Isoprene Emissions

Pierce, T., C. Geron, L. Bender, R. Dennis, G. Tonnesen, and A. Guenther, Influence of Increased Isoprene Emissions on Regional Ozone Modeling, J. Geophys. Res., 103, 25611-25629 (1998). 

FIGURE 6.24 Effect of light on isoprene emission rate from (a) aspen leaf and (b) velvet bean leaf (adapted from Monson et al., 1991, 1992 and Fall, 1999). 

FIGURE 6.25 Effect of willow leaf temperature on isoprene emission rate (adapted from Fall and Wildermuth, 1998 and Fall, 1999). 

Kesselmeier, J., K. Bode, L. Schafer, G. Schebeske, A. Wolf, E. Brancaleoni, A. Cecinato, P. Ciccioli, M. Frattoni, L. Dutaur, J. L. Fugit, V. Simon, and L. Torres, Simultaneous Field Measurements of Terpene and Isoprene Emissions from Two Dominant Mediterranean Oak Species in Relation to a North American Species, Atmos. Ent iron., 32, 1947-1953 (1998). 

Monson, R. K., A. J. Hills, P. R. Zimmerman, and R. Fall, Studies of the Relationship between Isoprene Emission Rate and C02 or Photon-Flux Density Using a Real-Time Isoprene Analyzer, Plant Cell Environ., 14, 517-523 (1991). 

Owen, S. M C. Boissard, B. Hagenlocher, and C. N. Hewitt, Field Studies of Isoprene Emissions from Vegetation in the Northwest Mediterranean Region, . /. Geophys. Res., 103, 25499-25511 (1998). 

Silver, G. M and R. Fall, Characterization of Aspen Isoprene Synthase, an Enzyme Responsible for Leaf Isoprene Emission to the Atmosphere, J. Biol. Chem., 270, 13010-13016 (1995). 

Tingey, D. T., M. Manning, L. C. Grothaus, and W. F. Burns, The Influence of Light and Temperature on Isoprene Emission Rates from Live Oak, Physiol. Plant., 47, 112-118 (1979). 

Wildermuth, M. C., and R. Fall, Light-Dependent Isoprene Emission. Characterization of a Thylakoid-Bound Isoprene Synthase in Salix discolor Chloroplasts, Plant Physiol, 112, 171-182 (1996). 

As expected, then, inclusion of biogenic emissions in models can have a significant effect under some conditions on the predicted effects of VOC versus NOx control. For example, Pierce et al. (1998) show that when increased isoprene emissions are included in the RADM model, ozone formation in many regions of eastern North America is predicted to be more sensitive to reductions in NOx rather than in VOC. 

The reaction between olefins and ozone produces light that can be measured and related to the concentration of the reactants. One of the preferred methods for measuring ambient ozone concentrations utilizes the chemiluminescence generated in the ozone-ethylene reaction for detection. Recently, Hills and Zimmerman (16) described the use of this detection principle for determining hydrocarbon concentrations. They utilized the chemiluminescence created when ozone reacts with isoprene for development of a continuous, fast-response isoprene analyzer. This real-time isoprene system is reported to be linear over three orders of magnitude and to have a detection limit of about 1 ppbv. Because the system doesn t include a preseparation of hydrocarbons, interferences from other olefins (ethylene, propylene, and so forth) could occur. Thus far the chemiluminescent detector has been used to monitor isoprene emissions under conditions in which the concentrations of olefins that could interfere are negligible compared to those of the biogenic hydrocarbon. 

This evidently accounts for the presence of isoprene in the breath.34 Isoprene is also formed by many plants and is released into the atmosphere in large amounts, which contribute to photochemical formation of haze. A Mg2+-dependent enzyme catalyzes the elimination of pyrophosphate.35 Isoprene emissions rise with increasing temperature, and it has been suggested that the isoprene may dissolve in chloroplast membranes and in some way confer increased heat resistance.36 37 Hydrolytic dephosphorylation can lead to dimethylallyl alcohol, which is oxidized in the liver to dimethy-lacrylyl-CoA (Eq. 22-1). 

Hayward et al. (2002) demonstrated that PTR-MS could reliably measure a wide range of VOCs and with a time resolution sufficiently fast to capture the dynamics of many environmental processes (e.g., the light dependency of isoprene emissions from vegetation). They also demonstrated that the components of the instrument output (signal plus noise) were easily characterized, enabling a simple interpretation of measurements. 

Sasaki, K., Saito, T., Lamsa, M., Oksman-Caldentey, K.M., Suzuki, M. and Ohyama, K. (2007) Plants utilize isoprene emission as a thermotolerance mechanism. Plant Cell Physiol., 48,1254-62. 

Sharkey, T.D. and Yeh, S. (2001) Isoprene emission from plants. Annu Rev Plant Physiol Plant Mol. Biol., 52, 407-36. 

Silver, G.M. and Fall, R. (1995) Characterization of aspen isoprene synthase, an enzyme responsible for leaf isoprene emission to the atmosphere. /. Biol. Chem., 270,13010-6. 

Guenther A, Karl T, Harley P, Wiedinmyer C, Palmer PI, Geron C. Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature). Atmos. Chem. Phys. Dis. 2006 6 3181-3210. 

Loivamaki M, Gilmer E, Fischbach RJ, Sorgel C, Bachl A, Walter A, Schnitzler JP. Arabidopsis, a model to study biological functions of isoprene emission Plant Physiol. 2007 144 1066-1078. 

Pierce T., Geron C., Bender L., Dennis R., Tonnesen G., and Guenther A. (1998) Influence of increased isoprene emissions on regional ozone modehng. J. Geophys. Res. 103, 25611-25630. 

Harley P.C, R.K. Monson and M.T. Lerdau Eeological and evolutionary aspects of isoprene emission from plants, Oecologia 118 (1999) 109-123. 

FIGURE 8 Changes in nonmethane hydrocarbon (isoprene) emissions predicted to accompany a shift from savanna grassland to a savanna woodland at the La Copita site in southern Texas (based on Guenther et al, 1999). Predictions from a coupled succession-NMHC emission model are compared with values measured from flux towers. The measured values shown for the historic landscape are from a tower located in a savanna grassland landscape with low woody cover. 

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