Elevated levels of glyoxal and methylglyoxal at a remote mountain site in southern China: Prompt in-situ formation combined with strong regional transport

Shaojun Lv; Daocheng Gong; Yaozhou Ding; Youjing Lin; Hao Wang; Hang Ding; Gengchen Wu; Chunqian He; Lei Zhou; Shawchen Liu; Zoran Ristovski; Duohong Chen; Min Shao; Yuanhang Zhang; Boguang Wang

doi:10.1016/j.scitotenv.2019.04.020

Elevated levels of glyoxal and methylglyoxal at a remote mountain site in southern China: Prompt in-situ formation combined with strong regional transport

Sci Total Environ. 2019 Jul 1:672:869-882. doi: 10.1016/j.scitotenv.2019.04.020. Epub 2019 Apr 3.

Authors

Shaojun Lv¹, Daocheng Gong¹, Yaozhou Ding¹, Youjing Lin¹, Hao Wang², Hang Ding¹, Gengchen Wu¹, Chunqian He¹, Lei Zhou¹, Shawchen Liu¹, Zoran Ristovski³, Duohong Chen⁴, Min Shao¹, Yuanhang Zhang⁵, Boguang Wang⁶

Affiliations

¹ Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China.
² Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China. Electronic address: wanghao@jnu.edu.cn.
³ JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, QLD 4001, Australia.
⁴ State Environmental Protection Key Laboratory of Regional Air Quality Monitoring, Guangdong Environmental Monitoring Center, Guangzhou 510308, China.
⁵ State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
⁶ Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China. Electronic address: tbongue@jnu.edu.cn.

PMID: 30978549
DOI: 10.1016/j.scitotenv.2019.04.020

Abstract

The dicarbonyls glyoxal (Gly) and methylglyoxal (Mgly) are key tracers for the oxidation of volatile organic compounds (VOCs) in the atmosphere, but their atmospheric chemistry in remote forest environments is not well understood. A study was carried out during Jul. 31-Nov. 5 of 2016 at the summit of Mt. Tianjing (1690 m.a.s.l.), a remote mountaintop site in southern China, to measure the levels of Gly and Mgly and explore their sources and fate. During the study period, the average mixing ratios of Gly and Mgly were 509 ± 31 pptv and 340 ± 32 pptv, respectively, with the Gly/Mgly ratios averaging 1.8 ± 0.2. Both the dicarbonyl concentrations and the Gly/Mgly ratios were significantly higher than those observed in other background sites. Production yield calculations and meteorological data analysis indicate that high levels of Gly and Mgly observed at the study site were largely a combined result of rapid in-situ formation and regional transport by prevailing winds. On average, in-situ formation from precursors is estimated to account for 67% of the observed Mgly and about 9% of the observed Gly. There were significant changes in Gly and Mgly mixing ratios among different time periods when air masses from different source regions dominated, indicating contribution of regional transport to the observed dicarbonyl mixing ratios at the study site. Biogenic emissions in eastern China and anthropogenic emissions in the Pearl River Delta region were the two main sources responsible for the dicarbonyls observed at the site during most of the sampling period, but large-scale biomass burning in central China was also important in the late autumn, as supported by a backward trajectory analysis of fire spot data and the identification of biomass burning tracers. This study provides insights into the background atmospheric chemistry and the impact of biogenic and anthropogenic sources on the dicarbonyls speciation.

Keywords: Dicarbonyls; Glyoxal; High-elevation mountain; Methylglyoxal; Regional transport.