概括
清洁空气中的大气氧含量在20.946%的体积上保持了显著的稳定性. 自1910年以来的全球测量显示没有显著变化,保持在分析的误差范围内.
科学领域:
- 大气化学 大气化学
- 地球科学 地球科学 地球科学
背景情况:
- 大气中的氧气 (O2) 是地球大气的重要组成部分.
- 了解其度和稳定性对于气候和生命科学研究至关重要.
研究的目的:
- 为了确定全球清洁空气中大气氧的精确度.
- 评估自1910年以来大气氧水平的时间变化.
主要方法:
- 从50°N和60°S度之间的各种海洋地点收集空气样本.
- 干燥空气样本中氧含量的精确体积分析.
主要成果:
- 观察到一个恒定的大气氧值为20.946%的体积.
- 自1910年以来,没有检测到氧气度的统计学意义上的全球变化.
结论:
- 大气中的氧气度在研究区域中高度稳定.
- 长期监测表明,在测量不确定性范围内,全球氧气水平的变化很小或没有明显变化.
相关概念视频
Gas Exchange and Transport
Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them.
Physiological Control of Respiration
Introduction
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Treatment for Pulmonary Arterial Hypertension: Oxygen Therapy for Respiratory Failure
Oxygen therapy has emerged as a significant tool in enhancing the quality of life for patients suffering from pulmonary arterial hypertension (PAH). While this therapy has principally been studied on patients with significant hypoxemia, this therapeutic approach helps prevent potential organ damage and can be administered in the comfort of one's home.
Oxygen therapy is vital in increasing and maintaining blood oxygen levels in PAH patients. As a result, it aids in reducing fatigue, improving...
Oxygen therapy is vital in increasing and maintaining blood oxygen levels in PAH patients. As a result, it aids in reducing fatigue, improving...
Oxygen Transport in the Blood
Hemoglobin (Hb) is a crucial molecule in the human body, consisting of four polypeptide chains, each bound to an iron-containing heme group. This unique structure enables hemoglobin to bind to oxygen, with each molecule capable of combining with four molecules of oxygen, leading to rapid and reversible oxygen loading. When fully loaded with oxygen, it is called oxyhemoglobin, while hemoglobin that has released oxygen is called reduced hemoglobin or deoxyhemoglobin. As hemoglobin binds oxygen,...
Oxygen Delivering System I: Nasal Cannula and Face Mask
The human body requires oxygen to function, and when the natural process of respiration is hindered, external devices, including the following, are needed to help deliver this vital gas.
Nasal Cannula
A nasal cannula is a lightweight tube split at one end into two prongs and placed in the nostrils. It is typically used to deliver low to medium levels of oxygen.
Suggested flow rate: The suggested flow rate for a nasal cannula typically ranges between 1 and 6 L/min.
Oxygen percentage setting:...
Nasal Cannula
A nasal cannula is a lightweight tube split at one end into two prongs and placed in the nostrils. It is typically used to deliver low to medium levels of oxygen.
Suggested flow rate: The suggested flow rate for a nasal cannula typically ranges between 1 and 6 L/min.
Oxygen percentage setting:...
Oxygen Delivering System II: Venturi Mask and Transtracheal Oxygen
Oxygen therapy is a pivotal aspect of medical care, particularly for patients with respiratory ailments. Two prominent oxygen-delivering systems include the Venturi mask and the transtracheal oxygen catheter.
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...


