辽东湾大气中多环芳烃的含量组成及气粒分配

Occurrence and Gas-particle Partitioning of Polycyclic Aromatic Hydrocarbons in the Air of Liaodong Bay

2016年5月和8月对辽东湾大气环境中气相和颗粒相样品进行了走航和定点采集,并对24种PAHs在气相和颗粒相中的含量和组成进行探讨,对15种PAHs的气粒分配过程进行了分析.结果表明:5月和8月辽东湾大气气相和颗粒相中Σ_(24)PAHs总平均含量分别为28.8 ng·m^(-3)和24.0 ng·m^(-3),气相中Σ_(24)PAHs含量5月小于8月,颗粒态Σ_(24)PAHs含量5月大于8月,低分子量PAHs主要分布在气相中,高分子量PAHs组分主要分布在颗粒相,中等分子量PAHs的气粒分配更容易受到气温等环境条件影响;气粒分配系数K_p随着PAHs分子量增加而增加;lgK_p-lgP_L模型和lgK_p-lgK_(OA)模型的斜率m分别为-0.35和0.37,偏离平衡态m为-1或+1,辽东湾气粒分配未达到平衡;假设达到平衡态时的lgK_p-lgK_(OA)模型、lgK_plgP_L模型和碳黑-空气模型均表明,5环PAHs的模型预测结果与实际测定结果之间的吻合程度较好,15种PAHs的碳黑-空气模型能够更好地接近野外实际测定值,低分子量和中等分子量PAHs的气粒分配受到碳黑影响较大.

The gas-and particle-phase polycyclic aromatic hydrocarbons（ PAHs） were collected from the air of Liaodong Bay in May and August to investigate their occurrence and gas/particle distribution. The 24 PAHs were analyzed for gas-and particle-phase samples,and the concentrations of total gas-and particle-phase PAHs were found to be 28. 8 ng·m^-3 and 24. 0 ng·m^-3,respectively.The concentrations of the gas-phase PAHs were higher in August than in May,and the concentrations of the particle-phase PAHs were higher in May than in August. The low molecular weight PAHs were mainly distributed in the gas-phase,and the high molecular weight PAHs were mainly distributed in the particle-phase; the medium molecular weight PAHs were more easily affected by the environmental conditions than the low and high molecular weight PAHs. The value of Kpincreased with an increase in the molecular weight. The slopes m for regressed lgKp-lgPL and lgKp-lgK（OA） plots were-0. 35 and 0. 37,deviated from-1 and ＋ 1 for the equilibrium states of gas/particle partitioning. The equilibrium states of the lgKp-lgK（OA） ,lgKp-lgPL ,and soot-air models were applied; the predicted results of the 5-ring PAHs fitted well with the field measure results. The predicted results of the soot-air model were much closer to the field measure results than the results of the lg KP-lgK（OA） and lg KP-lgPL models; compared to their heavier counterparts,the low and medium molecular weight PAHs were influenced to a greater extent by soot.