Novel approaches for quantifying the highly uncertain thermodynamics and kinetics of atmospheric gas-to-particle conversion

量化大气气体到颗粒转化的高度不确定的热力学和动力学的新方法

• 批准号: NE/J02175X/1
• 负责人: David Topping
• 金额: $ 54.46万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ02175X%2F1
• 关键词: Novel; approaches; quantifying; highly; uncertain

Atmospheric aerosol particles, which can be both anthropogenic and biogenic in origin, remain a major uncertainty in the Earth system: they impact the climate by directly scattering and absorbing solar radiation (the direct effect), as well as regulating the properties of clouds (the indirect effect). On regional scales, aerosol particles are among the main pollutants deteriorating air quality, their impacts on both poorly quantified. Reducing these critical uncertainties requires accurate knowledge on the chemical composition of these particles, their concentrations and size as they are suspended in the atmosphere. Unfortunately, there are currently huge uncertainties in many fundamental parameters that are required to predict these evolving chemical and physical characteristics of aerosols. This inhibits us from ultimately understanding their true environmental impacts. A significant fraction of atmospheric aerosol particles are comprised of organic material (20-90% of particle mass). Unfortunately, this fraction could comprise thousands of, largely unidentified, compounds with a wide range of chemical properties. This, in essence, creates the uncertainties listed above. The specifics of these uncertainties are now discussed.As aerosol particles reside in the atmosphere, condensation of low volatility organic compounds changes the amount and composition of condensed phase organic material, thus their climatic and health impacts. This condensation is highly dynamic and, presently, there are 3 fundamental restrictions in reconciling this behaviour from a single particle to wider scales:1) It is common to regard aerosol particles as a simple liquid comprised of multiple components. However, it is becoming increasingly evident that atmospheric particles exist as viscous amorphous states, rather than simple liquid/solid mixtures. Partitioning between the gas and condensed phase is then kinetically limited in such amorphous states. Traditional aerosol models do not account for this. This adds significant uncertainty to predictions of gas/particle mass transfer as mixing timescales are ultimately governed by the diffusion coefficients of the aerosol constituents in the aerosol, which, on the other hand, are connected to the viscosity of the particulate matter. For typical aerosol sizes, the characteristic time for mixing could increase from a few milliseconds to hours or even days! 2) In addition to diffusivity and viscosity, the equilibrium vapour pressure of each aerosol constituent is largely determined by its pure component saturation vapour pressure, which depends on the molecular properties of the compound. Saturation vapour pressures of organic components are currently poorly known, particularly for the least volatile compounds. The uncertainty in this parameter is already known to introduce 4 orders of magnitude of uncertainty in predicted aerosol mass!3) Finally, to assess the atmospheric importance of these phenomena, modelling approaches that treat the organic condensation/evaporation as a dynamic process and couple the gas phase transport to the condensed phase diffusion are urgently needed, although these remain almost non-existent. Presently, there is a fundamental lack of data and modelling tools to resolve the importance of these topical issues. Whilst predictive techniques for viscosity, diffusivity and vapour pressure exist, they are developed for chemical engineering purposes and remain unevaluated for atmospheric science. In this proposal we aim to make new and novel measurements of the properties listed here aswell as evaluating/improving existing models. Developing a new kinetic model we will assess the sensitivity to these properties at the single particle level and compare with actual measurements of single particle growth using optical tweezer experiments. We will also develop simple parameterised schemes so that large scale models can assess the wider sensitivity to the climate.

大气气溶胶粒子既可以是人为的，也可以是生物的，它仍然是地球系统中的一个主要不确定性：它们通过直接散射和吸收太阳辐射(直接影响)以及调节云的性质(间接影响)来影响气候。在区域尺度上，气溶胶颗粒是恶化空气质量的主要污染物之一，它们对这两种污染物的影响很难量化。要减少这些关键的不确定性，需要准确了解这些悬浮在大气中的颗粒物的化学成分、浓度和大小。不幸的是，目前在许多基本参数中存在着巨大的不确定性，这些参数是预测这些气溶胶不断演变的化学和物理特征所必需的。这阻碍了我们最终了解它们对环境的真正影响。很大一部分大气气溶胶颗粒由有机物质组成(占颗粒物质量的20%-90%)。不幸的是，这一组分可能包含数千种具有广泛化学性质的化合物，其中大部分是未知化合物。从本质上讲，这造成了上面列出的不确定性。现在讨论这些不确定性的细节。由于大气中存在气溶胶颗粒，低挥发性有机化合物的冷凝改变了凝聚相有机物质的数量和组成，从而影响了气候和健康。这种凝聚是高度动态的，目前，在将这种行为从单个粒子协调到更广泛的尺度上有三个基本限制：1)通常将气溶胶粒子视为由多个组分组成的简单液体。然而，越来越明显的是，大气颗粒以粘性无定形状态存在，而不是简单的液体/固体混合物。在这种无定形状态下，气体和凝聚相之间的分配受到动力学限制。传统的气溶胶模型没有考虑到这一点。这给气体/颗粒传质的预测增加了很大的不确定性，因为混合时间尺度最终由气溶胶中气溶胶成分的扩散系数决定，而气溶胶成分的扩散系数与颗粒物质的粘度有关。对于典型的气溶胶尺寸，混合的特征时间可能从几毫秒增加到几小时甚至几天！2)除了扩散系数和粘度之外，每个气溶胶组分的平衡蒸汽压在很大程度上取决于其纯组分饱和蒸汽压，这取决于化合物的分子性质。有机成分的饱和蒸汽压目前知之甚少，尤其是挥发性最低的化合物。已知该参数的不确定性将在预测的气溶胶质量中引入4个数量级的不确定性！3)最后，为了评估这些现象在大气中的重要性，迫切需要将有机冷凝/蒸发作为一个动态过程并将气相传输耦合到凝聚相扩散的模拟方法，尽管这些方法仍然几乎不存在。目前，根本缺乏数据和建模工具来解决这些热点问题的重要性。虽然存在粘度、扩散系数和蒸汽压的预测技术，但它们是为化学工程目的而开发的，仍未对大气科学进行评估。在这项建议中，我们的目标是对这里列出的属性进行新的和新的测量，以及评估/改进现有的模型。开发一个新的动力学模型，我们将在单个粒子水平上评估这些性质的敏感性，并与使用光镊仪实验测量的单个粒子生长的实际测量结果进行比较。我们还将开发简单的参数化方案，以便大型模型可以评估对气候的更广泛敏感性。

项目成果

Measured Saturation Vapor Pressures of Phenolic and Nitro-aromatic Compounds.

• DOI: 10.1021/acs.est.6b06364
• 发表时间: 2017-03
• 期刊: Environmental science & technology
• 影响因子: 11.4
• 作者: T. Bannan;A. M. Booth;Benjamin T. Jones;S. O'Meara;M. Barley;I. Riipinen;Carl J. Percival;D. Topping

Evaluating the mutagenic potential of aerosol organic compounds using informatics based screening

使用基于信息学的筛选评估气溶胶有机化合物的致突变潜力

• DOI: 10.5194/acp-2017-574
• 发表时间: 2017
• 作者: Decesari S

Evaluating the mutagenic potential of aerosol organic compounds using informatics-based screening

使用基于信息学的筛选评估气溶胶有机化合物的致突变潜力

• DOI: 10.5194/acp-18-2329-2018
• 发表时间: 2018
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: Decesari S

Size-resolved simulations of the aerosol inorganic composition with the new hybrid dissolution solver HyDiS-1.0: description, evaluation and first global modelling results

• DOI: 10.5194/gmd-9-3875-2016
• 发表时间: 2016-11-01
• 期刊: GEOSCIENTIFIC MODEL DEVELOPMENT
• 影响因子: 5.1
• 作者: Benduhn, Francois;Mann, Graham W.;Carslaw, Kenneth S.
• 通讯作者: Carslaw, Kenneth S.

Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate.

• DOI: 10.1002/2017gl073056
• 发表时间: 2017-05-28
• 期刊: Geophysical research letters
• 影响因子: 5.2
• 作者: Rastak N;Pajunoja A;Acosta Navarro JC;Ma J;Song M;Partridge DG;Kirkevåg A;Leong Y;Hu WW;Taylor NF;Lambe A;Cerully K;Bougiatioti A;Liu P;Krejci R;Petäjä T;Percival C;Davidovits P;Worsnop DR;Ekman AML;Nenes A;Martin S;Jimenez JL;Collins DR;Topping DO;Bertram AK;Zuend A;Virtanen A;Riipinen I
• 通讯作者: Riipinen I