RESUMO
Objective To study the pollution and source apportionment differences of different periods PM2.5 in the residential community of suburb in Tianjin City during heating and non-heating periods. Methods From 2015 to 2016, daytime and nighttime PM2.5 samples were collected at a community in the suburb of Tianjin. The mass concentration of PM2.5 samples and major chemical components in PM2.5, including metal elements, polycyclic aromatic hydrocarbons (PAHs) and inorganic water-soluble ions were monitored. Positive matrix factorization (PMF) model was used to apportion potential sources of metal elements, PAHs and inorganic water-soluble ions in daytime and nighttime PM2.5. Results In the heating period, the concentrations of some metal elements of suburban residential community were higher in the daytime than in the nighttime. In the non-heating period, the concentrations of some PAHs and inorganic water-soluble ions of suburban residential community were higher in the nighttime than in the daytime. Meanwhile, the concentrations of some metal elements were greater in the daytime than in the nighttime. When in heating period, the main source of PM2.5 in the suburban residential community was coal combustion during daytime and its source contribution rate was 50.1% while secondary aerosol and fuel combustion emissions of gasoline and diesel vehicles were main sources during nighttime and their source contribution rates were 41.0% and 35.9%. The principal source of daytime PM2.5 in the suburban residential community was indoor activity emissions during non-heating period, and secondary aerosol was main source during nighttime and their source contribution rates were 29.8% and 31.1%. Conclusions The pollution status of PM2.5 in residential communities of suburban is serious, and the source apportionment of day and night PM2.5 samples has different in different heating periods.