An examination of volcanic rocks has uncovered significant amounts of nitrogen compounds, likely formed by volcanic lightning. This process could have supplied the nitrogen necessary for the evolution and flourishing of early life forms.
Nitrogen is a crucial element in amino acids, the building blocks of proteins essential for all life. While nitrogen gas is abundant, plants cannot convert it into a usable form, unlike carbon dioxide.
Plants usually obtain nitrogen from bacteria that can convert nitrogen gas into compounds like nitrate. However, nitrogen-fixing bacteria did not exist when life first emerged. Therefore, there must have been a non-biological nitrogen source in the early stages. One potential origin is lightning from thunderstorms, a process demonstrated by the Miller-Urey experiment in the 1950s, showing that lightning could produce nitrogen compounds, including amino acids, in Earth's early atmosphere.
Now, a team led by Slimane Bekki at Sorbonne University in Paris has proposed another source: lightning occurring in ash clouds during certain volcanic eruptions. Analyzing volcanic deposits from Peru, Turkey, and Italy, the researchers found unexpectedly high levels of nitrates in some layers. Isotopic analysis revealed that these nitrates were atmospheric and not emitted by the volcanoes. The quantities were too substantial to be attributed to thunderstorm lightning, indicating they were likely generated by volcanic lightning.
Bekki notes that massive volcanic eruptions are known to produce abundant lightning, making volcanic lightning the most plausible explanation. Tamsin Mather at the University of Oxford supports this conclusion, stating that volcanic lightning might have contributed to the abundance of nitrogen compounds around volcanoes, potentially serving as a conducive environment for the origin of life.
This finding aligns with the notion that life could have originated around volcanoes. Jeffrey Bada at the Scripps Institution of Oceanography, who previously demonstrated that volcanic lightning can produce molecules like amino acids, sees this study as reinforcing the idea that volcanic lightning played a crucial role in the early stages of life's origin.
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