北京东南郊大气中多环芳烃的相分配及其致癌毒性表征

Phase distribution and carcinogenic of atmospheric polycyclic aromatic hydrocarbons in the southeastern suburb of Beijing,China

采用索氏提取法提取2005年3月至2006年1月间北京市东南郊3个采样点大气总悬浮颗粒物（TSP）样品和气相样品中的多环芳烃（PAHs），利用GC／MS分析其质量浓度，对PAHs在颗粒相和气相间的分配行为进行研究。结果表明，2环组分在气相PAHs中占优势地位，全年平均在95％左右；4环组分在颗粒相PAHs中全年平均占56％左右；5-6环组分几乎全部分布在颗粒相中。引入苯并[a]芘等当量毒性因子（TEFs），探讨致癌毒性组分在2相间的分配行为，研究发现低毒高质量浓度的低环组分与高毒低质量浓度的高环组分对致癌性贡献相当；利用苯并[a]芘等效质量浓度与16种PAHs组分质量浓度进行多元线性回归，得到的回归方程用于粗略计算大气中PAHs致癌性组分的等效质量浓度；在分析PAHs分配行为的季节变化规律基础上，结合气象参数和空气污染指数分析PAHs在大气气相和颗粒相中分配系数的影响因素，并提出了分配系数与气象参数和API指数的回归方程，并利用回归方程来计算PAHs组分在大气中的分配系数。

TSP samples and gas phase samples were collected at 3 sampling sites in the southeastern suburb of Beijing from March, 2005 to January, 2006. 16 PAHs in the samples were extracted by soxhlet extraction method, and concentrations of PAHs were analyzed using GC/MS. Behavior of particle-gas phase distribution of PAHs was also studied. The 2-ring components dominated in gas phase, and the annual average percentage was about 95%; the average percentage of 4-ring components in particle phase was about 56%; Almost all 5-6-ring PAHs existed in the particle phase. Distribution of carcinogenic components at the two phases was discussed using toxic equivalency factors （TEFs） of benzo （a） pyrene. Contributions of low ring components to carcinogenic equal that of high ring components, which have higher toxicity but lower concentration. Regression equation between equivalency of benzo （a） pyrene and concentration of 16 PAHs was used to calculate the equivalency ofbenzo （a） pyrene for 16 PAHs in ambient air. Based on seasonal changes of PAHs distribution, influencing factors for distribution coefficient were analyzed by using meteorological parameters and air pollution indexes, and regression equation was created to calculate the distribution coefficient of PAHs in atmosphere.