VOCs Estimate Of Biogenic Sources Emissions And The Impact On Regional Air Quality

Volatile Organic Compounds are important precursors in the formation of ozone, also one ofthe important precursors in the formation of Secondary Organic Aerosol, play an important rolein tropospheric chemistry, many components of VOCs have a high degree of chemical activity,react easily with various gases (such as NO and NO2), oxidant, OH radical and other ions in theatmosphere. They play an important role in tropospheric photochemical processes andparticularly in ozone photochemical processes. Organic acids, aerosols, and secondary producedfrom photochemical processes are serious harm to the atmospheric environment. As one of theimportant precursors in the formation of ozone, it is an important object of study ofphotochemical pollution, and atmospheric environmental quality control, also have an indirecteffect of climate warming.In regional and global scale, the vegetation emissions of VOCs have been far more than theanthropogenic emissions. Guenther (1995) estimated that global BVOCs emissions amounted toimmediate availability of 1.150×1012g, about 90% of all VOCs emissions; isoprene andmonoterpene are the largest two classes of global annual emissions of the Volatile OrganicCompounds; isoprene is about 44% proportion of the total BVOCs emissions. Therefore, thestudy on regional vegetation isoprene emissions can provide an important basis to further explorethe vegetation contribution to the atmospheric environment.The numerical simulation is a new research that has developed rapidly in recent years, itplays an important role for understanding the mechanism and its environment and climate effectsof atmospheric chemical processes, it can not only quantify the combined effects of manyphysical and chemical processes, but also can give the detailed spatial and temporal distributionof chemical substances in the atmosphere and the relative size of the contribution of differentphysical and chemical processes, and provides many new analytical techniques and means forlong-range transport of air pollution. Therefore, the use of numerical simulation to study thedistribution of the atmospheric concentration of chemicals, evolution, and discussion of themutual influence and contribution of each region are very important.July 2010 , for example , with the use of natural emissions of gases and aerosol modelMEGAN ( Model of Emissions of Gases and Aerosols from Nature) to estimate emissions fromnatural sources of VOCs in the East Asian region, combined with the regional air quality modelCAMx (Comprehensive Air Quality Model with extensions), We simulate typical summer ozone spatial and temporal distribution, and give a quantitative analysis of the contribution of naturalsource of VOCs for the key areas of ozone formation in East Asia with OSAT (Ozone SourceApportionment Technology), and explore ozone source apportionment of key areas. We form thehigh-resolution regional air quality model system covering the entire East Asian region, knowthe major gaseous pollutants and aerosol delivery and distribution characteristics of the East Asiaregion and ascertain the typical air pollutant source - receptor relationships between the mainareas of the East Asian region.We use 30s resolution standard emission factors to calculate the East Asia region isopreneemissions for 91.24Tg in 2010, China contributes 13.1Tg, Beijing area 0.045Tg, the Chinacontribution of East Asia isoprene emission can be 14.4%; in the same time, we can find that theEast Asia biogenic emissions of VOCs (isoprene conversion) are far more than the anthropogenicemissions. Isoprene emission has very distinct seasonal characteristics, where the summercatches the maximum, winter minimum, it may be the seasonal variation of temperature and light,and this seasonal variation is very significant in the China region, isoprene emissions areconcentrated in southern China, this may be related to vegetation cover in the region and theemission rate. But in Southeast Asia, emissions are the highest in the period of April in the year,it may be impacted by light which is less in the rainy season in July in Southeast Asia, which willaffect the luminous flux, and ultimately affect the canopy environment revised. Compared withother domestic and foreign researchers’simulation of regional isoprene emissions, they arebasically the same; this study can be the input conditions of the regional air quality model. InEast Asian emissions of ozone also has a significant diurnal variation, with the photochemicalreaction with light.