The chaotic flashes of lightning in the sky may have played a significant role in making essential elements like phosphorus more available for early life on Earth. Now, scientists have discovered geological evidence suggesting that lightning associated with volcanic eruptions may have also helped fix nitrogen, making it usable for biological processes. Since Earth was much more volcanically active in its early days, this finding implies that frequent volcanic activity may have been crucial for life’s emergence.
Researchers, led by geoscientist Adeline Aroskay of Sorbonne University, have found substantial amounts of nitrate in volcanic deposits from large explosive eruptions. This discovery supports the idea that volcanic lightning played a unique role in supplying essential elements for life’s emergence on Earth.
Before life existed, nitrogen was needed for life to begin. Nitrogen, a key nutrient for building proteins and other essential molecules, is abundant in Earth’s atmosphere, but it needs to be transformed into more reactive compounds like nitrates or ammonia for biological use.
While life now helps process nitrogen, lightning was likely crucial for kickstarting this process before life existed. Lightning can fix nitrogen, a concept established in 1784. Given that lightning is common during volcanic eruptions, scientists speculated that volcanic lightning might have jumpstarted the nitrogen cycle before life developed.
Experimental studies supported this idea, but evidence from geological records was scarce. Aroskay and her team examined ancient volcanic deposits from eruptions in Turkey and Peru, dating between 1.6 and 20 million years ago, and found significant concentrations of nitrates. These nitrates likely formed during volcanic eruptions, as indicated by their features and the absence of gradual deposition over time.
The researchers also found nitrates in younger volcanic deposits, further supporting their hypothesis. The presence of sulfur and chlorine in these deposits aligns with a volcanic origin, suggesting that volcanic lightning could fix nitrogen in quantities significant enough to contribute to life’s emergence.
This discovery not only sheds light on the role of volcanic lightning in Earth’s history but also provides a tool for interpreting nitrate deposits worldwide. It challenges previous assumptions about the origin of nitrate deposits and highlights the potential importance of volcanic activity in supplying essential elements for life.
