Keri Hornbuckle, a University at Buffalo researcher and assistant professor in the department of Civil, Structural and Environmental Engineering has been awarded a grant from the National Science Foundation to examine the effect of climate on the distribution of persistent organic compounds between terrestrial plants and the atmosphere. Hornbuckle's project, entitled "Gas-Phase Dynamics of Persistent Organic Compounds: An Investigation of the Effect of Climate using a Controlled Chamber," has been funded for four years by the NSF's Faculty Early Career Development (CAREER) Program.

This work will contribute to the understanding of how persistent organic compounds are transported through the atmosphere. Many of these compounds, which include chlorinated pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs), bioaccumulate, cause reproductive harm or are probable endocrine disrupters. They have been measured in all parts of the world. Although is known that these compounds are distributed worldwide through the air, the details of atmospheric transport are not well understood. This project will investigate the role that green plants play in the global transport of persistent organic (non-reactive) chemicals. Hornbuckle hypothesizes that plants mediate the transfer of these chemicals by acting as temporary resting points for vapor-phase compounds. Her work indicates that the chemicals undergo numerous exchanges with plant surfaces. It is suspected that the rate of these exchanges is controlled by climate.

Hornbuckle's project will involve a large (600m³) atmospheric chamber owed by Calspan, SRL. The size of the chamber and its ability to reproduce environmental conditions makes this study an important link between climate controlled laboratory studies with small chambers and field studies performed under natural but uncontrolled climate conditions. Hornbuckle and her graduate students will be modifying the chamber to allow the precise measurement of climate indicators such as relative humidity, temperature, ultraviolet light, pressure, and turbulence. They will study the independent effects of these climate indicators on the exchange of persistent organic compound vapors with plant surfaces. Experiments will be performed under controlled environmental conditions while the chamber is empty and populated with Ficus benjamina, a common tree-like house plant.

Results from this project are expected to contribute to atmospheric transport modeling, predictions of chemical fate, and determination of non-point sources of toxics to lakes and tributaries. This work will support atmospheric transport modeling and chemical deposition modeling by providing a near surface exchange model. At this time, it is difficult to predict atmospheric transport and dispersion of vapor-phase chemicals that continuously volatilize and deposit to the earth's surface. This project is designed for the development and validation of a kinetic model for exchange with plant surfaces.

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