Spatial Variation and Controlling Factors of H and O Isotopes in Lancang River Water, Southwest China

Kunhua Yang,Jinke Liu,Jie Zeng,Bin Liang,Guilin Han,Man Liu,Rui Qu

doi:10.3390/ijerph16244932

Abstract

Climate changes and other human activities have substantially altered the hydrological cycle with respect to elevation. In this study, longitudinal patterns in the stable isotopic composition (δ2H and δ18O) of Lancang River water, originating from the Qinghai–Tibetan Plateau, are presented, and several controlling factors in the wet season are hypothesized. Lancang River water δ2H (−145.2‰ to −60.7‰) and δ18O (−18.51‰ to −8.49‰) were low but close to those of the Global Meteoric Water Line. In the upper reaches of the river, δ2H decreased longitudinally, potentially due to groundwater inputs and melting ground ice in the headwater zone and to an increasing proportion of glacier meltwater with decreasing elevation. In the middle reaches of the river, δ2H values increased slowly moving downstream, likely due to shifts in precipitation inputs, as evidenced by the isotopic composition of tributaries to the main stream. In the lower reaches of the river, the isotopic composition was relatively invariant, potentially related to the presence of large artificial reservoirs that increase the water resident time. The results reveal different hydrological patterns along an alpine river in central Asia associated with both natural and anthropogenic processes. Understanding the degree and type of human interference with the water cycle in this region could improve water management and water security.

Highlights

Climate changes and human activities have impacted the hydrological cycles and local environment in the Qinghai–Tibetan Plateau, which is the largest and highest plateau in the world and is called the “Water Tower of Asia” and the “Third Pole” [1,2,3]
For Lancang River water, the δ2 H values ranged from −145.2% to −60.7%, and the mean value was −98.4%, whereas the δ18 O values ranged from −18.51% to −8.49%, and the mean value was
The results showed that the stable isotopic composition (δ2 H and δ18 O) of the Lancang River water was lower than that of the Yellow River, the Huai River, the Yangtze River, the Jiulong River, and the Mun River in Asia

Summary

Introduction

Climate changes and human activities have impacted the hydrological cycles and local environment in the Qinghai–Tibetan Plateau, which is the largest and highest plateau in the world and is called the “Water Tower of Asia” and the “Third Pole” [1,2,3]. The Lancang-Mekong river originates from the Qinghai–Tibetan Plateau and is one of ten largest Asian rivers [4]. Covering 24% of the total area of the Lancang-Mekong River basin, the Lancang River basin (LRB) has recorded the annual discharge of. Under the impacts of natural and anthropogenic activities, the water cycle and distribution of water resources have been altered in the LRB [6,7,8]. Human activities have factually exerted an influence on

Methods

Results

Conclusion