The Distribution Of Polycyclic Aromatic Hydrocarbons In Airborne Particulate Matter In The Winter Season Of Xi'an

Polycyclic aromatic hydrocarbons (PAH_s) are ubiquitous environmental pollutants with carcinogenic and mutagenic activities. PAH_s are formed primarily during incomplete combustion of organic matter, such as fossil fuels (coal and oil), biomass, tobacco, plastic, etc. The majority of PAH_s with serious carcinogen is the heavy one that are mainly sorbed on fine inhalable particles with a high concentration on airborne particles of sub-micron diameters, which can be deposited in the respiratory tract, hence, increasing the potential health effects. Therefore, it have received a considerable research interest.As the core of western cities in China, Xi'an is endued with important significance in history, education, tourism, science and technology throughout the world. However, Xi'an also is a seriously polluted city and lacks the necessary measurement to PAHs for city air. The method to analyze PAH_s was established using HPLC-UV detector in order to investigate the distribution of PAH_s during heating period in winter. In addition, several typical sampling sites were selected to study their concentrations and sources, the conclusions are summarized as followed:(1) The method to analyze PAH_s associated with particulate matter was established. Meantime, we obtained multiple-unit gradient program and appropriate absorbance wavelength to measure 15 PAH_s with controlled priority listed by the US EPA. The detection limits of the above 15 PAH_s were 0.49²3.27pg, the recoveries were 82.5% 106.4%.(2) Eight sampling sites are typical of heavy traffic, industrial, agricultural, populous, commercial, cultural and resident zones, respectively. With the designed method, 13 particle-associated PAH_s in various functional zones were analyzed, the characteristic of their concentration and distribution as followed:â‘  The average concentration of the total of 13 PAH_s reached to 183.9 ng m^-3, BaP was 11.32 ng m^-3 in winter in Xi'an;â‘¡ For different functional zones, the concentrations of particle-associated PAH_s in ambient air changed in order of heavy traffic areas> student residence with heavy coal-burning emission > agricultural areas > high-tech industrial zones > shopping center > campus;â‘¢ There was higher concentration of PAH_s at the daytime than at the nighttime(3) The fractions of PAHS with various rings analyzed in 12 samples was 38.64( four rings) > 25.17(five rings) > 18.83( six rings) > 10.25( three rings), the ratio to FA/PY was 0.90— 1.80, averagely 1.13; the ratio to BaP/BghiP was 0.33⁰.70, averagely 0.51.(4) The continuous monitoring to TSP and PAHS in relatively clean areas—the Department of Environmental Science & Engineering (DESE) and a building site at Chang'an University showed that:(D There is a higher concentration of TSP and PAHS in the building site than in DESE. (2) PAHS with three rings competes with the one with five rings. Furthermore, the concentrations of PAHS with six rings are stable and comparable with the shift of TSP, while PAHS with three rings is so volatile that their reversible absorbance on particulate matter are responsible for the instability of their concentrations.