Misattribution of biomass burning sources in PM2.5
More levoglucosan (Lev), a key molecular tracer of biomass burning in PM2.5, is released by cooking than agricultural burning.
Image Credit: Osaka Metropolitan University
Scientific Frontline: Extended "At a Glance" Summary: Atmospheric Degradation of Levoglucosan
The Core Concept: Levoglucosan, a molecular tracer traditionally used to measure fine particulate matter (PM2.5) emissions from biomass burning, degrades chemically in the atmosphere significantly faster than previously assumed. Up to 88 percent of the compound is lost to volatilization and atmospheric degradation before it can be measured.
Key Distinction/Mechanism: Conventional environmental models operate on the assumption that levoglucosan remains chemically stable once emitted. This revised framework corrects for rapid chemical deterioration accelerated by sunlight, necessitating mathematically adjusted calculations to accurately identify the original pollution emission sources.
Major Frameworks/Components:
- Molecular Tracer Analysis: The analytical use of levoglucosan to detect the combustion of plant cellulose, including wood, charcoal, and agricultural residues.
- Atmospheric Degradation Correction: Adjusting environmental monitoring models to account for severe compound loss prior to data collection.
- Source Apportionment Re-evaluation: Shifting the identified origin of PM2.5 emissions based on corrected data (e.g., reattributing pollution in Ho Chi Minh City from rural crop burning to urban hardwood and charcoal cooking fires).
Branch of Science: Atmospheric Chemistry, Environmental Science, and Analytical Chemistry.
Future Application: The development of highly accurate source apportionment frameworks for urban air quality management globally, specifically targeting tropical regions where intense sunlight accelerates chemical breakdown.
Why It Matters: Failing to account for atmospheric degradation leads to the misidentification of pollution sources and the ineffective allocation of financial and regulatory resources. Accurate modeling ensures that environmental mitigation strategies target actual emission contributors, such as urban fuel use, rather than misattributed agricultural practices.
Biomass burning, including the combustion of wood, charcoal, and agricultural residues, is a major source of PM2.5, a fine particulate matter that degrades air quality and poses risks to human health. Much of this pollution is tracked by analyzing levels of levoglucosan, a chemical formed when plant cellulose is burned during biomass combustion processes, such as residential fuel use, cooking, and open burning.
However, what if the atmospheric loss of levoglucosan is not properly accounted for?
That is the question posed in a new study by Osaka Metropolitan University (OMU), which found that levoglucosan undergoes significant chemical degradation after being emitted into the atmosphere.
“We estimate that about 88% of it was lost due to atmospheric degradation and volatilization,” said Associate Professor Yusuke Fujii of the Graduate School of Sustainable System Sciences at OMU. “Conventional analyses that do not account for this loss risk misidentifying emission sources.”
This is especially true in tropical areas, as sunlight accelerates the chemical's degradation. Consequently, this raises concerns that previous research based on the assumption that levoglucosan remains stable may not provide a complete picture. Misidentifying pollution sources could lead to the ineffective allocation of financial resources.
The study's findings supported this concern. In Ho Chi Minh City, Vietnam, researchers found that without correcting for chemical degradation, the pollution appeared to originate primarily from crop residue and grass burning, which are common rural practices in Southeast Asia.
However, after correcting for the lost levoglucosan, the data instead pointed to hardwood and charcoal burning, particularly cooking-related emissions within the urban areas of Ho Chi Minh City.
“In Vietnam, urban air pollution remains a serious concern,” said Ngoc Tran, a Vietnamese researcher from OMU’s Graduate School of Sustainable System Sciences. “There is a strong need to clarify the detailed contributions of these sources, specifically what is being burned and where, to develop effective mitigation strategies.”
“By optimally integrating established methods with local environmental conditions, it is possible to more accurately evaluate the types and relative contributions of biomass burning that were previously difficult to distinguish. This approach will contribute to improving the accuracy of source apportionment in urban areas worldwide,” Fujii added.
Funding: This work was supported in part by the Heiwa Nakajima Foundation, the Japan Science and Technology Agency (JST)-SPRING Program (JPMJSP2139), and the Technology Development Fund (JPMEERF20245004) of the Environmental Restoration and Conservation Agency of Japan.
Published in journal: ACS Omega
Authors: Ngoc Tran, Yusuke Fujii, To Thi Hien, and Norimichi Takenaka
Source/Credit: Osaka Metropolitan University
Edited by: Scientific Frontline
Reference Number: as062626_01
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