A research team led by Prof. Shen Yan’an from the University of Science and Technology of China (USTC) has made significant progress in studying the sources and formation mechanisms of haze. Through coal combustion experiments and high-precision sulfur isotope analysis, the researchers drew the conclusion that particulate matter from coal combustion is one of the main sources of haze in North China. The findings were published online in Proceedings of the National Academy of Sciences on December 10.
Due to the impact of human activities and natural conditions, air pollution has reached a severe level, with haze weather severely affecting economic development and human health, making it theoretically and practically significant to study the sources and formation mechanisms of haze.
The researchers systematically gathered coal samples from representative coal mines in northern China across different geological eras and conducted combustion experiments at 1000°C. Then they collected aerosol particles samples with a diameter less than 2.5 micrometers and performed high-precision sulfur isotope analysis on the sulfate components.
The results showed significant differences in sulfur isotope composition between coal and its combustion products. Combined with theoretical calculations, the researchers found that the combustion exhibited the phenomenon of the mass-independent sulfur isotope fractionation (S-MIF) which, according to previous studies, mainly appears in rock samples before 2.2 billion years. Thus, the combustion of coal represents a new mechanism of S-MIF, which holds great theoretical significance.
Further analysis indicated a striking similarity in isotope composition between particulate matter generated from coal combustion and sulfate particles found in haze over North China. While there had been different understandings regarding the sulfur isotope anomalies in the haze particles of sulfate in North China, the results of coal combustion experiments proved that particulate matter from coal combustion is a significant contributor to the haze in the region.
The researchers also found that similar anomalies in sulfur isotope composition also appear on the black sulfate crusts on the surfaces of European cultural relics, sculptures, and ancient buildings. Since the 1960s, European scientists have proven that the formation of black sulfate crusts involves complex physical and chemical processes, in which atmospheric pollution and volcanic eruptions may both play an important role.
Through systematic sulfur isotope analysis, the researchers proposed that the products of coal combustion are an important source of sulfate crusts on historical monuments such as European statues and buildings, a conclusion that is highly consistent with the history of atmospheric pollution caused by the extensive use of coal during the development of industry and agriculture in Europe at the time.
The research findings provide new research ideas and evidence for the sources and formation mechanisms of haze, offer new scientific basis for the formulation of policies to prevent atmospheric particulate matter pollution, and fully demonstrate the crucial role of sulfur isotopes in deciphering present and early earth environments.
More information:
Yanan Shen et al, Sulfur isotope anomalies in coal combustion: Applications to the present and early Earth environments, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2408199121
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University of Science and Technology of China
Citation:
Decoding haze sources and formation mechanisms with coal combustion experiments and sulfur isotopes (2024, December 30)
