EXHALE: EXploiting new understanding of Heterogeneous production of reactive species from AIRPRO: Links to haze and human health Effects

呼气将根据ahh - china第一阶段AIRPRO现场活动的主要发现进行有针对性的研究，这些发现发现污染物化学比预期的更复杂，特别是在所谓的雾霾事件中，当颗粒物（PM）的负荷很高时。在夏季和冬季，包括雾霾事件期间，都观察到高浓度的羟基自由基（OH），这是出乎意料的。OH控制着大多数微量气体的大气寿命和臭氧、二次有机气溶胶（SOA）等二次污染物的形成，而北京地区的主要OH前体是HONO。然而，详细的模型无法完全解释HONO， OH和其他自由基，特别是在污染的雾霾事件期间。EXHALE将利用北京大学（PKU）的中国合作者在北京环境气溶胶过滤器上收集的颗粒物（PM），包括在雾霾事件期间，量化气溶胶表面的亚硝酸（HONO）和自由基的异质来源。过滤器样品将通过各种分析方法进行离线分析，以确定PM的组成，这是非常复杂的。过滤器样品将被送到利兹，从这些过滤器中提取的提取物将在实验室中用于产生气溶胶，并使用配备有非常灵敏的HONO， HO2或RO2自由基探测器的照明气溶胶流管装置来确定HONO和自由基的产生速率。生产速率将被确定为大气变量的函数，并被参数化，并作为框模型的输入，限制在AIRPRO活动期间进行的详细测量。盒子模型将使用详细的主化学机制，并将评估异质生产过程对臭氧产生的自由基水平和速率的影响，臭氧是一种对健康有害的二次污染物。新确定的臭氧生成速率也将用于大规模的区域模型，首先用于北京，然后用于中国其他大城市，以量化非均匀臭氧生成对臭氧和二次有机气溶胶区域事件的影响。我们将使用来自中国空气质量监测网络（bbb1000个地点）的公开数据，以及来自中国合作伙伴的额外数据，使用区域模拟来扩大这些来源的影响，并将结果转化为中国各地的数据。呼气由一个中英联盟组成，在大气科学的实验和建模方面具有互补的专业知识和能力。在利兹，有自由基和HONO的超灵敏测量和气溶胶吸收/产生反应物质的实验专业知识，以及使用方框，区域和全球模型在一系列尺度上对气相和气溶胶化学和物理过程进行建模的专业知识。北京大学在环境气溶胶采样和北京气溶胶成分的详细离线分析方面具有专业知识。该项目得益于与其他中国科学家在其他大城市研究城市空气污染的合作。在“呼气”项目即将结束时，我们将与北大的合作伙伴一起，在北京组织一个为期两天的利益相关者研讨会，讨论“呼气”项目的成果以及对空气污染及其控制的更广泛影响。我们将与上海交通大学的项目合作伙伴一起，于2020年在上海组织一所暑期学校，主要针对博士生和早期职业研究人员，由EXHALE的研究人员、我们的中国合作者和项目合作伙伴授课。

EXHALE will conduct targeted research following on from major findings during the APHH-China phase-1 AIRPRO field campaigns which found that pollutant chemistry is more complex than expected, particularly during the so-called haze events when loadings of particulate matter (PM) were high. Large concentrations of the hydroxyl radical (OH) were observed in both summer and winter, including during haze events, which was unexpected. OH controls the atmospheric lifetime of most trace gases and the formation of secondary pollutants such as ozone and secondary organic aerosols (SOA), and HONO was found to be the dominant OH precursor in Beijing. However, detailed models were unable to fully account for HONO, OH and other radicals, especially during the polluted haze events.EXHALE will quantify heterogeneous sources of nitrous acid (HONO) and radicals at aerosol surfaces using particulate matter (PM) collected on filters from Beijing ambient aerosol by our Chinese collaborators at Peking University (PKU), including during haze events. The filter samples will be analysed off-line by a variety of analytical methods to determine the composition of the PM, which is known to be highly complex. The filter samples will be sent to Leeds, and the extract from these filters will be used to generate aerosols in the laboratory, and the HONO and radical production rates determined using an illuminated aerosol flow-tube apparatus equipped with a very sensitive detector for HONO, HO2 or RO2 radicals. The production rates will be determined as a function of atmospheric variables and parameterised, and used as input into a box model, constrained to detailed measurements made during the AIRPRO campaigns. The box model will use the detailed Master Chemical Mechanism, and will evaluate the impact of the heterogeneous production processes on radical levels and rates of ozone production, a secondary pollutant harmful to health.The newly determined production rates will also be used in large-scale regional models, initially for Beijing but then for other Chinese mega-cities, to quantify the impact of heterogeneous production towards regional episodes of ozone and secondary organic aerosol. We will use publically available data from the Chinese air quality monitoring network (>1000 locations), and together with additional data from our Chinese partners, will use regional simulations to scale up implications of these sources, and translate the results across China.EXHALE consists of a UK-Chinese consortium with complementary expertise and capabilities in both experimental and modelling aspects of atmospheric science. At Leeds there is experimental expertise in the ultra-sensitive measurement of radicals and HONO and aerosol uptake/production of reactive species, and expertise in modelling of gas-phase and aerosol chemical and physical processes on a range of scales using box, regional and global models. At PKU there is expertise in sampling of ambient aerosol and detailed off-line analysis of the composition of Beijing aerosol. The project benefits from collaboration with other Chinese scientists working on urban air pollution in other mega-cities. Towards the end of the EXHALE project, and together with our collaborators at PKU, we will organise a 2-day stakeholder workshop in Beijing to discuss the results from EXHALE and the wider implications for air pollution and its control. In conjunction with our project partners at Shanghai Jiao Tong University we will organise a summer school in 2020 in Shanghai, primarily aimed at PhD students and early career researchers, and to be taught by the EXHALE investigators and our Chinese collaborators and project partners.