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The Origin of Life on Earth: Emergence Amid Volcanic Lightning

The speculation surrounding the tumultuous crackling in the sky suggests a significant role in liberating elements like phosphorus during ancient times on Earth. Recently, researchers have unearthed geological evidence indicating that lightning discharges linked to volcanic activities may have facilitated nitrogen fixation, thereby making it accessible for biological processes. Given Earth’s presumed heightened volcanic activity in its early stages, this revelation implies that extensive volcanism could have been pivotal in the genesis of life as we currently understand it.

Geoscientist Adeline Aroskay from Sorbonne University led a study that unveiled substantial nitrate quantities within volcanic deposits resulting from massive explosive eruptions. These findings underscore the unique contribution of subaerial explosive eruptions to energy-demanding processes, crucial for providing the fundamental components necessary for life’s inception on Earth.

In the distant past, Earth’s transformative processes amalgamated various elements to kickstart life, with nitrogen being a vital requirement for constructing essential biological compounds such as proteins, amino acids, and nucleic acids. While nitrogen is abundant on Earth, its atmospheric form as molecular nitrogen (N2) is inaccessible to biology; hence, nitrogen atoms must be dissociated and combined with other elements to form reactive compounds like nitrates or ammonia.

In the absence of life, non-biological mechanisms were essential for initiating nitrogen fixation, with electrical discharges like lightning playing a key role in this process. Given the prevalence of lightning during volcanic eruptions, scientists hypothesized that volcanic lightning might have jumpstarted the nitrogen cycle before the advent of life.

Experimental investigations supported the plausibility of this phenomenon, yet solid geological evidence confirming fixed nitrogen due to volcanic lightning was scarce until Aroskay’s team made their discovery. By analyzing samples from ancient volcanic deposits in Turkey and Peru, dating back 1.6 to 20 million years, the researchers identified significant nitrate concentrations formed predominantly during volcanic eruptions.

Moreover, the team detected nitrates in younger volcanic deposits from less explosive eruptions, indicating a consistent presence of nitrates irrespective of the deposit’s age. This instantaneous deposition of compounds into volcanic rock, rather than gradual processes over extended periods, suggests a substantial role for volcanic lightning in nitrogen fixation.

The concentrations of sulfur and chlorine in these deposits align with a volcanic origin, further supporting the hypothesis that volcanic lightning can effectively fix nitrogen in quantities substantial enough to influence the emergence of life. This discovery not only provides a geological record of N-fixation by volcanic lightning but also offers insights into interpreting nitrate deposits globally, potentially reshaping our understanding of essential processes in Earth’s history.

The study, shedding light on the unique role of subaerial explosive eruptions in supplying crucial components for life’s genesis, has been detailed in a publication.