青藏高原植被产氧量及其对近地表大气氧含量的贡献率

Vegetation oxygen production and its contribution rate to near-surface atmospheric oxygen concentration on the Qinghai-Tibet Plateau

青藏高原极端缺氧环境对人畜健康有巨大影响,研究植被对青藏高原大气氧含量的贡献率,有助于厘清青藏高原大气氧含量变化对人畜健康的环境效应。目前关于青藏高原植被对大气氧含量贡献率的研究较少,且缺乏青藏高原植被产氧量对近地表大气氧含量贡献率的时空分布图。本文使用植被净初级生产力时空分布数据计算青藏高原的植被产氧量,并使用大气相对氧含量经验方程和理想气体状态方程计算青藏高原大气绝对氧含量,进而获得植被产氧量对近地表大气氧含量贡献率的时空分布。结果表明,青藏高原植被在2019年的全年总产氧量为1.0353×10^(9) t,其对青藏高原全域近地表大气氧含量贡献率的理论上限值平均为0.2788%/d,但存在巨大的时空差异(0.00~4.62%/d):时间上贡献率在年内呈“∧”型的变化特征,一年中贡献率最低值出现在12月,最高值出现在8月中旬;空间上贡献率呈现自东南向西北逐渐降低的分布格局,最低值分布在西北部,最高值分布在东南部。从各植被类型来看,单位面积的贡献率由高到低依次为森林、栽培植被、草原、沼泽湿地和灌丛。从海拔分布来看,单位面积的贡献率总体上呈现随海拔升高而逐渐降低的变化特征。本文首次制作了青藏高原植被产氧量对近地表大气氧含量贡献率的时空分布图,并揭示了青藏高原植被产氧量对近地表大气氧含量贡献率的理论上限值及其时空差异,可为青藏高原近地表大气氧含量变化及其对人畜健康的环境效应研究提供参考。

The extremely anoxic environment on the Qinghai-Tibet Plateau has a great impact on human and animal health.Studies of the contribution of vegetation to the atmospheric oxygen concentration on the Qinghai-Tibet Plateau are useful to clarify the environmental effects of changes in atmospheric oxygen concentration on human and animal health.Up to now,however,there are few such studies,and there is no spatio-temporal distribution map of the contribution rate.In this study,the vegetation net primary productivity was used to calculate the vegetation oxygen production on the Qinghai-Tibet Plateau,and the empirical equation of atmospheric relative oxygen concentration and the Ideal-Gas Equation were used to calculate the atmospheric absolute oxygen concentration,and then the ratio of the vegetation oxygen production and atmospheric absolute oxygen concentration was used to obtain the contribution rate.The results showed that the annual total vegetation oxygen production was 1.0353×10^(9) t on the Qinghai-Tibet Plateau in 2019.The theoretical upper limit value of the contribution rate of vegetation oxygen production to near-surface atmospheric oxygen concentration was 0.2788%/d on average over the plateau in 2019,but there were great differences across time and space(0.00%/d to 4.62%/d).In terms of temporal distribution,the change of contribution rate during the year is like a"∧"shape,the lowest value of the contribution rate in a year appeared during December through February of the next year,and the maximum value appeared in mid-August.In terms of spatial distribution,the contribution rate gradually decreased from southeast to northwest,with the lowest value in the northwest and the highest value in the southeast.From the perspective of vegetation types,the contribution rate per unit area from high to low was forest,cultivated vegetation,grassland,swamp wetland and shrub.From the perspective of altitude,the contribution rate per unit area gradually decreased with the increase of altitude.The spatial and temporal distribution map of the contribution rate was constructed in this paper,and the theoretical upper limit value of the contribution rate of vegetation oxygen production to atmospheric oxygen concentration on the plateau and its spatio-temporal variations were revealed.The results of this study can provide a reference for the studies on the changes of near-surface atmospheric oxygen concentration and its environmental effects on human and livestock on the Qinghai-Tibet Plateau.