Source variability of WSOC in atmospheric precipitation

大气降水中 WSOC 的来源变异性

• 批准号: NE/H010327/1
• 负责人: Robert Upstill-Goddard
• 金额: $ 5.75万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH010327%2F1
• 关键词: Source; variability; WSOC; atmospheric; precipitation

A wide range of organic (carbon containing) compounds produced both naturally by biological and chemical processes but also by mans activities (fires, vehicle and industrial emissions etc.) readily dissolve in water. Together these compounds are termed 'water soluble organic carbon', or WSOC for short. In some senses WSOC can be considered as a somewhat vague and all-encompassing term because it is a complex mixture of organic molecules which vary in their contributions to the total and are extremely difficult to isolate and analyse individually. Nevertheless, as a so-called 'bulk' component, WSOC is an important constituent of atmospheric water and is reactive. Its constituent molecules undergo sunlight-induced (photochemical) reactions that result in a range of reactive products which influence atmospheric chemical processes, influencing the climate on both local and global scales. WSOC can be an important source of cloud condensation nuclei (CCN) which are required for cloud formation, it contributes to rainwater acidity, and it can be a nutrient source to lakes, rivers and the ocean. Recent trends of increasing rainfall in the UK and worldwide mean that the need for detailed study of WSOC will become ever more important. In order to predict its impact on the environment, its various individual sources need to be better identified and characterised in terms of their composition and variabilty in time and space. Detailed chemical analysis of WSOC is costly, not readily accesible and in any case does not provide a high level of identification; rather only 'average compositions'. Recently a large fraction of WSOC was found to be fluorescent, which means that it emits electromagnetic radiation, especially visible light, if stimulated by the absorption of incident radiation from some source. The wavelength spectrum emitted can be analysed and used as a 'fingerprint' to characterise WSOC (and other forms of dissolved organic matter) of different 'types' (so-called 'flourophores') that enable a means to deduce information about different WSOC sources contributing to a sample and provide a measure of their relative importance (from their fluorescence intensities). The advantages of fluorescence are its relative simplicity and low cost. The idea of this work is to collect rainwater samples from specific rainfall 'events' and analyse these by fluorecence to identify the fluorophores present and their intensities. Using these measurements along with meteorological data from an adjacent meteorological mast and software that uses these data to predict areas from which air masses have originated, it will be possible to determine the regions in which the various source 'types' identified originated. This will be an important first step towards a better understanding of the origin and subsequent fate of WSOC in the environment. The results from this short-duration study will be used to help formulate a more detailed programme of WSOC research in the near future.

生物和化学过程自然产生的有机（含碳）化合物以及人类活动（火灾、车辆和工业排放等）产生的各种有机（含碳）化合物很容易溶解在水中。这些化合物统称为“水溶性有机碳”，简称 WSOC。从某种意义上说，WSOC 可以被认为是一个有些模糊且包罗万象的术语，因为它是有机分子的复杂混合物，其对总体的贡献各不相同，并且极难单独分离和分析。然而，作为所谓的“主体”成分，WSOC 是大气水的重要组成部分并且具有反应性。其组成分子经历阳光引起的（光化学）反应，产生一系列影响大气化学过程的反应产物，从而影响局部和全球范围内的气候。 WSOC 是云形成所需的云凝结核 (CCN) 的重要来源，它有助于提高雨水酸度，并且可以成为湖泊、河流和海洋的营养源。最近英国和全球降雨量增加的趋势意味着对 WSOC 进行详细研究的必要性将变得更加重要。为了预测其对环境的影响，需要更好地识别其各种单独来源，并根据其组成以及时间和空间的变化来表征。 WSOC 的详细化学分析成本高昂，不易获得，而且在任何情况下都不能提供高水平的识别；而只是“平均成分”。最近发现 WSOC 的很大一部分具有荧光性，这意味着如果受到某些来源的入射辐射吸收的刺激，它会发射电磁辐射，尤其是可见光。可以分析发射的波长光谱并将其用作“指纹”来表征不同“类型”（所谓的“荧光团”）的 WSOC（以及其他形式的溶解有机物），从而能够推断出有关不同 WSOC 源的信息对样品有贡献并提供其相对重要性的衡量标准（根据其荧光强度）。荧光的优点是相对简单且成本低廉。这项工作的想法是从特定的降雨“事件”中收集雨水样本，并通过荧光对其进行分析，以确定存在的荧光团及其强度。使用这些测量值以及来自邻近气象塔的气象数据以及使用这些数据来预测气团起源区域的软件，将有可能确定所识别的各种源“类型”的起源区域。这将是更好地了解 WSOC 在环境中的起源和后续命运的重要第一步。这项短期研究的结果将用于帮助在不久的将来制定更详细的 WSOC 研究计划。