2011 - Cooperative Institute for Research in Environmental Sciences ...

atmospheric removal of methylglyoxal, and demonstrated
that reaction with the NO3 radical represents a minor atmospheric
loss process for methylglyoxal and glyoxal.
Product: Davis, ME, and JB Burkholder (2011), Rate coefficients
for the gas-phase reaction of OH with (Z) 3 hexen 1 ol,
1 penten 3 ol, (E) 2 penten 1 ol, and (E) 2 hexen 1 ol between
243 and 404 K, Atmos. Chem. Phys., 11, 3347-3358.
Talukdar, RK, L Zhu, KJ Feierabend, and JB Burkholder
(2011), Rate coefficients for the reaction of methylglyoxal
(CH3COCHO) with OH and NO3 and glyoxal (HCO)2 with
NO3, Atmos. Chem. Phys. Disc., 11, 18211-18248.
Milestone 2: Initiate laboratory investigation of switch
grass emissions to quantify volatile organic compounds
emitted by different switch grass species, and to prepare for
a summer 2011 field study of agricultural switch grass emissions.
Impact: This CIRES research will provide information
needed to assess the environmental impact of a large-scale
production and use of alternative fuels produced from biofuel
crops. Emissions of volatile organic compounds from
vegetation can play a significant role in the formation of
ozone and aerosol in polluted atmospheres.
Work continued on the characterization of volatile organic
compound (VOC) emissions from biofuel crops. In addition
to the measurements of VOCs from different switchgrass
cultivars, field measurements of VOCs from switchgrass
and corn were made in an agricultural field in Fort Collins,
Colo. VOC emissions from switchgrass were determined in
units of kilograms of carbon per hectare. In combination with
industry numbers on the amount of switchgrass required per
fuel volume produced, these results allow the environmental
effects of biofuel use to be assessed in more detail than previously
possible. Switchgrasses are found to be very low emitters
of oxygenated species and monoterpenes. The growing
of these species for biofuel production will have a much
smaller impact on atmospheric composition than for other
biofuel crops such as hybrid poplar. In 2011, a more detailed
field study to measure the VOC emissions from corn will be
conducted in collaboration with colleagues from Colorado
Figure 2
124 CIRES Annual Report 2011
State University in Fort Collins.
Products: Eller, ASD, K Sekimoto, JB Gilman, WC Kuster,
JA de Gouw, RK Monson, M Graus, E Crespo, C Warneke,
and R Fall (2011), Volatile organic compound emissions from
switchgrass cultivars used as biofuel crops, Atmos. Environ.,
45, 3333-3337.
Graus, M, A Eller, R Fall, B Yuan, Y Qian, P Westra, J de
Gouw, and C Warneke, VOC exchange of C4 biofuel crops, in
preparation.
Milestone 3. Develop and test the Acid chemical ionization
mass spectrometry (CIMS) system for measuring organic
and inorganic acids in the atmosphere. Impact: The Acid
CIMS will enable measurement of a large number of organic
and inorganic acids, rapidly and with high sensitivity.
This capability can be applied to research as diverse as
ecosystem fluxes, emissions from combustion sources and
the participation of organic acids in secondary organic
aerosol formation.
A CIMS instrument based on acetate ion chemistry was
developed and used at a ground site in Pasadena, Calif.,
during the CalNex field study in 2010. The instrument
worked very well during its first field deployment and
provided quantitative measurements of a series of organic
(formic, acrylic, methacrylic, propionic and pyruvic acid)
and inorganic acids (nitrous, nitric and isocyanic acid and
hydrogen chloride). It was found that most of these gases
were formed efficiently by photochemical production from
urban emissions. For the organic acids, these findings are
not understandable in terms of known gas-phase chemical
reactions. However, these reactions are important to understand
as organic acids represent a significant fraction of the
mass of organic carbon emissions. In summer 2010, the acid
CIMS was used to sample emissions from the Fourmile Canyon
Fire near Boulder, Colo. These measurements confirmed
earlier laboratory findings of the importance of isocyanic
acid (HNCO) as an emission from biomass burning.
Figure 3
Product: Burling, IR, RJ Yokelson, DWT Griffith, TJ Johnson,
P Veres, JM Roberts, C Warneke, SP Urbanski, J Reardon,
DR Weise, WM Hao, and J de Gouw (2010), Laboratory measurements
of trace gas emissions from biomass burning of
fuel types from the Southeastern and Southwestern United
States, Atmos. Chem. Phys., 10, 11115–11130.