Deciphering the source and formation mechanism of haze using coal combustion experiments and sulfur isotopes

A research team led by Professor Shen Yan’an of 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, researchers concluded that particulate matter from coal combustion is one of the main sources of haze in northern China. The findings were published online in the Proceedings of the National Academy of Sciences on December 10th.

Due to the influence of human activities and natural conditions, air pollution has reached a serious level, and haze weather has serious effects on economic development and human health, and we study the sources and formation mechanisms of haze. This is of theoretical and practical importance.

The researchers systematically collected coal samples from representative coal mines from different geological periods in northern China and conducted combustion experiments at 1000 degrees Celsius. They then collected aerosol particle samples less than 2.5 micrometers in diameter and performed high-precision sulfur isotope analysis for sulfate content.

The results showed that there are significant differences in sulfur isotope composition between coal and its combustion products. Combined with theoretical calculations, the researchers found that this combustion exhibits a mass-independent sulfur isotope fractionation (S-MIF) phenomenon. According to previous research, this phenomenon mainly appears in rock samples older than 2.2 billion years. Therefore, coal combustion represents a new mechanism of S-MIF and is of great theoretical importance.

Further analysis showed striking similarities in isotopic composition between particulate matter produced by coal combustion and sulfate particles found in northern China’s haze. Although there has been mixed understanding of sulfur isotope anomalies in sulfate haze particles in northern China, results from coal combustion experiments indicate that particulate matter from coal combustion contributes significantly to haze in this region. Proved.

The researchers also found that similar anomalies in sulfur isotopic composition appear in black sulfate crusts on the surfaces of cultural artifacts, sculptures, and ancient buildings in Europe. Since the 1960s, European scientists have shown that the formation of black sulfate crust involves complex physical and chemical processes, in which both air pollution and volcanic eruptions play important roles. We have proven that it is possible.

Through systematic sulfur isotope analysis, the researchers proposed that coal combustion products were an important cause of the formation of sulfate films on historic monuments such as statues and buildings in Europe. This conclusion is very consistent with the history of air pollution caused by the widespread use of coal. At that time, coal was being used in Europe during the development of industry and agriculture.

The results of this study provide new research ideas and evidence on the sources and formation mechanisms of haze, provide a new scientific basis for policy formulation to prevent atmospheric particulate matter pollution, and provide a new scientific basis for policy formulation to prevent atmospheric particulate matter pollution. The important role of sulfur isotopes in deciphering the environment is well demonstrated. .