Atmospheric PAHs in North China: spatial distribution, sources and control strategies

Formed from incomplete combustion process,polycyclic aromatic hydrocarbons (PAHs) post great threat to human health.To illustrate and evaluate spatial distribution and sources of PAHs in North China,gridded PAHs passively sampled in North China during June to September in 2011 were obtained and clustered.Four categories of PAH spatial distribution in North China were identified,with average PAH concentration level of135,266,446 and 611 ng/m3,respectively,representing (1) light polluted North China,(2) medium polluted North China,(3) pollution belt in North China Plain (NCP),and (4) heavy pollution in Shanxi province.Category 4,with significantly high concentration level and different source patterns from the other three categories,was dominant with coke process and coal combustion sources (contributing to more than 80% of all sources based on emission inventory.Coal combustion,biomass burning and transportation were three major sources for Category1-3,which shared much similarity in source pattern.Residential sources showed a decreasing trend in contribution fraction as the PAH concentration increased from Category 1 to 4.Moreover,a new meteorological factor was identified in this study to explain the intensified pollution level and distinctive source pattern in Category 4 in Shanxi province,from a meteorological aspect.13-1