Dry deposition processes of volatile organic compounds (VOCDep)

大量不同的挥发性有机化合物（VOCs）从植被和人类活动（如化石燃料燃烧和消费者护理产品的使用）释放到大气中。挥发性有机化合物与氮氧化物是形成对流层地面臭氧污染的两个关键成分之一，对人类健康、生物多样性下降和作物损失造成影响。同样，通过大气中的一系列化学反应，许多挥发性有机化合物最终形成颗粒物（PM）的有机部分，对全球人类健康产生重大影响。在预测空气质量及其影响和气候变化的模型中需要VOC排放。这些模型用于评估减少排放以保障人类健康和环境的措施。为了使这些模型预测可靠，模型需要准确地代表VOC排放、化学转化，以及对植被的沉积。虽然在前两个方面已经付出了相当大的努力，但人们对各种VOC化合物的沉积知之甚少，沉积速率通常是根据其他（无机）化合物的行为来估计的，没有通过实际测量来验证。该项目将利用最近改进的挥发性有机化合物测量技术，首次全面研究控制各种不同的环境问题挥发性有机化合物沉积的速度和过程。这将通过三种不同的互补实验方法来实现：(a)在实验室使用气体交换室研究挥发性有机化合物对植被的吸收，(b)研究挥发性有机化合物对天然和人工液态水膜的吸收，以及(c)两次测量挥发性有机化合物与植被的交换，重点是城市公园和森林。这些测量结果和项目合作伙伴提供的现有数据集将用于推导沉积过程的改进模型描述，以便纳入数值模型。然后，我们将使用两个大气化学和输送模型，一个是可以在高空间分辨率下运行并用于支持欧洲和英国政策的更简单的模型，另一个是对异戊二烯的化学性质进行更详细描述的模型，该化合物在全球范围内主导植物排放，以评估新的沉积速率对模型性能的影响，重点是臭氧形成、PM形成和异戊二烯在PM形成中的特殊作用。

A large range of different volatile organic chemical compounds (VOCs) are released to the atmosphere from vegetation and human activities such as fossil fuel burning and the use of consumer care products. Together with nitrogen oxides, VOCs are one of the two key ingredients for the formation of tropospheric ground-level ozone pollution, causing impacts on human health, biodiversity decline and crop losses. Similarly, through a series of chemical reactions in the atmosphere, many VOCs end up forming the organic fraction of particulate matter (PM) with major impacts on human health around the globe. VOC emissions are needed in models to predict air quality and its impacts and climate change. These models are used to assess measures to reduce emissions to safeguard the health of humans and the environment. For these model predictions to be reliable, the models need to accurately represent VOC emissions, chemical transformation, but also the deposition to vegetation. Whilst considerable effort has gone into the first two aspects, very little is known about the deposition of the various VOC compounds, with deposition rates usually estimated from the behaviour of other (inorganic) compounds with no validation through actual measurements.This project will make use of recent improvements in VOC measurement technology to perform the first comprehensive study of the rate and processes that control the deposition of a wide range of different VOC compounds of environmental concern. This will be achieved through three different, complementary experimental approaches: (a) the study of VOC uptake to vegetation in the laboratory using gas exchange chambers, (b) the study of VOC uptake to natural and artificial liquid water films and (c) two measurement campaigns of VOC exchange with vegetation, focussing on urban parkland and forest. The results from these measurements and existing datasets from project partners will be used to derive improved model descriptions of the deposition process for incorporation into the numerical models. We will then use two atmospheric chemistry and transport models, a simpler model that can be operated at high spatial resolution and is used to support European and UK policy, and a model with a more detailed description of the chemistry of isoprene, the compound that dominates plant emissions globally to assess the impacts of the new deposition rates on model performance with emphasis on ozone formation, PM formation and the particular role of isoprene in PM formation.