Discoveries suggest that Earth may have had freshwater just 600 million years after its formation, a relatively short time in geological terms. This indicates that freshwater could have been circulating actively on Earth much earlier than previously believed. Previous research has shown evidence of a robust water cycle dating back to at least 3.2 billion years ago, involving rain and evaporation from land to atmosphere and back again. Even if a freshwater cycle existed 4 billion years ago, it does not necessarily imply the presence of life on Earth at that time. However, it does provide a crucial component for life to develop. The oldest known evidence of life on Earth comes from fossilized microbial mats in Australia dating back 3.5 billion years.
Cycles of evaporation and rain play a role in altering the chemical composition of water molecules. The process involves the lighter oxygen-16 evaporating faster than the heavier oxygen-18 when water evaporates from the ocean’s surface, leaving the salt behind. This lighter water may then precipitate over land and evaporate again, leading to a concentration of oxygen-16 in freshwater compared to seawater.
2024-06-03 10:00:00
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