Methanol biogenic emissions

Dufour, G, S. Szopa, D.A. Hauglustaine, C.D. Boone, C.P. Rinsland, and Bemath, P. F. (2007), The influence of biogenic emissions on upper-tropospheric methanol as revealed from space, Atmos. Chem. Phys., 7, 6119-6129. 

In addition to these larger VOCs, there are biogenic sources of a wide variety of small alcohols, aldehydes, ketones, and acids. For example, emissions of methanol and acetone have been reported from plant leaves, grass, and clover (e.g., MacDonald and Fall, 1993 Nemecek-Marshall et al., 1995 Fall and Benson, 1996 Kirstine et al., 1998). Table 6.25 shows some of the compounds measured in grass and clover emissions (Kirstine et al., 1998). Clearly, a wide variety of oxygen-containing species are emitted from this one source alone. Direct emissions of formaldehyde, ac-etaldehye, and formic and acetic acids have been observed from oaks and pines (Kesselmeier et al., 1997). 

There are over 70 alcohols in the atmosphere as a result of biogenic and anthropogenic emissions [67]. For example methanol and ethanol [68-70] have been used as fuels additives to reduce automobile emissions of carbon monoxide and hydrocarbons [71], in particular ethanol has been used in Brazil as a fuel for over 20 years [72]. 1-Propanol is widely used as a solvent in the manufacturing of different electronic components. The high volatility of these compounds causes their relative abundance in the troposphere and makes it relevant to determine their degradation pathways. During daytime the major loss process for alcohols is their reaction with OH radicals [68]. Accordingly, several experimental [69,70,73-84] and theoretical [85-88] kinetic studies of alcohols -F OH reactions have been performed. 

Methanol, ethanol, and methyl tertiary butyl ether (MTBE) are OxHCs added to fuels to decrease tailpipe emissions of NMHCs and CO. Some alcohols, aldehydes, and ketones are emitted from biogenic sources others are also produced in the atmosphere through photochemical oxidation. The levels of some of the light OxHCs (e.g., acetaldehyde, methanol, ethanol, and acetone) are substantial. In the rural atmosphere, these can dominate the VOCs distribution (see,... 

The emissions of isoprene, acetaldehyde, methanol, and monoterpenes from Sitka spruce correlating with photosynthetic photon flux and temperature have been investigated, and an anticorrelation phenomenon between isoprene and acetaldehyde was reported during the sudden light-dark transitions [44]. Biogenic VOCs... 

Spirig et al. have reported PTR-MS measurements taken in a mixed deciduous forest in north-west Germany coupled to eddy covariance methodology for the determination of biogenic VOC fluxes [82], Fluxes for isoprene and the monoterpenes were shown to be consistent with light and temperature dependent emissions of these compounds. Average daytime emissions of methanol, isoprene and monoterpenes were determined to be 0.087 pg s 0.94 pg s and 0.3 pg m s respectively. 

---