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The Impact of Molecular Oxygen on Anion Composition in a Hazy Archean Earth Atmosphere.
Astrobiology ( IF 3.5 ) Pub Date : 2020-04-30 , DOI: 10.1089/ast.2019.2145
Melissa S Ugelow 1, 2, 3, 4 , Jennifer L Berry 1, 2 , Eleanor C Browne 1, 2 , Margaret A Tolbert 1, 2
Affiliation  

Atmospheric organic hazes are common in planetary bodies in our solar system and likely exoplanet atmospheres as well. In addition, geochemical data support the existence of an organic haze in the early Earth's atmosphere. Much of what is known about organic haze formation derives from studies of Saturn's moon Titan. It is believed that on Titan ions play an important role in haze formation. It is possible, by using Titan as an analog for the Archean Earth, to consider that an Archean haze could have formed by similar processes. Here, we examine the anion chemistry that occurs during laboratory simulations of early Earth haze formation and measure the composition of gaseous anions as a function of O2 mixing ratio. Gaseous anion composition and relative abundances are measured by an atmospheric pressure interface time-of-flight mass spectrometer and are compared to previous photochemical haze mass loading measurements. Numerous anions are observed spanning from mass-to-charge ratio 26 to 246, with a majority of the identified anions containing carbon, hydrogen, nitrogen, and/or oxygen. A shift in the anion composition occurs with increasing the precursor O2 mixing ratio. With 0–20 ppmv O2 in CH4/CO2/N2 mixtures, ions contain mostly organic nitrogen, with CNO being the most intense ion peak. As the precursor O2 is increased to 200 and 2000 ppmv, inorganic nitrogen ions become the dominant chemical group, with NO3 having the most intense ion signal. The clear shift in the ionic composition could be indicative of a modification to the gas-phase chemistry that occurs in the transition from an anoxic atmosphere to an oxygen-containing atmosphere, with potential astrobiological significance.

中文翻译:

分子氧对朦胧的太古代地球大气中阴离子组成的影响。

大气有机霾在我们太阳系的行星体中很常见,而且系外行星大气也很常见。此外,地球化学数据支持地球早期大气中有机雾的存在。关于有机霾形成的许多已知信息都来自对土星卫星土卫六的研究。据信,泰坦离子在雾度形成中起重要作用。通过使用土卫六作为太古代地球的类似物,有可能考虑到太古代雾霾可能是由相似的过程形成的。在这里,我们检查了在早期地球霾形成的实验室模拟过程中发生的阴离子化学,并测量了作为O 2的函数的气态阴离子的组成混合比例。通过大气压界面飞行时间质谱仪测量气态阴离子组成和相对丰度,并将其与先前的光化学雾度质量负载测量值进行比较。观察到许多阴离子,其质荷比为26至246,其中大多数已鉴定的阴离子包含碳,氢,氮和/或氧。随着前体O 2混合比的增加,阴离子组成发生变化。用0-20 ppmv的直径:2的CH 4 / CO 2 / N 2的混合物,离子主要含有有机氮,与CNO -是最强烈的离子峰。作为前体O 2增大到200个至2000 ppmv的,无机氮离子成为主导的化学基团,以NO 3 -具有最强烈的离子信号。离子组成的明显变化可能表明在从缺氧气氛向含氧气氛的转变中发生的气相化学变化,具有潜在的天体生物学意义。
更新日期:2020-04-30
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