Chemical characteristics and source apportionment of PM₁₀ during a brown haze episode in Harbin, China

This study investigates the correlation between PM₁₀ and meteorological factors such as wind speed, atmospheric visibility, dew point, relative humidity, and ambient temperature during a brown haze episode. In order to identify the potential sources of PM₁₀ during brown haze episode, respirable particulate matter (PM₁₀) was collected during both non-haze days and haze days and further analyzed for metallic elements, ionic species, and carbonaceous contents. Among them, ionic species contributed 45-64% to PM₁₀, while metallic elements contributed 7-21% to PM ₁₀ which was smaller than the other chemical constituents. The average OC/EC ratio (42) in haze days was about three times of the average OC/EC ratio (14) in non-haze days. By using chemical mass balance (CMB) receptor model, the major sources were apportioned, including traffics, incinerators, coal combustion, steel industry, petrochemical industry, and secondary aerosols, etc. The contribution to PM₁₀ concentration of each source was calculated for all the samples collected. The results showed that coal combustion was the major source of PM₁₀ in non-haze days and secondary aerosols were the major source in haze days, followed by petrochemical industry, incinerators, and traffics, while other sources had negligible effect.