Environmental Chemistry: Surface Films as Active Environmental Interfaces
Abstract
Environmental surface films (urban films) are ubiquitous coatings on exterior surfaces that form as biogenic and anthropogenic emissions deposit from the atmosphere onto surfaces. These films cover nearly all impervious surfaces and build to thicknesses that range from 100 s of nm to 10,000 s of nm (several thousandths of an inch) and spread over large areas to create a significant volume that serves as a reservoir for persistent atmospheric pollutants. The absorption of pollutants into these films significantly affects their fate and transport as well as human and environmental health. A sponge-like analogy has been suggested, in which the surface films absorb pollutant species during cool, dry weather, and release them during warmer weather or rain events. The morphology and maturation of these films is poorly defined but significantly impacts their ability to 1) partition pollutant species from the atmosphere, 2) act as a matrix for chemical transformation, and 3) release the pollutants, or their degradation products back into the environment. To address these issues this proposal will 1) examine an urban films life-cycle, detailing their morphology, aging, and interaction with pollutants over time, and 2) create laboratory based model films that mimic natural films chemical architectures. These model films will allow focused analytical studies of specific film components and/or characteristics of the natural films, including quantitative pollutant absorption/desorption behaviors as a function of film s aging process. We predict that more mature films will be increasingly oxidized, affecting film polarity and its interactions with various classes of pollutants. Targeted pollutant species for initial work include toluene, benzo[a]pyrene, and water. Results from these systems will provide a platform that is amenable to examining many of the other known pollutant species. Multiple analysis techniques and surface sensitive vibrational spectroscopies will provide data to improve quantitative understanding of pollutant fugacity, and fate and transport models. These results serve major goals to define urban film culpability in broad environmental issues including transport, storage, and transformation of pollutant species.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810085
Entities
People
- Scott K. Shaw
Organizations
- Army Contracting Command
- United States Army
- University of Iowa