RUI: Collaborative: Cycling of ethanol and acetaldehyde in coastal waters

将乙醇添加到汽油中可以提高辛烷值，降低大气中一氧化碳和表面臭氧的浓度。作为一种可再生燃料，乙醇也可能有助于减少我们对汽油的依赖。在美国和全球范围内，乙醇作为化石燃料的替代品和添加剂的使用增加，预计会增加大气中的乙醇含量。大气中的乙醇转化为乙醛，这是一种有害的污染物。要了解乙醇使用量增加的影响，重要的是要了解乙醇和乙醛在环境中的循环——它们是如何产生、消耗和相互转化的。因为这些化合物可以从空气进入水中，这就需要了解这些化合物在大气、海水和其他地表水中发生了什么。该提案的重点是提高我们对沿海海水和其他沿海地表水（如河口和盐沼）中乙醇和乙醛的生产和消耗过程的理解。该项目将测量乙醇和乙醛光化学生产的速率，以及它们的化学和生物降解速率。该项目还将测量这些水域微生物从乙醇中生物生产乙醛的速度和效率。科学家们在让本科生（包括代表性不足的少数族裔）参与他们的研究和作为出版物的共同作者方面有着良好的记录，他们计划在这个项目中继续这种趋势。这些学生将接受分析化学和环境研究方面的训练，并将在地方和国家会议上介绍他们的研究成果。最后，pi还计划与高中STEM项目开展外展活动，以提高学生在环境研究方面的多样性。对流层中乙醇的主要吸收是与OH反应生成乙醛。预计对流层中的乙醛水平也会随着乙醇使用的增加而增加。这些物种在大气中浓度的变化预计会对对流层的氧化能力产生重大影响。为了了解未来的影响，重要的是要了解当前对流层预算，这对两个物种都有很大的不确定性。不确定性的最大来源之一是海洋和地表水在这些物种进出对流层的循环中的作用。目前的认识受到空气和水中环境浓度测量数据库非常小以及对控制海水和地表水浓度的过程的不完全了解的限制；这些过程代表了生物和光化学源和汇以及空气-水交换之间复杂的相互作用。为了提高目前对沿海海水和地表水中乙醇和乙醛循环的认识，本项目将测量：1)沿海水域中乙醇和乙醛的化学和生物降解率；2)微生物从乙醇生物生产乙醛的速率和效率；3)空气和地表水中的乙醇和乙醛浓度；4)河口和盐沼沉积物的乙醇和乙醛源强度；5)地表水中乙醇和乙醛的光化学生成速率。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Ethanol is added to gasoline to increase octane levels and lower the concentrations of carbon monoxide and surface ozone in the atmosphere. As a renewable fuel, ethanol may also help decrease our dependence on gasoline. Increased use of ethanol in the United States and globally as a fossil fuel substitute and additive is expected to increase ethanol levels in the atmosphere. Atmospheric ethanol is converted to acetaldehyde which is a hazardous pollutant. To understand the impact of increasing ethanol usage, it is important to understand the cycling of ethanol and acetaldehyde in the environment--how they are produced, consumed, and interconverted. Because these compounds can cross from air into water, this requires understanding what happens to these compounds in both the atmosphere and in seawater and other surface waters. This proposal focuses on improving our understanding of processes that produce and consume ethanol and acetaldehyde in coastal seawater and other coastal surface waters like estuaries and salt marshes. This project will measure the rates of photochemical production of ethanol and acetaldehyde, as well as their chemical and biological degradation rates. The project will also measure the rate and efficiency of the biological production of acetaldehyde from ethanol by microbial organisms in these waters. The scientists have an excellent track record of involving undergraduate students, including underrepresented minorities, in their research and as co-authors on publications, a trend they plan to continue with this project. These students would be trained in analytical chemistry and environmental research and would present their research findings at local and national conferences. Lastly, the PIs also plan outreach activities with high school STEM programs to improve student diversity in environmental research.The primary sink for ethanol in the troposphere is reaction with OH to produce acetaldehyde. Acetaldehyde levels in the troposphere are also expected to increase with increased use of ethanol. Changes in the atmospheric concentrations of these species are expected to have a significant impact on the oxidative capacity of the troposphere. To understand future impacts, it is important to understand current tropospheric budgets which have significant uncertainties for both species. One of the largest sources of uncertainty is the role of the oceans and surface waters in cycling these species into and out of the troposphere. The current understanding is limited by the very small database of ambient concentration measurements in both air and water and an incomplete insight into the processes that control concentrations in seawater and surface waters; these processes represent a complex interplay between biological and photochemical sources and sinks, and air-water exchange. To improve the current understanding of the cycling of ethanol and acetaldehyde in coastal seawater and surface waters, this project will measure: 1) chemical and biological degradation rates of ethanol and acetaldehyde in coastal waters; 2) the rate and efficiency of the biological production of acetaldehyde from ethanol by microbial organisms; 3) ethanol and acetaldehyde concentrations in air and surface waters; 4) the ethanol and acetaldehyde source strength of estuary and saltmarsh sediments; and 5) ethanol and acetaldehyde photochemical production rates in surface waters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.