Multiphase Chemistry in Soil and its Impact on Reactive Nitrogen Recycling

Indiana University, Bloomington IN

Investigators

Abstract

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.