Chemical characteristics and source apportionment of atmospheric particles during heating period in Harbin, China

Atmospheric particles(total suspended particles(TSPs);particulate matter(PM)with particle size below 10μm,PM10;particulate matter with particle size below 2.5μm,PM2.5)were collected and analyzed during heating and non-heating periods in Harbin.The sources of PM10and PM2.5were identified by the chemical mass balance(CMB)receptor model.Results indicated that PM2.5/TSP was the most prevalent and PM2.5was the main component of PM210,while the presence of PM10–100was relatively weak.SO-4and NO-3concentrations were more significant than other ions during the heating period.As compared with the non-heating period,Mn,Ni,Pb,S,Si,Ti,Zn,As,Ba,Cd,Cr,Fe and K were relatively higher during the heating period.In particular,Mn,Ni,S,Si,Ti,Zn and As in PM2.5were obviously higher during the heating period.Organic carbon(OC)in the heating period was 2–5 times higher than in the non-heating period.Elemental carbon(EC)did not change much.OC/EC ratios were 8–11 during the heating period,which was much higher than in other Chinese cities(OC/EC:4–6).Results from the CMB indicated that 11 pollution sources were identified,of which traffic,coal combustion,secondary sulfate,secondary nitrate,and secondary organic carbon made the greatest contribution.Before the heating period,dust and petrochemical industry made a larger contribution.In the heating period,coal combustion and secondary sulfate were higher.After the heating period,dust and petrochemical industry were higher.Some hazardous components in PM2.5were higher than in PM10,because PM2.5has a higher ability to absorb toxic substances.Thus PM2.5pollution is more significant regarding human health effects in the heating period.