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Development of concentration-gradient FACE experimental facilitics.

浓度梯度 FACE 实验设施的开发。

基本信息

批准号：
07556108
负责人：
KURATA Kenji
金额：
$ 5.5万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

Free Air CO2 Enrichment (FACE) experiments have been attracting much attention as a research method on vegetation reaction to the elevated CO2 concentration in the atmosphere. This study aims at developing a new FACE system. The CO2 concentration within the FACE ring would not be kept at a uniform level, as existing or planned FACE experiments, but a constant gradient of the concentration would be created, so that vegetation reactions to different CO2 concentrations would be investigated within one FACE ring. Main results are as follows :l.A simulation study revealed that even if the wind blows from the opposite direction, a similar concentration gradient could be created by adjusting the CO2 release positions and strength.2.Wind tunnel experiments showed that effects of blowers, pipes, and jets from the CO2 release facilities (machine effects) would be large in the existing configurations, much less if we use pure CO2 gas and irrigation tubes for CO2 release, and even much less with the use of many thin vertical tubes.3.Using irrigation tubes and pure CO2 gas, a prototype concentration-gradient FACE system was developed. The shape of the ring was a long and narrow hexagon. CO2 release was feedforward-controlled based on the wind speed and direction. In most cases, a concentration gradient could be created, though not constant. Difficult cases to create a gradient were that of the low wind speed (less than 0.5m/s) and that in which the wind blew from the high concentration area to the low one.As a conclusion, a prototype of a concentration-gradient FACE system was successfully developed. However, there remained much room for improvement of the control method.

自由空气CO2浓度升高（FACE）实验作为研究植物对大气CO2浓度升高反应的一种方法受到了广泛关注。本研究旨在开发一种新的FACE系统。FACE环内的CO2浓度不会保持在一个统一的水平，现有的或计划的FACE实验，但一个恒定的浓度梯度将被创建，使植被对不同的CO2浓度的反应将在一个FACE环内进行调查。主要研究结果如下：1.模拟研究表明，即使风向相反，通过调整CO2释放位置和强度，也可以产生类似的浓度梯度。2.风洞实验表明，现有配置中，CO2释放设施的风机、管道和射流的影响（机器效应）很大，如果使用纯CO2气体和灌溉管进行CO2释放，则影响更小，如果使用许多细垂直管，则影响更小。戒指的形状是一个狭长的六边形。CO2释放是基于风速和风向的前馈控制。在大多数情况下，可以产生浓度梯度，尽管不是恒定的。在低风速（小于0.5m/s）和从高浓度区向低浓度区吹的情况下，难以产生浓度梯度。然而，控制方法仍有很大的改进余地。