据了解，草本植物的生物源异戊二烯排放量通常低于树木。然而，研究发现，在草本莎草科植物中广泛存在异戊二烯排放，其对温度的响应强于目前的树木衍生模型。
研究人员测量并比较了生长在不同气候区域的莎草的异戊二烯排放量，所有莎草均显示出指数温度响应，Q10值范围为7.2-12，明显高于其他常见异戊二烯排放物的Q10值（约为3）。莎草独特的温度敏感性使它们成为一种隐藏的异戊二烯来源，在热浪中尤为明显，但在温和的天气中不容易被发现。例如，与预热波排放量相比，Carex praegracilis的异戊二烯排放量可增加320%，其峰值排放量超过100nmol m-2s-1。
在热浪期间，C.praegracilis的异戊二烯排放峰值可以与Lophostemon confertus相匹配，Lophostemon confertus是一种常见的行道树，由于其具有较高的生物量和排放能力，被认为是城市异戊二烯的主要来源。来自全球分布的莎草（包括城市景观中的莎草）的异戊二烯激增，可能导致热浪期间臭氧和气溶胶污染物达到峰值。
附：英文原文
Title: Heat waves may trigger unexpected surge in aerosol and ozone precursor emissions from sedges in urban landscapes
Author: Wang, Hui, Nagalingam, Sanjeevi, Welch, Allison M., Leong, Christopher, Czimczik, C. I., Guenther, Alex B.
Issue&Volume: 2024-10-21
Abstract: Biogenic isoprene emissions from herbaceous plants are generally lower than those from trees. However, our study finds widespread isoprene emission in herbaceous sedge plants, with a stronger temperature response surpassing current tree-derived models. We measured and compared isoprene emissions from sedges grown in different climatic zones, all showing an exponential temperature response with a Q10 range of 7.2 to 12, significantly higher than the Q10 of about 3 for other common isoprene emitters. The distinct temperature sensitivity of sedges makes them a hidden isoprene source, significant during heat waves but not easily detected in mild weather. For instance, isoprene emissions from Carex praegracilis can increase by 320% with a peak emission of over 100 nmol m-2 s-1 compared to preheat wave emissions. During heat waves, the peak isoprene emissions from C. praegracilis can match those from Lophostemon confertus, a commonly used street tree species which is considered the dominant urban isoprene source due to higher biomass and emission capacities. This surge in isoprene from globally distributed sedges, including those in urban landscapes, could contribute to peak ozone and aerosol pollutants during heat waves.
DOI: 10.1073/pnas.2412817121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2412817121