Isoprene oxidation and OH recycling

异戊二烯氧化和OH回收

• 批准号: NE/J009210/1
• 负责人: Carl Percival
• 金额: $ 27.82万
• 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: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ009210%2F1
• 关键词: Isoprene; oxidation; OH; recycling

The surface temperature of the Earth varies dramatically from polar regions through to equatorial ones. There are many factors that give rise to this temperature variation but the main ones are; the amount of heat energy arriving at the surface from the sun (which is smaller at the poles than the equator), the reflectivity of the Earth (called the albedo) which determines how much of the sun's energy is simply reflected back to space (and includes clouds and ice at the surface) which cool the surface and the amount of greenhouse gases in the atmosphere which act as a blanket around the Earth (preventing heat from the Earth from escaping to space) and warm the surface up. Plants play a vital role in the Earth system, converting carbon dioxide and water into sugars and oxygen (essential for life) during photosynthesis. They also absorb a range of pollutants on their surfaces and are planted in urban areas in part to reduce the levels of particulate matter. However, plants also release a cocktail of chemicals for a variety of reasons, e.g. attracting pollinators, defence against predators and protection against a variety of pollutants such as ozone. The hydroxyl radical (OH) is a species produced in the atmosphere that acts like a chemical detergent, mopping up pollutants and cleansing the atmosphere. It was believed that these chemicals released by plants suppressed the hydroxyl radical and therefore would increase the level of greenhouse gases. However, recent measurements of the level of OH in the tropics suggest that this idea is wrong and that these chemicals actually lead to OH recycling. If this is correct then plants and in particular those in tropical regions, will be playing a significant role in off-setting climate change. If the recycling of OH is correct then these plant emissions are leading to a reduction in the amount of greenhouse gases present in the atmosphere.In addition, it is believed that these emissions may also lead to aerosol species that will help to form cloud and further cool the planet. Therefore, this combination of effects could be extremely important to our understanding of the Earth's climate (past, present and future). It will also of course have important implications for forest ecosystems, the enhanced negative impact of deforestation in tropical regions and land-use strategies in general. A variety of scientists have speculated about how these chemicals may be leading to a recycling of OH, some based on laboratory experiments. However, the ones that appear to have the biggest potential impact and may resolve, at least in part, the discrepancy between measurements and computer simulations, are based on computer based calculations themselves. Therefore, it is vital that these theoretical studies be verified in the laboratory. These reactions are difficult to study and so we propose to add tags (swapping hydrogen for deuterium)to some of the chemicals we wish to study so that we can follow the reaction pathway more easily. We will use a range of detectors in concert with both a flow system and a static reaction chamber. Both systems will allow us to stufy different aspects of the chemical system. The detectors we will use include mass spectrometry (where we identify compounds by their weight) and spectroscopy (where we identify compounds by the amount of a specific colour of light that they absorb). These instruments have been developed at the two Universities involved (Bristol and Manchester) and allow them to be uniquely placed to be one of the few teams in the world able to carry out these studies.

地球的表面温度从极地区域到赤道差异很大。有许多因素引起了这种温度变化，但主要因素是；从太阳到达表面的热能量（在极点小于赤道），地球的反射率（称为反击），它决定了多少太阳的能量只是反射回空间（和在表面上包括云和冰），这些云和冰块冷却表面和大气中的温室气体量，这些温室气体充当地球周围的毯子（防止地球从地球逃脱到太空）并加热表面。植物在地球系统中起着至关重要的作用，将二氧化碳和水转化为糖和氧气（对生命必不可少的）。他们还在其表面上吸收一系列污染物，并在城市地区种植，部分原因是降低颗粒物水平。但是，由于多种原因，植物也释放了一种化学物质的鸡尾酒，例如吸引传粉媒介，对掠食者的防御和对臭氧等各种污染物的保护。羟基自由基（OH）是一种在大气中产生的物种，其作用像化学洗涤剂，擦拭污染物并清洁大气。人们认为，植物释放的这些化学物质抑制了羟基自由基，因此会增加温室气体的水平。但是，在热带地区的OH水平的最新测量表明，这一想法是错误的，这些化学物质实际上导致OH回收。如果这是正确的，那么植物，尤其是在热带地区的植物，将在偏离气候变化中发挥重要作用。如果OH的回收是正确的，那么这些植物的排放会导致大气中存在的温室气体量减少。此外，人们相信这些排放也可能导致气溶胶物种，这些气溶胶物种将有助于形成云，进一步形成云冷却星球。因此，这种影响的组合对于我们对地球气候（过去，现在和未来）的理解可能非常重要。当然，它将对森林生态系统产生重要意义，森林砍伐地区在热带地区的负面影响以及一般的土地利用策略。许多科学家猜测这些化学物质可能如何导致OH的回收，其中一些是基于实验室实验的。但是，似乎具有最大潜在影响的人，至少部分地解决了测量和计算机模拟之间的差异，是基于基于计算机的计算本身。因此，在实验室中验证这些理论研究至关重要。这些反应很难研究，因此我们建议在我们希望研究的某些化学物质中添加标签（将氢交换为氘），以便我们可以更轻松地遵循反应途径。我们将使用一系列探测器与流动系统和静态反应室一起使用。这两个系统都将使我们能够stufy化学系统的不同方面。我们将使用的检测器包括质谱法（我们通过其重量来识别化合物）和光谱法（在其中通过吸收的特定颜色的颜色识别化合物）。这些工具是在涉及的两所大学（布里斯托尔和曼彻斯特）开发的，并允许它们独特地成为世界上为数不多的能够进行这些研究的团队之一。