Spatial and Temporal Volatile Organic Compound Measurements in New England: Key Insight on Sources and Distributions

Volatile organic compounds (VOCs) in the atmosphere act as precursors in the formation of tropospheric ozone and their emissions and oxidation products can contribute to secondary organic aerosol formation and growth. In examining their effects on regional chemistry and pollution events, considerable uncertainties exist in our understanding of the relative contributions from different sources and classes of compounds as well as their transport from other regions. To quantitatively improve VOC emission estimates for New England, such as propane from widespread LPG leakage and biogenic emissions of toluene, we have conducted regional surveys for VOCs in northern New England to map their spatial variability. This has included repeated one-day quarterly sampling trips covering four 250 to 300 mile loops throughout Maine, New Hampshire, Massachusetts and small portions of Vermont, Connecticut, and Rhode Island and more intensive diurnal hourly-sampling at selected locations within the measurement area. Additionally, long-term VOC measurements from the AIRMAP atmospheric monitoring station at Thompson Farm in rural Durham, New Hampshire are utilized to characterize the mixing ratios, seasonal to interannual variability, and sources of VOCs in this region. The combination of the spatial temporal data sets has provided key insight on the various sources (e.g., fossil fuel combustion, gasoline, LPG, fuel or solvent evaporation, industry, biogenic) and distributions of VOCs throughout New England. Nonmethane hydrocarbon emission rate estimates from the regional sampling campaigns and Thompson Farm ranged from ~109-1010 molecules cm-2 s-1. Moreover, emission rates based on our spatial and temporal measurements are compared with the (2002 and 2005) EPA National Emissions Inventory for the northeastern U.S. Finally, details regarding our analytical techniques and long-term calibration scales will be presented for measurements of C2-C10 nonmethane hydrocarbons, C1-C2 halocarbons, C1-C5 alkyl nitrates, oxygenated-VOCs and selected sulfur compounds using i) canister samples, ii) cryogen-free in situ gas chromatographic systems and iii) proton transfer reaction mass spectrometers.