Quantifying Sources of Nitrogen Oxides in Remote Environments: From Biosphere-Atmosphere Exchange to Renoxification

TitleQuantifying Sources of Nitrogen Oxides in Remote Environments: From Biosphere-Atmosphere Exchange to Renoxification
Publication TypeThesis
Year of Publication2021
AuthorsShi Q
Academic DepartmentPhysical and Environmental Sciences
DegreeDoctor of Philosophy
Number of Pages191
Date Published07/2021
UniversityUniversity of Toronto
CityToronto, Ontario
Thesis TypeDissertation
ISBN Number9798522912420
Abstract

Nitrogen oxides (NOx = NO + NO2) are an important constituent to the global atmosphere due to their strong connection to ozone (O3) and hydroxyl radical (OH). Anthropogenic NOx emissions have been regulated worldwide, leading to a decreasing trend over the past 15 years in North America and Europe, which makes biogenic sources and recycling pathways more important, especially in remote regions that are less influenced by human activities.

A two-channel chemiluminescence instrument with high precision and time resolution was used to quantify NOx in the field and the laboratory. In the field, direct measurements of biosphere-atmosphere exchange of NOx were made above a temperate broadleaf forest using the eddy covariance flux method. Near-zero NOx fluxes suggest that the soil NO emissions barely escape the canopy, and an air mass back trajectory analysis indicates that the morning NOx maximum is mainly associated with long-range transport of pollution. Flux divergence observed at this site is a consequence of fast chemical processes and different light intensity above and below the canopy.

URLhttps://proxy.lib.umich.edu/login?url=https://www.proquest.com/dissertations-theses/quantifying-sources-nitrogen-oxides-remote/docview/2561507372/se-2?accountid=14667