Heterogeneous Chemistry in the Lower Atmosphere: From Pesticides to Particles
Barbara Finlayson-Pitts (University of California, Irvine)
It is believed that chemistry on surfaces ("heterogeneous chemistry") in the lower atmosphere has significant impacts on both the uptake of gases from air as well as formation of new surface species and emission of products of these reactions into the atmosphere. While traditional surface science approaches have provided a wealth of information on some reactions relevant to the atmosphere, they are often not suited to studying reactions at one atmosphere in air in the presence of water vapor. As a result, this area remains one of the least understood aspects of atmospheric chemistry.
Studies from this laboratory on two heterogeneous systems using a variety of experimental techniques will be described. The first is the chemistry and photochemistry of thin films of neonicotinoid (NN) pesticides on surfaces. These pesticides have found increasing use since their introduction in 1991. Their presence in the environment has been associated with bee colony collapse, which has led to regulations in Europe and in some states in the U.S. such as Minnesota. However, assessments of toxicity typically only address the parent compound, and do not take into account transformations in the environment that can form more toxic products. We have used a combination of experiments and theory, in collaboration with the group of R. B. Gerber, to show that atmospheric reactions of the NNs on surfaces can indeed form more toxic products as well as N2O, a potent greenhouse gas, and to elucidate the mechanisms involved.
The second system is the reaction of solid dicarboxylic acids with gas phase amines. Knudsen cell and associated studies show that there is a distinct difference in reactivity and mechanisms for odd carbon compared to even carbon diacids, with the reactions of the odd carbon species forming ionic liquid layers on the surface. The implications for atmospheric reactions will be discussed.
Barbara Finlayson-Pitts (University of California, Irvine)
Studies from this laboratory on two heterogeneous systems using a variety of experimental techniques will be described. The first is the chemistry and photochemistry of thin films of neonicotinoid (NN) pesticides on surfaces. These pesticides have found increasing use since their introduction in 1991. Their presence in the environment has been associated with bee colony collapse, which has led to regulations in Europe and in some states in the U.S. such as Minnesota. However, assessments of toxicity typically only address the parent compound, and do not take into account transformations in the environment that can form more toxic products. We have used a combination of experiments and theory, in collaboration with the group of R. B. Gerber, to show that atmospheric reactions of the NNs on surfaces can indeed form more toxic products as well as N2O, a potent greenhouse gas, and to elucidate the mechanisms involved.
The second system is the reaction of solid dicarboxylic acids with gas phase amines. Knudsen cell and associated studies show that there is a distinct difference in reactivity and mechanisms for odd carbon compared to even carbon diacids, with the reactions of the odd carbon species forming ionic liquid layers on the surface. The implications for atmospheric reactions will be discussed.
Barbara Finlayson-Pitts (University of California, Irvine)
| Building: | Chemistry Dow Lab |
|---|---|
| Event Type: | Other |
| Tags: | Chemistry, Science |
| Source: | Happening @ Michigan from Department of Chemistry |
