中国生物源挥发性有机物(BVOCs)时空排放特征研究

生物源挥发性有机物(BVOCs)对O_3和二次有机气溶胶(SOA)生成具有重要的影响.本研究基于MODIS卫星遥感数据和WRF模拟的气象结果,运用MEGAN3.0模型对中国2005—2016年BVOCs排放量进行估算,分析了BVOCs及其亚类化学物种的时空分布特征.同时,对人为源挥发性有机物(AVOCs)排放量、总挥发性有机物(TVOCs)排放量和OMI卫星反演获取的甲醛柱浓度之间的关系进行了初步探讨.结果表明:2005—2016年中国BVOCs年均排放量约为10 Tg,其中,异戊二烯约为6.13 Tg,甲醇约为1.47 Tg,单萜烯约为1.03 Tg,其余生物源挥发性有机物(OBVOCs)约为2.84 Tg;近10年我国BVOCs排放量略呈下降趋势,AVOCs呈明显的波动上升趋势,而TVOCs则呈现逐年增加趋势;BVOCs存在明显的季节性变化,呈现夏季高、冬季低的规律,夏、冬两季排放量各占全年排放量的51.50%和3.40%;BVOCs排放量高值分布于中国东南植被密集区域,主要分布于广西(0.87 Tg)、云南(0.84 Tg)和湖南(0.81 Tg);不同土地覆盖类型的BVOCs排放贡献具有显著差异,其中,森林(43.93%)最大,灌木(31.62%)和农田(15.13%)次之,草地(9.31%)最小.本研究所获取的中国近10年BVOCs的时空分布特征可为后续定量评估BVOCs对O_3和SOA生成的贡献提供基础支撑.

Spatiotemporal distribution of biogenic volatile organic compounds emissions in China

Biogenic volatile organic compounds (BVOCs) play a crucial role in the formation of ozone and secondary organic aerosols (SOA). In order to investigate the BVOCs emissions and their spatiotemporal characteristics during 2005-2016 in China, the Model of Emissions of Gases and Aerosols from Nature version 3.0 (MEGAN3.0) was applied in this study. The land cover types and 8-day leaf area index (LAI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the meteorological data simulated by the Weather Research and Forecasting (WRF) model were used as inputs to the MEGAN model. The simulated BVOCs emissions were compared with the anthropogenic VOCs (AVOCs) emissions and the relationship between total VOCs (TVOCs) and the OMI retrieved formaldehyde vertical columns density (VCD) was explored. The MEGAN simulations showed that the annual averaged BVOCs emissions in China during 2005-2016 were approximately 10 Tg that included emissions of isoprene (6.13 Tg), methanol (1.47 Tg), monoterpenes (1.03 Tg), and other BVOCs (2.84 Tg). The annual BVOCs emissions during 2005-2016 exhibited a slight decreasing trend while AVOCs and TVOCs emissions increased continually. Significant seasonal variations of the BVOCs emissions were observed with the highest emissions in summer (51.50% of the annual total) and the lowest in winter (3.40% of the annual total). Spatially the BVOCs emissions were higher in the Southeast China, which is populated with high BVOCs emitting vegetation types, including the provinces of Guangxi (0.87 Tg), Yunnan (0.84 Tg), and Hunan (0.81 Tg). The relative contribution of different land cover types to BVOCs emissions in China is in the order of forest(43.93%) > shrub(31.62%) > cropland (15.13%) > grassland(9.31%). This study presents the temporal and spatial distribution characteristics of BVOCs emissions in China and can provide support for subsequent quantifying and modeling the contribution of BVOCs to the generation of O₃ and SOA in the future.