Hydrocarbon measurements in the southeastern United States: The Rural Oxidants in the Southern Environment (ROSE) Program 1990

Abstract

An automated gas Chromatographic system was employed at a rural site in western central Alabama to measure atmospheric hydrocarbons and oxygenated hydrocarbons (oxy‐hydrocarbons) on an hourly basis from June 8 to July 19, 1990. The location, which was a designated site for the Southern Oxidant Study (SOS), was instrumented for a wide variety of measurements allowing the hydrocarbon and oxy‐hydrocarbon measurements to be interpreted both in terms of meteorological data and as part of a large suite of gas phase measurements. Although the site is situated in a Loblolly pine plantation, isoprene was observed to be the dominant hydrocarbon during the daytime with afternoon maxima of about 7 parts per billion by volume (ppbv). Decrease of isoprene after sunset was too rapid to be accounted for solely on the basis of gas phase chemistry. During the nighttime, α‐pinene and β‐pinene were the dominant hydrocarbons of natural origin. The ratio of α‐pinene to β‐pinene showed a well‐defined diurnal pattern, decreasing by more than 30% during the night; a decrease that could be understood on the basis of local gas phase chemistry. Oxy‐hydrocarbons, dominated by methanol and acetone, were the most abundant compounds observed. On a carbon atom basis, the oxy‐hydrocarbons contributed about 46% of the measured atmospheric burden during the daytime and about 40% at night. The similarity of the observed diurnal methanol variation to that of isoprene and subsequent measurements [McDonald and Fall, 1993] indicate that much of the observed methanol was of local biogenic origin. Correlation of acetone with methanol suggests that it, also, has a significant biogenic source. In spite of the site's rural location, anthropogenic hydrocarbons constituted, on a carbon atom basis, about 21% of the hydrocarbon burden measured during the daytime and about 55% at night. Significant diurnal variations of the anthropogenic hydrocarbons, with increases at night, appeared to be driven by the frequent formation of a shallow nocturnal boundary layer.

North American acetone sources determined from tall tower measurements and inverse modeling

“…Atmospheric acetone at the KCMP tall tower is well correlated with methanol (R = 0.83 for the full year, n = 6637), consistent with observations elsewhere (Goldan et al, 1995;Riemer et al, 1998;Salisbury et al, 2003;Singh et al, 2004;Schade and Goldstein, 2006). However, due to the different mechanisms driving plant emissions of these two compounds, the seasonal peak for acetone occurs roughly one month later than that for methanol (mid-August versus mid-July).…”

“…The other principal source of atmospheric acetone is thought to be photochemical oxidation of precursor VOCs, including the predominantly anthropogenic 2-methyl alkanes (propane, isobutane, isopentane) as well as the biogenic 2-methyl-3-buten-2-ol (MBO) and monoterpenes (Alvarado et al, 1999;Reissell et al, 1999). Other terrestrial sources include biomass burning (Simpson et al, 2011) and direct anthropogenic emissions (Goldan et al, 1995;Goldstein and Schade, 2000;de Gouw et al, 2005). Globally, the oceans appear to be both a gross source and a gross sink for atmospheric acetone (Fischer et al, 2012); however, the magnitude and variability of the corresponding net flux is quite uncertain (de Reus et al, 2003;Williams et al, 2004;Lewis et al, 2005;Marandino et al, 2005;Sinha et al, 2007;Taddei et al, 2009;Fischer et al, 2012;Read et al, 2012;Sjostedt et al, 2012).…”

Eddy covariance emission and deposition flux measurements using proton transfer reaction – time of flight – mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

“…8-10 for the 6 species with the highest fluxes and/or mixing ratios which were measured by both instruments. In addition, we show the average diurnal flux of acetic acid detected by PTR-TOF-MS, because it was one of the species emitted in highest quantity, however its vertical gradients were not measured by PTR-MS. Methanol is the most abundant non-methane VOC in the troposphere with mixing ratios often exceeding 10 ppbv in the boundary layer in vegetated regions during summer (Goldan et al, 1995;Lamanna and Goldstein, 1999;Holzinger et al, 2001;Schade and Goldstein, 2006), and it is known to be either directly emitted from plants or deposited to wet surfaces such as leaves and soil (Schade et al, 2011;Karl et al, 2004). Consistently, methanol mixing ratios at this site were the highest of all the VOC observed with a range from 7.3-43.6 ppbv.…”

Atmospheric levels of BTEX compounds during the 2008 Olympic Games in the urban area of Beijing

“…Oxidants (such as O 3 etc.) were eliminated via a Na 2 SO 3 scrubber tube connected to the upstream end of the absorption tube (Goldan et al, 1995).…”