The possible role of aerosols on stomatal conductivity for water vapour
The possible role of aerosols on stomatal conductivity for water vapour
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DOI：
10.1078/1439-1791-00062
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发表时间：
2001-01-01
影响因子：
3.8
通讯作者：
Goldbach, HE
中科院分区：
文献类型：
--
作者：
Burkhardt, J;Kaiser, H;Goldbach, HE
气孔导度控制水蒸气和二氧化碳的交换，被认为严格由气孔孔径决定。然而，水分输送过程可能会因叶表面吸湿性盐的沉积而改变。为此，我们对用亚微米 NaNO3 气溶胶处理前后的黑接骨木叶片进行了气体交换和气孔孔径的同步测量。叶片的气溶胶处理导致更高的蒸腾作用，在小孔径处尤其明显，导致最小叶片电导率提高了 45% 至 90%。气溶胶处理并没有增强接骨木叶子的二氧化碳吸收，因此在小气孔孔径处水分利用效率下降，由带有过滤膜的小水库组成的人造叶子在气溶胶处理后也显示出蒸发增加，这表明对接骨木叶子的发现的主要物理解释。由于层流子层厚度的变化和进入湍流元素“爆发”，盐沉积物对水的吸收和解吸被认为是一种可能的解释结果。在 50% 相对湿度 (RH) 下，在改变边界层电导的情况下，用显微镜观察了叶表面水的冷凝和蒸发的循环基本过程。因此，在液态水沿着盐溶液膜通过气孔输送后，吸湿颗粒可能充当中间短期储存或主要蒸发位点。动态模型描述了盐短期储存循环的影响。讨论了植物水关系可能产生的后果。
Stomatal conductance, which controls both the exchange of water vapour and CO, is thought to be strictly determined by stomatal aperture. However, water transport processes might be modified by deposition of hygroscopic salts on the leaf surface. For this reason, simultaneous measurements of gas exchange and stomatal aperture were performed on Sambucus nigra leaves before and after treatment with sub-micrometer NaNO3 aerosol.Aerosol treatment of the leaves led to higher transpiration, which was particularly pronounced at small apertures, leading to an enhancement of minimum leaf conductance between 45 and 90%. CO-uptake of Sambucus leaves was not enhanced by aerosol treatment, and consequently water use efficiency decreased at small stomatal apertures, Artificial leaves consisting of small water reservoirs tapped with filter membranes also showed an increase in evaporation after aerosol treatment, which indicates a mainly physical explanation for the findings with Sambucus leaves.Absorption and desorption of water by salt deposits due to changing thickness of the laminar sub-layer and entering turbulent elements -'bursts'- is suggested to be a possible explanation of the results. The cyclic elementary process, condensation and evaporation of water on the leaf surface, was observed microscopical ly under changing boundary layer conductance at 50% relative humidity (RH). Hygroscopic particles might therefore act as intermediate short-term storage or as primary evaporation sites after liquid water transport along films of salt solution through stomatal pores. A dynamic model describes the effects of cycles of short-term storage of salts. Possible consequences for plant water relations arc discussed.