Abstract
This paper describes a study of local biogenic volatile organic compounds (BVOC) emissions from the Hong Kong Special Administrative Region (HKSAR). An improved land cover and emission factor database was developed to estimate Hong Kong emissions using MEGAN, a BVOC emission model developed by Guenther et al. (2006). Field surveys of plant species composition and laboratory measurements of emission factors were combined with other data to improve existing land cover and emission factor data. The BVOC emissions from Hong Kong were calculated for 12 consecutive years from 1995 to 2006. For the year 2006, the total annual BVOC emissions were determined to be 12,400 metric tons or 9.82 × 10 9 g C (BVOC carbon). Isoprene emission accounts for 72%, monoterpene emissions account for 8%, and other VOCs emissions account for the remaining 20%. As expected, seasonal variation results in a higher emission in the summer and a lower emission in the winter, with emission predominantly in day time. A high emission of isoprene occurs for regions, such as Lowest Forest-NT North, dominated by broadleaf trees. The spatial variation of total BVOC is similar to the isoprene spatial variation due to its high contribution. The year to year variability in emissions due to weather was small over the twelve-year period (−1.4%, 2006 to 1995 trendline), but an increasing trend in the annual variation due to an increase in forest land cover can be observed (+7%, 2006 to 1995 trendline). The results of this study demonstrate the importance of accurate land cover inputs for biogenic emission models and indicate that land cover change should be considered for these models.
Highlights
Volatile Organic Compounds (VOCs) in the troposphere react photochemically with oxides of nitrogen (NOx) in the presence of solar radiation to form smog which contains various secondary air pollutants such as ozone and peroxyacetyl nitrate (PAN)
Grouping of field survey data The field survey data were grouped by Plant-functional types (PFT) classes so that each class had several representative sites and plant species
Following the approach of Tsui et al (2009), this work continued the development of a biogenic volatile organic compounds (BVOC) emission model for the estimation of biogenic VOC emissions from vegetation in the Hong Kong Special Administrative Region (HKSAR)
Summary
Volatile Organic Compounds (VOCs) in the troposphere react photochemically with oxides of nitrogen (NOx) in the presence of solar radiation to form smog which contains various secondary air pollutants such as ozone and peroxyacetyl nitrate (PAN). Petrochemical plants, motor vehicles, and industrial/commercial use of paints, thinners and dry cleaning solvents are some examples of anthropogenic sources while vegetation (trees, grasses and marshes) is an important source of natural biogenic VOC. These biogenic sources emit a significant amount of VOCs into our atmosphere with a composition, including isoprene and terpenes, which is considerably more reactive than anthropogenic VOCs. Biogenic VOC studies enhance our knowledge of BVOC emission modeling is a multi-disciplinary research topic, which involves knowledge in botanical science, scientific computing, atmospheric science, and geography. An extended summary of standard emission factors with data related to plant genus and species is included for isoprene and monoterpenes in the paper
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