RUI: Impact of Changing Fuel Usage on the Atmospheric Cycling of Ethanol, Optically Active Organic Compounds and Iron (Fe) in Rainwater

RUI：改变燃料使用对雨水中乙醇、光学活性有机化合物和铁 (Fe) 的大气循环的影响

• 批准号: 1003078
• 负责人: Robert Kieber
• 金额: $ 62.24万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1003078&HistoricalAwards=false
• 关键词: RUI; Impact; Changing; Fuel; Usage

The overarching goal of the research is to delineate potential impacts of current and future fossil fuel usage and emission changes on the chemistry of the troposphere. The first objective explores the link between increased ethanol production and use to possible increased levels of ethanol and volatile organic carbon compounds in precipitation. The first detailed seasonal and temporal profile of ethanol concentrations in rainwater will be developed with an emphasis on the influence of air mass origin on concentrations. Rainwater will be collected in Wilmington, NC and in São Paolo, Brazil where ethanol makes up 40% of vehicle fuel. This comparison will provide a unique and novel opportunity to examine how shifting ethanol usage in North America could ultimately impact the chemistry of the troposphere. The second objective examines how fossil fuel emissions from various combustion sources including 85% ethanol vehicle fuel (E85), gasoline and diesel fuels as well as coal and fuel oil combustion impact the abundance of light absorbing or chromophoric dissolved organic material (CDOM) in rainwater. Specific questions to be addressed involve determining the chemical composition of CDOM produced from various fuel sources initially and as a function of irradiation time in comparison to changes observed in analogous rainwater samples. The final objective of the research explores the relationship between fossil fuel emissions and the speciation of iron in atmospheric waters. Preliminary evidence suggests the chromophoric material in rainwater contains ligand(s) of fossil fuel origin that stabilize Fe(II) allowing significant concentrations to occur in precipitation even in the presence of micromolar concentrations of the oxidant hydrogen peroxide. Recent data suggest that the abundance of these ligands is changing over time in rainwater although it is unclear why. This phase of the research will determine if DOM obtained from various fuel sources is capable of binding Fe(II) and Fe(III) and whether the abundance of these ligands is changing.Exploring the importance of shifting fuel usage on the composition of the troposphere is central to the understanding of a host of current as well as future atmospheric processes as the quantity and quality of fuel used in energy production changes. Results of this research will have important implications for global climate change because chromophoric material directly influences the spectral attenuation of sunlight reaching the earth's surface. An additional consequence of the production of chromophoric material in rainwater from combustion sources is the potential impact on the oxidizing capacity of the troposphere by generating significant quantities of aqueous phase hydrogen peroxide. Addressing the redox chemistry of iron is important because any change in iron speciation affects the lifetime and bioavailability of iron as a nutrient, which in turn will alter the rate of marine primary productivity. Marine primary productivity is known to play a significant role in removal of carbon dioxide from the atmosphere and hence impacts the magnitude of global warming. The project will support a post-doctoral researcher, two master's level graduate students, three undergraduates and one high school student per year. Young students are attracted to this type of study because they perform high profile environmental research of international interest. This ultimately motivates them to continue their education and choose a career in science which enhances the recruiting and retaining of young students in critical STEM fields.

研究的总体目标是描述当前和未来化石燃料使用和排放变化对对流层化学的潜在影响。 第一个目标探讨了乙醇生产和使用的增加与降水中乙醇和挥发性有机碳化合物水平可能增加之间的联系。 将编制雨水中乙醇浓度的第一份详细的季节和时间分布图，重点是气团来源对浓度的影响。 雨水将在北卡罗来纳州威尔明顿和巴西圣保罗收集，那里乙醇占汽车燃料的40%。 这种比较将提供一个独特而新颖的机会，以研究北美乙醇使用的变化如何最终影响对流层的化学。第二个目标是研究各种燃烧源的化石燃料排放，包括85%乙醇汽车燃料（E85），汽油和柴油燃料以及煤和燃油燃烧如何影响雨水中光吸收或发色溶解有机物（CDOM）的丰度。 要解决的具体问题涉及确定CDOM的化学成分产生的各种燃料源最初和作为一个功能的照射时间相比，在类似的雨水样品中观察到的变化。 研究的最终目的是探索化石燃料排放与大气沃茨中铁的形态之间的关系。 初步证据表明，雨水中的发色物质含有化石燃料来源的配体，其稳定Fe（II），即使在微摩尔浓度的氧化剂过氧化氢存在下，也允许在沉淀中发生显著浓度。 最近的数据表明，这些配体的丰度随着时间的推移在雨水中发生变化，尽管原因尚不清楚。 这一阶段的研究将确定从各种燃料来源获得的DOM是否能够结合Fe（II）和Fe（III），以及这些配体的丰度是否正在改变。探索燃料使用量对对流层组成的重要性，对于理解当前和未来的大气过程是至关重要的，因为能源生产中使用的燃料的数量和质量会发生变化。 这项研究的结果将对全球气候变化产生重要影响，因为发色物质直接影响到达地球表面的太阳光的光谱衰减。燃烧源在雨水中产生发色物质的另一个后果是通过产生大量的水相过氧化氢而对对流层的氧化能力产生潜在影响。 解决铁的氧化还原化学问题很重要，因为铁形态的任何变化都会影响铁作为营养物质的寿命和生物利用率，这反过来又会改变海洋初级生产力的速度。 众所周知，海洋初级生产力在清除大气中的二氧化碳方面发挥着重要作用，因此影响到全球变暖的程度。 该项目每年将资助一名博士后研究员、两名硕士研究生、三名本科生和一名高中生。 年轻学生被吸引到这种类型的研究，因为他们进行国际感兴趣的高调环境研究。 这最终激励他们继续接受教育，并选择科学职业，从而增强了关键STEM领域年轻学生的招聘和保留。