College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
Beijing Key Laboratory of Airborne Particulate Matter Monitoring Technology, Beijing Municipal Ecological and Environment Monitoring Center, Beijing, 100048, China.
Environ Pollut. 2024 Nov 15;361:124895. doi: 10.1016/j.envpol.2024.124895. Epub 2024 Sep 6.
Variability in biogenic volatile organic compound (BVOC) emissions across species and seasons poses challenges for accurate regional emission estimates and effective ozone (O) control policies. To address this issue, we conducted in-situ measurements of emission factors for six dominant tree species in Beijing across four seasons. Subsequently, we developed monthly dynamic standard emission factors (SER-MDs) to model monthly BVOC emissions and their impacts on O formation at citywide and district levels. Our observations revealed pronounced seasonal differences in the BVOC composition and emission rates, as well as their responsiveness to monthly average temperature. By introducing the SER-MDs, we estimated BVOC emissions from the dominant tree species in Beijing to be 38.2 Gg yr, with monoterpenes and isoprene contributing 49% and 11%, respectively. This calculation reduced the overestimation associated with constant standard emission factors by 31%-38% at district level. The estimates also revealed regional differences in plant compositions rather than simple feedback from regional temperature and photosynthetically active radiation periods. Under these conditions, the maximum monthly BVOC-induced O concentration occurred in August and ranged from 4 to 17 μg m across districts, with isoprene being the dominant contributor. Quercus mongolica and Populus tomentosa played significant roles in the formation of BVOC-induced O due to their strong isoprene emitting potential in July-August. These results indicate the necessity of introducing species-specific rhythms of BVOC emissions from dominant species in the development of urban BVOC emission inventories. This approach could inform the development of air pollution management policies that are consistent with the local vegetation composition and O pollution characteristics. For Beijing and other similar northern cities, reducing the use of tree species emitting substantial amounts of isoprene during periods of regional peak ambient O concentrations could constitute an effective nature-based solution for improving urban air quality in the future.
物种和季节间生物源挥发性有机化合物（BVOC）排放的可变性对准确的区域排放估算和有效的臭氧（O）控制政策构成了挑战。为了解决这个问题，我们对北京的六种主要树种在四个季节进行了现场排放因子测量。随后，我们开发了月度动态标准排放因子（SER-MD），以模拟全市和各区的月度 BVOC 排放及其对 O 形成的影响。我们的观测结果表明，BVOC 组成和排放率存在明显的季节性差异，以及它们对月平均温度的响应。通过引入 SER-MD，我们估计北京主要树种的 BVOC 排放量为 38.2 Gg yr，其中单萜和异戊二烯分别贡献 49%和 11%。与使用常数标准排放因子相比，这一计算在区级水平上降低了 31%-38%的高估。这些估计还揭示了植物组成的区域差异，而不仅仅是区域温度和光合有效辐射期的简单反馈。在这些条件下，最大的月度 BVOC 诱导的 O 浓度出现在 8 月，各区范围为 4-17μg m，其中异戊二烯是主要贡献者。由于 7-8 月具有强烈的异戊二烯排放潜力，蒙古栎和毛白杨在 BVOC 诱导的 O 形成中发挥了重要作用。这些结果表明，在开发城市 BVOC 排放清单时，有必要引入主要物种的 BVOC 排放的特定物种节律。这种方法可以为制定与当地植被组成和 O 污染特征一致的空气污染管理政策提供信息。对于北京和其他类似的北方城市，在区域环境 O 浓度峰值期间，减少使用大量排放异戊二烯的树种，可能是未来改善城市空气质量的一种有效的基于自然的解决方案。
