植物叶片氮同位素(δ^(15)N)指示大气氮沉降的探讨

A Discussion on the Deposition of Atmosphereic Nitrogen Indicated by the Nitrogen Isotopic Compositions(δ^(15)N) of the Plant Leafage

大气氮沉降的植物监测还未得到重视,尤其是氮同位素(δ15N)示踪技术的研究在国内基本还没有开展。大气中的氮能够被叶片吸收而成为植物生长的氮源使得叶片氮同位素可以用于指示大气氮沉降,但影响因素甚多其可靠性不确定。本文总结了大气氮沉降输入及其被叶片的吸收机制,进而探讨利用叶片氮同位素识别大气氮沉降存在的问题。此外,近年来的研究表明,苔藓氮同位素是指示和评价大气氮沉降的可靠工具,还探讨了苔藓氮同位素指示大气氮沉降的可行性和优势,目的在于促进从氮同位素的角度认识地表植物对大气氮的吸收,为深入开展植物氮同位素指示大气氮沉降的研究提供理论依据。

The application of plant to monitor the deposition of atmospheric nitrogen has been carried out in Europe and North America many years ago, but it has not been paid attention in China, especially, the application of nitrogen isotopic （δ^15N） tracing method into this research field has basically not been started in China. The δ^15N can be used to trace the deposition of atmospheric nitrogen because the plant leafage can uptake atmospheric nitrogen, though the reliability of this method is not yet understood due to the influence of many potential factors. This paper has reviewed the mechanisms of the deposition of atmospheric nitrogen and the input and absorption of plant leafage, and discussed some problems existed in the method of tracing the deposition of atmospheric nitrogen by using the δ^15N values of plant leafage. In addition, this paper has also discussed the special significance of the δ^15N of mosses for tracing and assessing the deposition of atmospheric nitrogen as it has been recognized as a useful and realistic tool for the researches in recent years. The purpose of this review is to deeply understand the mechanism of the plant uptake or adsorption of atmospheric substances in the point of nitrogen isotopes and to provide theoretical evidences for the research on tracing the deposition of atmospheric nitrogen by application of nitrogen isotopes of plants.