Research
Research Overview: Air/water pollution and climate change are global issues, requiring immediate attention and innovative cross-disciplinary research to understand and mitigate their effects on our planet. To this end, the Slade lab studies fundamental chemical and physical processes affecting the formation, evolution, toxicity, and climate properties of atmospheric aerosols. We are interested in applying and developing novel analytical methodologies (e.g., in mass spectrometry) to understand the detailed multiphase chemistry and kinetics of organic aerosol formation and interactions with gas-phase oxidants and reactive semivolatile species in different environments (urban, coastal, forested, and biomass burning). Our three main thrusts involving both laboratory and field work currently are (1) chemical aging and toxicity studies of emerging priority chemicals in marine aerosol, (2) reactive organic nitrogen multiphase chemistry of urban secondary organic aerosol, and (3) fundamental interrelationships between aerosol phase and composition.
Emerging Plastic Contaminants in Marine Aerosol: Chemical Aging and Toxicity Studies
Plastic contaminants are ubiquitous in marine aerosol particles, which provide a conduit for reintroduction to the terrestrial environment and additional pathway for human exposure. Evidence suggests that these plastic contaminants are widespread as a result of long-range aerosol transport, and found in such remote regions as the Arctic. In the atmosphere, aerosol particles are susceptible to chemical transformation through routes such as heterogeneous oxidation and photochemistry, which can degrade particle- phase compounds as well as modulate their toxicity via formation of reactive oxygen species (ROS). We will study the heterogeneous/multiphase oxidation of emerging plastic contaminants in marine aerosol (PCMA), by different atmospheric oxidants - O3, OH, NO2, and NO3, to better understand PCMA lifetimes, products, and its effect on the toxicity of PCMA compounds and formation of ROS.
Reactive Organic Nitrogen Multiphase Chemistry of Urban Secondary Organic Aerosol
Despite recent reductions in NOx (NO+NO2), NOx-mediated ground-level O3 and particulate matter (PM) are major concerns for human health and the environment, particularly in urban and peri-urban areas, where most of the population lives. Reactive organic nitrogen (RON) compounds, including organic nitrates (RONO2), formed when volatile organic compounds are oxidized in the presence of NOx, are known to increase the SOA burden and perturb O3 by sequestering NOx. RON can also cause oxidative stress, leading to inflammation, aging, and death. We will pursue a mechanistic understanding of the role of RON in SOA formation, and thus its impact on PM and O3 in urban environments.
Phase State and Chemical Composition of Atmospheric Nanoparticles Indoors and Outdoors
The air that we breathe typically contains thousands of nano-sized aerosol particles (100 nm or less in diameter) in every cubic centimeter. In each breath, we can inhale millions of nanoparticles. These ultrafine particles can penetrate deep into the alveolar regions of our lungs, causing a range of adverse health effects. Due to the complexity of gas–particle interactions that nanoparticles experience over their lifetimes, particle phase state is expected to change significantly over short spatiotemporal scales, requiring application of novel in situ analytical methods to capture the dynamic, transient processes associated with particle formation, aging, and their interrelationships with phase state. We will investigate how particle physical and chemical properties vary during different stages of formation, following aging by atmospheric oxidants - OH, NO3, and O3, and in the field to examine how environmental and meteorological factors affect the composition and phase of ambient aerosol particles.