays an important role in atmospheric ozone (O₃) formation. To accurately identify the sources of HCHO, carbonyls and volatile organic compounds (VOCs) were measured at three urban sites (Taoyuan, TY-U; Jinyuan, JY-U; Xiaodian, XD-U) and a suburban site (Shanglan, SL-B) in Taiyuan during a high O₃ period (from July 20 to August 3, 2020). The average mixing ratio of HCHO at XD-U (8.1 ± 2.8 ppbv) was comparable to those at TY-U (7.4 ± 2.1 ppbv) and JY-U (7.0 ± 2.3 ppbv) but higher (p < 0.01) than that at SL-B (4.9 ± 2.3 ppbv). HCHO contributed to 54.3-59.9 % of the total ozone formation potentials (OFPs) of non-methane hydrocarbons (NMHCs) at four sites. The diurnal variation of HCHO concentrations reached a peak value at 12:00-15:00, which may be attributed to the strong photochemical reaction. To obtain more accurate source results of HCHO under the condition of photochemical loss, the initial concentrations of NMHCs were estimated based on photochemical age parameterization and incorporated into the positive matrix factorization (PMF) model (termed IC-PMF). According to the IC-PMF results, secondary formation (SF) contributed the most to HCHO at XD-U (35.6 %) and SL-B (25.1 %), whereas solvent usage (SU) (40.9 %) and coking sources (CS) (36.0 %) were the major sources at TY-U and JY-U, respectively. Compared to the IC-PMF, the conventional PMF analysis based on the observed data underestimated the contributions of SU (100.5-154.2 %) and biogenic sources (BS) (28.5-324.7 %). Further reapportionment of secondary HCHO by multiple linear regression indicated that SU dominated the sources of HCHO at SL-B (28.3 %) and TY-U (41.7 %), while industrial emissions (IE) and CS contributed the most to XD-U (26.6 %) and JY-U (43.0 %) in Taiyuan from north to south, respectively.

Keywords: Formaldehyde; Photochemical loss; Source apportionment; Spatial distribution.