Date: Thursday, October 15, 2009 4:30 PM
Location: 366 Hollister
According to the World Health Organization, outdoor air pollution causes 200,000 deaths per year worldwide; and in the absence of new approaches to the problem, it will be responsible for a total of 8 million premature deaths between the years 2000 and 2020. In fact, more people are killed by air pollution from vehicles than by traffic accidents. Additionally, air pollution is responsible for global climate change and degradation of visibility. Air pollution emission inventories are critical tools for improving air quality, but they are known to contain large uncertainties that can limit progress toward scientific and policymaking goals. Independent verification of emissions is needed to ensure their accuracy and to identify uncertainties in them. In response to the need for new approaches to quantifying emissions, we have designed a mobile Flux Laboratory for the Atmospheric Measurement of Emissions (FLAME). We equipped a television news van with an eddy covariance system capable of measuring fluxes of carbon dioxide (CO2), nitrogen oxides (NOx), fine particulate matter (PM2.5), and certain volatile organic compounds (VOCs). We have deployed the FLAME to three different settings: the large urban area of Norfolk, Virginia; schools in the medium-sized city of Roanoke, Virginia; and a rural Appalachian town where coal transport is the dominant industry. Over the scale of a few kilometers within a city, emissions were highly heterogeneous in both space and time. With certain pollutants in certain locations, flux measurements confirmed official emission inventories, but in others, they disagreed by factors of up to five, suggesting that sectors of the inventory may be severely over- or underestimated. In particular, observed fluxes of PM2.5 were much smaller than reported in the inventory. Around schools, idling vehicles appeared to be the dominant source of emissions of air toxics. Emission factors calculated for barges passing through the measurement footprint agreed with those measured by more intrusive methods. This research demonstrates that a mobile eddy covariance system can be used successfully to measure fluxes of multiple pollutants in a variety of settings. Results will aid the assessment of uncertainties in emission inventories and promote improvements in their fidelity.
Linsey Marr is an associate professor in the Department of Civil and Environmental Engineering at Virginia Tech. She received her Ph.D. in Civil and Environmental Engineering from the University of California at Berkeley and her B.S. in Engineering Science from Harvard.
Refreshments will be served at 4:15 PM
