Reactions of OH with a-pinene and (260 Tg C yr -•, ~25%) and larger than that from •-pinene were studied for the purpose of fossil fuel combustion (190 Tg C yr -1 ~18%) obtaining the basic data to estimate the emission [World Meteorological Organization (•40), •986]. rate of CO from the photooxidation of terpenes in The measurement of the concentration of tropothe atmosphere. In the presence of NO the main spheric CO from a space shuttle [Reichle et al., product was pinonaldehyde and 6,6-dimethyl-1986] revealed that the highest concentration of bicyclo[3.1.1]heptan-2-one from •-and •-pi-CO was recorded above South AmeriCa and central nene, respectively, and the yield was 56 ñ 4 and Africa. It indicates the importance of the 79 ñ 8%, respectively. In the absence of NO the photooxidation of natural hydrocarbons emitted yield was remarkably lower, and the yield of from tropical rain forests as well as the direct organic aerosols was enhanced. For •-pinene 56 emission of CO from biomass burning. ñ 3 % was obtained as a yield of aerosols on the Monoterpenes are among the most important carbon number basis. Gross annual emission of CO natural hydrocarbons, and their atmospheric from the reactions of OH with terpenes was esti-reactions play an essential part in the global mated to be 22 Tg C yr-1 (50 Tg CO yr-•) by carbon cycle. The global emission rates of regarding • -pinerie as the representative of terpenes were estimated to be 175-830 Tg yr-1 terpenes, on the basis of the annual emission [Went, 1960; Robinson and Robbins, 1968; rate of terpenes, estimated lifetime of pinches Rasmussen, 1972; Zimmerman et al., 1978], which in the atmosphere, the apparent rate constant for exceed the emission rates of anthropogenic hydrothe intermediate to form CO, and the estimated carbons' 65-75 Tg yr-• [Duce, 1978; Robinson, yield Of CO from the secondary oxidation of 1978]. However, only very limited information is pinonaldehyde. The ultimate yield of CO from the available so far on the formation of CO from the tropospheric oxidation of terpenes (including photooxidation of terpenes. Hanst et al. [1980] both ozone and OH reactions) was estimated to be estimated the yield of CO from the oxidation of 20% on the carbon number basis, and the total terpenes by use of C1 atoms in place of OH radiannual emission of CO was evaluated to be 96 Tg C cals. Recently, we reported [Hatakeyama et al., yr-1 (222 Tg CO yr-1). 1989] the estimate of the ultimate yield of CO from the oxidation of terpenes initiated by Introduction ozone, and the gross annual emission of CO with respect to the ozone-terpene reactions was esti-Carbon monoxide (CO) plays a major role in mated to be 74 Tg C yr-• In order to obtain a controlling the concentration of OH radicals in more complete estimate o• CO emission the yield the atmosphere. OH radicals are known to be the of CO from the oxidation of terpenes initiated by most important atmospheric trace species which OH radicals is needed, since terpenes are condetermine the lifetime of most of the other sumed by both ...

Reactions of ozone with α‐pinene and β‐pinene were studied for the purpose of obtaining the quantitative yields of gaseous and particulate products. Major gaseous products from α‐pinene were CO, CO2, HCHO, and aldehydes mainly composed of pinonaldehyde and nor‐pinonaldehyde, while those from β‐pinene were CO2, HCHO, and 6,6‐dimethylbicyclo[3.1.1]heptan‐2‐one. Average molar yields from α‐pinene were CO; 9±1%, CO2; 30±2%, HCHO; 22±1%, and aldehydes; 51±6%. Average molar yields from β‐pinene were CO2; 27±2%, HCHO; 76±2%, and 6,6‐dimethylbicyclo[3.1.1]heptan‐2‐one; 40±2%. Particulate products were found to include pinonaldehyde, nor‐pinonaldehyde, pinonic acid, and nor‐pinonic acid from α‐pinene. The yields of the particulate aldehydes decreased with the reaction time, whereas the yields of the acids increased. This observation suggests the sequential oxidation of aldehydes to carboxylic acids. From β‐pinene, only 6,6‐dimethylbicyclo[3.1.1]heptan‐2‐one was identified as a particulate product. For α‐pinene, most of the products are explainable in terms of the reaction mechanism similar to that for the cyclohexene/ozone reaction, whereas for β‐pinene the principal reaction path is that of the doubly substituted Criegee intermediate. The total yields of organic aerosols from both α‐ and β‐pinene were measured with their concentrations at a lower ppb level. The yields were found almost constant in a pinene concentration range from 10 up to 100 ppb, being 18.3±1.1 and 13.8±0.8% for α‐ and β‐pinene, respectively, which are much lower than the previously reported values.

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Regional‐ and national‐scale emission rates of halocarbons have been a great concern in the field of global environmental studies and policy making. Emissions have been inventoried mainly by bottom‐up approaches, which involve adding up emissions from various industrial sources. To verify and supplement those bottom‐up inventories, top‐down approaches based on measurements of air concentrations are required. In this study, aircraft monitoring over Sagami Bay, Japan, was used to estimate the emission ratios of halocarbons (perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), CFCs, hydrochlorofluorocarbons (HCFCs), and others) from Japan. The enhanced concentrations in the boundary layer of air masses having traveled over Japanese mainland were used for the calculation under the assumption that the air masses over Sagami Bay represented average emission ratios for anthropogenic halocarbons on a countrywide basis. Given their emission ratios, a single compound with a credible emission rate can yield the emission estimates for all the other compounds. When we employed an inventory‐based emission estimate of HCFC‐22 from the Pollutant Release and Transfer Register (PRTR) system 2002 of Japan (9.1 Gg/yr) as the reference, the estimated emission rates of HCFC‐141b, HCFC‐142b, CFC‐12, chloroform, and trichloroethylene for 2002 were consistent with their PRTR values within 10%. Emissions of carbon tetrachloride (CCl4) and 1,1,1‐trichloroethane (CH3CCl3) were much higher than their PRTR values, suggesting that their sources are not adequately accounted for in the current inventories. The present study also presents probable annual emission rates for individual HFCs and PFCs that previously had no reported estimates; for example, 4.4 Gg/yr for HFC‐134a as of 2002.

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