IGPP Seminar Series

Chemistry of Reactive Halogen Species in the Troposphere

by Prof. Jochen Stutz
Department of Atmospheric and Oceanic Sciences, UCLA

Abstract

Reactive halogen species can have a significant impact on gas and aerosol chemistry in the troposphere. Catalytic cycles involving halogens destroy ozone, leading to its complete depletion in the polar boundary layer in spring. The presence of halogens also modifies NOx and HOx cycling, thus impacting the only chemical formation pathway of ozone in the troposphere. Chlorine and bromine compounds influence the marine sulfur cycle by oxidizing dimethylsulfide, and S(IV). A close link between atmospheric halogen and mercury chemistry has also been found. Despite the potential role of reactive halogens for air quality and global climate many aspects of their chemistry and their sources in the troposphere are not well understood. Few observations of reactive halogen species and their precursors have been reported. In this presentation I will review our current understanding of tropospheric halogen chemistry and present observations of halogen species at the Great Salt Lake in Utah, the Isles of Shoals in the Gulf of Maine, and Malibu, CA. The results from these field studies are analyzed with respect to the sources and chemistry of halogens at each location. The field data allows a better evaluation of the potential impact of halogen chemistry on the composition of the troposphere on larger scales.
Tuesday, 09 January 2007
3845 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM