Understanding the changing sources of volatile organic compounds in the UK over the last two decades and implications for the future

挥发性有机化合物(VOCs)从各种来源排放到大气中，可以是人为的(人造的)或生物的(自然产生的)。碳氢化合物的主要来源在全球和区域范围内差异很大，这取决于周围环境中的人口、植被和工业。震源强度的这种变化往往会导致不同物种的重要性相应的变化。一旦排放到大气中，VOC浓度会受到多种因素的影响，包括气象、干湿沉积和化学反应。挥发性有机化合物的大气化学主要由羟基自由基主导，羟基自由基导致它们在从几个小时到几个月的一系列时间尺度上氧化，具体取决于它们的结构。最终，它们的氧化会导致二氧化碳(CO2)的形成，这是一种重要的气候气体。然而，它们对大气的最大意义是它们在氧化过程中产生的二次污染物，这些污染物往往危害更大，包括臭氧、甲醛和其他高含氧化合物，它们都被认为是导致人类呼吸系统疾病的关键因素，并通过损害植物气孔和叶片限制作物产量。不同的VOCs在大气中产生这些重要二次污染物的效率取决于它们的结构，因此，对大气中单个(形态)VOCs的观测至关重要，因为对VOC总浓度的整体测量几乎不能告诉我们它们的潜在危害。该项目旨在：1.向英国提供三个城市站点的VOCs的连续质量控制测量，以便更好地了解它们在英国大气中的作用。在不同城市之间进行比较，以确定不同局部化来源和气象对其周围浓度的重要性。提供近乎实时的自动化观测，以获得有关这些地点当地空气质量的重要信息。将产生的数据放在英国空气质量现场收集的历史数据和英国实地项目期间设备的短期部署的背景下，以调查过去30年来个别污染源对环境VOCs的变化组成和贡献。将当前和历史上对VOCs的观察结果与国家大气排放清单的输出进行比较，以评估其在预测英国环境中VOCs水平方面的有效性。学生将发展在大气观察的质量评估和评估方面的可移植技能。他们将应用数据分析工具，利用各种统计技术对大气气体的长期趋势进行测量、比较和分析。他们还将获得理解和知识，使他们能够把他们的意见放在历史、区域和全球组成的更广泛的背景下。

Volatile Organic Compounds (VOCs) are emitted into the atmosphere from a wide variety of sources and can be anthropogenic (man-made) or biogenic (naturally produced) in origin. Dominant sources of hydrocarbons vary greatly on global and regional scales, depending upon the population, vegetation and industry within the surrounding environment. This variation in source strength often leads to a corresponding variation in the significance of different species. Once emitted into the atmosphere, VOC concentrations are influenced by a number of factors including meteorology, dry and wet deposition and chemical reactions. The atmospheric chemistry of VOCs is dominated by the hydroxyl radical which leads to their oxidation at a range of timescales, from hours to months, dependent upon their structure. Ultimately their oxidation leads to the formation of carbon dioxide (CO2), an important climate gas. Their greatest significance to the atmosphere, however, is the secondary pollutants produced during their oxidation which tend to be more harmful, including ozone, formaldehyde and other highly oxygenated compounds which are all implicated as key contributors to respiratory illnesses in people as well as limiting crop yields through damage to plant stomata and leaves. The efficiency with which different VOCs can produce these important secondary pollutants in the atmosphere is dependent upon their structure so it is, therefore, vitally important to make observations of individual (speciated) VOCs in the atmosphere as a bulk measurement of the total VOC concentration tells us very little about their potential for harm.This project aims to:1. Provide the UK with continuous quality controlled measurements of VOCs at three urban sites in order to better understand their role in the UK atmosphere. Compare between different cities to identify the significance of different localised sources and meteorology to their ambient concentrations. Provide near real-time, automated observations to yield important information regarding local air quality at these locations.2. Place the data produced in the context of historic data collected at UK air quality sites and short-term deployments of equipment during field projects in the UK to investigate the changing composition and the contributions of individual sources to the ambient VOCs over the last thirty years.3. Compare current and historic observations of VOCs to the National Atmospheric Emissions Inventory outputs to evaluate its effectiveness in predicting ambient levels of VOCs in the UK.The student will develop transferable skills in quality assessment and evaluation of atmospheric observations. They will apply data analysis tools for measurement comparison and analysis of long term trends of atmospheric gases using a variety of statistical techniques. They will also gain understanding and knowledge to enable them to place their observations in the wider context of historical, regional and global composition.