Impact of climatic and environmental factors on δD of n-alkanes in the lake surface sediments of arid Tibet

Abstract

The hydrogen isotope composition (δD) of paleoclimatic archives is increasingly being used as a proxy for the reconstruction of Quaternary hydroclimatic variability, but the factors controlling δD in arid/semi-arid regions remain poorly understood. We compared the hydrogen isotope composition of individual n-alkanes in the surface sediments of a series of lakes and puddles in Tibet with local meteorological and hydrological data. The results show that the δD of short-chain and long-chain n-alkanes is sensitive to hydroclimatic conditions, with δDp being the predominant control. δD becomes less depleted where precipitation amount and humidity are lower or evaporation is stronger. In addition, temperature is a significant factor affecting δD of mid-chain n-alkanes, with a significant negative correlation, and the temperature in spring, autumn and winter is an important influence on it. We believe that the δD of long-chain n-alkanes is still a good paleohydrological index in the arid/semi-arid region; δD indices of mid-chain and short-chain n-alkanes are also useful, and more mechanism research is needed.