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

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

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:

Published: July 2019

AI Article Synopsis

  • The study investigates the atmospheric chemistry of dicarbonyls glyoxal (Gly) and methylglyoxal (Mgly) in remote forest environments, particularly at Mt. Tianjing, China, to understand their sources and behavior.
  • Measurements taken from July to November 2016 revealed that both Gly and Mgly levels were significantly higher than those in other remote areas, with Gly contributing about 9% and Mgly roughly 67% from in-situ production.
  • The findings indicate that biogenic emissions from eastern China and anthropogenic emissions from the Pearl River Delta are key sources of these compounds, with additional contributions from biomass burning in central China during late autumn.

Article 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.

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Source
http://dx.doi.org/10.1016/j.scitotenv.2019.04.020DOI Listing

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