Biogenic aerosol production in the Great Lakes region
Abstract
Aerosols are important because of their impacts on human health and radiative forcing. Recent studies have focused on aerosol formation in forested and maritime environments because of their supposed impacts on cloud properties, and thus climate forcing. However, not much is understood about their precursors and atmospheric conditions that drive their production. It is thought that aerosol formation often begins with inorganic constituents; however recent studies of aerosol formation have suggested that low-volatility, low-vapor pressure organic molecules produced from the oxidation of volatile organic compounds emitted from vegetation can influence new particle formation because of their gas-particle partitioning qualities. This influences the production of secondary organic aerosol, which is thought to act as seed particles for cloud condensation nuclei (CCN). In turn, CCN produces cloud droplets, which reflect incoming UV radiation back to space, causing a net decrease in sunlight that strikes the surface, which can have a net cooling effect on the earth. Two field campaigns were organized over two summers in the vicinity of a mixed deciduous/coniferous forest and Lake Michigan in the northern part of Michigan's Lower Peninsula to better understand the influence of forest succession on new particle formation. Gas phase molecules that are thought to influence new particle formation were measured, as well as direct measurements of the aerosol size distributions. We determined that new particle formation in this environment can occur from biogenic volatile organic compound (BVOC) emissions from the forest canopy. While conducting these measurements, we discovered a source of new particle formation over Lake Michigan. These new particles correlated well with wind speed and thus breaking waves on the surface of the Great Lakes, and is not discussed in the literature or included in current aerosol models.
Degree
M.S.
Advisors
Shepson, Purdue University.
Subject Area
Atmospheric Chemistry|Analytical chemistry|Atmospheric sciences
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