Light absorption and emissions inventory of humic-like substances from simulated rainforest biomass burning in Southeast Asia

Jiao Tang; Jun Li; Yangzhi Mo; Mahdi Safaei Khorram; Yingjun Chen; Jianhui Tang; Yanlin Zhang; Jianzhong Song; Gan Zhang

doi:10.1016/j.envpol.2020.114266

Light absorption and emissions inventory of humic-like substances from simulated rainforest biomass burning in Southeast Asia

Environ Pollut. 2020 Jul:262:114266. doi: 10.1016/j.envpol.2020.114266. Epub 2020 Feb 29.

Authors

Jiao Tang¹, Jun Li², Yangzhi Mo², Mahdi Safaei Khorram², Yingjun Chen³, Jianhui Tang⁴, Yanlin Zhang⁵, Jianzhong Song², Gan Zhang⁶

Affiliations

¹ State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
³ Department of Environmental Science and Engineering, Fudan University, Shanghai 200092, PR China.
⁴ Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China.
⁵ Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science and Technology, Nanjing 210044, China.
⁶ State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. Electronic address: zhanggan@gig.ac.cn.

PMID: 32155548
DOI: 10.1016/j.envpol.2020.114266

Abstract

Humic-like substances (HULIS) are complex mixtures that are highly associated with brown carbon (BrC) and are important components of biomass burning (BB) emissions. In this study, we investigated the light absorption, emission factors (EFs), and amounts of HULIS emitted from the simulated burning of 27 types of regionally important rainforest biomass in Southeast Asia. We observed that HULIS had a high mass absorption efficiency at 365 nm (MAE₃₆₅), with an average value of 2.6 ± 0.83 m² g^-1 C. HULIS emitted from BB accounted for 65% ± 13% of the amount of water-soluble organic carbon (WSOC) and 85% ± 10% of the light absorption of WSOC at 365 nm. The EFs of HULIS from BB averaged 2.3 ± 2.1 g kg^-1 fuel, and the burning of the four vegetation subtypes (herbaceous plants, shrubs, evergreen trees, and deciduous trees) exhibited different characteristics. The differences in EFs among the subtypes were likely due to differences in lignin content in the vegetation, the burning conditions, or other factors. The light absorption characteristics of HULIS were strongly associated with the EFs. The annual emissions (minimum-maximum) of HULIS from BB in this region in 2016 were 200-371 Gg. Furthermore, the emissions from January to April accounted for 99% of the total annual emissions of HULIS, which is likely the result of the burning activities during this season. The most significant emission regions were Cambodia, Burma, Thailand, and Laos. This study, which evaluated emissions of HULIS by simulating open BB, contributes to a better understanding of the light-absorbing properties and regional budgets of BrC in this region.

Keywords: Brown carbon; Emission factors; Mass absorption efficiency; Regional emissions.

MeSH terms

Aerosols
Air Pollutants / analysis*
Asia, Southeastern
Biomass
Cambodia
Carbon / analysis
Environmental Monitoring
Particulate Matter / analysis*
Rainforest
Thailand

Substances

Aerosols
Air Pollutants
Particulate Matter
Carbon