HR: 0800h
AN: A51C-0791    [Abstracts]
TI: Anthropogenic Emissions of Non-Methane Hydrocarbons in the Northeastern U.S.: 10 Years of Measured Seasonal and Interannual Variations
AU: * Lee, H K
EM: lagoseco@berkeley.edu
AF: Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720-3110 United States
AU: Munger, W J
EM: jwm@io.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 United States
AU: Wofsy, S C
EM: scw@io.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 United States
AU: Goldstein, A H
EM: ahg@nature.berkeley.edu
AF: Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720-3110 United States
AB: Harvard Forest, a rural site in central Massachusetts located downwind of major urban-industrial centers, provides an excellent location to monitor anthropogenically emitted trace gases. Air that arrives at Harvard Forest from the southwest is affected by emissions from the east-coast urban corridor, and may have residual influence from emissions in the upper Ohio Valley and Great Lakes region further to the west. Pollution plumes that reach the site represent a homogenized mixture of regional anthropogenic emissions. Concentrations of C$_{2}$-C$_{6}$ hydrocarbons along with CO, NO$_{y}$ and CH$_{4}$ were measured nearly continuously from August 1992 through July 2002. By ratioing observed concentrations to acetylene, which is almost solely produced from fossil-fuel combustion processes, we are able to detect seasonal and interannual trends in relative emission rates for this series of trace gases. Furthermore, the variations in relative concentrations indicate seasonal shifts in decomposition and deposition rates for shorter-lived compounds. Seasonal changes in butane and isobutane emissions are dominated by changes in gasoline formulation that occur in the spring and fall transition. The seasonality of pentane, isopentane and hexane emissions is dominated by temperature driven evaporative processes. Emissions of ethane and propane lack seasonality and correlate less with acetylene than other gases, which indicate sources of these two gases are strongly influenced by relatively local liquid propane, wood combustion and/or natural gas emissions that are not associated with regional combustion sources. A strong seasonal shift in the CO to acetylene slope suggests that secondary production of CO from oxidation of primary hydrocarbons in the summer significantly contributes to regional CO concentrations. The slope of NO$_{y}$ to acetylene provides a better estimate of the fraction of NO$_{y}$ removed by deposition within the region during summer than compared to the slope to CO.
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting