交通拥堵产生的超细颗粒物的动态分布及控制策略研究

Recently plenty of investigations and observations have been carried out on particulate matter in urban area especially in the congested downtown, which could impair living quality and city image. Unfortunately, to date, most of them are based on the particle mass concentrations in terms of PM10 and PM2.5. Little knowledge has been revealed systematically in urban area about the particle number distributions of the ultrafine particles (UFP) within the range of 0.1μｍ (PM0.1), which are mainly originated from vehicular emissions and has serious negative impacts on human health. Therefore, a exploration of UFP is urgently needed to quantify its dispersion at hot traffic spots and provides more accurate air quality information for further modelling and analysis. In this project, we plan to extend our long-term and successful research efforts to investigation of UFP in traffic jam situation. Specifically, we intend to 1) characterise the UFP by measuring the spatial and time series particle number distributions via in-site surveys and measurements; 2) understand the longmemory effects, multifractal characteristics, and diffusion properties of UFP in various traffic jam situations by modelling and analysis; 3) reveal the influence of traffic jam on UFP diffusion; and 4) provide guiding information for critical vehicular emission control. We expect that these new findings and analytic results from the proposed study will enhance our knowledge about UFP, which will be of significant relevance to the evaluation of UFP dispersion at hot traffic spots and the fulfilment of the haze goal set by Chinese Environmental Thirteenth Five-Year Plan.

在交通拥堵中，走走停停的机动车持续不断地在交通瓶颈处排放出超细颗粒物, 远远超过了周围空气的自净能力和规定标准，严重危及驾驶员和周边行人的身心健康。本项目从城市超细颗粒物排放的源头出发，开展大量的交通拥堵观测与超细颗粒物监测，利用交通流理论量化交通拥堵的演化过程，归纳不同交通拥堵状态下超细颗粒物的时空分布特征和非线性特性，构建交通拥堵演化中超细颗粒物扩散的动力学模型，揭示交通从畅通到拥堵的演化过程中超细颗粒物的扩散规律，进而探讨交通拥堵的强度、范围和持续时间对超细颗粒物扩散的影响机理，并以减轻超细颗粒物排放和缓解交通拥堵程度为目标，对机动车行驶状态进行动态优化和控制，制定切实可行的方案。研究成果有助于揭示城市交通拥堵产生的超细颗粒物的分布特征和扩散规律，为治理城市雾霾问题提供科学的理论依据。

在交通拥堵中，走走停停的机动车持续不断地在交通瓶颈处排放出颗粒物, 远远超过了周围空气的自净能力和规定标准，严重危及驾驶员和周边行人的身心健康。本项目从交通排放的源头出发，展开大量的交通污染监测，取得的结论如下： .1）揭示了城市交通颗粒物排放的非线性变化特征：通过交通污染监测，收集交通拥堵中产生的超细颗粒物，揭示超细颗粒物的粒径分布特征，利用多重分形理论，揭示不同粒径超细颗粒物自身的长程相关特征，研究不同粒径超细颗粒物之间的长程互相关行为。.2）交通颗粒物排放对行人健康的风险评估：通过交叉口路边的定点实测，揭示了交叉口污染物浓度周期性的变化特征，探讨了交叉口污染物的扩散规律，利用移动监测，对比了在不同的出发时刻下，行人通过人行横道时空气污染暴露情况的变化特征，根据呼吸道颗粒沉积模型，对比了行人在路边等待和通过人行横道时空气污染暴露的健康风险。.3）交通限行政策对城市交通排放物的影响研究：进博会期间的交通限行措施，能够有效降低城市区域交通排放的一次气态污染物浓度值。除此之外进博会期间交通限行和其他减排措施的共同作用还可以缓解城市局地和区域的颗粒物污染水平；新冠疫情期间，上海由于严格的封锁措施，交通活动显著减少，导致交通污染监测站点空气质量大幅改善，尤其是NO2，PM2.5，PM10和SO2，而O3污染水平却出现了显著的增加。与不同封锁政策相比，空气质量在全封锁阶段(复工复产前)改善最为明显。.本项目以问题为导向、以数据为驱动，深入探讨了交通与污染的相关问题。研究成果有助于揭示交通拥堵与交通污染之间的关系，为治理城市雾霾问题提供科学的理论依据。