Pollution Characteristics and Source Apportionment of PM2.5 in Heating and Non-heating Periods in Shenyang

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To study the atmospheric PM2.5 pollution characteristics and sources in heating and non-heating periods in Shenyang, 113 groups of effective PM2.5 samples were collected from January 29, 2015 to January 26, 2016, and the water-soluble ions, carbon constituents and elements in PM2.5 were tested. The results indicated that the average PM2.5 mass concentration in Shenyang during the sampling period was 66 μg·m-3. Among the sampled PM2.5 concentrations, 31.0% exceeded the daily value of the secondary standard limit of the Chinese National Ambient Air Quality Standard (75 μg·m-3). The average concentration and over-standard rate of PM2.5 in the heating period (90 μg·m-3, 68.6%) was higher than that of the non-heating period (51 μg·m-3, 31.4%). The concentrations of the 21 elements (except Mg, Ti, Ca, Fe, and Si), water-soluble ions (except Ca2+), OC, and EC were all higher in the heating period than in the non-heating period. The ratio of[NO3-]/[SO42-]showed that the influence of moving source increased obviously in the non-heating period, and fixed source was still the main contributor in the heating period. The water-soluble ions were the result of the interaction of fixed source and moving source. The NOR and SOR analyses showed that the secondary conversion of NOx was weak, and the secondary conversion of SO2 was obvious, especially in the non-heating period. The enrichment factor showed that the elements with high EF value mainly came from coal burning, traffic pollution, and industrial emissions. The reconstructed PM2.5 masses were highly correlated with the measured ones. The main constituents of PM2.5 in both heating and non-heating seasons were organic matter (28.0%, 23.1%), mineral dust (14.5%, 26.0%), and sulfate (15.1%, 19.9%), and PM2.5 was mainly affected by the secondary particles, combustion sources and dust sources.