Abstract Ammonium sulfate (AS) particles of submicron size are a major component of inorganic aerosol, and are regarded as a long-range transboundary air pollutant in Asia. However, only a few studies have focused on the effects of submicron AS particles on plants. In the present study, we investigated the amount of submicron AS particles deposited on the leaf surface of komatsuna plants (Brassica rapa L. var. perviridis), and their effects on nocturnal leaf (gnight) and cuticular (gcut) conductance. The plants were grown for 23 days after sowing in a naturally lit phytotron at air temperature of 25.0 ± 1.0 °C/18.0 ± 1.0 °C (6:00–18:00/18:00–6:00) and relative air humidity of 70 ± 5%, and were artificially exposed to submicron AS particles at the 21st day after sowing. The exposure to submicron AS particles resulted in average daily atmospheric concentration of SO42− in PM2.5 inside the phytotron of 16.5 μg m−3. After the end of exposure, the plants were kept under light or dark conditions for 48 h in the phytotron. The amount of SO42− deposited on the leaf surface reduced over time, but did not significantly differ between the plants kept under light and dark conditions at 0, 6, 12, 18, 30, and 48 h after the end of exposure. An exposure to submicron AS particles with average daily atmospheric concentration of SO42− in PM2.5 inside the phytotron of 24.7 μg m−3 did not significantly affect the gcut of the plants. At 1.5 and 5 h after the end of exposure, the gnight was significantly higher in the submicron AS particle-exposed plants than in the non-exposed control plants. These results indicate that submicron AS particles deposited on the leaf surface enhance the nocturnal water consumption of komatsuna plants.

中文翻译：

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沉积在叶类蔬菜（Komatsuna, Brassica rapa L. var. perviridis ）叶表面的亚微米硫酸铵颗粒被叶吸收并增强夜间叶电导

摘要 亚微米尺寸的硫酸铵（AS）颗粒是无机气溶胶的主要成分，在亚洲被视为一种远距离跨界空气污染物。然而，只有少数研究关注亚微米 AS 颗粒对植物的影响。在本研究中，我们调查了沉积在 komatsuna 植物（Brassica rapa L. var. perviridis）叶表面上的亚微米 AS 颗粒的数量，以及它们对夜间叶 (gnight) 和表皮 (gcut) 电导的影响。在 25.0 ± 1.0 °C/18.0 ± 1.0 °C (6:00–18:00/18:00–6:00) 的空气温度和相对空气湿度下，将植物在自然光照的植物加速器中播种后生长 23 天70 ± 5%，并在播种后第 21 天人工暴露于亚微米 AS 颗粒。暴露于亚微米 AS 颗粒导致 phytotron 内 PM2.5 中 SO42− 的平均每日大气浓度为 16.5 μg m−3。暴露结束后，将植物在植物加速器中保持在光或暗条件下 48 小时。沉积在叶表面的 SO42− 量随时间减少，但在暴露结束后 0、6、12、18、30 和 48 小时保持在明暗条件下的植物之间没有显着差异。暴露于植物加速器内 PM2.5 中 SO42- 平均每日大气浓度为 24.7 μg m-3 的亚微米 AS 颗粒对植物的 gcut 没有显着影响。在暴露结束后 1.5 和 5 小时，亚微米 AS 颗粒暴露植物中的黑夜显着高于未暴露的对照植物。