Biogenic VOCs

D. Simpson, Biogenic VOC Emissions in Europe Modelling the Implications for Ozone Control... 

TABLE 6.24 Estimated Global Annual Biogenic VOC Emissions (Tg yr ... 

Although some of the biogenic VOCs are relatively simple compounds such as ethene, most are quite complex in structure (e.g., Figs. 6.22 and 6.26). Furthermore, they tend to be unsaturated, often with multiple double bonds. As a result, they are very reactive (see Chapter 16.B) with OH, 03, NO, and Cl atoms (e.g., Atkinson et al., 1995a). In addition, because they are quite large and of relatively low volatility, their polar oxidation products are even less volatile. This makes elucidating reaction mechanisms and quantifying product yields quite difficult. For a review of this area, see Atkinson and Arey (1998). 

In remote marine regions where there are not significant sources of large, biogenic VOCs, OH is removed by reaction with CO and CH4 ... 

Konig, G., M. Brunda, H. Puxbaum, C. Hewitt, C. Duckham, and J. Rudolph, Relative Contribution of Oxygenated Hydrocarbons to the Total Biogenic VOC Emission of Selected Mid-European Agricultural and Natural Plant Species, Atmos. Enriron., 29A, 861-874(1995). 

Biogenic VOC and NO emissions are calculated on-line based on land use data, simulated surface temperature and radiation. Anthropogenic emissions of primary pollutants, like NOx, SO2, and hydrocarbons, as well as emissions of primary particulate matter have to be supplied either at hourly intervals or as yearly data from gridded emission inventories. Validation studies with MCCM have shown its ability to reproduce observed meteorological quantities and pollutant concentrations for different conditions and regions of the Earth (Forkel and Knoche 2006 Forkel et al. 2004 Grell et al. 1998, 2000 JazcUevich et al. 2003 Kim and Stockwell 2007 Suppan and Skouloudis 2003 Suppan and Schadler 2004 Suppan 2010). 

Among freshly emitted pollutants, the initial rate of ozone formation is often controlled by the amount and chemical composition of VOCs. For this reason, ozone formation in urban centers is often (but not always) controlled by VOCs. As air moves downwind, ozone formation is increasingly controlled by NO rather than VOCs (Milford et al, 1989). Ozone in far downwind and rural locations is often (but not always) controlled by upwind NOjc emissions (Roselle and Schere, 1995). Rural areas also tend to have NO -sensitive conditions due to the impact of biogenic VOCs (see Section 9.11.2.2.5). However, this description represents a general trend only and is not universally vahd. NO c-sensitive conditions can occur even in large urban centers, and VOC-sensitive conditions can occur even in aged plumes. For a more complete discussion, see NARSTO (2000) and Sillman (1999). 

The major significance of biogenic VOCs with regard to ozone hes in their imphcations for the... 

Despite new advances, models for photochemical smog formation are subject to a number of uncertainties. Estimates for emission rates represent the largest uncertainty. In 1995 it was discovered that biogenic VOC emissions in the... 

Atmospheric Profiles of Biogenic VOCs and Their Oxidation Products... 

Figure 10, Principal connponent analysis of signature VOCs observed by PTR-MS monitoring of ambient air at the Sonnblick Observatory from 11 to 16 November 1999. Details are discussed in the text. The component listed as M57 is the PTR-MS signal at m/z 57, which can be derived from both anthropogenic and biogenic VOCs. Data replotted from Ref. [33].

Biogenic VOCs also originate due to stresses on plants such as fiooding, and due to the action of bacteria and fungi in dead biomatter and in soil. Analysis of these processes represents future additional applications of... 

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