文摘
A USEPA, procedure, ISCLT3 (Industrial Source ComplexLong-Term), was applied to model the spatial distribution ofpolycyclic aromatic hydrocarbons (PAHs) emitted fromvarious sources including coal, petroleum, natural gas, andbiomass into the atmosphere of Tianjin, China. Benzo[a]pyrene equivalent concentrations (BaPeq) were calculatedfor risk assessment. Model results were provisionallyvalidated for concentrations and profiles based on theobserved data at two monitoring stations. The dominantemission sources in the area were domestic coal combustion,coke production, and biomass burning. Mainly becauseof the difference in the emission heights, the contributionsof various sources to the average concentrations atreceptors differ from proportions emitted. The shares ofdomestic coal increased from ~43% at the sources to 56%at the receptors, while the contributions of cokingindustry decreased from ~23% at the sources to 7% atthe receptors. The spatial distributions of gaseousand particulate PAHs were similar, with higher concentrationsoccurring within urban districts because of domesticcoal combustion. With relatively smaller contributions, theother minor sources had limited influences on theoverall spatial distribution. The calculated average BaPeqvalue in air was 2.54 ± 2.87 ng/m3 on an annual basis.Although only 2.3% of the area in Tianjin exceeded thenational standard of 10 ng/m3, 41% of the entire populationlives within this area.