An Aerodyne quadrupole aerosol mass spectrometry (Q-AMS) was utilized to measure the size-resolved chemical composition of non-refractory submicron particles (NR-PM₁) from October 27 to December 3, 2014 at an urban site in Lanzhou, northwest China.  

The average NR-PM₁ mass concentration was 37.3 μg m⁻³ (ranging from 2.9 to 128.2 μg m⁻³) under an AMS collection efficiency of unity and was composed of organics (48.4%), sulfate (17.8%), nitrate (14.6%), ammonium (13.7%), and chloride (5.7%).  

Positive matrix factorization (PMF) with the multi-linear engine (ME-2) solver identified six organic aerosol (OA) factors, including hydrocarbon-like OA (HOA), coal combustion OA (CCOA), cooking-related OA (COA), biomass burning OA (BBOA) and two oxygenated OA (OOA1 and OOA2), which accounted for 8.5%, 20.2%, 18.6%, 12.4%, 17.8% and 22.5% of the total organics mass on average, respectively.  

Primary emissions were the major sources of fine particulate matter (PM) and played an important role in causing high chemically resolved PM pollution during wintertime in Lanzhou. Back trajectory analysis indicated that the long-range regional transport air mass from the westerly was the key factor that led to severe submicron aerosol pollution during wintertime in Lanzhou. 

This research achievement is published on Environmental Pollution. 

Keywords: Non-refractory submicron particles (NR-PM₁); Mass concentration; Organic aerosol (OA);AMS; Lanzhou 

Fig. (a) Geographical location of Lanzhou in China. (b) Topography map of Lanzhou Basin and its adjacent areas. (c) The locations of sampling site and one air quality station (CNEMC Station) during this study in Chengguan District of Lanzhou.