Multiphase Chemistry in Soil and its Impact on Reactive Nitrogen Recycling

在这个由美国国家科学基金会化学部环境化学科学项目资助的项目中，印第安纳大学的乔纳森·拉夫教授正在研究活性氮氧化物（NOy）气体如何与土壤表面相互作用。NOy在燃料燃烧过程中产生，是自由基的重要前体，自由基既控制污染物的寿命，又产生有害的副产物（如臭氧和颗粒物）。尽管土壤是一种具有高反应性和高表面积的基质，但通过吸附土壤表面去除NOy的过程在很大程度上仍未被探索。土壤包括地球表面的大片区域。其他活动包括为研究生（包括那些在科学领域代表性不足的群体）提供在环境化学科学领域进行前沿和相关研究的机会。拉夫博士正在开发一个推广项目，为当地的中学生和他们的老师提供便携式污染物监测仪，用于实地考察和课堂实验。这项研究的目的是研究NOy吸附在土壤上的速度有多快，以及将氮“再循环”回大气的化学过程。利用土壤化学、物理化学和生物化学技术，研究了几种NOy在不同土壤相关基质上的多相化学。这些活动的结果最终有助于更好地了解土壤中活性氮的命运和保护人类健康免受恶劣空气质量的影响。随着地面臭氧空气质量标准的日益严格，受土壤排放和地表NOy多相化学作用影响的NOy本底水平变得越来越重要。动力学研究使建模者能够在化学运移模型中更准确地参数化土壤NOy排放。这种模拟被用来预测污染物的形成和运动，并为污染控制政策提供信息。

In this project, funded by the Environmental Chemical Sciences Program in the Division of Chemistry at the National Science Foundation, Professor Jonathan Raff of Indiana University is investigating how reactive nitrogen oxide (NOy) gases interact with soil surfaces. NOy is generated during fuel combustion and is an important precursor to the radicals that both control the lifetime of pollutants and generate harmful byproducts (e.g., ozone and particulate matter). Removal of NOy through adsorption to soil surfaces is a process that remains largely unexplored despite the fact that soil is a substrate with high reactivity and high surface area. Soil comprises vast areas of the Earth's surface. Additional activities include providing graduate students (including those from groups that are underrepresented in the science) with opportunities to perform cutting-edge and pertinent research in the environmental chemical sciences. Dr. Raff is developing an outreach program that provides local middle and high school students and their teachers with access to portable pollutant monitors for field trips and in-class experiments.The goal of the research is to study how fast NOy adsorbs onto soil and the chemical processes that "recycle" nitrogen species back into the atmosphere. The multiphase chemistry of several NOy species on a variety of soil-related substrates are studied under environmentally relevant conditions using soil chemistry, physical chemistry, and biochemistry techniques. Results from the activities ultimately contribute to an improved understanding of the fate of reactive nitrogen in soil and the protection of human health against poor air quality. As air quality standards for ground-level ozone become more strict, background levels of NOy that are influenced by soil emissions and multiphase chemistry of NOy on ground surfaces become more important. The kinetics studies allow modelers to more accurately parameterize soil NOy emissions in the chemical transport models. Such simulations are used to predict the formation and movement of pollutants and inform pollution control policy.