Intermediate-scale horizontal isoprene concentrations in the near-canopy forest atmosphere and implications for emission heterogeneity
Intermediate-scale horizontal isoprene concentrations in the near-canopy forest atmosphere and implications for emission heterogeneity
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DOI：
10.1073/pnas.1904154116
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发表时间：
2019-09-24
影响因子：
11.1
通讯作者：
Martin, Scot T.
中科院分区：
文献类型：
--
作者：
Batista, Carla E.;Ye, Jianhuai;Martin, Scot T.
挥发性有机化合物（VOCs）的排放、沉降和化学过程被认为受到热带森林内不同森林亚型之间数百米中等水平尺度下潜在的景观异质性的影响。然而，在这些尺度上的定量观测和科学认识仍然缺乏，这在很大程度上是由于历史上无法进入林冠以及缺乏合适的观测方法。在此，通过在2018年雨季的上午和下午早些时候，在亚马逊中部的高原和坡地森林上方水平飞行数百米的无人驾驶飞行器（UAV）进行采样，对近林冠大气中VOC浓度的水平异质性进行了研究。与萜烯浓度不同，高原森林上方近林冠大气中的异戊二烯浓度比坡地森林上方的高60%。一个受数据约束的梯度传输模型表明，这些森林亚型的异戊二烯排放差异为220%到330%，这与大多数当今的生物圈排放模型中所采用的0%差异（即均匀排放）形成对比。在中等水平尺度上对VOC浓度、排放和其他过程进行量化，对于理解VOCs在生态和地球系统中的作用以及在气候和空气质量模型中对其进行表征至关重要。
The emissions, deposition, and chemistry of volatile organic compounds (VOCs) are thought to be influenced by underlying landscape heterogeneity at intermediate horizontal scales of several hundred meters across different forest subtypes within a tropical forest. Quantitative observations and scientific understanding at these scales, however, remain lacking, in large part due to a historical absence of canopy access and suitable observational approaches. Herein, horizontal heterogeneity in VOC concentrations in the near-canopy atmosphere was examined by sampling from an unmanned aerial vehicle (UAV) flown horizontally several hundred meters over the plateau and slope forests in central Amazonia during the morning and early afternoon periods of the wet season of 2018. Unlike terpene concentrations, the isoprene concentrations in the near-canopy atmosphere over the plateau forest were 60% greater than those over the slope forest. A gradient transport model constrained by the data suggests that isoprene emissions differed by 220 to 330% from these forest subtypes, which is in contrast to a 0% difference implemented in most present-day biosphere emissions models (i.e., homogeneous emissions). Quantifying VOC concentrations, emissions, and other processes at intermediate horizontal scales is essential for understanding the ecological and Earth system roles of VOCs and representing them in climate and air quality models.