兰州城区多环芳烃的多介质归趋模拟研究

利用城市多介质逸度模型模拟了稳态假设下兰州市区16种PAHs在大气、水体、土壤、沉积物、悬浮颗粒物、鱼体、植物和有机膜相中的浓度分布,同时与实测值进行对比,并根据模拟结果计算了相间迁移通量.结果表明,多环芳烃在空气中浓度最小,在不透水有机膜中浓度最大.化石燃料燃烧是PAHs进入环境的主要途径,迁移过程包括扩散、沉降和侵蚀等,土壤降解是PAHs在系统中损失的主要途径:土壤是PAHs主要的汇(占99.86％),但随着环数的增加,其通过大气平流途径从系统中消失的量明显减少,在气相中的降解损失亦降低.有机膜相的存在加速了多环芳烃在大气-有机膜相-水体之间的交换和运动.模型计算浓度与实测浓度吻合较好,验证了模型的可靠性,并通过灵敏度分析,确定了模型的关键参数.

Fate simulation of PAHs in Lanzhou City by multimedia model

The Multi-media Urban Model (MUM) was used to simulate the concentration distribution of 16 species of PAHs in the air, water, soil, sediment, suspended solid, fish, vegetation, and organic film of Lanzhou City under a steady-state assumption. Comparing with the measuring value and according to simulation results, the transferring or exchanging fluxes between the phases were calculated. By using MUM, it was shown that the organic film achieved the highest concentrations in contrast to air, water, soil, sediment, suspended solid, fish, and vegetation, while the concentration of PAHs in the air were the lowest. It was demonstrated that the major source of PAHs in the area was combustion of fossil fuel. The transport process included diffusion, sedimentation, erosion, etc.; while degradation in soil was the main loss in the system. The largest sink for PAHs in Lanzhou City is soil, accounting for about 99.86% of the total amount remaining in the system. With the increasing rings, the advective outflow flux in the air decreased gradually, and the reaction loss proportion of PAHs in the air also decreased. The organic film on impervious surface enhanced the exchange and mobility of PAHs at the interface between air and water. The reliability of the model was verified by the coincidence between the calculated and measured the concentrations. The key parameters of the model were identified by sensitivity analysis.