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Department of Environmental Sciences
University of Virginia
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RESEARCH INTERESTS
Biogenic hydrocarbons
Although
it has been known for more than half a century that plants release a
plethora of non-methane hydrocarbons (NMHCs), it was not until the
mid-1980s that scientists firmly established the links between ozone
formation/destruction and ambient NMHCs. Owing to their high
reactivity, it is now well known that NMHCs can augment ozone formation
in environments rich in nitrogen oxides. In jurisdictions such as the
northeastern part of North America, this is a serious environmental
issue as summer-time ozone levels frequently exceed the National
Ambient Air Quality Standard set by the U.S. Environmental Protection
Agency. I have conducted research to separate the contribution of
biogenic precursors to ozone formation. My most active research area
concerns field and theoretical investigations involving turbulent
transport theory and chemical processing of biogenic NMHCs inside and
above forests. My early work on this topic involved the development of
measurement protocols to investigate the environmental and vegetation
controls on hydrocarbon emissions at foliage and plant canopy levels.
The fieldwork I conducted in the temperate and boreal forests of Canada
led me to develop and test one-dimensional canopy models to scale
hydrocarbon emissions from single leaves to the canopy dimension.
Theoretical studies showed that in remote environments (where nitrogen
oxide levels are negligible) these scaling processes yield credible
results provided that the variation of the physical environment within
the modeling domain is correctly prescribed. Hydrocarbon
emissions depend on leaf temperature
and light levels impinging on foliage control. I have contributed with
research to develop and test models to describe the physical
environment inside forest canopies, and thus estimate hydrocarbon
emisions and chemical processing. These models are based on the
state-of-the-science turbulent transport and radiative transfer theory,
which has been integrated and adopted to address my NMHC research. Much
of my recent research involves the understanding of the seasonal
controls on biogenic production from deciduous forests. Lately,
we have been investigating the aerosol yields from hydrocarbon
oxidation. The impetus of this latest research is to quantify the
radiative forcing by phytogenic aerosols and to discern the influence
of phytogenic aerosols on cloud formation processes. The hydrocarbon
research is being carried in places such as Canada, Brazil, the
Piedmont of Virginia, the Florida Everglades and New Mexico.
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