陆地植物是大气中挥发性有机物的主要来源,准确获得中国典型生态系统,特别是亚热带森林植物挥发性有机物的排放通量,对碳循环、空气质量、大气化学和光化学等方面的研究都是一项具有重要意义的工作.2013年5月—2016年1月,采用松弛涡度积累(Relaxed Eddy Accumulation)和梯度技术在江西省亚热带人工林冠层上测量了植物挥发性有机物(BVOCs,包括异戊二烯和单萜烯)的排放通量,同步测量了气象参数、太阳辐射(总辐射、直接辐射、光合有效辐射PAR)等.基于冠层尺度BVOCs排放经验模式和测量数据,计算了2013年1月—2016年12月亚热带人工林BVOCs的排放通量.2013—2016年,通量塔100 km内异戊二烯的年排放量分别为1.2×105、2.4×105、2.1×105、1.6×105kg,单萜烯的年排放量分别为2.1×105、2.1×105、1.9×105、2.0×105kg.4年间,亚热带森林甲醛柱浓度表现出显著的季节变化,夏季高、冬季低,与BVOCs的排放特征基本一致.结合分析卫星测量的甲醛HCHO(molec·cm-2)柱浓度月平均数据,发现亚热带人工林BVOCs排放通量(mg·m-2·h-1)与HCHO柱浓度(cHCHO)月均值之间存在良好的线性关系:异戊二烯排放通量F1=1.29×10-16cHCHO-0.77、单萜烯排放通量F2=1.02×10-16cHCHO-0.21、BVOCs排放通量F=2.31×10-16cHCHO-0.98.因此,基于卫星测量的HCHO数据,可以估算BVOCs排放通量,异戊二烯、单萜烯和BVOCs的计算偏差低于30%.该研究可为获取大范围BVOCs排放通量提供一种新方法,也为卫星数据的广泛应用提供了借鉴.%Terrestrial vegetation is the dominant source of atmospheric volatile organic compounds. To better understand the terrestrial carbon cycle, air quality and atmospheric chemistry and photochemistry, it is an important task to accurately obtain the amount of biogenic volatile organic compounds (BVOCs) emissions from typical ecosystems, especially from subtropical Pinus plantation in China. Emission fluxes of BVOCs (including isoprene and isoprene) were measured using a relaxed eddy accumulation (REA) technique and a gradient method on an above-canopy tower in a subtropical Pinus plantation in Jiangxi Province, China from May, 2013 to January, 2016. Meteorological parameters, solar global and direct radiation, and photosynthetically active radiation (PAR) were also measured during the same time period. BVOC emissions from January 2013 to December 2016 were calculated using an empirical model of BVOC emissions and observational data. From 2013 to 2016, the annual total emission amounts in the region 100 km2around the flux tower were 1.2×105, 2.4×105, 2.1×105, 1.6×105kg for isoprene, 2.1×105, 2.1×105, 1.9×105, 2.0×105 kg for monoterpenes, respectively. Satellite retrieved formaldehyde (HCHO) vertical column densities (VCDs) showed strong seasonal variation similar to BVOCs, higher in summer and lower in winter during 2013—2016. Combined with using HCHO VCDs, good linear relationships were determined between isoprene, monoterpene and BVOC emissions (mg·m-2·h-1) and HCHO VCDs (cHCHO, molec·cm-1): isoprene emission F1=1.29×10-16cHCHO-0.77, monoterpene emissions F2=1.02×10-16cHCHO-0.21, and BVOC emissions F=2.31×10-16cHCHO-0.98. Thus, BVOC emissions were estimated by using the relationship of BVOCs-HCHO. The relative biases between the simulations using the relationship of BVOCs-HCHO and empirical model of BVOC emissions were less than 30% for isoprene, monoterpene and BVOC emission estimates, respectively. It provides a new method to obtain BVOC emissions on a regional scale and a useful reference for wide application of satellite data.
展开▼
