餐饮源气相与颗粒相多环芳烃排放特征

Emission Characteristics of Gas-and Particle-Phase Polycyclic Aromatic Hydrocarbons from Cooking

多环芳烃(PAHs)是导致大气二次污染严重和臭氧浓度高的原因之一.通过对深圳市3家商业性餐馆和1家食品加工厂的采样调查,分析对比了我国主要中式餐饮源排放的PAHs在气相和颗粒相之间的差异,也重点关注了餐饮源烷基PAHs的排放特征.结果表明,食品加工厂排放的颗粒相和气相ρ(总PAHs)为(1381.6±140.5)ng·m^(-3),ρ(PAHs-川菜)为(1030.2±116.4)ng·m^(-3),ρ(PAHs-粤菜)为(908.3±111.9)ng·m^(-3),ρ(PAHs-浙菜)为(838.0±93.5)ng·m^(-3).超过60%的PAHs分布于气相之中,尤其是4环的■及其之前的相对分子质量较低的PAHs,萘气相占比最高,各餐馆均超过了75%;苯并(b)荧蒽之后的相对分子质量较高的PAHs则主要分布于颗粒相中.餐饮源排放的烷基PAHs总量远低于对应的母体PAHs,且餐饮源烷基多环芳烃的分布特征与其他污染源存在较大差异.lgK_(p)和lgP_(L)线性拟合结果显示3家商业性餐馆的斜率范围为-0.25~-0.28,食品加工厂的斜率为-0.18,均未达到平衡.

Polycyclic aromatic hydrocarbons(PAHs)play a key role in the formation of secondary organic areole and ozone.This study sampled three commercial Chinese restaurants and a food plant in Shenzhen to analyze the emission characteristics of PAHs,especially the alkyl PAHs in both gas and particle phases.The results showed that theρ(total PAHs)in the particle and gas phase were(1381.6±140.5)ng·m^(-3),(1030.2±116.4)ng·m^(-3),(908.3±111.9)ng·m^(-3),and(838.0±93.5)ng·m^(-3) in the food plant,Sichuan,Cantonese,and Zhejiang restaurants,respectively.More than 60%of the PAHs were distributed in the gas phase,especially the lower molecular weight PAHs(lower than Chrysene).The gas phase proportion of naphthalene was the highest,with over 75%of it distributed in the gas phase.However,the PAHs with a higher molecular weight than that of benzo(b)fluorescence were mainly distributed in the particle phase.The total concentration of alkyl PAHs emitted from cooking was much lower than that of the corresponding parent PAHs,and the distribution characteristics of alkyl PAHs were quite different from those of other emission sources.The linear fitting of lgK_(p) and lgP_(L) showed that the slopes of the three commercial restaurants ranged from-0.25 to-0.28,whereas for the food plant,the value was-0.18,which indicates that the gas-particle partitioning of PAHs were not in equilibrium.