Inicio  /  Atmosphere  /  Vol: 9 Núm: 2 Par: Februar (2018)  /  Artículo
ARTÍCULO
TITULO

Day-Night Differences, Seasonal Variations and Source Apportionment of PM10-Bound PAHs over Xi?an, Northwest China

Xin Wang    
Zhenxing Shen    
Yaling Zeng    
Fobang Liu    
Qian Zhang    
Yali Lei    
Hongmei Xu    
Junji Cao and Liu Yang    

Resumen

Day-night PM10-bound PAHs were studied at an urban site of Xi?an from 20 December 2006 to 28 October 2007. The annual mean concentration of nighttime PAHs (285.0 ng m-3) was higher than that in daytime (239.4 ng m-3). A significant difference of PAH concentrations between daytime and nighttime was found in autumn with a coefficient of divergence (CD) of 0.23 (significant level 0.2). However, no distinct difference was observed in other seasons (with CD values < 0.2), although the difference of PAHs partition capacity in PM10 between daytime and nighttime was significant in the four seasons. Remarkable seasonal variations were observed in the total PAH levels, with a highest mean concentration of 344.6 ng m-3 in winter and a lowest mean concentration of 177 ng m-3 in summer. Positive matrix factorization results revealed that residential emission for heating is the major contributor of the elevated PAH levels in winter, accounting for 49% of the total PAH levels. The coal combustion including industrial and residential usage, contributed over 40% of the PAH emissions in PM10 of Xi?an during the one-year sampling period. These results can provide guidance for taking measures in reducing PAHs levels in the air.

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