正构烷烃氢同位素示踪海拔变化的研究进展

n-alkane δD tracing altitudinal variation:a review

全球大气降水的氢同位素组成存在海拔效应,这种海拔效应被继承在不同海拔高度生长的植物叶蜡中,并被很好地保存在地质记录中,这是氢同位素应用于古高度研究的基础。随着GC-TC-IRMS分析技术的发展,有机质氢分子的研究越来越深入,源于植物叶蜡的正构烷烃氢同位素在环境重建中的应用备受关注。本文概述了正构烷烃氢同位素示踪海拔变化的原理、影响因素(降水、植被类型、环境参数等)以及存在的问题等。正构烷烃氢同位素在示踪海拔高度变化中具有良好的应用前景,但是解释地质记录中正构烷烃氢同位素与定量重建海拔高度时,需要对一些影响氢同位素一高度关系的因素进行评估。

The altitude effect on the isotopic composition of precipitation （δ^18O and δD）, inherited by higher plant lipid along altitude transects, could be well documented in sediments and soils, which is the principle of paleoelevation reconstruction. With the development of GC-TC-IRMS, hydrogen isotope geochemistry of specific compounds in natural organic matter has been studied well and applied to trace paleoenvironmental change widely. This review gives a brief account about the principles, feasibility, influencing factors（ precipitation, plant life forms and environmental parameter） and existing problems of n-alkane δD tracing altitudinal variation. Although some achievements have been gained using this method to trace paleoelevation, environmental factors affecting the relationship between the isotopic composition and altitude should be evaluated when stable isotope-based paleoaltimetry is applied.