Source apportionment of PM_2.5 using dispersion normalized positive matrix factorization (DN-PMF) in Beijing and...

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Air Quality Management

Background:

• High concentrations of fine particulate matter (PM2.5) frequently occur during the heating season in Beijing and Baoding, China.
• PM2.5 pollution poses significant health risks and environmental challenges in urban areas.

Purpose of the Study:

• To identify and differentiate the sources of PM2.5 pollution in Beijing and Baoding.
• To analyze seasonal variations in PM2.5 sources and their inter-city transport.
• To inform targeted air pollution mitigation strategies for neighboring cities.

Main Methods:

• Dispersion Normalized Positive Matrix Factorization (DNPMF) for source apportionment.
• Mann-Whitney Rank Sum Test for seasonal difference analysis.
• Pearson correlation, Conditional Bivariate Probability Function (CBPF), and joint-Potential Source Contribution Function (PSCF) for source analysis and transport pathways.

Main Results:

• Secondary nitrate was the primary PM2.5 contributor in Beijing (37.3%), while residential heating/biomass burning dominated in Baoding (27.1%).
• Significant seasonal differences in PM2.5 sources were observed in both cities, with specific sources like secondary nitrate, mobile, and biomass burning varying between seasons.
• Long-range transport and seasonal sources like oil combustion and soil showed high correlations between the two cities, indicating shared pollution influences.

Conclusions:

• PM2.5 source profiles differ between Beijing and Baoding, necessitating city-specific pollution control measures.
• Seasonal variations and transboundary transport play crucial roles in PM2.5 pollution dynamics.
• Effective air quality management requires understanding and addressing both local and regional PM2.5 sources, especially during the heating season.