Foliage surface ozone deposition:: a role for surface moisture?
Foliage surface ozone deposition:: a role for surface moisture?
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DOI：
10.5194/bg-3-209-2006
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发表时间：
2006-01-01
期刊：
影响因子：
4.9
通讯作者：
Hari, P.
中科院分区：
文献类型：
--
作者：
Altimir, N.;Kolari, P.;Hari, P.
本文讨论了地面湿度在臭氧沉积到植物叶片中的潜在作用。我们研究了苏格兰松叶片在现场条件下在芬兰的SMEARII现场测量站。我们使用的组合数据从通量测量在拍摄（外壳）和冠层尺度（涡度协方差），信息从叶面湿度传感器，以及广泛的辅助测量，如辐射，降水，温度和相对湿度。环境条件被定义为下雨时潮湿或相对湿度高，以及在此类事件发生后的12小时内，这种情况在该北方场地很常见。从所测得的通量，我们估计臭氧电导率使用它作为臭氧去除表面汇或总沉积的强度的表达式。此外，我们估计气孔的贡献和剩余的沉积被解释和分析的非气孔sink.The合并的时间序列的测量结果表明，拍摄和冠层尺度的臭氧总沉积增强时，潮湿的条件下发生。平均而言，估计的气孔沉积占一半的测量去除在拍摄规模和冠层规模的三分之一。然而，在干燥条件下，估计气孔吸收预测的行为测得的沉积，但在潮湿的条件下，有分歧。估计的非气孔汇进行了分析，对几个环境因素和最清晰的连接被发现与环境相对湿度。在70%的相对湿度下，这种关系消失了，这一阈值与根据叶表面湿度测量在叶面收集表面水分的值相吻合。这表明，非气孔臭氧汇的树叶调制的表面膜。我们试图提取这种潜在的调制与估计的膜形成通过吸附的理论表达式。虽然这一程序可以预测的行为，非气孔汇，它意味着一个化学汇，是不是简单的臭氧分解负责。我们讨论了其他机制的存在，其相关性在臭氧的去除需要澄清，特别是：一个显着的夜间气孔孔径忽略的估计，和一个潜在的大化学汇提供的反应性生物有机挥发性化合物。
This paper addresses the potential role of surface wetness in ozone deposition to plant foliage. We studied Scots pine foliage in field conditions at the SMEARII field measurement station in Finland. We used a combination of data from flux measurement at the shoot ( enclosure) and canopy scale (eddy covariance), information from foliage surface wetness sensors, and a broad array of ancillary measurements such as radiation, precipitation, temperature, and relative humidity. Environmental conditions were defined as moist during rain or high relative humidity and during the subsequent twelve hours from such events, circumstances that were frequent at this boreal site. From the measured fluxes we estimated the ozone conductance using it as the expression of the strength of ozone removal surface sink or total deposition. Further, we estimated the stomatal contribution and the remaining deposition was interpreted and analysed as the non-stomatal sink.The combined time series of measurements showed that both shoot and canopy-scale ozone total deposition were enhanced when moist conditions occurred. On average, the estimated stomatal deposition accounted for half of the measured removal at the shoot scale and one third at the canopy scale. However, during dry conditions the estimated stomatal uptake predicted the behaviour of the measured deposition, but during moist conditions there was disagreement. The estimated non-stomatal sink was analysed against several environmental factors and the clearest connection was found with ambient relative humidity. The relationship disappeared under 70% relative humidity, a threshold that coincides with the value at which surface moisture gathers at the foliage surface according to the leaf surface wetness measurements. This suggests the non-stomatal ozone sink on the foliage to be modulated by the surface films. We attempted to extract such potential modulation with the estimated film formation via the theoretical expression of adsorption. Whereas this procedure could predict the behaviour of the non-stomatal sink, it implied a chemical sink that was not accountable as simple ozone decomposition. We discuss the existence of other mechanisms whose relevance in the removal of ozone needs to be clarified, in particular: a significant nocturnal stomatal aperture neglected in the estimations, and a potentially large chemical sink offered by reactive biogenic organic volatile compounds.