Factors contributing to spatial\u2013temporal variations of observed oxygen concentration over the Qinghai-Tibetan Plateau

Peijun Shi,Yanqiang Chen,Yonggui Ma,Gangfeng Zhang,Peng Gong,Jidong Wu,Shunlin Liang,Zhi Chen,Tao Ye,Haiping Tang,Deyong Yu,Jing Yang,Jing’Ai Wang

doi:10.1038/s41598-021-96741-6

Abstract

Oxygen (O2) is the most abundant molecule in the atmosphere after nitrogen. Previous studies have documented that oxygen concentration remains nearly constant (20.946%) at all altitudes. Here we show for the first time that oxygen concentration varies significantly from earlier consensus and shows strong spatial and seasonal differences. Field observations on the Qinghai-Tibetan Plateau (QTP) indicate oxygen concentration of 19.94–20.66% (2018, n = 80), 19.98–20.78% (2019, n = 166) and 19.97–20.73% (2020, n = 176), all statistically different from earlier reports (p < 0.001) and are lower than the nearly constant. The mean oxygen concentration in summer (20.47%) is 0.31% higher than that of winter (20.16%) (n = 53) at identical locations in 2019, sampled in the Qilian Mountains, northwest QTP. We used LMG (The Lindeman, Merenda and Gold) method to estimate the relative contributions of altitude, air temperature and vegetation index (Fractional Vegetation Cover, FVC and Leaf Area Index, LAI) to oxygen concentration, which are 47%, 32% and 3% (FVC, R2 = 82%); 45%, 30% and 7% (LAI, R2 = 82%), respectively. These findings provide a new perspective for in-depth understanding on population risk in high altitude regions in the context of global climate change, to ensure the health and safety of residents and tourists in high altitude regions and promoting the stability, prosperity and sustainable development of high-altitude regions worldwide.

Highlights

Oxygen (O2) is the most abundant molecule in the atmosphere after nitrogen
The oxygen concentrations sampled in the margin areas of Qinghai-Tibetan Plateau (QTP)
In the study by Shi et al (2019), the main factors affecting oxygen concentration on the QTP included altitude, 500 hPa air temperature and fractional vegetation covers (FVCs). 500 hPa air temperature was negatively correlated with oxygen c oncentration[19], but our results show a positive correlation between near-surface air temperature and oxygen concentration

Summary

Introduction

Oxygen (O2) is the most abundant molecule in the atmosphere after nitrogen. Previous studies have documented that oxygen concentration remains nearly constant (20.946%) at all altitudes. For the first time, we systematically investigate the spatial–temporal variation of near-surface oxygen concentration and quantify the relative contributions of altitude, temperature, and vegetation to it. We conduct field observations on the QTP and its vicinities and collect 487 samples, with altitude varied from 645 to 5238 m above sea level.

Results

Conclusion