A newly developed proton-transfer ion-trap mass spectrometer (PIT-MS) will be used for measurement and on-line identification of reactive volatile organic compounds (VOCs) in air impacted by urban, biogenic, or forest fire emissions. Specifically, it is intended: 1. To study the primary and secondary sources of oxygenated VOCs in urban atmospheres during two upcoming experiments: the Megacity Initiative: Local and Global Research Observations (MILAGRO) study in Mexico City in early 2006 and the Texas Air Quality Study (TexAQS) later in 2006. 2. To identify the "missing" biogenic VOCs that have been observed at a ponderosa pine/oak forest field site (Blodgett Forest, CA), and that have been postulated from OH lifetime and ozone uptake measurements. This work will include laboratory measurements of VOC photo-oxidation to simulate expected field data. In addition, the first simultaneous measurements of isoprene, methylbutenol, and their three primary oxidation products will be made at the field site. 3. To explore the analytical capabilities of the PIT-MS instrument to measure VOCs emitted from biomass burning, at the Fire Sciences Laboratory in Missoula, MT.
Broader impacts resulting from these activities include a detailed understanding of the sources and chemistry of VOCs in the atmosphere. Ozone and secondary organic aerosol (SOA) are formed as byproducts of VOC removal, and both of these are major pollutants in urban air, with adverse effects on human health. In addition, ozone and SOA have the potential to affect Earth's climate by changing its radiation budget and oxidative capacity. Understanding the atmospheric chemistry of VOCs may help in designing air-management strategies to minimize the build-up of ozone and SOA in polluted air. The project will provide training for the next generation of atmospheric scientists at the undergraduate and graduate level. In addition, the MILAGRO component will help to promote scientific collaborations with colleagues in Mexico and help to disseminate some of the latest developments in atmospheric science and instrumentation.
