Grant: Discovery Grants Program - Individual

The lower atmosphere, or troposphere, comprises a large concentration of minute airborne particles known as aerosols. Atmospheric aerosols are emitted from natural sources (e.g. dust, sea salt), and from human activities (e.g. soot). They have complex chemical composition and they impact the global climate by influencing the amount of sunlight reaching the Earth's surface. 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. Thus, it is imperative to address scientific questions related to the chemistry of aerosols through experimental studies. The funding requested in this proposal will be used to tackle an important scientific problem, which is the role of solar radiation and metals in transforming organic matter in aerosols. The organic content of aerosols originates from pollution stemming from human activity, natural sources (emissions from trees and animals), and biomass burning. We will work with mimics of multicomponent aerosols composed of photoreactive chemicals and metals, and ubiquitous humic-like substances and amino acids. We will use experimental techniques that allow monitoring reactions on the surfaces of these materials under controlled environments, mimicking atmospheric conditions, so that results may be extrapolated to the ""real world"" system. Results obtained from these studies will increase our understanding of the role of photochemistry in modifying the chemical and physical properties of atmospheric particulate matter and its impact on gas phase species.