Grant: Discovery Grants Program - Individual

The lower atmosphere, known as the troposphere, comprises a large concentration of minute airborne particles known as aerosols. Aerosols in the troposphere have complex chemical composition and they impact our lives in a number of ways.  Reduced visibility seen on hazy days and respiratory health problems are just two examples of aerosols impact on a regional scale.  On a global scale, aerosols contribute to climate change as they influence the amount of sunlight reaching the Earth's surface, alter properties of clouds, and provide media for chemical reactions in the atmosphere.  Computer simulations of the climate give us the capability of quantifying the magnitude of aerosols contribution to climate change. Yet aerosols representation in these simulations is still inadequate mainly because aerosols are complicated in nature and their reactivity and properties change with time while suspended in air.  Thus, it is imperative to address scientific questions related to aerosols through experimental studies to better our understanding of the aerosols impact on our climate system. The funding requested in this proposal will be used to tackle an important scientific problem, which is the processing and aging of aerosol particles, especially those coated with organic matter.  Organic matter on aerosols originates from pollution stemming from human activity, natural sources (emissions from trees and animals), and biomass burning. Since reactions occur mainly on aerosols surfaces, and in order to simplify the complex chemical nature of aerosols, we will work with model surfaces composed of the most abundant chemical compounds identified in real aerosol particles.  The processing and aging of aerosols are mainly caused by reactions with pollutant gases found in the atmosphere.  We will use experimental techniques that allow monitoring reactions on surfaces under controlled environments as close as possible to atmospheric conditions, so that results can be extrapolated to the "real world" system.  Results obtained from these studies will increase our understanding of the aging process of aerosols and their overall impact on the global climate.