| An inventory of natural NOx and VOC emissions for China was developed. For the year 2000, it was estimated that the annual soil NOx and vegetation VOC emissions amounted to 225.75 Gg and 13.23 Tg, respectively, in which the total VOC was comprised of 7.77 Tg isoprene, 1.86 Tg monoterpene and 3.60 Tg other VOC. The emissions also showed large seasonal and regional variation. And with the aid of models MM5 and Calgrid, the effects of the emissions on the photochemical formation of O3, NOx, HNO3 and PAN over China were investigated. Countrywide mean concentrations of these pollutants respectively varied 15.3%, 15.7%, 25.5%, 6.5% on account of soil NOx emissions, 5.6%, -4.9%, -19.3%, 142.3% as a result of vegetation VOC emissions, and 26.1%, 8.8%, 4.3%, 177.9% owning to their synthetic effects. The variation was much higher in summer than in any other seasons. In addition, the distribution of the pollutants was affected by the natural emissions because of the different meteorological conditions, pollutant emissions and NMHC/NOx ratios in different regions. The role of natural NOx and VOC emissions on tropospheric photochemistry can not be neglected. |
